UXL Encyclopedia of Diseases and Disorders, Volume 5: Sh-Z

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V OLUME 5

U•X•L Encyclopedia of Diseases and Disorders

U•X•L Encyclopedia of Diseases and Disorders VOLUME 5: Sh-Z

Rebecca J. Frey Larry I. Lutwick, Editor

U•X•L Encyclopedia of Diseases and Disorders Rebecca J. Frey, Author Larry I. Lutwick, Editor Project Editor: Kristine Krapp Editorial: Debra Kirby, Kathleen Edgar, Elizabeth Manar, Kimberley McGrath Rights Acquisition and Management: Robyn Young Composition: Evi Abou-El-Seoud, Mary Beth Trimper Manufacturing: Rita Wimberley Product Manager: Julia Furtaw

For product information and technology assistance, contact us at Gale Customer Support, 1-800-877-4253. For permission to use material from this text or product, submit all requests online at www.cengage.com/permissions. Further permissions questions can be e-mailed to [email protected] Cover photographs: Images courtesy of Dreamstime and Getty. While every effort has been made to ensure the reliability of the information presented in this publication, Gale, a part of Cengage Learning, does not guarantee the accuracy of the data contained herein. Gale accepts no payment for listing; and inclusion in the publication of any organization, agency, institution, publication, service, or individual does not imply endorsement of the editors or publisher. Errors brought to the attention of the publisher and verified to the satisfaction of the publisher will be corrected in future editions.

Art Director: Jennifer Wahi Product Design: CMB Design Partners © 2009 Gale, Cengage Learning ALL RIGHTS RESERVED. No part of this work covered by the copyright herein may be reproduced, transmitted, stored, or used in any form or by any means graphic, electronic, or mechanical, including but not limited to photocopying, recording, scanning, digitizing, taping, Web distribution, information networks, or information storage and retrieval systems, except as permitted under Section 107 or 108 of the 1976 United States Copyright Act, without the prior written permission of the publisher.

LIBRARY OF CONGRESS CATALOGING-IN-PUBLICATION DATA

Frey, Rebecca J. UXL encyclopedia of diseases and disorders / Rebecca J. Frey, author ; Larry I. Lutwick, editor. p. cm. – Includes bibliographical references and index. ISBN 978-1-4144-3065-2 (set : hardcover) – ISBN 978-1-4144-3066-9 (v. 1 : hardcover) – ISBN 978-1-4144-3067-6 (v. 2 : hardcover) – ISBN 978-1-41443068-3 (v. 3 : hardcover) – ISBN 978-1-4144-3069-0 (v. 4 : hardcover) – ISBN 978-1-4144-3070-6 (v. 5 : hardcover) 1. Diseases–Encyclopedias. I. Lutwick, Larry I. II. Title. III. Title: Encyclopedia of diseases and disorders. RB155.5.F74 2009 616.003–dc22

2008047947

Gale 27500 Drake Rd. Farmington Hills, MI, 48331-3535 ISBN-13: 978-1-4144-3065-2 (set) ISBN-13: 978-1-4144-3066-9 (vol. ISBN-13: 978-1-4144-3067-6 (vol. ISBN-13: 978-1-4144-3068-3 (vol. ISBN-13: 978-1-4144-3069-0 (vol. ISBN-13: 978-1-4144-3070-6 (vol.

1) 2) 3) 4) 5)

ISBN-10: ISBN-10: ISBN-10: ISBN-10: ISBN-10: ISBN-10:

1-4144-3065-5 (set) 1-4144-3066-3 (vol. 1) 1-4144-3067-1 (vol. 2) 1-4144-3068-X (vol. 3) 1-4144-3069-8 (vol. 4) 1-4144-3070-1 (vol. 5)

This title is also available as an e-book. ISBN-13: 978-1-4144-3074-4 (set) ISBN-10: 1-4144-3074-4 (set) Contact your Gale sales representative for ordering information.

Printed in China 1 2 3 4 5 6 7 13 12 11 10 09

Table of Contents

VOLUME 1

List of Entries by Disease Type xiii Preface xvii Reader’s Guide xix Words to Know xxiii Achondroplasia 1 Acne 6 AIDS 12 Alcoholism 19 Allergies 26 Alzheimer Disease 32 Anaphylaxis 39 Anemias 45 Anorexia 46 Anthrax 51 Appendicitis 58 Arthritis 63 Asperger Syndrome 64 Asthma 70 Astigmatism 77 Attention-deficit Hyperactivity Disorder 82 Autism 89 Autism Spectrum Disorders 95 v

Table of Contents

Avian Influenza 96 Bipolar Disorder 103 Brain Tumors 110 Breast Cancer 117 Bronchitis 124 Bulimia 130 Burns and Scalds 135 Cancer 143 Canker Sores 144 Carbon Monoxide Poisoning 149 Cataracts 155 Celiac Disease 161 Cerebral Palsy 166 Chickenpox 173 Child Abuse 179 Childhood Obesity 185 Chlamydia 192 Chronic Fatigue Syndrome 196 Chronic Obstructive Pulmonary Disease 202 Cleft Lip and Palate 203 Clubfoot 208 Where to Learn More Ixiii List of Organizations Ixvii Index Ixxi

VOLUME 2

List of Entries by Disease Type xiii Preface xvii Reader’s Guide xix Words to Know xxiii Cold Sore 215 Colorectal Cancer 220 Common Cold 227 vi

UXL Encyclopedia of Diseases and Disorders

Table of Contents

Concussion 232 Congenital Heart Disease 239 Conjoined Twins 246 Conjunctivitis 252 Coronary Artery Disease 257 Creutzfeldt-Jakob Disease 263 Crohn Disease 270 Cystic Fibrosis 276 Depression 283 Dermatitis 290 Developmental Disability 297 Diabetes 303 Down Syndrome 310 Dyslexia 317 Ear Infection 325 Eating Disorders 332 Ebola and Marburg Hemorrhagic Fevers 333 Eczema 338 Edwards Syndrome 344 Emerging Diseases 350 Emphysema 351 Encephalitis 359 Fetal Alcohol Syndrome 367 Fibromyalgia 373 Food Poisoning 378 Fractures 384 Fragile X Syndrome 391 Frostbite 396 Gangrene 403 Gastroesophageal Reflux Disease 410 Genetic Disorders 416 Genital Herpes 417 Gigantism 422 Glaucoma 428 Gonorrhea 435


vii

Table of Contents

Graves Disease 440 Gulf War Syndrome 445 Where to Learn More lxiii List of Organizations Ixvii Index Ixxi VOLUME 3

List of Entries by Disease Type xiii Preface xvii Reader’s Guide xix Words to Know xxiii Hand-Foot-and-Mouth Disease 451 Hantavirus Infection 456 Hashimoto Disease 461 Hay Fever 466 Headache 472 Hearing Loss 478 Heart Attack 485 Heart Diseases 492 Heart Failure 492 Heat Cramps 499 Heat Exhaustion 503 Heat Stroke 508 Hemophilia 515 Hepatitis A 521 Hepatitis B 527 Hepatitis C 533 Hives 539 Hodgkin Disease 544 HPV Infection 550 Huntington Disease 556 Hutchinson-Gilford Syndrome 562 Hydrocephalus 566 Hypercholesterolemia 572 viii


Table of Contents

Hyperopia 578 Hypertension 583 Hypoglycemia 590 Hypothermia 596 Hypothyroidism 603 Infectious Diseases 611 Infectious Mononucleosis 612 Influenza 617 Iron-Deficiency Anemia 624 Irritable Bowel Syndrome 630 Klinefelter Syndrome 637 Lactose Intolerance 643 Laryngitis 648 Lead Poisoning 652 Learning Disorders 658 Leukemia 659 Lice Infestation 665 Lung Cancer 670 Lupus 677 Lyme Disease 683 Lymphoma 690 Where to Learn More Ixiii List of Organizations Ixvii Index Ixxi VOLUME 4

List of Entries by Disease Type xiii Preface xvii Reader’s Guide xix Words to Know xxiii Malaria 697 Marfan Syndrome 704 Marijuana Use 711


ix

Table of Contents

Measles 717 Meningitis 723 Mosquito-Borne Diseases 730 Motion Sickness 731 Multiple Sclerosis 737 Muscular Dystrophy 743 Myopia 750 Narcolepsy 757 Necrotizing fasciitis 763 Obesity 769 Obsessive-Compulsive Disorder 776 Osteoarthritis 783 Osteoporosis 790 Panic Disorder 797 Parasitic Diseases 802 Parkinson Disease 803 Patau Syndrome 810 Periodontal Disease 815 Phenylketonuria 821 Plague 826 Pneumonia 832 Polio 839 Postpartum Depression 846 Posttraumatic Stress Disorder 851 Prematurity 858 Prostate Cancer 865 Rabies 873 Restless Legs Syndrome 880 Reye Syndrome 884 Rheumatic Fever 889 Rheumatoid Arthritis 894 Rubella 901 Scarlet Fever 907 Schizophrenia 912 Scoliosis 920 Seasonal Affective Disorder 926 x


Table of Contents

Seizure Disorder 932 Severe Acute Respiratory Syndrome 938 Sexually Transmitted Diseases 944 Where to Learn More Ixiii List of Organizations Ixvii Index Ixxi VOLUME 5

List of Entries by Disease Type xiii Preface xvii Reader’s Guide xix Words to Know xxiii Shaken Baby Syndrome 947 Sickle Cell Anemia 951 Sjögren Syndrome 958 Skin Cancer 963 Sleep Apnea 970 Sleep Disorders 977 Smallpox 977 Smoke Inhalation 984 Smoking 990 Sore Throat 997 Spina Bifida 1002 Spinal Cord Injury 1008 Sprains and Strains 1014 Staph Infection 1020 Steroid Use 1027 Strabismus 1033 Strep Throat 1039 Stress 1043 Stroke 1050 Sudden Infant Death Syndrome 1057 Sunburn 1063 Syphilis 1068 UXL Encyclopedia of Diseases and Disorders

xi

Table of Contents

Tendinitis 1075 Tetanus 1081 Thalassemia 1086 Tick-borne Diseases 1092 Tonsillitis 1093 Tooth Decay 1098 Tourette Syndrome 1104 Toxic Shock Syndrome 1110 Toxoplasmosis 1116 Triple X Syndrome 1122 Tuberculosis 1126 Turner Syndrome 1133 Ulcerative Colitis 1141 Ulcers 1147 Urinary Tract Infection 1153 Vision Disorders 1161 Vitiligo 1162 Warts 1169 West Nile Virus Infection 1174 Whiplash 1180 Whooping Cough 1185 Xeroderma Pigmentosum 1191 Zoonoses 1199 Where to Learn More Ixiii List of Organizations Ixvii Index Ixxi

xii


List of Entries by Type of Disease

Genetic Achondroplasia Celiac disease Conjoined twins Cystic fibrosis Down syndrome Edwards syndrome Fragile X Hashimoto disease Hemophilia Huntington disease Hutchinson-Gilford syndrome Klinefelter syndrome Marfan syndrome Muscular dystrophy Patau syndrome Phenylketonuria Sickle cell anemia Thalassemia Triple X syndrome Turner syndrome Xeroderma pigmentosum Infectious Bacteria Anthrax Chlamydia

Gonorrhea Necrotizing fasciitis Periodontal disease Plague Rheumatic fever Scarlet fever Tetanus Tooth decay Toxic shock syndrome Tuberculosis Urinary tract infection Whooping cough Virus AIDS Avian influenza Chickenpox Cold sore Common cold Ebola and Marburg hemorrhagic fevers Encephalitis Genital herpes Hand-foot-and-mouth disease Hantavirus infection Hepatitis A Hepatitis B Hepatitis C

HPV infection Infectious mononucleosis Influenza Measles Lyme disease Polio Rabies Rubella Severe acute respiratory syndrome Smallpox Staph infection Strep throat Syphilis Warts West Nile virus infection Bacteria and/or Virus Ear infection Meningitis Tonsillitis Parasite Lice infestation Malaria Toxoplasmosis Injury Burns and scalds Concussion xiii


Fractures Frostbite Heat cramps Heat exhaustion Heat stroke Lead poisoning Shaken baby syndrome Smoke inhalation Spinal cord injury Sprains and strains Sunburn Tendinitis Whiplash Multiple Acne Alcoholism Allergies Alzheimer disease Anemias Anorexia Arthritis Asthma Brain tumors Bronchitis Bulimia Cancer Cataracts Child abuse Childhood obesity Chronic obstructive pulmonary disease Conjunctivitis Coronary artery disease Creutzfeldt-Jakob disease Depression Dermatitis Developmental disability Eating disorders Emphysema Food poisoning Gangrene xiv

Gastroesophageal reflux disease Gigantism Glaucoma Headache Hearing loss Heart attack Heart diseases Heart failure Hives Hydrocephalus Hypercholesterolemia Hyperopia Hypertension Hypoglycemia Hypothermia Hypothyroidism Iron-deficiency anemia Lactose intolerance Laryngitis Learning disorders Lung cancer Marijuana use Motion sickness Myopia Obesity Obsessive-compulsive disorder Osteoarthritis Osteoporosis Panic disorder Pneumonia Postpartum depression Posttraumatic stress disorder Prematurity Scoliosis Seasonal affective disorder Seizure disorder Skin cancer Sleep apnea

Sleep disorders Smoking Sore throat Steroid use Stress Stroke Ulcers Vision disorders Other Anaphylaxis Appendicitis Carbon monoxide poisoning Fetal alcohol syndrome Unknown Asperger syndrome Astigmatism Attention-deficit hyperactivity disorder Autism Autism spectrum disorders Bipolar disorder Breast cancer Canker sores Chronic fatigue syndrome Cleft lip and palate Clubfoot Colorectal cancer Congenital heart disease Crohn disease Diabetes Dyslexia Eczema Fibromyalgia Graves disease Gulf War syndrome Hay fever Hodgkin disease Irritable bowel syndrome UXL Encyclopedia of Diseases and Disorders


Leukemia Lupus Lymphoma Multiple sclerosis Narcolepsy Parkinson disease Prostate cancer


Restless legs syndrome Reye syndrome Rheumatoid arthritis Schizophrenia Sjögren syndrome Spina bifida Strabismus

Sudden infant death syndrome Tourette syndrome Ulcerative colitis Vitiligo

xv

Please Read—Important Information

The U•X•L Encyclopedia of Diseases and Disorders is a medical reference product designed to inform and educate readers about a wide variety of health issues related to diseases and injuries. Cengage Gale believes the product to be comprehensive, but not necessarily definitive. It is intended to supplement, not replace, consultation with a physician or other healthcare professional. While Cengage Gale has made substantial efforts to provide information that is accurate, comprehensive, and up-to-date, Cengage Gale makes no representations or warranties of any kind, including with limitation, warranties of merchantability or fitness for a particular purpose, nor does it guarantee the accuracy, comprehensiveness, or timeliness of the information contained in this product. Readers should be aware that the universe of medical knowledge is constantly growing and changing, and that differences of medical opinion exist among authorities. They are also advised to seek professional diagnosis and treatment for any medical condition, and to discuss information obtained from this book with their healthcare provider.

xvi

Preface

“Only the curious will learn and only the resolute overcome the obstacles to learning. The quest quotient has always excited me more than the intelligence quotient.” - Eugene S. Wilson (1968) Eugene “Bill” Wilson (1900–1981) was Dean of Admission at Amherst College. He was known for his sense of humor and his genuine interest in the welfare of each student. This quote attributed to him, published in Reader’s Digest in April of 1968, summarizes education to me, that is, it is learning itself that is most exciting, not the knowledge per se that one gathers from it. It is truly the lifelong ride of learning, not the final destination, that makes us what we are. As both a college and medical student and now as a medical educator, I have personally seen numerous, and far too many, individuals whose goal is not learning for learning sake but rather come to me, my brilliant lecturer-wife Suzanne, or any other instructor with the unfortunately all-to-common request of “what do I have to know to pass the exam?” Would you consult a physician who only knows what he needed to pass the test? Would you hire a tax preparer that could pass the qualifying exam but knew no more? Would you allow your child to drive an automobile with only the knowledge acquired in the Driver’s Education manual? The answer to all these questions should be a resounding no. Whether or not you are using this reference text because you are thinking about, or even planning, a career in a medical field, remember that books such as this one are limited in scope. That is, the information here should be a starting place for anyone who has the true desire to xvii

Preface

understand the topic. Each entry includes further references for some additional reading, and you are encouraged to follow up on the topic. Additionally, remember that textbooks provide a snapshot of the information available at that time. The half-life of truth can be short because new information appears. Currency, that is, being current, is vital in understanding issues. As the editor of this text, I wish each of its readers success in your future plans. “Earning a living,” so to speak, implies working to live. I hope that you will have the opportunity, as I do, to truly live to work. A career can more than a job, more than just a way of paying the bills. By living to work, the work is not really work in the true sense but rather it is what you do, it is part of your essence. As it is said, “Those who love their jobs do not work a day in their lives.” Remember life is all about the ride, not the destination. Those who feel that “he who dies with the most toys wins” have missed all the scenery. Keep your eyes wide open. Larry I. Lutwick, editor

xviii


Reader’s Guide

The U*X*L Encyclopedia of Diseases and Disorders is devoted to helping younger students and general readers understand the nature of diseases and disorders of every type, including communicable diseases, genetic disorders, common conditions, and injuries. This book is a collection of more than 200 entries on diseases, from avian flu, to cystic fibrosis, to warts. The entries start with a definition section and highlight the basic facts of the disease to explain the causes, symptoms, and treatments. Other sections give a more detailed description, talk about demographics, and discuss the future of the disease, for example, if any new treatments are under development or if the disease is becoming more or less prevalent. The U*X*L Encyclopedia of Diseases and Disorders uses everyday language when possible, and explains medical terms as they arise. Terms are also defined in Words to Know sidebars within entries, and a collected Words to Know section is included in the beginning of each book. Entries are designed to instruct, challenge, and excite less-experienced students, while providing a solid foundation and reference for students already captivated by medicine.

Essential features of U*X*L Encyclopedia of Diseases and Disorders This book contains 192 main entries and 18 overview entries. Overview entries are short descriptions of a group of disorders, like learning disorders. Each overview entry points the reader to specific entries that are part of that group. All articles in the book are meant to be understandable by anyone with a curiosity about diseases. xix

Reader’s Guide

Entries are arranged alphabetically throughout the volumes. See also references at the end of entries alert the readers to related entries across the three-volume set that may provide additional resources or insights each topic. A List of Entries by Disease Type section allows readers to quickly identify diseases by types, such as infectious or genetic. Each entry contains a Words to Know section to help students understand important or complex terms. A general compendium of these terms is also included in the book. A Where To Learn More section lists helpful print material and Web sites, while a comprehensive General Index guides the reader to topics and terms mentioned in the book. Photos and color illustrations are included throughout the book where they might stimulate interest or understanding.

Advisors and Contributors While compiling this volume, the editors relied on the expertise and contributions of Rebecca J. Frey, medical writer. Frey is a freelance writer and editor who has contributed to Gale/Cengage health and medical publications since 1997. A member of the American Medical Writers Association, she completed her B.A. at Mount Holyoke College and her Ph.D. at Yale University. She lives in New Haven, Connecticut. The editor would like to thank his contacts at Gale, Kristine Krapp and Debra Kirby, for their invaluable assistance in the technical aspects of putting this collection together. Personally, he is indebted to his wife Suzanne for her love and encouragement during this project and to their children Rachel, Zachary, Arielle, and Nina for setting such examples of how to pursue goals in life based on happiness potential, not financial reward. To their grandchildren Talora and Zev, they hope that the information in this collection serves to spark intellectual curiosity so you two will follow your hearts and minds in making this a better world. Larry I. Lutwick, editor Brooklyn, New York

December 2008 Larry I. Lutwick MD is an academically trained Infectious Diseases physician who is Director of the Infectious Disease Section at the Brooklyn Campus of the Veterans Affairs New York Harbor Health Care xx


Reader’s Guide

System. He is also Professor of Medicine at the State University of New York, Downstate Medical School, also in Brooklyn, New York. Dr. Lutwick has authored or coauthored more than 100 scientific papers, 26 book chapters, and is the editor of several books, including (along with his wife Suzanne) Beyond Anthrax: The Weaponization of Infectious Diseases. He is also the creator of the medical educational tool, “Bug of the Month,” in which the protagonist, a politically incorrect Infectious Disease physician named Dr. Schmeckman, solves medical mysteries.


xxi

Words to Know

Abscess: A collection of pus that has formed in a body cavity or hollow. Abstinence: 1.) Complete stopping of alcohol consumption. 2.) Not

having sexual intercourse with anyone. Acclimation: The process of adjusting to seasonal climate changes or to a

new climate. Accommodation: The medical term for the eye's ability to change its

focus automatically for viewing objects at different distances. Acetaldehyde: A colorless liquid chemical that is produced when the

body begins to digest alcohol. A chemical that causes hangovers after heavy drinking, it also contributes to fetal alcohol syndrome. Achilles tendon: The tendon that connects the calf muscle to the back

of the heel. Tendinitis in the Achilles tendon is common in sports that involve running and jumping. Acromegaly: A condition in which a person’s body produces too much

growth hormone in adult life. Actinic keratosis: A patch of thickened or scaly skin caused by sun expo-

sure. It is not itself a form of skin cancer but may develop progressively into a skin cancer. Acupuncture: A form of alternative medicine in which very fine needles

are inserted into the skin at specific points on the body for pain relief. xxiii

Words to Know

Acute: Referring to a disease or symptom that is severe or quickly

worsens. Addiction: A chronic disease characterized by compulsive drug use and

by long-lasting chemical changes in the brain. Adipose tissue: Fatty tissue. Adrenaline: A hormone that can be used in medicine to open the

breathing passages in patients with severe tissue swelling. It is also called epinephrine. Affective disorder: A type of mental disorder characterized by disturbed

emotions and feelings rather than problems with memory, thinking, or learning. After drop: A term that doctors use to refer to lowering of the body’s

core temperature that continues while the person is being rewarmed. Against-the-rule astigmatism: A type of astigmatism in which the eye

sees horizontal lines more clearly than vertical lines. Agoraphobia: An irrational fear of venturing outside the home or into

open spaces, so strong that a large number of activities outside the home are limited or avoided altogether. Agoraphobia is often associated with panic attacks. Allergen: A substance that causes an allergic reaction in individuals who

are sensitive to it. Alveoli (singular, alveolus): Tiny air sacs in the lungs where carbon

dioxide in the blood is exchanged for oxygen from the air. Amaranth: An herb that produces seeds used as grain in India, Nepal,

Mexico, and parts of South America. Amblyopia: Dimness of sight in one eye without any change in the

structure of the eye. It is also known as lazy eye. Amenorrhea: Stopping of normal menstrual periods. Amino acids: A group of twenty compounds that are the building blocks

of proteins in humans and other animals. Ammonia: A chemical produced during the breakdown of protein in the

body. It is usually converted in the liver to another chemical called urea and then discharged from the body in the urine. Amputation: Surgical removal of a limb. xxiv


Words to Know

Anabolic: Referring to tissue building. Anabolic steroids build up

muscle and bone tissue. Anaerobic: Capable of living in the absence of oxygen. Anaphylaxis: A severe allergic reaction to a trigger (most commonly a

food, medication, insect sting, or latex) that involves most major body systems. Androgen: The generic term for the group of male sex hormones pro-

duced by the body. Anemia: A condition in which a person’s blood does not have enough

volume, enough red blood cells, or enough hemoglobin in the cells to keep body tissues supplied with oxygen. Aneurysm: A weak or thin spot on the wall of an artery. Angina: Chest pain caused by an inadequate supply of blood to the

heart muscle. Angioedema: The medical term for the swelling of tissues can be part of

an allergic reaction. Antibody: A protein found in blood that is specific to a particular for-

eign substance, which may be an allergen or a disease organism. The antibody identifies that antigen and neutralizes it. Anticipation: A condition in which the symptoms of a genetic disorder

appear earlier and earlier in each successive generation. Antidepressant: A type of drug given to treat eating disorders as well as

mood disorders like anxiety and depression. Antiemetic: A type of drug given to control nausea and vomiting. Anti-psychotics: A group of drugs used to treat schizophrenia. The older

anti-psychotic drugs are also called neuroleptics. Antispasmodic: A type of drug given to relieve the cramping of the

intestines or other muscles. Aorta: The large artery that carries blood away from the heart to be dis-

tributed to the rest of the body. Aortic dissection: A tear in the wall of the aorta that allows blood to seep

between the layers of tissue that form the artery and push the layers apart. Aphthous ulcer: The medical term for canker sore. Apnea: Temporary stopping of breathing.


xxv

Words to Know

Appendectomy: Surgical removal of the appendix. Arboviruses: A family of viruses spread by blood-sucking insects. Area postrema: The part of the brain stem that controls vomiting. Arson: The intentional setting of a fire in a building or other property.

Arson is a criminal act in the United States. Arthroscopy: The use of a small device called an arthroscope to look

inside and diagnose or treat an arthritic joint. Aseptic meningitis: A term that is sometimes used for meningitis that is

not caused by bacteria. Aspie: An informal name for a person with Asperger syndrome. Aspiration: The entry of food, liquids, or other foreign substances into

the lungs during the breathing process. Astigmatism: A vision problem caused by irregularities in the shape of

the cornea or the lens of the eye. Asymptomatic: Having no symptoms. Atherosclerosis: Stiffening or hardening of the arteries caused by the

formation of plaques within the arteries. Atopic disease: Any allergic disease that affects parts of the body that are

not in direct contact with the allergen. Asthma, eczema, and hay fever are all atopic diseases. Atopy: The medical term for an allergic hypersensitivity that affects parts

of the body that are not in direct contact with an allergen. Hay fever, eczema, and asthma are all atopic diseases. Atrium (plural, atria): One of the two upper chambers of the heart. Audiologist: A health care professional who is specially trained to eval-

uate hearing disorders. Auditory: Pertaining to the sense of hearing. Aura: A symptom that precedes migraine headaches in some people.

The person may see flashing or zigzag lights, or have other visual disturbances. Autism: A developmental disorder that appears by three years of age and

is characterized by limited communication skills, difficulties in communicating with others, and difficulties forming relationships. Autoantibody: An antibody formed in reaction against the tissues of the

individual producing it. xxvi


Words to Know

Autoimmune disease: A disease in which the body’s immune system

attacks its own cells and tissues. Autoimmune disorder: A disorder characterized or caused by autoanti-

bodies that attack the cells or organs of the organism producing them. Automatic behavior: Activity that a person with narcolepsy can carry

out while partially awake but is not conscious of at the time and cannot recall afterward. Autopsy: The examination of a body after death to determine the cause

of death. Avian: Pertaining to birds.

B cell: A type of white blood cell produced in the bone marrow that

makes antibodies against viruses. Babesiosis: A malaria-like disease that can be transmitted by ticks. Baby blues: An informal term for the temporary sad feelings some

mothers feel for a week or so after childbirth. It is less serious than postpartum depression and usually goes away by itself. Bacteremia: The presence of bacteria in the bloodstream. Bedsore: A type of wet gangrene that develops when a bedridden person

cannot turn over to relieve pressure on soft tissue caused by the weight of the body. Bedsores are sometimes called pressure ulcers. Benign: Not cancerous. Benign prostatic hypertrophy (BPH): A noncancerous condition in

which the swelling of the prostate gland squeezes the urethra and causes difficulty in urination. Beta blockers: A group of drugs given to treat abnormal heart rhythms

and reduce the risk of aortic dilation in MFS patients. Bile: A yellow-green fluid secreted by the liver that aids in the digestion

of fats. Binge: An episode of eating in which a person consumes a larger amount

of food within a limited period of time than most people would eat in similar circumstances. UXL Encyclopedia of Diseases and Disorders

xxvii

Words to Know

Binge drinking: A period of heavy drinking that lasts for two days or

longer. Biofeedback: An alternative treatment for headaches (and other condi-

tions) that consists of teaching patients to consciously control their blood pressure, muscle tension, temperature, and other body processes. Biological therapy: An approach to cancer treatment that is intended to

strengthen the patient’s own immune system rather than attack the cancer cells directly. Biomarker: A substance produced by the body that is distinctive to a

particular disease and can be used to identify its presence or track its progress. Bioterrorism: The use of disease agents to frighten or attack civilians. Biphasic reaction: A recurrence of the symptoms of anaphylaxis about

six to eight hours after the first episode. Blackout: Alcohol-related memory loss. Bladder: A hollow organ in the lower abdomen that collects urine from

the kidneys and stores it prior to urination. Blunt: A cigar that has been cut open and refilled with marijuana. Body mass index: BMI. An indirect measurement of the amount of

body fat. The BMI of adults is calculated in English measurements by multiplying a person’s weight in pounds by 703.1, and dividing that number by the person’s height in inches squared. Bone marrow: The soft spongy tissue inside the long bones of the body

where blood cells are formed. Bong: A water pipe used to smoke marijuana. Botulism: A rare but potentially fatal paralytic illness caused by a bac-

terial toxin in contaminated food. Brain stem: The lowest part of the brain that connects directly to the

spinal cord. It controls such basic life functions as breathing, blood pressure, and heart beat. Bronchiole: A very small thin-walled air passage in the lungs that

branches off from a bronchus. Bronchodilator: A type of drug that opens up the bronchi, increasing

airflow and relieving wheezing and other asthma symptoms. xxviii


Words to Know

Bronchoscope: A flexible lighted tube that can be inserted into the pas-

sages leading to the lungs for examination or treatment. Bronchus (plural, bronchi): One of the two major divisions of the airway

that lead into the right and left lungs. Bubo: A swollen lymph node in the neck, armpit, or groin area.

Café-au-lait spots: Brownish-white birthmarks that appear as part of a

nervous system disorder that can cause scoliosis in some children. Café au lait is the French expression for “coffee with milk” and describes the color of the spots. Capsule: The outermost layer of the lens of the eye. Carcinoma: The medical term for any type of cancer that arises from the

skin or from the tissues that line body cavities. Carcinoma in situ: A cancer that has not spread or is still in one location

in the body. Cardiac arrest: Heart attack; a condition in which the circulation of the

blood stops abruptly because the heart stops beating. Carditis: Inflammation of the heart. Caries: The medical name for tooth cavities. Carrier: A person who is infected with a disease and can spread it to

others but who has no symptoms of the disease. Cartilage: A type of dense connective tissue that serves to cushion bones

within joints. Case management: An approach to healthcare based on personalized

services to patients. Cataplexy: Sudden loss of tone in the voluntary muscles. Catatonia: A condition in which a person sits motionless for long per-

iods of time and does not respond to others. Catheter: A thin tube inserted into the urethra to drain urine from the

bladder. Cerebellum: The part of the brain at the lower back of the head just

above the brain stem. UXL Encyclopedia of Diseases and Disorders

xxix

Words to Know

Cerebral cortex: The part of the brain that controls thinking, memory,

paying attention, decision making, and using language. Cervix: The neck or lowermost part of a woman’s uterus that opens into

the vagina. Chancre: A painless ulcer that forms on the skin during the early stage of

syphilis. Chelation therapy: A form of treatment to reduce overly high levels

of iron (or other metals) in the body by giving the patient a chemical that allows the body to get rid of the excess metal in urine or stool. Chiropractic: A form of alternative medicine that treats disorders of

the joints and muscles by adjusting the patient’s spine or other joints. Chlamydia: A sexually transmitted disease caused by a bacterium that is

a common cause of eye infections. Cholesterol: A fatty substance produced naturally by the body that

is found in the membranes of all body cells and is carried by the blood. Chorea: A general term for movement disorders marked by loss of coor-

dination and involuntary motions of the head and limbs. Chorionic villus sampling (CVS): A prenatal test that involves taking a

small sample of the placenta, the organ that forms inside the uterus during pregnancy and supplies the baby with oxygen and nutrients carried by the blood. Chronic: Referring to a disease or symptom that goes on for a long time,

tends to recur, and usually gets worse slowly. Circadian rhythm: The medical name for the daily sleep/wake cycle in

humans. Cirrhosis: Disruption of normal liver function by the formation of scar

tissue and nodules in the liver. It is most commonly caused by alcoholism or hepatitis C. Clap: A slang term for gonorrhea. Clinically isolated syndrome (CIS): A term applied to patients who have

had one episode of illness that suggests they have a disease but do not yet meet the full criteria for diagnosis. xxx


Words to Know

Closed-head injury: An injury to the head in which the skull is not

broken or penetrated. Clubbing: Thickening of the tips of the fingers or toes. Coagulation cascade: The complex process in which platelets, coagula-

tion factors, and other chemicals in the blood interact to form a clot when a blood vessel is injured. Coagulation factors: Proteins in blood plasma involved in the chain of

chemical reactions leading to the formation of blood clots. They are also called clotting factors. Cochlea: A snail-shaped fluid-filled chamber in the inner ear. Cognitive: Related to thinking, memory, and other conscious intellec-

tual activities or processes. Cognitive-behavioral therapy (CBT): An approach to therapy that aims

at changing distorted thinking patterns, beliefs, and behaviors in order to change the patient’s feelings. Colon: The part of the large intestine that extends from the cecum to

the rectum. Colonization: The process by which bacteria form colonies in or on the

bodies of humans and other animals. Comedo (plural, comedones): The medical term for a whitehead or

blackhead. Community-acquired: Referring to a disease that a person gets in the

course of ordinary activities rather than in a hospital or clinic. Compression fracture: A fracture caused by the collapse of a vertebra in

the spinal column, usually caused either by trauma or by weakening of the bone in osteoporosis. Compulsion: A repeated behavior or mental act carried out to control or

neutralize obsessions. Conditioning: The process of becoming physically fit through a program

of diet, exercise, and rest. Congenital: Present at birth. Congenital rubella syndrome (CRS): A group of birth defects that may

affect a baby born to a mother who had rubella during the first three months of pregnancy. UXL Encyclopedia of Diseases and Disorders

xxxi

Words to Know

Conjunctiva (plural, conjunctivae): The clear membrane that covers the

white part of the eyeball and lines the eyelids. Contact dermatitis: Inflammation of the skin caused by direct contact

with an allergen or irritating substance, such as poison ivy, certain dyes, or certain metals. Contracture: Shortening or tightening of the muscles surrounding cer-

tain joints that limits the movement of the joints. Cooley’s anemia: Another name for the most severe form of beta-

thalassemia. Coprolalia: The medical term for uncontrollable cursing or use of dirty

words. Cornea: The transparent front part of the eye where light enters the

eye. Cortex: The part of the lens underneath the capsule. Cortisol: A hormone produced by the adrenal glands near the kidneys in

response to stress. Co-sleeping: Allowing a baby to sleep in the same bed as its parents. It

is also called bed sharing. Crabs: A slang term for pubic lice. Cretinism: A form of hypothyroidism found in some newborns. Cryotherapy: The use of extreme cold to destroy cancerous tumors or

other diseased tissue. It is also called cryosurgery. Cushing syndrome: A disorder caused by the excess secretion of cortisol

by the pituitary gland. Cutaneous: Pertaining to the skin. Cyanosis: A blue discoloration of the lips, inside of the mouth, and nail

beds caused by lack of oxygen in the blood vessels near the skin surface. Cycling: Using steroids in periods of several weeks or months (a time

cycle) separated by short rest phases of not using the drugs. Cyclothymia: A mild form of bipolar disorder. Cyst: A capsule or sac containing a parasite in its resting stage. Cystitis: The medical term for an infection of the urinary bladder. xxxii


Words to Know

Dander: Tiny skin, feather, or fur particles from household pets that

cause allergic reactions in some people. Debridement: The medical term for the surgical removal of dead or

damaged soft tissue. Decibel (dB): A unit of measurement for expressing the relative intensity

of sounds. Decoding: In education, the ability to associate letters of the alphabet

with sounds. Degenerative disorder: A type of disorder in which a person gradually

loses certain abilities that he or she had acquired at an earlier age. Dehydration: Loss of water from the body. It may be caused by fever,

vomiting, diarrhea, or excessive sweating. Delirium: A suddenly developing mental disturbance characterized by

confused thinking, difficulty focusing attention, and disorientation. Delirium tremens: A severe physical reaction to withdrawal from alcohol

in which the person hallucinates and has unstable blood pressure and breathing patterns. Delusion: In medicine, a false belief that a person holds to despite evi-

dence or proof that it is false. Dementia: Loss of memory and other mental functions related to

thinking or problem-solving. Dengue: A tropical disease caused by a virus similar to the virus that

causes West Nile infection. It is also spread by mosquitoes. Dentin: A firm tissue that lies between the enamel and the pulp of a

tooth. Dermabrasion: Technique for making acne scars less noticeable by

removing the top layer of skin with a rapidly rotating wire brush or a sandy material. Dermatitis: The medical term for inflammation of the skin. Dermatographism: A type of hives produced by scratching or stroking

the skin. Dermatologist: A doctor who specializes in diagnosing and treating dis-

eases and disorders of the skin. UXL Encyclopedia of Diseases and Disorders

xxxiii

Words to Know

Dermatology: The branch of medicine that deals with skin problems

and disorders. Dermis: The lower layer of skin that contains blood vessels, sweat

glands, and hair follicles. Desensitization: A form of treatment for allergies that involves a series of

shots containing the allergen to reduce the patient's sensitivity to that particular trigger. Desensitization is also called immunotherapy. Detoxification: A process or treatment program for clearing an alco-

holic's body of alcohol. It usually includes medications to help manage the physical symptoms of withdrawal. Diagnosis of exclusion: A diagnosis that the doctor arrives at by ruling

out other diseases one by one rather than making the diagnosis on the basis of laboratory tests or imaging studies, or other test results. Dialysis: A process in which the blood of a patient with kidney failure is

cleansed of the body’s waste products by being pumped through a machine that filters the blood and then returns it to the body. Diaphragm: A sheet of muscle extending across the bottom of the rib

cage that separates the chest from the abdomen. Diastolic blood pressure: The blood pressure when the heart is resting

between beats. Directly observed therapy (DOT): Treatment in which nurses or health

care workers administer medications to patients in a clinic or doctor’s office to make sure that the patients take the drugs correctly. Disseminated gonococcal infection (DGI): A complication of gonorrhea

in which the disease organisms get into the bloodstream and cause arthritis, eye disease, skin rashes, or inflammation of the heart valves. Diuretic: A type of drug that increases the body’s production of urine. Dopamine: A chemical produced in the brain that is needed to produce

smooth and controlled voluntary movements. Dronabinol: A medication that contains synthetic THC, given to relieve

nausea and improve appetite in AIDS and cancer patients. Duodenum: The first part of the small intestine. Dysthymia: A mood disorder characterized by a long-term low-key

depression. Dystrophin: A protein found in muscle whose absence or defectiveness is

one of the causes of muscular dystrophy. xxxiv


Words to Know

Echinacea: A plant native to the eastern United States that is thought by

some to be a useful cold remedy. It is also known as purple coneflower. Ectopic pregnancy: A pregnancy in which the fertilized egg starts

growing outside the uterus, usually in the abdomen or in the tubes leading to the uterus. Effusion: The medical term for an abnormal collection of fluid in a body

cavity. Ehrlichiosis: A tick-borne disease found primarily in dogs that can also

be transmitted to humans. Electroconvulsive therapy (ECT): A form of treatment for severe depres-

sion that consists of passing a low dose of electric current through the patient’s brain under anesthesia. Electrolytes: Minerals that are essential for proper body functioning.

They include potassium, sodium, calcium, and magnesium. Embolus: The medical term for a clot that forms in the heart and travels

through the circulatory system to another part of the body. Embryo: The medical term for an unborn baby from the time of concep-

tion to the end of its first eight weeks of life. Emerging infectious disease (EID): A disease that has become more

widespread around the world in the last twenty years and is expected to become more common in the future. Enamel: The hard, smooth, white outer surface of a tooth. Encephalitis: Inflammation of the brain. Endemic: A term applied to a disease that maintains itself in a particular

area without reinforcement from outside sources of infection. Endocarditis: An inflammation of the tissues lining the inside of the

heart and its valves. Endocrine system: A system of small organs located throughout the

body that regulate metabolism, growth and puberty, tissue function, and mood. The thyroid gland is part of the endocrine system. Endocrinologist: A doctor who specializes in disorders of the pancreas

and other glands. Endophthalmitis: Inflammation of the tissues inside the eyeball. UXL Encyclopedia of Diseases and Disorders

xxxv

Words to Know

Epidemiology: The branch of medicine that deals with the frequency,

distribution, and control of disease in a population. Epidermis: The outermost layer of the skin. Eradication: The complete elimination of a disease. Erythema chronicum migrans (EM): The medical name for the distinc-

tive rash that is often seen in early-stage Lyme disease. Esophagus: The muscular tube that carries food downward from the

lower throat to the stomach. Essential hypertension: High blood pressure that is not caused by med-

ications, pregnancy, or another disease. Estrogen: A female hormone produced in the ovaries. Euphoria: An exaggerated feeling of well-being. Eustachian tube: The passageway that connects the middle ear with the

upper throat. Eustress: A term that is sometimes used to refer to positive stress. Euthanasia: Sometimes called mercy killing; the act of killing a hope-

lessly ill human or pet in a painless way. Eversion injury: An ankle injury caused when the foot is suddenly forced

to roll outward. Exophthalmos: Abnormal protrusion of the eyeballs. Exotoxin: A toxin secreted by a bacterium or other disease organism into

the body tissues of an infected individual.

Failure to thrive: A term used to describe children whose present weight

or rate of weight gain is markedly lower than that of other children of their age and sex. Fascia: A sheet of connective tissue that covers and binds together

the muscles, glands, blood vessels, and internal organs of the body. Fasting hypoglycemia: A type of hypoglycemia in people without dia-

betes that is caused by hormone deficiencies, medication side effects, or tumors rather than by reaction to a sugar-rich meal.

xxxvi


Words to Know

Fatal familial insomnia (FFI): A very rare inherited disease in which the

person dies of sleeplessness. Fatigue: A feeling of weariness or tiredness after work, exercise, or emo-

tional stress. Female athlete triad: A group of three symptoms that often occur

together in female athletes: amenorrhea, osteoporosis, and disordered eating. Fibro fog: A term that has been coined to describe memory loss and dif-

ficulty concentrating in fibromyalgia patients. Fibroblast: A type of cell that provides structure during the healing of a

broken bone or other wound. Fibrosis: The medical term for the formation of scar tissue. Filaggrin: A protein in the skin that is defective or lacking in some

patients with eczema. Filovirus: The category of viruses that includes Ebola and Marburg

viruses. Filoviruses look like long pieces of thread under a microscope. Fistula: An abnormal tunnel or passage that forms between one part of

the intestine and another or between the intestine and the body surface. Fixation: The medical term for holding a broken bone in its correct

position to speed healing and prevent further injury. Flare: A return or worsening of symptoms. Flashback: A temporary reliving of a traumatic event. Folic acid: A form of vitamin B9 that helps to prevent spina bifida. Follicle: Small canal in the skin surrounding the root of a hair. Forchheimer spots: Tiny reddish spots that appear inside the mouth of a

patient with scarlet fever. Fragility fracture: A fracture that occurs as a result of a fall from standing

height or less. A person with healthy bones would not suffer a broken bone falling from a standing position. Fulminant: Referring to any disease or condition that strikes rapidly and

is severe to the point of being life-threatening.


xxxvii

Words to Know

Fundoplication: A surgical procedure in which the upper part of the sto-

mach is wrapped around the lower end of the esophagus to prevent stomach acid from rising into the esophagus.

Gait: A person’s characteristic pattern of walking. Gangrene: Decay and death of soft tissue due to loss of blood supply. Gastric: Related to the stomach. Gastroenterologist: A doctor who specializes in diagnosing and treating

diseases of the digestive system. Gene therapy: An approach to treating disease by inserting healthy genes

into a person’s genetic material or by inactivating defective genes. Genotype: The genetic makeup of a cell or organism. Germ cell: A cell involved in reproduction. In humans the germ cells are

the sperm (male) and egg (female). Unlike other cells in the body, germ cells contain only half the standard number of chromosomes. Gestational: Pertaining to pregnancy. Gestational age: An infant’s age at birth counting from the date of the

mother’s last menstrual period. Gigantism: Excessive production of growth hormone in children who

are still growing. Gingivitis: The medical term for inflammation of the gums. Glial cells: Cells in brain tissue that hold nerve cells in place, supply

them with oxygen and nutrients, and remove dead nerve cells. Glioma: A type of brain tumor that starts in the glial cells. Glucagon: A hormone secreted by the pancreas that raises blood sugar

levels by signaling the liver to convert glycogen to glucose. Glucometer: A small blood testing device that can be used to screen for

diabetes or used at home to monitor blood sugar levels. Gluten: A protein found in certain grains, particularly wheat, barley, and

rye. Glycogen: A form of glucose that is stored in the liver as an energy

reserve. xxxviii


Words to Know

Goiter: A swelling in the neck caused by an enlarged thyroid gland. Gonococcus: The bacterium that causes gonorrhea. Gout: A disorder of the large toe or other joints caused by deposits of

uric acid crystals in the affected joint. Group A streptococcus: A sphere-shaped bacterium that grows in long

chains and causes strep throat as well as scarlet fever and some forms of tonsillitis. Growth plate: A cartilage plate in the long bones of children where the

lengthening of bone takes place. Guarding: Stiffening of the muscles in response to a doctor’s touch. Gumma: A soft noncancerous growth of tissue found in patients with

tertiary syphilis.

Hair cells: Special cells in the cochlea that convert the movement of the

fluid inside the cochlea into electrical signals that travel to the brain via the auditory nerve. Hallucination: Perceiving something that is not really there. Hallucina-

tions can affect any of the five senses. Hard palate: A thin bony plate located in the front portion of the roof of

the mouth. Hashish: A concentrated resin prepared from the flowering tops of

hemp plants. Hashitoxicosis: A temporary phase in some patients with Hashimoto

disease in which there is too much thyroid hormone in the blood due to leakage from damaged and dying cells in the thyroid gland. Heat illness: A general term for heat-related disorders, ranging from heat

cramps (the mildest) to heat stroke (the most serious). Heelstick: A method for taking a sample of blood from a newborn by

pricking the baby’s heel with a needle and collecting a drop or two of blood on special filter paper. Hematocrit: The proportion of blood volume occupied by red blood

cells. UXL Encyclopedia of Diseases and Disorders

xxxix

Words to Know

Hematologist: A doctor who specializes in diagnosing and treating dis-

orders of the blood. Hemoglobin: An iron-containing protein in red blood cells that carries

oxygen from the lungs to the rest of the body. Hepatitis: A general term for inflammation of the liver. It can be caused

by toxic substances or alcohol as well as infections. Herpetiform: Resembling blisters caused by herpes. Hiatal hernia: A condition in which the upper part of the stomach

bulges upward into the chest cavity through a weak spot in the diaphragm. Highly active antiretroviral therapy (HAART): An individualized combi-

nation of three or more antiretroviral drugs used to treat patients with HIV infection. It is sometimes called a drug cocktail. Histamine: A chemical contained in mast cells that is released during an

allergic reaction. Hit: A single intake of marijuana smoke from a joint or bong. Holoprosencephaly: A disorder in which a baby’s forebrain does not

develop normally. The infant’s brain fails to divide into two cerebral hemispheres; this failure in turn leads to facial deformities and abnormal brain structure and function. Hormone: Any chemical produced by living cells that stimulates organs

or tissues in parts of the body at some distance from where it is produced. Hospice: A facility or program for meeting the spiritual as well as the

physical needs of people who are terminally ill. Host: An organism that is infected by a virus, bacterium, or parasite. Hydrocephalus: Abnormal accumulation of cerebrospinal fluid within

the cavities inside the brain. Hydrops fetalis: The most severe form of alpha thalassemia, leading to

death before or shortly after birth. Hyperammonemia: Overly high levels of ammonia in the blood; it often

indicates liver damage. Hyperarousal: A state of increased emotional tension and anxiety, often

including jitteriness and being easily startled. xl


Words to Know

Hyperbaric oxygen (HBO): Oxygen that is delivered to a patient in

a special chamber at two to three times normal atmospheric pressure. Hyperextension: Stretching or moving a part of the body beyond its

normal range of motion. Hyperopia: The medical term for farsightedness. Hyperthyroidism: A disease condition in which the thyroid gland pro-

duces too much thyroid hormone. Hypnagogic: Referring to the period of partial alertness on the boundary

between sleeping and waking. Hypocretin: A protein produced by certain brain cells that promotes

wakefulness and helps to regulate the sleep/wake cycle. It is also known as orexin. Hypomania: A less severe form of mania that does not interfere with

normal functioning. Hypothalamus: The part of the brain that controls body temperature,

hunger, thirst, and response to stress. Hypothyroidism: A disease condition in which the thyroid gland does

not produce enough thyroid hormone. Hypotonia: The medical term for poor muscle tone.

Ideal weight: Weight corresponding to the lowest death rate for indivi-

duals of a specific height, gender, and age. Identical twins: Twins that develop from a single fertilized egg that

divides to form two separate embryos. Idiopathic: The medical term for a disorder whose cause is unknown. Immunoglobulin E (IgE): An antibody in blood that activates mast cells

during an allergic reaction. Incest: Sexual activity between closely related persons, often within the

immediate family. Indolent: The medical term for a tumor or disease that grows or

develops slowly. UXL Encyclopedia of Diseases and Disorders

xli

Words to Know

Infestation: A condition in which a parasite develops and multiplies on

the body of its host rather than inside the body. Inhalation: The part of the breathing cycle in which a person takes in air

from the outside. Insulin: A hormone secreted by the pancreas that causes the cells in the

liver, muscle and fatty tissues of the body to use the glucose carried in the bloodstream after a meal. Intractable: Referring to a disease or disorder that cannot be easily

treated or cured. Inversion injury: A type of ankle injury caused when the foot is suddenly

forced to roll inward. Involuntary: Not under the control of the will. Iris: The circular colored structure at the front of the eyeball that con-

trols the amount of light entering the eye by changing the size of the pupil. Irradiation: A technique for treating raw meat and poultry with gamma

rays, x rays, or electron beams to destroy disease organisms. Ischemia: Loss of blood supply to a tissue or organ resulting from the

blockage of a blood vessel.

Jaundice: A yellowish discoloration of the skin and whites of the eyes

caused by increased levels of bile pigments from the liver in the patient’s blood. Jet lag: A sleep disorder or disturbance in the sleep/wake cycle related to

rapid travel across time zones. Joint: A cigarette made with marijuana instead of tobacco.

Karyotype: A photomicrograph of the chromosomes in a single human

cell. Making a karyotype is one way to test for genetic disorders. xlii


Words to Know

Keratoconus: An eye disorder in which the tissue of the cornea grows

thinner over time. Koplik spots: Small reddish spots with white centers seen on the tissues

lining the cheeks in early-stage measles. Kuru: A fatal brain disease related to CJD that was epidemic in Papua

New Guinea in the mid-1950s. Kuru is thought to have been spread by cannibalism.

Lactase: An enzyme that breaks down lactose into simpler sugars during

the process of digestion. Lactose: A complex sugar found in milk and other dairy products. It is

sometimes called milk sugar. Lactose intolerance: An inability to digest lactose, the form of sugar

found in milk and milk products. Laparoscope: A fiberoptic instrument resembling a telescope that can be

inserted through a small incision to allow a doctor to see the inside of the abdomen during surgery. Larva: The immature form of an insect. Larynx: The medical name for the voice box located at the base of the

throat. Latent: Referring to a disease that is inactive. Lesion: A general term for any skin injury. Levothyroxine: The chemical name for the synthetic thyroid hormone

given to treat Hashimoto disease. Ligament: A tough fibrous band of tissue that joins bones together. Lobule: One of the glands in the breast that produce milk. Lymph nodes: Part of the lymphatic system, the lymph nodes trap for-

eign particles and are important to defend the body from disease. Lymphocyte: A type of white blood cell that fights infection. Lympho-

cytes are divided into two types, T cells (produced in the thymus gland) and B cells (produced in the bone marrow). Lymphoma: A type of cancer that affects the lymphatic system. UXL Encyclopedia of Diseases and Disorders

xliii

Words to Know

Macule: A spot on the skin or patch that is different in color from

normal skin but is usually not raised up above the skin surface. Mad cow disease: A prion disease that affects cattle and can be trans-

mitted to humans by eating meat from infected cattle. Malabsorption: Inability to absorb the nutrients in food through the

digestive tract. Malar rash: The medical term for the butterfly-shaped facial rash found

in lupus. Malignant: Cancerous. Mania: The high-energy phase of bipolar disorder. Mast cells: Specialized white blood cells that are found in connective

tissue and contain histamine. Mastectomy: Surgical removal of the breast. Meconium: A dark greenish type of stool passed by a newborn during

the first few days of life. Medulloblastoma: A type of malignant brain tumor that develops in the

cerebellum. It is the most common type of brain tumor in children. Melanin: A brownish or dark reddish pigment that is the primary deter-

minant of skin, hair, and eye color in humans. Melanocyte: A type of skin cell that produces melanin. Melanoma: The most serious form of skin cancer. Sunburn increases the

risk of melanoma. Melatonin: A hormone produced in the pineal gland in the brain that

regulates the sleep/wake cycle. Meninges (singular, meninx): The protective membranes that cover the

brain and spinal cord. Meningioma: A type of brain tumor that starts in the meninges. Meningitis: Inflammation of the membranes that cover the brain and

line the brain and spinal cord. Metabolism: The chemical changes in living cells in which new mate-

rials are taken in and energy is provided for vital processes, Metastasis (plural, metastases): The spread of a cancer from its original

location to other organs or parts of the body. xliv


Words to Know

Migraine: A type of primary headache characterized by severe pain,

nausea and vomiting, and sensitivity to light. It may occur on only one side of the head. Milestone: A physical development or accomplishment that most chil-

dren reach within a specific age range. Mixed state: A condition in which a person with bipolar disorder has

the energy of the manic phase of the disorder combined with the hopeless and sad mood of the depressed phase. Mohs surgery: A technique for removing skin cancers in very thin layers

one at a time in order to minimize damage to healthy skin. Monosomy: A type of genetic disorder in which a cell contains only one

copy of a particular chromosome instead of the normal two. Mosaicism: A condition in which a person has some body cells con-

taining an abnormal number of chromosomes and other cells containing the normal number. Mosaicism results from random errors during the process of cell division that follows conception. Motor neuron: A type of cell in the central nervous system that controls

the movement of muscles either directly or indirectly. Mucous membrane: Soft tissues that line the nose, throat, stomach, and

intestines. Multiple chemical sensitivity (MCS): A controversial health condition

related to a patient's belief that his or her symptoms are caused by exposure to environmental chemicals. Mutate: A change in the genetic material of an organism. Viruses can

mutate rapidly. Mutation: A change in the genetic material of an organism. Mycoplasma: A very small bacterium that causes a mild but long-lasting

form of pneumonia. Myelin: A fatty substance that insulates nerve fibers and allows for

speedy and accurate transmission of nerve impulses. Myeloid: Relating to bone marrow. Myocardial infarction: The medical term for a heart attack. Myopia: The medical term for nearsightedness. Myosin: A protein involved in muscle movement. UXL Encyclopedia of Diseases and Disorders

xlv

Words to Know

Myxedema: A synonym for hypothyroidism. Myxedema coma is a con-

dition in which a person with untreated hypothyroidism loses consciousness. It is potentially fatal.

Nebulizer: A device that delivers medication in a fine spray or mist. Necrotizing: Causing the death of soft tissue. Neglect: Failing to meet a child’s basic needs for food, clothing, shelter,

and medical care. Negri bodies: Round or oval bodies found within the nerve cells of ani-

mals infected by the rabies virus. They were first described by Dr. Adolchi Negri in 1903. Neonatal: The medical term for newborn. Neural tube: The medical term for the folds of tissue in the human

embryo that eventually form the brain and spinal cord. Neurologic: Pertaining to the nervous system. Neurologist: A doctor who specializes in diagnosing and treating disor-

ders of the nervous system. Neurology: The branch of medicine that studies and treats disorders of

the nervous system. Neurotransmitters: Chemicals produced in the brain that transmit nerve

impulses to other nerve cells and eventually to muscles. Nicotine: A chemical found in tobacco that acts as a stimulant in

humans. Nits: The eggs of lice. Nodule: The medical term for a small rounded lump of tissue. Nondisjunction: A genetic error in which one or more pairs of chromo-

somes fail to separate during the formation of germ cells, with the result that both chromosomes are carried to one daughter cell and none to the other. Non-rapid eye movement (NREM) sleep: The first phase of a sleep

cycle, in which there is little or no eye movement. xlvi


Words to Know

Norepinephrine: A brain chemical that affects a person's ability to pay

attention. Nosocomial: Referring to a disease that a person gets while hospitalized. Nucleotide excision repair (NER): A mechanism that allows cells to

remove damage caused by ultraviolet light to the cell’s DNA. Nucleotides: The basic structural units of DNA and RNA, a cell's

genetic material. Nucleus: The innermost part of the lens of the eye. Nymph: The second stage in the life cycle of the deer tick.

Obsession: A recurrent, distressing, intrusive thought, image, or

impulse. Occult: The medical term for a cancer that is too small to produce a

visible tumor. Oncogene: A gene that has the potential to cause a normal cell to

become cancerous. Ophthalmia neonatorum: The medical name for bacterial conjunctivitis

in newborn babies caused by a sexually transmitted infection in the mother. Ophthalmologist: A doctor who specializes in diagnosing and treating

eye disorders and can perform eye surgery. Opportunistic infection: An infection that occurs only in people with

weakened immune systems. Optician: An eye care professional who fills prescriptions for eyeglasses

and corrective lenses. Optometrist: An eye care professional who diagnoses refractive errors

and other eye problems and prescribes corrective lenses. Orphan drug: A drug defined by the Food and Drug Administration

(FDA) as intended to treat a disease or condition that affects less than 200,000 people in the United States, or a disease or condition that affects more than 200,000 people and there is no reasonable expectation that the company can recover the costs of developing the drug. UXL Encyclopedia of Diseases and Disorders

xlvii

Words to Know

Orthokeratology: A treatment for astigmatism that consists of wearing

hard contact lenses overnight to reshape the cornea during sleep. The lenses are removed during the day. Orthopaedics (also spelled orthopedics): The branch of medicine that

diagnoses and treats disorders of or injuries to the bones, muscles, and joints. Ossicles: A group of three small bones in the middle ear that transmit

sound waves to the cochlea. Osteopenia: The medical name for low bone mass, a condition that

often precedes osteoporosis. Osteophyte: A bony outgrowth or spur that develops in a joint affected

by osteoarthritis. Osteophytes usually cause pain and limit the motion of the joint. Osteoporosis: A disease in which bones lose their density and are more

likely to break or fracture under stress. Otitis: The medical term for inflammation of the ear. Otolaryngologist: A doctor who specializes in diagnosing and treating

diseases of the ears, nose, and throat. Otoscope: An instrument with a light and magnifying lens that allows a

doctor to examine the eardrum and ear canal.

Paget disease: A chronic disorder caused by a slow virus infection that

results in deformed or enlarged bones. Pancolitis: Ulcerative colitis that affects the entire colon. Pancreas: A small organ that lies between the stomach and the liver and

secretes insulin. PANDAS disorders: A group of disorders with psychiatric symptoms

that develop in some children after strep throat or scarlet fever. The acronym stands for Pediatric Autoimmune Neuropsychiatric Disorders Associated with Streptococcal infections. Pandemic: A disease epidemic that spreads over a wide geographical area

and affects a large proportion of the population. xlviii


Words to Know

Panic attack: An episode of intense fear that lasts for several minutes and

is accompanied by physical symptoms or temporary disturbances of thinking. Pap test: A screening test for cervical cancer devised by Giorgios Papani-

kolaou (1883–1962) in the 1940s. Papule: A small cone-shaped pimple or elevation of the skin. Paradoxical undressing: A symptom sometimes seen in people with

moderate or severe hypothermia, thought to be caused by a malfunction of the hypothalamus. The person becomes confused, disoriented, and begins to remove clothing. Paraplegia: Paralysis that affects only the lower body. Parotid glands: Glands that produce saliva, located on each side of the

face below and in front of the ear. Pasteurization: A process in which milk or fruit juice is partially steri-

lized by heating to a temperature that destroys disease bacteria without causing major changes in appearance and taste. Pastia’s lines: Bright red lines that appear in the body folds of a patient

with scarlet fever after the rash develops. Patent: The medical term for open or unobstructed. Peak airflow meter: A handheld device that asthma patients can use at

home to monitor their lung capacity in order to treat the warning signs of an asthma attack as soon as possible. Pelvic inflammatory disease (PID): Inflammation of the uterus, fallo-

pian tubes, and ovaries caused by chlamydia or gonorrhea. It can lead to permanent inability to have children if not treated. Peptic ulcer: The medical term for an ulcer in the digestive tract. Perinatal: Related to the period around the time of a baby’s birth. Periodontitis: The medical term for gum disease that involves the con-

nective tissue and bone beneath the gums. Peritonitis: Inflammation of the membrane that lines the abdominal

cavity and covers some of the internal organs. Pertussis: The medical name for whooping cough. Pervasive developmental disorder (PDD): A diagnostic category for a

group of childhood disorders characterized by problems in communication skills and social interactions. UXL Encyclopedia of Diseases and Disorders

xlix

Words to Know

Petechiae: Tiny reddish or purplish spots in the skin caused by the

breaking of small blood vessels during intense coughing or vomiting. Pewter: A metal made mostly of tin and small quantities of copper.

Modern pewter is no longer made with lead. Phacoemulsification: A technique for removing cataracts by breaking up

the lens of the eye with ultrasound waves and removing the pieces of the lens by suction. Pharyngitis: The medical term for sore throat. Phenylalanine: The amino acid that cannot be used by the bodies of

people with phenylketonuria. Philadelphia chromosome: A genetic abnormality in chromosome 9

associated with CML. Its name comes from the location of the University of Pennsylvania School of Medicine, where it was discovered in 1960. Phlegm: Thick mucus secreted in the throat and lungs during an upper

respiratory infection. Phobia: An unfounded or morbid dread of a specific object or situation

that arouses feelings of panic. Photophobia: A feeling of discomfort or pain in the eyes during expo-

sure to light. Photopter: A device positioned in front of a patient’s eyes during an eye

examination that allows the examiner to place various lenses in front of the eyes to determine the strength of corrective lenses required. Phototherapy: Method of treating skin disorders by exposing the

affected skin to daylight or to specific wavelengths of visible or ultraviolet light. Pica: An abnormal craving for substances that are not normally consid-

ered food, like soil, chalk, paper, or ice cubes. Pinna: The visible part of the outer ear. Pitch: The highness or lowness of the voice or a musical note. Pituitary gland: A pea-sized gland located at the base of the brain behind

the nose that secretes growth hormone and other hormones that affect sexual development and the body’s response to stress. Plantar: Located on or referring to the sole of the foot. l


Words to Know

Plaque (arterial): A deposit of cholesterol and dead white cells along the

inside wall of an artery. Plaque (dental): A film that forms on the surface of teeth containing

bacteria, saliva, and dead cells. Plasma: The liquid part of blood, about 55 percent of blood by volume. Platelet: A small flat disk-shaped body in human blood that helps to

form blood clots by sticking to other platelets and to damaged tissue at the site of an injury. Platelets are also called thrombocytes. Plumbism: The medical name for lead poisoning. Polymyositis: Inflammation of the muscles that causes weakness and

difficulty in moving or swallowing. Polyp: A growth of tissue protruding from a mucous membrane such as

the colon. Polysomnograph: A machine used in a sleep laboratory to monitor chest

movement, air flow, brain waves, heart rhythm, and other data relevant to diagnosing sleep disorders. Popcorn cell: An abnormal cell found in nodular lymphocyte predomi-

nant Hodgkin disease (NLPHD). Post-concussion syndrome (PCS): A condition characterized by several

weeks or months of headache following a head injury. Postexposure prophylaxis (PEP): A treatment given after exposure to the

rabies virus. It consists of one dose of rabies immune globulin and five doses of rabies vaccine. Postmortem: Referring to the period following death. Postpartum: Referring to the period of time after giving birth. Postpartum depression: A type of depression that some women experi-

ence after the birth of a baby. Postpartum psychosis: A severe mental disorder in which the mother

suffers from delusions or hallucinations. Prader-Willi syndrome: A rare genetic disorder characterized by mental

retardation and an uncontrollable appetite for food. Premutation: An abnormally large number of repeated triplets in certain

genes that does not cause obvious symptoms of a genetic disorder but can expand into a full mutation when transmitted to offspring. Prenatal: Before birth. UXL Encyclopedia of Diseases and Disorders

li

Words to Know

Presbyopia: Age-related farsightedness caused by loss of flexibility in the

lens of the eye. Pressure points: Specific locations on the body where people with fibro-

myalgia feel pain even with light pressure. Primary disease: A disease that develops by itself and is not caused by a

previous disease or injury. Prion: An abnormal infectious protein particle. Proctitis: The medical term for ulcerative colitis limited to the rectum. Prodrome: A period before the acute phase of a disease when the patient

has some characteristic warning symptoms. Progeria: A disease characterized by abnormally rapid aging. The term

can be used to refer specifically to Hutchinson-Gilford syndrome or to a group of diseases characterized by accelerated aging. Progressive: Referring to a disease or disorder that gets worse over time. Prophylaxis: The use of a medication or other therapy to maintain

health and prevent disease. Prostate: A walnut-sized gland in males that secretes seminal fluid. Protozoan (plural, protozoa): A one-celled animal-like organism with a

central nucleus enclosed by a membrane. Many protozoa are parasites that can cause disease in humans. Pseudostrabismus: A condition in which a child may seem to have stra-

bismus because of certain facial features that change as the child’s face matures. Psychosis: Severe mental illness marked by hallucinations and loss of

contact with the real world. Psychostimulant: A type of drug that increases the activity of the parts

of the brain that produce dopamine. Pulp: The soft living material in the center of a tooth that contains blood

vessels and nerve endings. Pupil: The circular opening in the center of the iris. Pus: A whitish-yellow material produced by the body in response to a

bacterial infection. It consists of tissue fluid and dead white blood cells. lii


Words to Know

Pyelonephritis: The medical term for a urinary tract infection that has

spread from the bladder or other parts of the urinary tract upward to the kidneys.

Quadriplegia: Paralysis that affects both arms and both legs. It is also

known as tetraplegia. Quarantine: The practice of isolating people with a contagious disease

for a period of time to prevent the spread of the disease. Quinoa: A plant grown in Peru and Bolivia for its edible seeds. It is high

in protein and easy to digest.

Radiologist: A doctor who specializes in medical imaging techniques to

diagnose or treat disease. Radon: A colorless and odorless gas produced by the breakdown of ura-

nium known to cause lung cancer. Rapid cycling: Four or more episodes of illness within a 12-month

period. Rapid eye movement (REM) sleep: The phase of a sleep cycle in which

dreaming occurs; it is characterized by rapid eye movements. Raynaud's phenomenon: Discoloration of the fingers and toes caused by

blood vessels going into spasm and decreasing the flow of blood to the affected digits. Reactive hypoglycemia: A condition in which a person develops hypo-

glycemia between two and five hours after eating foods containing high levels of glucose. Rebound tenderness: Pain experienced when the doctor releases pres-

sure on the abdomen. Rectum: The lowermost portion of the large intestine, about 6 inches

(15.2 centimeters) long in adults. UXL Encyclopedia of Diseases and Disorders

liii

Words to Know

Reed-Sternberg cell: An abnormal type of B lymphocyte that is found in

classic Hodgkin lymphoma. Reefer: Another name for a marijuana cigarette. Reflux: The medical term for the backward flow of stomach acid from

the stomach into the esophagus. Refractive error: A general term for vision problems caused by the eye’s

inability to focus light correctly. Regurgitation: Throwing up; effortless flow of undigested stomach con-

tents back up the esophagus into the mouth. Reiter’s syndrome: A type of arthritis than can develop in untreated

people with chlamydia. It is characterized by inflammation of the genitals and the eyelids as well as sore and aching joints. Relapse: Recurrence of an illness after a period of improvement. Remission: A period in the course of a disease when symptoms disap-

pear for a time. Reservoir: The term used by biologists for the natural host species of a

disease organism. Bats are thought to be the reservoir of viral hemorrhagic fevers. Resilience: The capacity to recover from trauma and other stressful

situations without lasting damage. Resorption: The removal of old bone from the body. Retina: The light-sensitive layer of tissue at the back of the eyeball. Retinal detachment: A disorder in which the retina pulls away from its

underlying tissues at the back of the eye. Rheumatoid factor (RF): An antibody that attacks the body’s own tissues

that is found in some patients with rheumatoid arthritis and is measured as part of the diagnostic process. Rheumatologist: A doctor who diagnoses and treats diseases of the mus-

cles, joints, and connective tissue. Rheumatologist: A doctor who specializes in diagnosing and treating

arthritis and other diseases of the muscles and joints. Rheumatology: The branch of medicine that deals with disorders of the

muscles, joints, and connective tissue. liv


Words to Know

Rhinitis: The medical term for inflammation of the mucous tissues

lining the nose. It can be caused by infections or chemical irritants as well as by allergies. RNA virus: A virus whose genetic material is composed of ribonucleic

acid (RNA) and does not need DNA to copy itself and multiply. Rocker-bottom feet: Abnormally long and slender feet with pointed

heels turned outward like the bottom rails of a rocker. Rotator cuff: A group of four muscles that attach the arm to the shoulder

blade.

Scald: A burn caused by steam or a hot liquid. Scaling: Scraping tartar away from the teeth around the gum line. Scintigraphy: A technique for detecting the location and extent of soft-

tissue injury by injecting a small quantity of a radioactive element and following its distribution in the tissue with a scanner. Sclera: The opaque white portion of the eyeball. Scleroderma: A disorder of connective tissue characterized by thickening

and tightening of the skin as well as damage to internal organs. Sclerosis: Hardening or scarring of tissue. Scoliosis: Abnormal curvature of the spine from side to side. Scrapie: A prion disease of sheep and goats. Sebum: An oily lubricant secreted by glands in the skin. Secondary disease: A disease that is caused by another disease or condi-

tion or by an injury. Selective serotonin reuptake inhibitors (SSRIs): A group of antidepres-

sants that work by increasing the amount of serotonin available to nerve cells in the brain. Senile cataract: Another term for cataracts caused by the aging process. Sepsis: The presence of bacteria or their toxic products in the blood-

stream or other tissues, leading to inflammation of the entire body. Septum (plural, septa): A partition that separates two cavities or cham-

bers in the body. UXL Encyclopedia of Diseases and Disorders

lv

Words to Know

Serotonin: A brain chemical that influences mood, anger, anxiety, body

temperature, and appetite. Shingles: A skin inflammation caused by reactivation of the chickenpox

virus remaining in the nervous system. Shock: A medical emergency in which there is a drop in blood pressure

and a reduced volume of blood circulating in the body. Shunt: A flexible plastic tube inserted by a surgeon to drain cerebrosp-

inal fluid from the brain and redirect it to another part of the body. Sickle cell crisis: Sudden onset of pain and organ damage in the chest,

bones, abdomen, or joints caused by defective red blood cells blocking blood vessels. Sleep cycle: A period of NREM sleep followed by a shorter phase of

REM sleep. Most adults have four to six sleep cycles per night. Slit lamp: An instrument that focuses light into a thin slit. It is used by

eye doctors to examine eyes for a wide variety of disorders. Smoking cessation: A term that refers to a product or program to help

people quit smoking. Snellen chart: A series of letters arranged in lines on a chart to be viewed

from a distance of 20 feet (6.1 meters) used to measure visual acuity (clearness of vision). Soft palate: The soft tissue at the back of the roof of the mouth that

does not contain bone. Solar keratoses (singular, keratosis): Rough scaly patches that appear

on sun-damaged skin. They are considered precancerous. Spasticity: Stiffness or spasms in the muscles. Spectrum disorder: A disorder whose symptoms vary in severity from

one patient to the next. Sphincter: A ring-shaped muscle that can contract to close off a body

opening. Sphygmomanometer: The device used to measure blood pressure. It

consists of an inflatable cuff that compresses an artery in the arm. The doctor listens through a stethoscope as the air pressure in the cuff is released in order to measure the blood pressure. Spirochete: A spiral-shaped bacterium. Lyme disease is caused by a

spirochete. lvi


Words to Know

Spirometer: A device that is used to test the air capacity of a person's

lungs and the amount of air that enters and leaves the lungs during breathing. Spleen: An organ located behind the stomach that cleans old blood cells

out of the blood and holds a reserve of red blood cells. Sporadic: Occurring at random. Spore: The dormant stage of a bacterium. Sputum: Mucus and other matter that is coughed or brought up from

the lungs or throat. Stacking: Using several different types of steroids at the same time. Status epilepticus: An ongoing seizure that lasts longer than five min-

utes; it is a medical emergency. Stem cell: A type of unspecialized cell that can reproduce itself and dif-

ferentiate into different types of specialized cells. Stem cells act as a repair system for the body. Stenosis: The medical term for abnormal narrowing of the opening of a

blood vessel. Stillbirth: The birth of a baby that has died before or during delivery. Stimulant: Any drug or chemical that temporarily increases the user’s

awareness or alertness. Stoma: An opening made in the abdomen following surgery for digestive

disorders, including colon cancer, that allows wastes to pass from the body. Stomatitis: The medical term for an inflammation of the

mouth. Strabismus: A condition in which the eyes are not properly aligned with

each other. Strain: A genetic variant or subtype of a bacterium. Strawberry tongue: A swollen and intensely red tongue that is one of the

classic signs of scarlet fever. Stress management: Any set of techniques intended to help people deal

more effectively with stress in their lives by analyzing specific stressors and taking positive actions to minimize their effects. Stressor: Any event or stimulus that provokes a stress response in a

human or animal. UXL Encyclopedia of Diseases and Disorders

lvii

Words to Know

Stricture: The medical term for an abnormal narrowing of a hollow

organ like the bowel. Substance P: A chemical in the central nervous system that transmits pain

signals back and forth between the brain and the rest of the body. Sulcus (plural, sulci): The space or crevice between a tooth and the sur-

rounding gum tissue. Sun poisoning: A term sometimes used to refer to a severe reaction to

sunburn, consisting of fever, chills, fluid loss, dizziness, and nausea. Sunsetting: A term used to describe a downward focusing of the eyes. Surfactant: A protein-containing substance secreted by cells in the lungs

that helps to keep them properly inflated during breathing. Surveillance: Monitoring of infectious diseases by public health doctors. Synapse: The medical term for specialized connections between nerve

cells. Syndrome: A group of signs or symptoms that occur together

and characterize or define a particular disease or disorder. Synovium: A type of tissue lining the joints that ordinarily secretes a

fluid that lubricates the joints. Systemic: Referring to a disease or disorder that affects the entire body. Systolic blood pressure: The blood pressure at the peak of each heartbeat.

Targeted therapy: A newer type of cancer treatment that uses drugs to

target the ways cancer cells divide and reproduce or the ways tumors form their blood supply. Tartar: Hardened plaque. Tendon: A thick band or cord of dense white connective tissue that

attaches a muscle to a bone. Teratogen: Any substance that causes birth defects in children. Alcohol

is a teratogen. Testosterone: The principal male sex hormone. Thalassemia trait: A condition in which a person is missing one or two

genes required to make the proteins in the alpha chains of the lviii


Words to Know

hemoglobin molecule. The person does not have the symptoms of thalassemia but can pass the genetic deficiency to their children. THC: The abbreviation for delta-9-tetrahydrocannabinol, the main

mind-altering chemical in marijuana. Thrombus: A blood clot that forms inside an intact blood vessel and

remains there. Thymus: A small organ located behind the breastbone that is part of the

lymphatic system and produces T cells. Thyroid storm: A medical emergency marked by a rise in body tem-

perature as well as other symptoms caused by untreated hyperthyroidism. Thyroiditis: Inflammation of the thyroid gland. Tic: A sudden repetitive movement or utterance. Tourette syndrome is

considered a tic disorder. Tick: A small bloodsucking parasitic insect that carries Lyme disease and

several other diseases. Tinnitus: The medical term for ringing in the ears. Tolerance: The need for greater and greater amounts of a drug to get the

desired effects. Tonometer: An instrument used by an ophthalmologist to measure the

pressure of the fluid inside the eye. Tonsillectomy: Surgical removal of the tonsils. Topical: Referring to a type of medication applied directly to the skin or

outside of the body. Tourette syndrome: A neurological disorder characterized by recurrent

involuntary body movements and repeated words or grunts. Toxin: A poisonous substance produced by a living cell or organism. Trachoma: An infectious disease of the eye caused by chlamydia bacteria

that can lead to blindness if untreated. Traction: The use of braces, casts, or other devices to straighten broken

bones and keep them aligned during the healing process. Transdermal: Referring to a type of drug that enters the body by being

absorbed through the skin. UXL Encyclopedia of Diseases and Disorders

lix

Words to Know

Transient ischemic attack (TIA): A brief stroke lasting from a

few minutes to twenty-four hours. TIAs are sometimes called ministrokes. Translocation: A genetic error in which a part of one chromosome

becomes attached to another chromosome during cell division. Trauma: A severe injury or shock to a person's body or mind. Tremor: Trembling or shaking caused by a physical disease. Triglyceride: A type of fat made in the body. Triplet: In genetics, a unit of three nucleotides that starts or stops the

production of a specific protein. Triplets are also called codons. Trismus: The medical name for the spasms of the jaw muscles caused by

tetanus. Trisomy: A type of genetic disorder in which a cell contains three copies

of a particular chromosome instead of the normal two. Triticale: A grain that is a cross between wheat and rye, first grown in

Scotland and Sweden in the nineteenth century. T-score: The score on a bone density test, calculated by comparing the

patient's bone mineral density to that of a healthy thirty-year-old of the same sex and race. Tumor: An abnormal mass or growth of tissue that may be either can-

cerous or noncancerous. Tumor markers: Substances found in blood, urine, or body tissues that

can be used to detect cancer.

Ureter: A muscular tube that carries urine from the kidney to the

bladder. Urethra: The tube that allows urine to pass from the bladder to the out-

side of the body. Urologist: A doctor who specializes in diagnosing and treating disorders

of the kidneys and urinary tract. Urticaria: The medical term for hives. Uveitis: Inflammation of the interior of the eye.

lx


Words to Know

Uvula: A triangular piece of soft tissue located at the back of the soft

palate.

Vasoconstriction: A narrowing of the blood vessels in response to cold

or certain medications. Vector: An insect or other animal that carries a disease from one host to

another. Ventricle (brain): One of four hollow spaces or cavities in the brain that

hold cerebrospinal fluid. Ventricle (heart): One of the two lower chambers of the heart. Verruca (plural, verrucae): The medical term for a wart. Vertebra (plural, vertebrae): One of the segments of bone that make up

the spinal column. Vesicle: A small blister or sac containing fluid. Vestibular system: The group of organs in the inner ear that provide

sensory input related to movement, orientation in space, and balance. Villi (singular, villus): Small finger-like projections along the walls of the

small intestine that increase the surface area of the intestinal wall. Viral load: A measure of the severity of HIV infection, calculated by esti-

mating the number of copies of the virus in a milliliter of blood. Virilization: The development of male sexual characteristics in females. Vital signs: Measurements taken to evaluate basic body functions. They

are temperature, pulse rate, blood pressure, and breathing rate. Vocal folds: Twin folds of mucous membrane stretched across the

larynx. They are also known as vocal cords.

Wasting: Loss of lean muscle tissue. Werner syndrome: A genetic disease characterized by accelerated aging.


lxi

Words to Know

Wheal: A suddenly formed flat-topped swelling of the skin; a welt. Wheezing: A continuous harsh whistling sound produced by the air-

ways of an asthma patient when the air passages are partly blocked. Whipple triad: A group of three factors used to diagnose hypoglycemia:

symptoms; blood sugar measuring below 45 mg/dL for a woman and 55 mg/dL for a man; and rapid recovery following a dose of sugar. Window period: The period of time between a person’s getting infected

with HIV and the point at which antibodies against the virus can be detected in a blood sample. Withdrawal: A collection of signs and symptoms that appear when a

drug (including alcohol, caffeine and nicotine) that a person has used for a long time is suddenly discontinued. With-the-rule astigmatism: A type of astigmatism in which the eye sees

vertical lines more clearly than horizontal lines. Wood's lamp: A special lamp that uses ultraviolet light to detect certain

types of skin infections and infestations.

Xerostomia: The medical term for dry mouth.

Yaws: A tropical, bacterial infection of the skin, bones, and joints.

Zoonosis (plural, zoonoses): A disease that can be transmitted from ani-

mals to humans.

lxii


Sh

Shaken Baby Syndrome Definition

Also Known As Shaken infant syndrome, SBS, abusive head trauma, pediatric traumatic brain injury Cause Violent shaking of an infant or toddler by an adolescent or adult Symptoms Brain damage, learning disabilities, mental retardation, blindness, paralysis, seizures, death Duration May be lifelong

Shaken baby syndrome (SBS) is a form of child abuse in which an adult forcefully shakes a baby or toddler by the arms, chest, or shoulders, causing the head to whiplash back and forth on the neck and leading to bleeding inside the skull from broken blood vessels. The syndrome was first identified by Dr. John Caffey (1895–1978), a pediatric radiologist, who published a landmark paper on it in 1972.

Description Shaken baby syndrome is a type of traumatic brain injury that results when a baby or young child is grasped by the upper body and shaken back and forth by a teenager or adult. A baby has a relatively large and heavy head in comparison to the rest of its body, and it has weaker neck muscles than older children or adults. When the baby is shaken, or its head is struck against a wall or other hard surface, its brain moves back and forth inside the skull, causing tissue to bruise and small blood vessels to break. Blood can collect inside the skull and put pressure on the brain, leading to permanent brain damage, seizures, or death.

Demographics The American Academy of Pediatrics (AAP) estimates that there are between 600 and 1,400 cases of SBS in the United States each year, 947

Shaken Baby Syndrome

Advice for Caregivers about SBS (source: The Arc) There are three key words to remember when dealing with a crying or fussy baby: Stop. Calm down. Try again: • Stop: Do not handle the baby if you are upset or angry. Place the child in a safe place like a crib or playpen. • Calm down: Leave the room but stay close enough to hear the baby. Listen to calming music for a short time; then call a friend or the hotline below for support or advice. Another approach is to run the vacuum cleaner; the noise will drown out the sound of the crying; it also calms some babies. Keep in mind, too, that the baby may be crying from an earache, teething, or other illness as well as hunger or a wet diaper. If the baby cannot be soothed and keeps crying for a long time, it is best to call the doctor. • Try again: After calming down, try again to help the baby.

though it is possible that the true number is higher because some cases are misdiagnosed as the result of accidental falls or auto accidents. What is known is that shaken baby syndrome is the most common cause of mortality and long-term disability in infants and young children due to physical abuse. The syndrome has been reported in infants as young as five days and children as old as five years, but most victims are two years of age or younger. SBS occurs in all racial groups in the United States but is more likely to be caused by males than by females. Adult males in their early twenties are the perpetrators in 65 to 90 percent of cases; most often they are the baby’s father or the mother’s boyfriend. Female perpetrators are more likely to be a teenage babysitter or nanny than the baby’s mother. The usual trigger for the abuse is crying lasting for several hours or repeated diaper soiling, although in some cases involving men, the abuser is angry because he is jealous of the attention the baby receives from its mother.

Causes and Symptoms

Keep the number of the Childhelp National Child Abuse Hotline on the refrigerator or near the telephone: 1-800-4-A-CHILD (1-800-4224453). The hotline is staffed twenty-four hours a day, 365 days a year.

The cause of SBS is brain damage resulting from bleeding beneath the skull and bruising of brain tissue due to the brain’s moving up against the inside of the skull during shaking. In some cases the brain is also damaged by loss of its oxygen supply. The symptoms of severe SBS include:

• Bleeding into the retina of the eye • Bleeding into the space between the brain and the layers of tissue that cover the brain • Swelling of the head from fluid accumulating in the tissues of the brain • Damage to the spinal cord and soft tissues of the neck 948



• Fractures of the ribs or other bones • Convulsions • Loss of consciousness Babies who are less severely injured when shaken may have symptoms that are easy to confuse with the symptoms of flu: • • • • •

Vomiting or other flu-like symptoms without fever or diarrhea Crankiness and irritability over a period of time Poor feeding, loss of appetite Breathing problems Unusual drowsiness

Diagnosis The doctor’s greatest help in making a correct diagnosis of shaken baby syndrome is a description of what happened by the perpetrator or a witness. In many cases an abuser will tell the doctor that the child fell or was in a car accident, or that the abuser shook the baby trying to revive it. One important clue is that the injuries caused by SBS are usually much more severe than would be caused by a fall or other accidental head injury. The doctor can tell that a shaken baby has a closed-head injury by taking imaging studies, usually a CT scan or an MRI. X-ray studies will reveal broken ribs or other bones. Bleeding into the retina of the eye can be detected by an ophthalmologist (doctor who specializes in eye disorders). In some cases, the doctor may order laboratory tests to rule out meningitis and other infectious diseases that can affect the brain and cause a seizure or coma.

Treatment Children with severe injuries from shaken baby syndrome require emergency treatment, usually brain surgery to relieve pressure on the brain and respiratory support to help them breathe. Treatment of the blindness, learning disorders, mental retardation, and other long-term consequences of SBS may last for the rest of the child’s life. These children often need special education services, physical therapy, speech therapy, eye treatment, psychotherapy, and occupational therapy.

Prognosis SBS has a high mortality rate. It is estimated that a third of the babies who are abused in this way will die; another third will suffer severe permanent injuries; and the remaining third will recover. UXL Encyclopedia of Diseases and Disorders

949


Prevention Dr. Caffey believed in the value of education to prevent at least some instances of SBS. While some abusers are people with a history of substance abuse or poor impulse control, others do not understand how much an angry adolescent or adult can harm a baby by shaking it. Various prevention strategies that are used include showing videos about SBS to new parents; encouraging pediatricians to discuss the stresses of childrearing with parents and teach them some ways to soothe a crying child; asking social workers to help identify families at risk of child abuse; instructing workers in day care centers and others who work with small children about the syndrome; and advising parents to screen babysitters or nannies very carefully before hiring them for child care responsibilities. Specific tips for managing the stress of caring for a crying infant are described in the sidebar.

The Future It is difficult to tell whether the various preventive strategies for lowering the rate of shaken baby syndrome will have a significant effect in the years to come, as many abusive, addicted, or mentally disturbed people cannot be reached by educational measures. One hopeful development is that more doctors and nurses are aware of the syndrome and better able to diagnose it quickly. SEE ALSO

Child abuse; Whiplash

For more information BOO KS

Peinkofer, James R. Silenced Angels: The Medical, Legal, and Social Aspects of Shaken Baby Syndrome. Westport, CT: Auburn House, 2001. PE R I O DI C A L S

Foderaro, Lisa W. “A Simple Video Finds Success against Shaken Baby Abuse.” New York Times, May 29, 2001. Available online at http://query.nytimes. com/gst/fullpage.html?res=9B04EFD7153CF93AA15756C0A9679C8B63 &sec=&spon=&pagewanted=all (accessed April 30, 2008). This is an article about a video shown to new mothers at the Children’s Hospital of Buffalo about shaken baby syndrome. WE B S IT E S

The Arc of the United States. Fact Sheet on Shaken Baby Syndrome. Available online at http://www.thearc.org/NetCommunity/Page.aspx?&pid=1433& 950


Sickle Cell Anemia

WORDS TO KNOW Closed-head injury: An injury to the head in which the skull is not broken or penetrated.

Radiologist: A doctor who specializes in medical imaging techniques to diagnose or treat disease.

Meningitis: Inflammation of the protective membranes that cover the brain and spinal cord.

Retina: The layer of light-sensitive tissue at the back of the eyeball.

srcid=217 (updated March 2004; accessed April 30, 2008). The Arc is a worldwide organization that provides support and services for people with intellectual and developmental disabilities. National Center on Shaken Baby Syndrome. Frequently Asked Questions/Medical Facts. Available online at http://www.dontshake.org/Audience.aspx? categoryID=8&PageName=MedicalFactsAnswers.htm (accessed April 30, 2008). National Center on Shaken Baby Syndrome. Physical Consequences of Shaking an Infant or Toddler. Available online at http://www.dontshake.com/clips/ SBSPowerPoint_Lo.wmv (accessed April 30, 2008). This is an animation with voiceover of the effects of violent shaking within a baby’s head. It takes about a minute and a half to play. National Institute of Neurological Disorders and Stroke (NINDS). Shaken Baby Syndrome Information Page. Available online at http://www.ninds.nih.gov/ disorders/shakenbaby/shakenbaby.htm (updated February 14, 2007; accessed April 30, 2008).

Sickle Cell Anemia Definition Sickle cell anemia is an inherited blood disorder caused by a mutation in a gene responsible for the production of hemoglobin, the protein found in red blood cells that carries oxygen from the lungs to other body organs and tissues. The disorder was first described in 1910 by James Herrick (1861–1954), a doctor in Chicago who was examining a young black dental student from the West Indies. Herrick described the cells seen in a smear of the patient’s blood under the microscope as “thin, UXL Encyclopedia of Diseases and Disorders

951

Sickle Cell Anemia

sickle-shaped and crescent-shaped red cells.” The dental student died in 1916 at the young age of thirty-two. A person must inherit the defective gene that produces hemoglobin S from both parents in order to develop sickle cell anemia. A person who inherits the gene from only one parent is said to have sickle cell trait. People with sickle cell trait do not have the symptoms of the disease but can pass on the disease if they have children with another carrier.

Description

Also Known As Sickle cell disease, hemoglobin SS disease, HbS disease Cause Mutation in a gene on chromosome 11 Symptoms Fatigue, headache, pain attacks, swollen hands and feet, infections, vision problems Duration Lifelong 952

In sickle cell anemia, the red blood cells do not contain normal hemoglobin but a defective form of the protein called hemoglobin S. Whereas normal red blood cells are round, flexible, and able to move easily through the blood vessels, cells containing hemoglobin S can bend into crescent or sickle shapes and become sticky. They cause health problems for two reasons. First, blood cells containing hemoglobin S die much faster than normal red blood cells; this lowers their ability to carry enough oxygen to meet the body’s needs and leads to such symptoms as lack of energy and lightheadedness or dizziness. Second, the abnormal red blood cells tend to form clumps that block blood vessels and cause organ damage. When the sickle cells block blood vessels, they cause such symptoms as chest pain, damage to the spleen, liver, and kidneys, and stroke. Twothirds of all strokes in people with sickle cell anemia occur in children, with an average age of eight years. Another common complication is sickle cell crisis, a sudden severe attack of pain that affects the patient’s chest, joints, abdomen, bones, or extremities. Damage to the spleen caused by the abnormal blood cells makes patients with sickle cell anemia vulnerable to certain infections. Last, the effects of the sickle cells on the narrow blood vessels in the eyes lead to vision problems that include disorders of the retina and bleeding into the eye.

Demographics Geneticists think that the defective gene responsible for hemoglobin S originated independently in five different parts of Africa, including Cameroon and Senegal, and Saudi Arabia. The gene did not die out because, even though people with two copies of the defective gene did not usually live long enough to have children, those who had only the sickle cell trait were more resistant to one type of malaria. This advantage helped them to survive in parts of the world where malaria is UXL Encyclopedia of Diseases and Disorders

Sickle Cell Anemia Image of red blood cells, some misshapen as a result of sickle cell anemia. DR. DAVID M. PHILLIPS / VISUALS UNLIMITED / GETTY IMAGES.

widespread. Sickle cell anemia is still more common in Africa, India, parts of Central and South America, the Caribbean islands, Saudi Arabia, and Turkey than in Europe or North America. In the United States, sickle cell anemia primarily affects African Americans. About 80,000 people in the United States presently have sickle cell disease, which makes it the most common inherited blood disorder in North America. It occurs in one in every 375 live births among African Americans. According to the National Institutes of Health (NIH); 2 million Americans have sickle cell trait—one in twelve African Americans and one in every 100 Hispanics. Males and females are equally likely to inherit either the trait or the disease.

Causes and Symptoms Sickle cell anemia is caused by a mutation in the hemoglobin-beta gene on chromosome 11. The symptoms of sickle cell anemia do not usually appear in infants until they are about four months old. Severity differs from patient to patient. • Anemia. Symptoms of sickle cell disease related to anemia include fatigue, pale skin, dizziness or feeling faint, cold hands or feet, and shortness of breath. UXL Encyclopedia of Diseases and Disorders

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A Great Jazz Musician Miles Davis (1926–1991) was a jazz trumpeter and composer who was considered one of the most influential American musicians of the twentieth century. Davis helped to shape most of the major developments in jazz from the World War II period through his death in 1991. The son of a dentist in Alton, Illinois, Davis started to play the trumpet at age thirteen. He won a scholarship to the prestigious Julliard School of Music in New York in 1944, but quit to make his first professional recordings in 1945. Davis was fortunate in suffering from a relatively mild form of sickle cell disease. He did, however, make his condition worse by becoming addicted to heroin and other drugs during his first visit to Paris in 1949. He had to take frequent breaks from his career in the 1960s and 1970s because of the impact of his drug abuse on the health of his bones, already weakened by sickle cell anemia. Davis eventually had to have a hip replacement in 1976. His death at the age of sixty-five was caused by a stroke combined with pneumonia, both complications of a sickle cell crisis.

• Sickle cell crises. These are episodes of severe pain caused by defective red blood cells blocking the flow of blood through the blood vessels that supply the chest, joints, bones, or abdomen. Crises occur suddenly and may last for anywhere from a few hours to several weeks. Some people have only a few crises during their lifetime while others may have a dozen or more every year. • Vulnerability to infection. People with sickle cell anemia are more likely to get frequent infections because of damage to the spleen caused by the disease. Pneumonia, a lung infection, is the most common cause of death in children with sickle cell anemia. • Jaundice. Jaundice is a condition in which the whites of the eyes and the skin have a yellowish discoloration because of liver problems. • Hand/foot syndrome. This is often the first symptom of sickle cell anemia in babies. The child’s hands and feet become swollen because the defective blood cells block the veins in the hands and feet and do not allow blood to return freely to the circulation.

• Eye disorders. Defective red blood cells blocking the tiny blood vessels in the eyes can damage the retina, the light-sensitive layer of tissue at the back of the eyeball. • Stunted growth and delayed puberty. • Stroke. Although stroke is unusual in most children, about 11 percent of children with sickle cell disease suffer a stroke before they are twenty years old. Convulsions and partial paralysis often accompany stroke in this age group.

Diagnosis As of 2008, forty-nine states in the United States routinely screened newborns for sickle cell anemia through a blood test. A small amount of 954


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blood from the baby’s finger or heel and sends is sent to a laboratory where it is analyzed for hemoglobin S. Older children and adults can also be tested for hemoglobin S with a blood test. If the screening test is negative, no further testing is required. If the test results are positive for hemoglobin S, a second test is done to determine whether the person has sickle cell trait or the disease itself.

Treatment Treatment depends on the type and severity of the patient’s symptoms. The only cure for sickle cell anemia is a bone marrow transplant (BMT). Only about 18 percent of children with the disease, however, have a suitable donor—usually a full sibling. The transplant procedure itself is complex, and 6 percent of children die during the procedure. As of 2008, BMT was usually performed only on children with a high risk of stroke, major risk of bleeding in the brain, severe visual disorders, and more than two sickle cell crises per year for several years. Medications are the mainstay of treatment for patients with sickle cell anemia: • Pain relievers. Depending on the severity of pain, patients with sickle cell anemia may be given prescription pain relievers during a sickle cell crisis. In some cases they may be taken to the hospital for intravenous fluids and strong narcotic painkillers. • Antibiotics. Children diagnosed with sickle cell anemia are usually given penicillin from two months to five years of age to prevent infections. Adults with the disease may also be given antibiotics if they develop a bacterial infection. • Hydroxyurea. Hydroxyurea is a drug developed to treat cancer that helps some people with sickle cell disease. It stimulates the production of fetal hemoglobin, a type of hemoglobin usually found only in newborns. It can reduce the need for blood transfusions and the frequency of sickle cell crises. • Supplemental oxygen. Patients who are hospitalized with a severe crisis may be given supplemental oxygen to breathe to help raise the levels of oxygen in their blood and body tissues. Blood transfusions lower the risk of stroke and relieve anemia in children with sickle cell anemia. Healthy red blood cells are removed from donated blood and infused into the veins of sickle cell patients. The risk UXL Encyclopedia of Diseases and Disorders

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of blood transfusions, however, is the buildup of iron in the patient’s body, which can damage the liver and other organs. The Food and Drug Administration approved the drug Exjade in 2005, which removes excess iron from the blood. Some lifestyle adjustments can help to lower the risk of sickle cell crises. Fevers, exposure to cold weather, becoming dehydrated, and using recreational drugs and alcohol have been found to trigger crises. Avoiding exposure to infections, drinking plenty of fluids, lowering emotional stress levels, and avoiding drugs and alcohol are all recommended for those with sickle cell anemia.

Prognosis The prognosis for sickle cell anemia is still relatively poor. With the exception of children who benefit from bone marrow transplantation, most people with sickle cell anemia have shortened life expectancies. As recently as the 1990s, the average life span for patients with the disease was forty-two years for males and forty-eight years for females. As of 2008, about half of patients diagnosed with the disease lived into their early fifties.

Prevention The only way to prevent sickle cell disease is genetic counseling and testing. People can be tested for the sickle cell trait before starting a family and can talk to a counselor about their risk of having a child with sickle cell disease. It is also possible to test an unborn baby for sickle cell disease by a procedure called amniocentesis. The doctor uses a needle to withdraw a small sample of the fluid surrounding the baby in the mother’s uterus. The cells in the sample are then tested for the defective hemoglobin S gene.

The Future There were several potential treatments for sickle cell anemia under investigation as of 2008. One is gene therapy. Experiments done in mice in the early 2000s have encouraged some researchers to think that it might be possible to remove some of the bone marrow cells in patients with sickle cell anemia, replace the defective hemoglobin-beta gene with a normal gene, and return the “corrected” cells to the patient’s bone marrow. 956


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WORDS TO KNOW Anemia: A condition in which a person’s blood does not have enough volume, enough red blood cells, or enough hemoglobin in the cells to keep body tissues supplied with oxygen.

Sickle cell crisis: Sudden onset of pain and organ damage in the chest, bones, abdomen, or joints caused by defective red blood cells blocking blood vessels.

Hemoglobin: An iron-containing protein in red blood cells that carries oxygen from the lungs to the rest of the body.

Other treatments that are considered experimental are clotrimazole, an antifungal medication that appears to slow the production of sickle cells; and nitric oxide, a gas that helps to keep blood vessels open and reduce the stickiness of sickle cells. SEE ALSO

Malaria; Stroke; Thalassemia


Jones, Phill. Sickle Cell Disease. New York: Chelsea House, 2008. Peak, Lizabeth. Sickle Cell Disease. Detroit, MI: Lucent Books, 2008. Peterson, Judy Monroe. Sickle Cell Anemia. New York: Rosen Publishing Group, 2009. WE B S IT E S

Dolan DNA Learning Center. Sickle Cell Disease. Available online at http:// www.ygyh.org/sickle/whatisit.htm (accessed August 22, 2008). This is an interactive multimedia site about sickle cell anemia. Mayo Clinic. Sickle Cell Anemia. Available online at http://www.mayoclinic. com/health/sickle-cell-anemia/DS00324 (updated March 28, 2007; accessed August 22, 2008). National Heart, Lung, and Blood Institute (NHLBI).What Is Sickle Cell Anemia? Available online at http://www.nhlbi.nih.gov/health/dci/Diseases/ Sca/SCA_WhatIs.html (updated August 2008; accessed August 22, 2008). National Human Genome Research Institute (NHGRI). Learning about Sickle Cell Disease. Available online at http://www.genome.gov/10001219 (updated May 30, 2008; accessed August 22, 2008). Sickle Cell Disease Association of America (SCDAA). About Sickle Cell Disease. Available online at http://www.sicklecelldisease.org/about_scd/index.phtml (accessed August 22, 2008). UXL Encyclopedia of Diseases and Disorders

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SIDS

SIDS

See Sudden infant death syndrome.

Sjögren Syndrome Definition Sjögren (pronounced SHOW-gren) syndrome, or SS, is an autoimmune disorder that primarily affects the body’s tear glands and salivary glands. It is named for Henrik Samuel Sjögren (1899ndash;1986), the Swedish ophthalmologist (eye specialist) who described it in 1933. The disorder is also known as Gougerot disease or Gougerot-Sjögren syndrome, after Henri Gougerot (1881–1955), a French doctor who presented a case study of the disease in a French medical journal in 1925.

Description

Also Known As SS, Gougerot disease, Gougerot-Sjögren syndrome Cause Possibly a combination of genetic factors and an environmental trigger Symptoms Dry eyes, dry mouth, fatigue, vaginal dryness, joint swelling and stiffness Duration Years 958

Sjögren syndrome is a disorder in which the body’s immune system attacks the glands that produce saliva, tears, and (in women) vaginal fluid. It can also cause dryness in such other body tissues and organs as the kidneys, digestive tract, blood vessels, lung, liver, pancreas, and the central nervous system. Most patients also experience fatigue and pains in the joints. Doctors classify cases of Sjögren syndrome as either primary, meaning that the disorder occurs by itself; or secondary, which means that the patient has another connective tissue disorder. About half of all cases of SS are primary and the other half are secondary. The four most common diseases affecting patients with secondary Sjögren syndrome are rheumatoid arthritis, lupus, scleroderma, and polymyositis (inflammation of the muscles).

Demographics SS is thought to affect between 0.1 percent and 3 percent of the population in all countries. According to the American College of Rheumatology (ACR), between 400,000 and 3.1 million adults in the United States suffer from the disorder. Members of all races appear to be equally affected. SS is primarily a disorder of women, however; females get SS UXL Encyclopedia of Diseases and Disorders

Sjögren Syndrome Salivary gland of a person with Sjögren syndrome. © BIODISC/ VISUALS UNLIMITED / ALAMY.

nine times as frequently as males. It is unusual for adolescents or young adults to develop Sjögren syndrome; the average age of patients at onset is the late forties.

Causes and Symptoms The cause of Sjögren syndrome is not completely understood, but it is thought to be a combination of genetic factors, hormones, and environmental triggers, possibly infections. There is more than one gene that appears to be involved, but the connections between these genes and the onset of the disorder are not yet clear. Some researchers think that SS is triggered when people who are genetically susceptible are infected by a virus that has not yet been identified, and that the resultant infection causes the person’s immune system to turn against the glands that produce tears and saliva. These glands include the tear glands near the eyes and the parotid glands below and in front of the ears. The most noticeable symptoms of Sjögren syndrome are xerostomia, or dry mouth, and dry eyes. Patients with xerostomia may feel like their mouth is full of cotton or that they cannot easily talk or swallow. They are at increased risk of tooth decay because normal levels of saliva in the mouth help to protect against mouth infections and tooth decay. Patients with dry eyes may have a burning sensation in the eyes, blurred vision, or a gritty feeling beneath the eyelid. Drying of the eyes increases the risk of UXL Encyclopedia of Diseases and Disorders

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eye infections and damage to the cornea, the clear front part of the eye where light enters. Other symptoms that patients may have include: • • • • • • • •

Pain and stiffness in the joints and muscles Dry, itchy skin Rashes on the skin of the arms and legs Tingling sensations or numbness in the arms and legs Dryness in the vagina (in women) Chronic dry cough Fatigue or tiredness that is severe enough to interfere with daily life Enlargement of the parotid glands

Diagnosis The diagnosis of Sjögren syndrome is a long and complex process that may take years because the symptoms of the disorder are not specific to it; dry eyes and mouth, for example, can be caused by certain medications, by radiation therapy, or by anxiety disorders as well as by SS. Dry eyes can also be caused by disorders or factors other than SS. The National Institute of Arthritis and Musculoskeletal and Skin Diseases (NIAMS) found that patients who were eventually diagnosed with Sjögren syndrome received the diagnosis from primary care doctors, allergists, dentists, and cancer specialists as well as from rheumatologists, who are doctors who specialize in disorders of the muscles, joints, and connective tissue. Many rheumatologists think that the diagnosis of SS is often missed. The diagnosis is usually based on a combination of the patient’s symptom history and the results of laboratory tests and imaging studies. In taking the history, the doctor will ask about medications the patient may be taking and the amount of fluid that she or he drinks in an average day. In addition, the doctor will examine the patient’s mouth for evidence of an abnormally low production of saliva. In many cases of SS, the patient’s tongue will be dry enough to stick to the doctor’s tongue depressor. Specific laboratory tests and imaging studies may include: • Blood tests. These are done to check the blood cell count and also look for the presence of autoantibodies, which are proteins formed when to body’s immune system attacks its own tissues. • Schirmer tear test. This is a test in which the doctor measures the amount of tears produced by the patient’s tear glands by placing a 960


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•

•

• •

small piece of filter paper underneath the lower eyelid for five minutes and then measuring its wetness with a ruler. Another eye test that may be performed involves staining the surface of the patient’s eye with a dye called rose bengal. The dye will cling to areas of the cornea that have become dried out from SS. The doctor can then examine the patient’s eyes through a slit lamp to determine how much the eye has been damaged by dryness. Sialogram. A sialogram is a special type of imaging study in which a radioactive dye is injected into the patient’s parotid glands. The movement of the dye will help the doctor measure the flow of saliva from the gland into the patient’s mouth. Lip biopsy. The doctor may take a small sample of lip tissue to check for the presence of inflammatory cells associated with SS. Urine test. A urine sample may be analyzed to see whether the patient’s kidneys have been affected by SS.

Treatment There is no cure for Sjögren syndrome. Treatment for the disorder is aimed at relieving symptoms. Dry eyes can be treated by the application of artificial tears in the daytime and lubricating gels or ointments at night. The gels should not be used in the daytime because they can cause blurring of vision. Another drug that can be used is called Lacriserts. It comes in the form of small tablets that the patient places in the lower eyelid. When artificial tears are added, the Lacriserts tablet dissolves and forms a film over the patient’s tears that traps moisture. Patients with dry mouth can be given either Salagen or Evoxac. These are prescription medications that stimulate glands in the mouth to produce more saliva. Patients with SS must see their dentist on a regular basis to prevent tooth decay and eventual loss of teeth. In some cases the dentist may recommend fluoride treatment to provide additional protection for the teeth. Many patients find that taking small frequent sips of water or sugar-free lemon drops helps to relieve dryness in the mouth. Patients with muscle or joint pains caused by Sjögren syndrome can take nonsteroidal anti-inflammatory drugs, or NSAIDs. These drugs include aspirin as well as such pain relievers as ibuprofen and naproxen, and are usually available over the counter. Steroid medications can also be given to patients with SS, but the long-term use of these drugs can cause serious side effects. UXL Encyclopedia of Diseases and Disorders

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WORDS TO KNOW Cornea: The transparent front part of the eye where light enters the eye. Lymphoma: A type of cancer that affects the lymphatic system. Parotid glands: Glands that produce saliva, located on each side of the face below and in front of the ear. Polymyositis: Inflammation of the muscles that causes weakness and difficulty in moving or swallowing.

Rheumatologist: A doctor who diagnoses and treats diseases of the muscles, joints, and connective tissue. Scleroderma: A disorder of connective tissue characterized by thickening and tightening of the skin as well as damage to internal organs. Slit lamp: An instrument that focuses light into a thin slit. It is used by eye doctors to examine eyes for a wide variety of disorders. Xerostomia: The medical term for dry mouth.

Prognosis The prognosis of patients with Sjögren syndrome is generally good. About 5 percent of patients with SS eventually develop lymphoma, or cancer of the lymph nodes. Some patients also develop inflammatory disorders of the lungs, kidneys, or liver. The majority of patients, however, are able to manage the symptoms of the disease quite well and have a normal life expectancy. The most common complications of SS for the majority of patients are an increased risk of dental cavities and eye infections.

Prevention There is no known way to prevent Sjögren syndrome because the causes of the disorder are not yet completely understood.

The Future Sjögren syndrome is not likely to become more common in the general population because it is not inherited and is not contagious. Research in the early 2000s is focused on searching for the cause of the disorder, improving the speed and accuracy of diagnosis, and looking for potential cures. SEE ALSO

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Lupus; Lymphoma; Rheumatoid arthritis; Tooth decay UXL Encyclopedia of Diseases and Disorders

Skin Cancer


Carsons, Steven, and Elaine K. Harris, eds. The New Sjögren’s Syndrome Handbook. New York: Oxford University Press, 1998. This book was written for patients diagnosed with the disorder and their families. National Institute of Arthritis and Musculoskeletal and Skin Diseases (NIAMS). Questions & Answers about Sjögren’s Syndrome, revised edition. Bethesda, MD: NIAMS, 2006. This is a 40-page booklet about Sjögren’s syndrome for general readers. WE B S IT E S

American College of Rheumatology (ACR). Patient Education: Sjögren’s Syndrome. Available online at http://www.rheumatology.org/public/factsheets/ sjogrens.asp?aud=pat (accessed May 23, 2008). Mayo Clinic. Sjögren’s Syndrome. Available online at http://www.mayoclinic. com/health/sjogrens-syndrome/DS00147 (accessed May 22, 2008). Sjögren’s Syndrome Foundation (SSF). What Is Sjögren’s Syndrome? Available online in PDF format at http://www.sjogrens.org/images/SSF%20patient% 20brochure.pdf (accessed May 22, 2008).

Skin Cancer Definition Skin cancer is the uncontrolled growth of abnormal cells in the upper layer of the skin. It is the most common form of cancer among American adults. According to the American Cancer Society (ACS), more than a million cases of skin cancer are diagnosed each year in the United States.

Description Skin cancers develop in the epidermis, which is the outermost layer of the skin and contains several layers of cells within itself. In these layers there are several different types of cells. Skin cancers are classified by the type of epidermal cell that is affected: • Basal cell carcinoma (BCC). Basal cells are cells in the lowermost layer of the epidermis. Basal cell carcinoma is the single most common type of skin cancer. These cancers appear on the head, neck, and hands as small fleshy bumps, nodules, or red patches. UXL Encyclopedia of Diseases and Disorders

Also Known As Carcinoma of the skin; melanoma Cause Genetic factors and exposure to ultraviolet radiation Symptoms Unexpected changes in the color or texture of the skin; growths on the skin that bleed, appear suddenly, or do not heal Duration Months to years 963

Skin Cancer Tanning, from natural sunlight or from the use of tanning beds, can increase a person's risk of skin cancer. SHUTTERSTOCK.

They are slow-growing and rarely metastasize (spread to other parts of the body). • Squamous cell carcinoma (SCC). Squamous cells are flat scale-like cells that form one or more layers in the middle layer of the epidermis. SCC is the second most common type of skin cancer. It may be preceded by precancerous patches of scaly skin called solar keratoses, which develop from overexposure to sunlight. Squamous cell carcinomas are most likely to appear on the ears, lips, tongue, mouth, or face. Unlike basal cell carcinomas, SCCs can invade deeper layers of tissue and spread to other parts of the body. • Melanoma. Melanoma is the rarest type of skin cancer but also the deadliest. It develops in the melanocytes, which are cells in the lower part of the epidermis that produce a dark brownish-black pigment called melanin. Melanoma may appear suddenly as a dark patch on the skin or develop in or near a mole. It can spread rapidly to nearby lymph nodes and then to the liver, lungs, or brain.

Demographics Skin cancer affects adults far more often than children; basal cell carcinoma rarely occurs in people younger than forty years of age. The average age of people diagnosed with melanoma is fifty-three; however, it is the most common cancer in women aged twenty-five to twenty-nine years and is second only to breast cancer in women aged thirty to thirty-four years. 964


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About one in five persons in the United States will develop skin cancer in his or her lifetime. Most skin cancers—96 percent—are either basal cell carcinomas or squamous cell carcinomas. Though they rarely cause death, these two types of skin cancer cost the United States over $1.5 billion for treatment each year. Melanoma accounts for only 4 percent of skin cancers in the United States, but it is responsible for 75 percent of deaths from skin cancer. About 8,500 Americans die each year from melanoma, 5,500 men and 3,000 women. Although melanoma is more common in women than men up to age forty, in adults over forty it is more common in men. In the United States, melanoma affects Caucasians twenty times more often than African Americans, and six times more often than Hispanics. Risk factors for skin cancer include: • Having fair skin that freckles or burns easily • Living in areas that get high levels of ultraviolet radiation, such as mountainous regions or countries closer to the equator • Having a job that requires working outdoors during daylight hours • A family history of skin cancer • Having a disorder that affects the immune system, or a history of radiation therapy for cancer • Having scars or burns on the skin (Fragile skin is more easily damaged by sun.) • Exposure to certain chemicals in the environment, including arsenic and some types of weed killers • History of blistering sunburns in childhood or adolescence • Having a large number of moles • Developing solar keratoses

Causes and Symptoms The basic cause of skin cancer is overexposure to the sun or to artificial sources of ultraviolet light like sunlamps or tanning booths. Ultraviolet light can damage the DNA, or genetic information, in skin cells, changing their genetic code and altering the function of those cells. Uncontrolled multiplication of these damaged skin cells can result in cancer. Genetic factors are also involved. Skin color and sensitivity to the sun are inherited characteristics. In addition, melanoma is known to run UXL Encyclopedia of Diseases and Disorders

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in some families. Researchers have identified mutations in genes on chromosomes 1, 9, and 12 as linked to familial melanoma. The symptoms of basal cell and squamous cell carcinomas include: • Waxy or pearly bumps on the face, ears, or neck • Flat brownish patches on the chest or back • Firm red lumps or nodules on the face, lips, ears, neck, hands or arms • Flat patches or lesions with scaly, crusted surfaces on the face, ears, neck, hands or arms The signs of melanoma are sometimes called the ABCDs. A mole developing into melanoma may show: • Asymmetry. Half of the mole looks different from the other half in size, shape, or color. • Border irregularity. The mole has a ragged or poorly defined border. • Color. The color is not uniform; the mole has dashes of blue, red, or white mixed in with patches of brown or black. • Diameter. The mole is larger than the end of a pencil eraser (about 6 millimeters). Melanoma may also appear as skin growths that bleed easily or do not heal.

Diagnosis About 80 percent of skin cancers are found by patients who notice suspicious changes in their skin and go to their doctor. To diagnose skin cancer, the doctor will take a small sample of the abnormal skin to be sent to a laboratory for analysis under a microscope. This procedure is called a biopsy. The doctor may remove the entire growth, part of the growth, or shave a layer of cells from its surface. Biopsies are done under local anesthesia.

Treatment Surgery is the most common treatment for skin cancer and solar keratoses. If the entire growth was removed for a biopsy, no further treatment may be needed. In some cases the cancerous areas can be removed with topical (applied directly to the skin) medications. Other treatment options include: 966


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• Cryotherapy. This approach involves freezing the abnormal growths with liquid nitrogen. • Standard surgery. The doctor cuts out the entire cancer and surrounding tissue. If the cancer is on the face, plastic surgery may be required later to restore the patient’s appearance. • Electrodessication. This is a form of treatment that involves desiccating, or drying out, skin cancers with an electric needle. It is usually done to treat small or shallow basal cell carcinomas. • Laser surgery. This type of surgery is often done to treat cancers on the lips or cancers in the upper layers of the skin. • Mohs surgery. Named for the surgeon who developed the technique in the late 1930s, Mohs surgery involves removing very thin layers of cancerous tissue and examining each layer under the microscope until all the cancer has been removed while leaving nearby healthy tissue unaffected. It is generally used for basal cell and squamous cell carcinomas. • Radiation therapy and chemotherapy. These are used to treat metastatic melanoma and large BCCs and SCCs when surgery is not an option.

Prognosis The prognosis of skin cancer depends on a number of factors: the patient’s skin type, the type of cancer involved, the length of time before diagnosis and treatment, and the patient’s overall health. In general, skin cancer is highly curable. Basal cell carcinoma and squamous cell carcinoma do not spread to other parts of the body as readily as melanoma; they have a 95 percent cure rate when treated early. Melanoma, however, can metastasize to other parts of the body and is potentially deadly. Patients diagnosed and treated before their melanoma spreads to the lymph nodes have a five-year survival rate of 91 percent; however, those whose melanoma has spread to the lungs or liver have a five-year survival rate of only 7–10 percent, with an average life expectancy of six to nine months.

Prevention People cannot change their skin type, but they can lower their risk of skin cancer by taking the following precautions against sun exposure: UXL Encyclopedia of Diseases and Disorders

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• Avoid the use of tanning booths and sun lamps. • Stay out of the sun between 10 A.M. and 4 P.M. • Use a sunscreen with a sun protection factor (SPF) of 15 or higher every day. People with very fair skin should use a product with an SPF of 30 or higher. • Apply sunscreen over the entire body thirty minutes before going outside, and reapply the product every two hours. • Use a lip balm that contains sunscreen. • Wear clothing that covers as much of the body as possible, including a broad-brimmed hat and sunglasses to protect the eyes. • Keep infants under six months out of the sun altogether, and using sunscreen on infants older than six months. Another important form of preventive care is regular self-examination of one’s skin. The American Academy of Dermatology (AAD) outlines the steps: • A person should first become familiar with his or her birthmarks, moles, freckles, and other skin blemishes in order to spot new growths or suspicious changes. • Use a well-lit private room with a full-length mirror; take along a handheld mirror in order to see the back, buttocks, and other parts of the body that require a second mirror. • It is important to check all parts of the body, not just those exposed to sunlight. Begin with the upper body, front and back; then the arms. Women should look underneath their breasts. • Sitting in front of the mirror, examine the legs, genitals, soles of the feet, and the skin between the toes. • Examine the back of the neck and scalp using the handheld mirror. Part the hair at intervals to check the entire scalp. People with an increased risk of skin cancer should see a dermatologist regularly and also ask their primary care doctor to look for changes in their skin during checkups.

The Future Skin cancer is a major concern to doctors around the world because the rates of all types of skin cancer are increasing worldwide. These increases are partly the result of increased longevity, as the risk of skin cancer rises in 968


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WORDS TO KNOW Carcinoma: The medical term for any type of cancer that arises from the skin or from the tissues that line body cavities. Cryotherapy: The use of extreme cold to destroy cancerous tumors or other diseased tissue. It is also called cryosurgery. Dermatologist: A doctor who specializes in diagnosing and treating skin disorders. Epidermis: The outermost layer of the skin. Melanin: A brownish-black skin pigment. Melanoma: The most serious form of skin cancer.

Metastasis (plural, metastases): A secondary tumor caused by the spread of cancer from its primary location to another part of the body. Mohs surgery: A technique for removing skin cancers in very thin layers one at a time in order to minimize damage to healthy skin. Solar keratoses (singular, keratosis): Rough scaly patches that appear on sun-damaged skin. They are considered precancerous. Topical: Referring to any medication that is applied to the skin or the outside of the body.

people over forty and even higher in people over sixty-five. Another factor is the ongoing popularity of tanning, whether in the sun or under artificial sunlamps. Melanoma in particular has increased around the world since the 1990s, with the highest rates as of 2008 in Australia and New Zealand. SEE ALSO

Dermatitis; Sunburn; Xeroderma pigmentosum


Buckmaster, Marjorie L. Skin Cancer. New York: Marshall Cavendish Benchmark, 2008. McNally, Robert A., ed. Skin Health Information for Teens. Detroit, MI: Omnigraphics, 2003. So, Po-Lin. Skin Cancer. New York: Chelsea House, 2008. WE B S IT E S

American Academy of Dermatology (AAD). Skin Cancer. Available online at http://www.aad.org/public/publications/pamphlets/sun_skin.html (accessed August 8, 2008). American Academy of Family Physicians (AAFP). Skin Cancer: Saving Your Skin from Sun Damage. Available online at http://familydoctor.org/online/ famdocen/home/common/cancer/risk/159.html (accessed August 8, 2008). Centers for Disease Control and Prevention (CDC). Skin Cancer: Questions and Answers. Available online at http://www.cdc.gov/cancer/skin/ chooseyourcover/qanda.htm (accessed August 8, 2008). UXL Encyclopedia of Diseases and Disorders

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National Cancer Institute (NCI). What You Need to Know about Skin Cancer. Available online at http://www.cancer.gov/cancertopics/wyntk/skin/allpages (accessed August 8, 2008). National Human Genome Research Institute (NHGRI). Learning about Skin Cancer. Available online at http://www.genome.gov/10000184 (accessed August 8, 2008). National Library of Medicine (NLM). Skin Cancer. Available online at http:// www.nlm.nih.gov/medlineplus/tutorials/skincancerandmelanoma/htm/ index.htm (accessed August 7, 2008). This is an online tutorial with voiceover; viewers have the option of a self-playing version, a text version, or an interactive version with questions.

Sleep Apnea Definition

Also Known As Sleep apnea syndrome Cause Periodic pauses in breathing during sleep Symptoms Snoring, daytime tiredness, morning headaches, trouble concentrating, changes in mood or behavior Duration Months to years unless treated or corrected 970

Sleep apnea is a sleep disorder in which a person’s breathing stops and starts over and over in the course of their sleep time. There are three basic forms of sleep apnea: obstructive sleep apnea (OSA), in which the interruptions in breathing are caused by a physical blockage of the airway, usually loosened tissues in the back of the throat; central sleep apnea (CSA), which results from irregular signals from the part of the brain that controls breathing; and complex (or mixed) sleep apnea, which is a combination of obstructive sleep apnea and central sleep apnea. Obstructive sleep apnea is the most common type, accounting for about 90 percent of cases.

Description Sleep apnea is a sleep disorder characterized by interruptions in breathing in which the person misses one or more breaths over an interval of ten seconds or longer; these episodes of interrupted breathing occur repeatedly during sleep. Some people have as many as several hundred episodes of apnea during their sleep time. In normal sleep, the muscles at the back of throat relax, but remain open far enough to allow air to pass through the airway into the lungs. In obstructive sleep apnea, the muscles in the back of the person’s throat are too relaxed and allow the tongue, the tonsils, the soft palate, or the UXL Encyclopedia of Diseases and Disorders

Sleep Apnea Patient wearing a continuous positive airway pressure device used to diagnose and monitor patients with sleep apnea. © MEDICAL-ON-LINE / ALAMY.

uvula—a triangular flap of tissue at the back of the soft palate—to slip backward or downward and block the airway. In some people, airway blockage may be the end result of certain physical features, such as an unusually narrow airway, a large neck, or a recessed chin. When the airway closes, the person typically begins to snore or gasp for breath. As the oxygen supply in the person’s blood drops, the brain gives a signal that arouses the person from sleep in order to start breathing again. The person usually does not remember waking up in order to breathe; however, their sleep is not restful because of the frequent interruptions and the person feels tired or sleepy the next day. Central sleep apnea is unusual in people who are otherwise healthy. It is most likely to occur in people with heart disease, stroke, or damage to the brain stem—the part of the brain that controls breathing. Central sleep apnea occurs when the brain fails to transmit its normal signals to the breathing muscles. The affected person may awaken feeling short of breath or have a difficult time falling or staying asleep. As with obstructive sleep apnea, central sleep apnea can result in snoring and daytime sleepiness. Sleep apnea is a potentially severe long-term health problem. People who are not treated for sleep apnea have a 30 percent higher risk of heart attack or premature death because the drop in the oxygen level of the blood that occurs when breathing stops temporarily can eventually damage the heart. Sleep apnea also increases a person’s risk of stroke and UXL Encyclopedia of Diseases and Disorders

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high blood pressure. In addition, a study conducted in 2007 reported that the brains of people with obstructive sleep apnea show evidence of tissue shrinkage in the parts of the brain that store memory. These findings help to explain why sleep apnea can lead to memory loss. Sleep apnea can endanger the well-being of others as well as the patients themselves. Daytime sleepiness is a risk factor for motor vehicle accidents; one study showed that people with sleep apnea are three times more likely to be involved in accidents than people who do not have the disorder.

Demographics Sleep apnea is a common sleep disorder in the general American population. According to the National Institutes of Health (NIH), as many as eighteen million adults suffer from sleep apnea, with as many as ten million more who have the condition but have not been diagnosed. Several risk factors for sleep apnea have been identified: • Age. Middle-aged adults are more likely to have sleep apnea than children or adolescents. About 4 percent of middle-aged men and 2 percent of middle-aged women in the United States have been diagnosed with sleep apnea, while about one person in ten over the age of sixty-five has the disorder. • Sex. Men are twice as likely as women to develop sleep apnea • Race and ethnicity. African Americans, Pacific Islanders, and Hispanics are at greater risk of sleep apnea than Caucasians, Asian Americans, or Native Americans. • Weight. Obesity is a major risk factor in sleep apnea. • Physical features. A large neck, narrow airway, small mouth or nose, enlarged tonsils, or a receding chin can all increase a person’s risk of sleep apnea. • Lifestyle. Drinking alcohol and smoking increase the risk of sleep apnea. • Heredity. Sleep apnea is known to run in families, although no specific genes associated with sleep apnea have been identified as of 2008. • Medications. Certain types of prescription drugs, particularly antidepressants, tranquilizers, and sleeping pills, increase the risk of sleep apnea. 972


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• Allergies. Hay fever and other allergies that cause swelling of the tissues in the nose and throat increase a person’s risk of sleep apnea.

Causes and Symptoms Sleep apnea has a number of possible causes ranging from congenital abnormalities in the shape of the nasal passages and airway to medical disorders or lifestyle choices that contribute to blockage of the upper airway during sleep. In addition to daytime sleepiness, irritability, and difficulty concentrating, symptoms of sleep apnea may include: • • • • • • • •

Loud snoring Waking up abruptly and feeling short of breath Waking with a dry mouth or sore throat Having a headache in the morning Difficulty staying asleep High blood pressure Swelling of the legs Poor judgment and memory loss

Diagnosis The diagnosis of sleep apnea is often missed, particularly in those who live alone, because people with the disorder often do not remember being aroused from sleep by the need to start breathing again. Those who share a bedroom with another family member, however, may consult their doctor when the other person complains about snoring or notices that the person with sleep apnea sometimes stops breathing completely. The doctor will take the patient’s history, including a medication history, allergy history, and a family history of sleep apnea. The patient may be referred to a dentist or oral surgeon for detailed evaluation of their throat, mouth, and airway if appropriate. The patient may also be referred to a sleep laboratory or sleep disorder center for polysomnography. A polysomnograph is a machine that measures the patient’s heart, lung, and brain activity during sleep, along with their breathing patterns, arm and leg movements, and blood oxygen levels. There are also portable machines that will measure the patient’s blood oxygen level, airflow, and breathing patterns during sleep. In some circumstances the doctor may allow the patient to use one of these simpler machines at home to help diagnose sleep apnea. UXL Encyclopedia of Diseases and Disorders

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Treatment The treatment of sleep apnea depends partly on its cause or causes. Changes in lifestyle—particularly losing weight, quitting smoking, and cutting back on alcohol intake—may be enough to control obstructive sleep apnea in some people. According to the American Association for Respiratory Care, losing as little as 10 percent of body weight can reduce the number of times a person with obstructive sleep apnea stops breathing during sleep. If the sleep apnea is related to prescription medications, the patient’s doctor may be able to adjust the dosages or substitute different drugs. Nasal sprays or allergy medications may relieve sleep apnea caused by swollen nasal tissues. Changes in sleeping position may also help. The NIH recommends sleeping on the side rather than the back to help keep the throat open during sleep. Special pillows that prevent the person from turning onto the back are available. Another treatment that works well for some patients with mild to moderate sleep apnea is an oral appliance fitted by a dentist for use at night. These devices are designed to keep the throat open at night by bringing the jaw forward. The dentist will check the appliance periodically to make sure that it fits correctly and that the patient’s symptoms are improving. In children or adults with enlarged tonsils, a simple tonsillectomy may cure the sleep apnea. There are also surgical procedures that can be done to correct problems in the nasal passages, such as irregularly shaped passageways or benign growths of tissue called polyps. Severe obstructive sleep apnea, however, may involve one or more of the following types of surgery: • Surgery to remove or shrink part of the uvula or the soft palate. This type of procedure is usually done in a hospital under general anesthesia. • Relocation or repositioning of the upper and lower jaws. This procedure is usually done by a team that includes an oral surgeon and an orthodontist. Bringing the upper and lower jaws forward enlarges the space behind the soft palate and reduces the risk of airway obstruction during sleep. • Tracheostomy. This procedure is usually performed only when the person’s sleep apnea is life-threatening and other treatments have failed. The surgeon cuts a hole in the front of the neck and inserts 974


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a metal or plastic tube to provide the patient with an artificial airway. Patients with moderate or severe sleep apnea may benefit from continuous positive airway pressure, or CPAP. CPAP is a machine that delivers air through a mask into the patient’s nose during sleep. Positive pressure means that the air delivered by the machine is under slightly greater pressure than the air in the room, and this additional pressure keeps the airway open. CPAP machines have adjustable pressure settings, and the mask can also usually be adjusted for the patient’s comfort. Patients with central sleep apnea often benefit from having the underlying medical condition treated, particularly if heart failure is involved. Supplemental oxygen therapy and CPAP are also used to treat central sleep apnea.

Prognosis The prognosis of sleep apnea depends on its cause and its severity. People with mild sleep apnea usually do very well with lifestyle adjustments, allergy treatments, or changes in medications. CPAP is an effective treatment for moderate to severe sleep apnea; however, many patients find its side effects (dry nose, irritated facial skin, and headache) bothersome and stop using it. For those patients, surgery is often an effective alternative. Most patients, even those with severe sleep apnea, find that some form of treatment for this disorder can significantly improve their quality of life; it may simply take time to find the most effective treatment for a specific individual.

Prevention Sleep apnea related to a family history of the disorder or the physical characteristics of a person’s throat and facial structure cannot be prevented, only corrected. Keeping one’s weight at a healthful level for one’s sex, age, and height, drinking only in moderation, and quitting smoking (or never starting to smoke), however, can lower an individual’s risk of developing sleep apnea in middle age.

The Future Sleep apnea is a condition that is presently attracting many researchers in the fields of psychology and neurology as well as sleep medicine. As of 2008, the National Institutes of Health was conducting 134 different UXL Encyclopedia of Diseases and Disorders

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WORDS TO KNOW Apnea: Temporary stopping of breathing. Congenital: Present at birth. Polysomnograph: A machine used in a sleep laboratory to monitor chest movement, air flow,

brain waves, heart rhythm, and other data relevant to diagnosing sleep disorders. Uvula: A triangular piece of soft tissue located at the back of the soft palate.

studies on sleep apnea, ranging from evaluations of surgical treatments and mouth appliances to new drugs and improvements in CPAP. SEE ALSO

Allergies; Childhood obesity; Heart failure; Obesity; Smoking; Sudden infant death syndrome


Chokroverty, Sudhansu. Questions and Answers about Sleep Apnea. Sudbury, MA: Jones and Bartlett Publishers, 2009. Foldvary-Schaefer, Nancy. Getting a Good Night’s Sleep. Cleveland, OH: Cleveland Clinic Press, 2006. Pascualy, Ralph. Snoring and Sleep Apnea: Sleep Well, Feel Better. 4th ed. New York: Demos Health, 2008. WE B S IT E S

American Academy of Family Physicians (AAFP). Sleep Apnea. Available online at http://familydoctor.org/online/famdocen/home/articles/212.html (accessed July 18, 2008). American Association for Respiratory Care. Sleep Apnea Facts. Available online at http://www.yourlunghealth.org/lung_disease/sleep_apnea/facts/ (accessed July 18, 2008). American Sleep Apnea Association. Information for the Patient. Available online at http://www.sleepapnea.org/info/patient.html (accessed July 18, 2008). National Heart, Lung, and Blood Institute (NHLBI).What is Sleep Apnea? Available online at http://www.nhlbi.nih.gov/health/dci/Diseases/ SleepApnea/SleepApnea_WhatIs.html (accessed July 18, 2008). National Institute of Neurological Disorders and Stroke (NINDS). Sleep Apnea Information Page. Available online at http://www.ninds.nih.gov/disorders/ sleep_apnea/sleep_apnea.htm (accessed July 18, 2008). Sleep Apnea Specialty Centers of Michigan. Sleep Apnea Movies and Animations. Available online (links are located immediately below the box at the left of the web page) at http://www.sleepapneacenter.com/ (accessed July 18, 2008). The movie shows a patient with sleep apnea before and after using CPAP, while the animations demonstrate how the structure of the upper throat can lead to sleep apnea. 976


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Sleep Disorders Sleep disorders are a group of health problems that include difficulty falling or staying asleep, falling asleep at inappropriate times, excessive total sleep time, or abnormal behaviors associated with sleep. Doctors generally classify sleep disorders into three broad categories: those that involve either sleeping too much or not getting enough sleep; those that involve sleepwalking, nightmares, and other forms of arousal from sleep; and those related to medical or psychiatric conditions that affect sleep. The first category—disturbances in the amount of sleep—include narcolepsy, sleep apnea, and restless legs syndrome. Another type of sleep disorder in this category is jet lag, which is caused by changes in the person’s normal sleep/wake cycle resulting from travel across several time zones. Older adults sometimes have trouble getting enough sleep because their sleep/wake cycle does not work as well as it did when they were younger. Medical and psychiatric conditions that are associated with sleep disorders include alcoholism, depression, panic disorder, schizophrenia, and posttraumatic stress disorder. Most adults need about eight hours of sleep to feel fully alert during their waking hours. Teenagers need even more—8.5–9 hours of sleep per night. Getting help for a sleep disorder is important because lost sleep can affect physical coordination (including safe driving) as well as emotions and the ability to pay attention and think clearly. SEE ALSO

Alcoholism; Depression; Narcolepsy; Panic disorder; Posttraumatic stress disorder; Restless legs syndrome; Schizophrenia; Sleep apnea

Smallpox Definition Smallpox is an infectious disease caused by the variola virus. Researchers think that it originated in rats or mice somewhere in Africa and was UXL Encyclopedia of Diseases and Disorders

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transmitted to humans around 10,000 BCE. The disease presently affects only humans and cannot be acquired from any animal. There are two types of smallpox, variola major and variola minor. Variola major is the more severe of the two, accounting for about 90 percent of cases; it has a mortality rate of 30–35 percent. Variola minor, sometimes nicknamed white pox, cotton pox, or Cuban itch, is a milder disease that kills less than 1 percent of those infected. Each type of smallpox makes a person who survives it immune to both forms of the disease.

Description

Also Known As Variola major, variola minor Cause Virus Symptoms High fever; rash that becomes pus-filled sores; vomiting; severe headache; delirium Duration Two to three weeks 978

Smallpox is one of the most destructive diseases known to humankind. It was first called smallpox in the fifteenth century to distinguish it from syphilis, which was then called the Great Pox. About 400,000 people died each year from smallpox in Europe alone for most of the eighteenth century. During the twentieth century between 300 and 500 million people around the world died from smallpox. The mortality rate rose as high as 60 percent in some countries, with 80 percent of infected children dying from the disease. Smallpox was gradually eliminated following the development of an effective vaccine against it in 1796. Edward Jenner (1749–1826), an English doctor, had noticed that milkmaids rarely got smallpox and theorized that they were protected by exposure to cowpox, a disease similar to smallpox but much less deadly. Jenner tested his theory by inoculating an eight-year-old boy with pus taken from a milkmaid’s cowpox blisters and showing that the boy was immune to smallpox. Jenner’s early vaccine was refined and introduced in the developed countries during the nineteenth century. The term vaccination was derived from the French word for cow related to the original source of the immunization virus. By 1897, smallpox had been virtually eliminated in the United States; the last case of smallpox in North America was reported in 1949. In the 1960s, the World Health Organization (WHO) led a worldwide effort to eradicate smallpox. A team of scientists led by Donald Henderson (1928–) was formed to vaccinate people in developing countries. The last case of naturally occurring smallpox was diagnosed in Somalia in 1977. In 1980 WHO declared that smallpox had been eradicated. As of 2008 two laboratories, one at the Centers for Disease Control and Prevention (CDC) and the other in Russia, maintained small stocks of the smallpox virus for research purposes. UXL Encyclopedia of Diseases and Disorders

Smallpox Smallpox sores on the hand and arm. © MEDICAL-ON-LINE / ALAMY.

The disease itself is characterized by a prodrome, or period of warning symptoms, characterized by high fever (101–104°F [38.3°C–40°C]) and flu-like symptoms that include severe headache and fatigue. The prodrome lasts between two and five days and is followed by red spots on the face and in the mouth, developing into open sores that spread the virus within the mouth and throat. About a day later, a rash spreads over the body that turns into papules (raised pimples) within three days. Unlike chickenpox, the skin lesions of smallpox are all in the same stage of development at the same time. The papules fill with a pus-colored fluid and may feel as if a hard, small, marble bead is present under the skin. The papules gradually form scabs that fall off the body, often leaving scar tissue behind. In fatal cases, death occurs between ten and sixteen days after the first symptoms.

Demographics Smallpox is equally likely to infect people of any race or age group and people of either sex during an epidemic. The chief difference is the mortality rate. People who are at increased risk of dying from smallpox if they become infected include: • • • •

Pregnant women Young children Elderly adults Anyone who has never been vaccinated against smallpox


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Causes and Symptoms The cause of smallpox is the variola virus, which usually enters the body through the mouth and respiratory tract. In most cases the virus is usually transmitted from person to person by close contact (within 6 feet [2 meters]); smallpox is not as easily transmitted as measles or influenza. The virus has an incubation period of seven to seventeen days before the prodrome occurs. Once in the person’s mouth or throat, the smallpox virus multiplies rapidly in nearby lymph nodes and then enters the bloodstream. It is carried to the spleen, bone marrow, liver, and kidneys. People who have been infected with the virus can transmit it to others late during the prodrome; however, they are most contagious when the rash appears. In addition to high fever and the characteristic rash, the symptoms of smallpox may include: • Severe headache • Fatigue • Muscle aches and pains • Severe back pain • Vomiting, diarrhea, or both • Delirium • In some cases, heavy bleeding in the internal organs Patients who survive smallpox often have complications: • Permanent scars on the face. Called pock marks, these scars occur in about 80 percent of people who survive the disease. Queen Elizabeth I of England and the Russian dictator Josef Stalin were scarred by the disease; the queen wore heavy makeup in later life to try to hide her pock marks. • Eye infections. About 20 percent of survivors develop conjunctivitis; a few become permanently blind. • Infection of the bone. Between 2 and 20 percent of children who get smallpox develop an infection of the bone or bone marrow known as osteomyelitis.

Diagnosis The most important aspect of diagnosing smallpox is distinguishing it from chickenpox. This is particularly important since most doctors in 980


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developed countries have never seen a case of smallpox. There are three major differences between chickenpox and smallpox: • The skin lesions of chickenpox occur mostly on the face and trunk rather than the face, arms and legs. They are also shallower and do not feel as if there is a hard object inside them. • Chickenpox lesions occur in waves or crops, so that the patient may have lesions at different stages of development at the same time. In smallpox, the lesions are all at the same stage of development at a given time. • Chickenpox is contagious before the infected person feels sick, whereas smallpox is not contagious until the symptoms appear. Diagnosis is based on a combination of the patient’s history— particularly a prodrome with fever two to four days before the rash appeared, and the appearance of the rash (lesions are hard to the touch, appear to be deep within the skin, and appeared first on the face, mouth, and forearms)—and a laboratory test. To test for the virus, the doctor will swab the patient’s throat or take a smear from one of the skin lesions. The sample will be sent to a state health department laboratory for examination under an electron microscope or tested by a technique called polymerase chain reaction or PCR. Under a microscope, a cell infected with the smallpox virus will have pink clumps of the virus known as Guarnieri bodies, named for the Italian doctor who discovered them. PCR is a technique that identifies the virus’s DNA. Accurate diagnosis of a suspected case of smallpox is critical because it would be considered a major public health emergency. In the United States, the Centers for Disease Control and Prevention (CDC) and the United States Army Medical Research Institute of Infectious Diseases (USAMRIID) must be consulted and public health officials notified.

Treatment There is no medication that can be given to cure smallpox; the goal of treatment is to keep the patient alive and isolated from others until he or she is no longer contagious. Once the patient has been taken to the hospital, the mainstays of treatment are supportive care and antibiotics to prevent bacterial infections from developing. Vaccination with smallpox vaccine can lessen the severity of the infection if given within four days of infection. However, since the incubation period of the disease is longer than four days, vaccination is primarily useful in protecting UXL Encyclopedia of Diseases and Disorders

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health care workers and others who may have been in contact with the person. The most important treatment measure is isolating the patient in order to prevent the disease from spreading further. The procedure that it usually followed is called ring vaccination. Everyone who has been in contact with the patient within the previous seventeen days, including hospital staff, is placed in quarantine and given smallpox vaccine. In addition, local, state, and federal health authorities are notified at once.

Prognosis The prognosis for recovery from smallpox depends on the form of the disease and the patient’s age and general health. Variola major has a death rate around 30 to 35 percent in unvaccinated people, although the rate rises to 60 percent in unvaccinated pregnant women. Variola minor has a mortality rate of about 1 percent. There are rare forms of variola major called hemorrhagic smallpox and malignant smallpox, both of which have fatality rates above 99 percent.

Prevention Smallpox can be prevented by vaccination. Although compulsory vaccination for the general population was discontinued in 1980 and for military personnel in 1989, vaccination against smallpox was reintroduced after the terrorist attacks of 9/11 for health care workers and members of the armed forces. Some public health officials are concerned about the possibility of a major smallpox epidemic in the event of a laboratory accident or act of bioterrorism, as the smallpox vaccine is thought to be effective for only ten years. In addition to the fact that most people in the United States have not been vaccinated since 1980, an estimated 42 percent of the population has never been vaccinated. Apart from vaccination, the only preventive measures that are even partly effective are isolation and quarantine of persons thought to be infected with smallpox.

The Future The major concern for the future regarding smallpox is the possibility of large-scale epidemics in the event of accidents or terrorist attacks. Smallpox would be a deadly biological weapon because only ten to one hundred particles of the virus are needed to infect a person. In 1978, the 982


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WORDS TO KNOW Bioterrorism: The use of disease agents to frighten or attack civilians.

Papule: A small cone-shaped pimple or elevation of the skin.

Delirium: A suddenly developing mental disturbance characterized by confused thinking, difficulty focusing attention, and disorientation.

Prodrome: A group of warning signs or symptoms that appear before the onset of a disease.

Eradication: The complete elimination of a disease.

Quarantine: The practice of isolating people with a contagious disease for a period of time to prevent the spread of the disease.

Lesion: A general term for any skin injury.

year after the last reported case of naturally occurring smallpox, two people in England died of smallpox through a laboratory accident. As a result of the accident, all known stocks of the smallpox virus were either destroyed or sent to two laboratories, one at the CDC and the other in Russia. The remaining supplies of the virus were originally scheduled to be destroyed in 1995, but the WHO decided in 2002 to preserve the virus for development of new vaccines, diagnostic tests, and drugs that might be effective in treating smallpox. SEE ALSO

Anthrax; Chickenpox; Conjunctivitis; Plague


Krasner, Robert I. Twentieth-Century Microbe Hunters. Sudbury, MA: Jones and Bartlett Publishers, 2008. Chapter 6 is about Dr. Donald Henderson and the eradication of smallpox. Sherman, Irwin W. Twelve Diseases That Changed Our World. Washington, DC: ASM Press, 2007. Syphilis is the subject of Chapter 4, “Smallpox: The Speckled Monster.” Straus, Eugene, and Alex Straus. Medical Marvels: The 100 Greatest Advances in Medicine. Amherst, NY: Prometheus Books, 2006. PE R I O DI C A L S

Barquet, Nicolau, and Pere Domingo. “Smallpox: The Triumph over the Most Terrible of the Ministers of Death.” Annals of Internal Medicine 127 (October 15, 1997): 635–642. Available online at http://www.annals.org/ cgi/content/full/127/8_Part_1/635 (accessed September 11, 2008). This is an article about the history of smallpox epidemics, Jenner’s development of his vaccine, and the gradual eradication of the disease. UXL Encyclopedia of Diseases and Disorders

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Preston, Richard. “A Reporter at Large: The Demon in the Freezer.” New Yorker, July 12, 1999, 44–61. Available online at http://cryptome.org/ smallpox-wmd.htm (accessed September 12, 2008). This is an article about the potential use of smallpox as an agent of bioterrorism. WE B S IT E S

Centers for Disease Control and Prevention (CDC). Smallpox Home Page. Available online at http://emergency.cdc.gov/agent/smallpox/index.asp (accessed September 11, 2008). Mayo Clinic. Smallpox. Available online at http://www.mayoclinic.com/health/ smallpox/DS00424 (accessed September 11, 2008). National Institute of Allergy and Infectious Diseases (NIAID). Smallpox. Available online at http://www3.niaid.nih.gov/topics/smallpox/default.htm (accessed September 11, 2008). NOVA Online. Agents of Bioterror: Smallpox. Available online at http://www. pbs.org/wgbh/nova/bioterror/agen_smallpox.html (accessed September 12, 2008). TeensHealth. Smallpox. Available online at http://kidshealth.org/teen/ infections/skin_rashes/smallpox.html (accessed September 11, 2008).

Smoke Inhalation Definition Smoke inhalation (SI) is a health problem and potential emergency caused by exposure to the heat and smoke of a fire; to the products of cigarette smoke; or to other sources of outdoor or indoor air pollution. Also Known As Smoke-related injury, SI, inhalation injury Cause Heat, smoke, and other toxic products of a fire Symptoms Coughing, scratchy throat, difficulty breathing, headaches, chest pain, nausea, confusion Duration Seconds to hours 984

Description Smoke inhalation occurs when a person is forced to breathe in (inhale) the toxic gases and particles carried in smoke from a fire, volcanic eruption, or industrial process. Smoke can arise from natural as well as human causes, ranging from lightning strikes, wildfires, and volcanic eruptions to house or building fires, fires following railroad or aviation disasters, pipeline or factory explosions, arson and other criminal acts, and traffic exhaust. Some people also choose to inhale smoke, as when they light up a tobacco or marijuana cigarette. Smoke inhalation damages the respiratory system in one or more of three ways. First, the hot air from a fire can damage the mouth and upper UXL Encyclopedia of Diseases and Disorders

Smoke Inhalation Mother and her baby in Kenya, who suffer from smoke inhalation from their cooking fire. ADAM HART-DAVIS / PHOTO RESEARCHERS, INC.

airway. This thermal injury can be even worse if the hot air is accompanied by steam. Second, a fire can starve the body of needed oxygen, either because the fire is using up the oxygen in a closed space, or because the fire is producing carbon monoxide and other gases that interfere with the blood’s ability to transport oxygen to the brain and heart. Third, smoke often contains chemicals that irritate the tissues of the lungs, causing damage that ranges from triggering the body’s immune system to complete direct destruction of lung tissue.

Demographics Smoke inhalation, rather than burn injuries, is responsible for the majority of fire-related deaths in the United States. Between 50 and 80 percent of deaths related to house fires are caused by SI rather than burns. Fires are the third leading cause of accidental deaths in all age groups in the United States. Arson is the single most common cause of house fires (26 percent), followed by faulty electrical wiring (17 percent) and faulty heating systems (16 percent). Some persons are at greater risk of serious injury from smoke inhalation, including: • Firefighters and emergency workers. • People in occupations that involve making or transporting hazardous materials. UXL Encyclopedia of Diseases and Disorders

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Smoke Inhalation and Personal Safety Smoke inhalation, or SI, can be a serious threat to health. The Centers for Disease Control and Prevention (CDC) recommend the following steps in case of exposure to smoke in a fire or other emergency: • Get away from the source of the smoke as quickly as possible. If in a building, avoid smoke-filled hallways or stairwells. If there are no other ways out of the building, stay as low to the floor as possible and crawl under the smoke toward the closest exit. • Once in an area with fresh air, rest for a few moments and take several slow deep breaths. • Do not return to a burning home or other building until the fire has been completely extinguished and all the smoke has cleared. • Call the doctor if someone exposed to smoke feels feverish or develops a high temperature.

• Children, who are susceptible to airway damage because their airways are still developing and they breathe more air per pound of body weight than adults. • Elderly persons. • People with asthma, bronchitis, emphysema, or other disorders that affect the lungs. • People who are heavy smokers. • People who are under the influence of drugs or alcohol. • Persons who are physically disabled.

Causes and Symptoms Smoke inhalation causes injury or death by a combination of heat damage to the tissues of the mouth and upper throat; oxygen starvation of body tissues; and chemical damage to the tissues of the lungs. Some fires are more dangerous than others in terms of the inhalation injuries they can cause. There are several factors that affect the potential deadliness of smoke from a fire:

• Temperature of the fire. The hotter the fire, the greater the thermal injury to the upper airway. • Location of the fire. Fires inside closed spaces, such as houses or other buildings, aircraft fuselages, railroad cars, etc. use up the oxygen that people trapped inside the space need to breathe. • Materials being burned. Plastics, silk, and wool all release cyanide gas when burned. This gas increases the risk of damage to the central nervous system. The symptoms of smoke inhalation include:

• Call for emergency help at once if the person is wheezing, having trouble breathing, is vomiting, has burns on the face, or seems confused or unusually sleepy. In addition, do not let the injured person try to drive himself or herself to the hospital.

• Cough. The patient will usually bring up mucus, which may be either clear or black (if it contains soot or smoke particles). 986


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• Difficulty breathing, rapid breathing, or hoarse or noisy breathing. • Reddened eyes. • Abnormal skin color. Patients who are oxygen-starved may have pale or bluish skin. A cherry-red color may indicate carbon monoxide poisoning. • Soot in the nostrils or upper throat. • Headache. • Nausea and vomiting. • Changes in level of mental alertness or consciousness. Patients who have been severely affected by smoke inhalation may faint, have seizures, or go into a coma. In some cases the symptoms of smoke inhalation do not appear until a day or two after the fire. People who have been exposed to smoke but seem healthy should be observed or monitored at home for at least forty-eight hours after the fire. The doctor should be called if the person develops a hoarse voice, chest pains, long periods of coughing, or mental confusion.

Diagnosis The diagnosis of smoke inhalation is based on a combination of the patient’s history (which will be obvious if he or she has left or been rescued from a fire) and imaging or laboratory studies. Emergency rescue personnel can check the patient at the scene for evidence of facial burns, soot in the airway, and other external signs of SI. They can also measure the patient’s breathing, pulse, and level of consciousness. After the patient has been taken to the hospital, he or she will usually be given a chest x-ray to check for lung damage; an electrocardiogram to make sure that the heart is functioning adequately; and blood tests to measure the amount of oxygen in the blood or the presence of chemical byproducts of smoke inhalation. The doctor may also use a bronchoscope (a flexible lighted tube that allows the passages into the lungs to be examined and have fluid removed) to look for damage to the respiratory system. In a few cases the patient may be given a CT scan to assess possible brain injury.

Treatment Treatment is based on the severity of the patient’s injuries, as SI can range from minor irritation of the tissues lining the airway to an immediate threat to life. The most important emergency measure is keeping the airway open UXL Encyclopedia of Diseases and Disorders

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and supporting the patient’s breathing. The patient will be given oxygen through a mask or a tube inserted down the throat. The patient may also be given brochodilators, which are medications that relax the tissues in the airway and help to open up the breathing passages. Patients who have inhaled large amounts of carbon monoxide may be put in a hyperbaric oxygen (HBO) chamber, a special room in which the patient is given pure oxygen at two to three times normal atmospheric pressure. Treatment of SI may also include suctioning of excess fluid from the lungs by means of a bronchoscope. This instrument can be used for treatment as well as diagnosis of SI. Patients with mild symptoms from SI are usually kept in the emergency room for observation after treatment for four to six hours. They are advised to return to the hospital at once if their symptoms return or worsen. Those who were exposed to fire in a closed space for longer than ten minutes, have coughed up black mucus, have facial burns, are coughing severely, or have difficulty swallowing are usually admitted directly to the hospital for further treatment.

Prognosis The prognosis of recovery from smoke inhalation depends on a number of factors, including the patient’s age, previous health, the length of time one was exposed to the smoke, and whether he or she was burned in addition to inhaling smoke. The mortality rate from smoke inhalation by itself is about 7 percent; however, the mortality rate is about 29 percent for patients who suffer burns as well as SI. Some people may have chronic shortness of breath or permanent scarring of the lungs following smoke inhalation. These long-term problems are particularly likely to develop in people who smoked, or had asthma or other lung disorders before being exposed to smoke from a fire.

Prevention The CDC recommends the following measures to reduce the risk of illness or death from smoke inhalation: • Install fire, smoke, and carbon monoxide detectors in the home and check them regularly. The absence of a smoke detector increases the risk of death in a fire by about 60 percent. • Follow local air quality reports; listen for news reports about smoke or outdoor air pollution. 988


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WORDS TO KNOW Arson: The intentional setting of a fire in a building or other property. Arson is a criminal act in the United States.

Bronchodilator: A type of medication that relaxes the tissues of a congested or smoke-damaged airway, thus making it easier for the patient to breathe.

Bronchoscope: A flexible lighted tube that can be inserted into the passages leading to the lungs for examination or treatment. Hyperbaric oxygen (HBO): Oxygen that is delivered to a patient in a special chamber at two to three times normal atmospheric pressure. Inhalation: The part of the breathing cycle in which a person takes in air from the outside.

• If the local air quality index indicates that people should stay indoors, indoor air should be kept as clean as possible. Keep doors and windows closed. In hot weather, run the air conditioner with the fresh-air intake closed. • Do not add to indoor air pollution by smoking or by burning wood in fireplaces when outdoor air quality is poor. • Make an escape plan for the home to be followed in case of fire. Practice the escape route with the family, including evacuating pets.

The Future The United States has one of the highest rates of fire fatalities in the developed world—about 2.3 deaths per 100,000 population. A majority of these deaths are due to SI rather than burns. In addition to installing and properly maintaining smoke detectors and alarms, better methods of screening patients for injury from smoke inhalation are needed. One ongoing difficulty with emergency treatment of fire victims is the present lack of tests that are sensitive enough to identify patients who develop delayed reactions to smoke inhalation. SEE ALSO

Asthma; Bronchitis; Carbon monoxide poisoning; Emphysema; Smoking


Barraclough, Sue. Fire Safety. Chicago: Heinemann Library, 2008. Donahue, Jill Urban. Contain the Flame: Outdoor Fire Safety. Minneapolis: Picture Window Books, 2008. UXL Encyclopedia of Diseases and Disorders

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Centers for Disease Control and Prevention (CDC). Emergency Preparedness and Response: Wildfires. Available online at http://www.bt.cdc.gov/disasters/ wildfires/ (updated April 29, 2007; accessed May 28, 2008). eMedicine Health. Smoke Inhalation. Available online at http://www. emedicinehealth.com/smoke_inhalation/article_em.htm (accessed May 28, 2008). National Heart, Lung, and Blood Institute (NHLBI). How the Lungs Work. Available online at http://www.nhlbi.nih.gov/health/dci/Diseases/hlw/ hlw_all.html (accessed May 28, 2008). This page includes an animation with voiceover that describes the respiratory system and its role in the exchange of oxygen and carbon dioxide in the body. The animation takes about three minutes to play.

Smoking Definition Smoking refers to the burning of tobacco (or other plant, like marijuana) in a cigarette, cigar, or pipe in order to inhale the smoke. Smoking is a form of recreational drug use, because tobacco contains a chemical called nicotine that can be absorbed by the lungs when a person breathes in tobacco smoke.

Description Also Known As Nicotine addiction, nicotine dependence Cause Combination of genetic and psychological factors with addictive qualities of nicotine Symptoms Inability to stop smoking; withdrawal symptoms Duration Years 990

Smoking has been practiced by humans since at least 5000 BCE as part of offerings to divine beings or as a cleansing ritual. Most of these early forms of smoking used herbs, incense, or hallucinogens. Tobacco smoking appears to have started among the Maya and Aztecs of Mexico and Central America, first as a practice used by the priests to make contact with the spirit world, and later as a recreational activity among the Aztec nobles. By the time the Spanish conquistadors arrived in the 1520s, recreational smoking was widespread among wealthy Aztecs. Smoking quickly spread around the world in the sixteenth and seventeenth centuries, as European traders brought tobacco from the Americas to China and Ottoman Turkey as well as to Europe itself. Nicotine, the addictive chemical in tobacco, takes its name from Jean Nicot (1530–1600), a French diplomat who introduced tobacco to the UXL Encyclopedia of Diseases and Disorders

Smoking Normal lung tissue (left) and one damaged by smoking. © A. GLAUBERMAN/SCIENCE SOURCE/PHOTO RESEARCHERS, INC.

French court. One of the historical ironies of tobacco use is that smoking was originally thought to be beneficial to health. Some European doctors claimed that smoking could sober up alcoholics and cure sexually transmitted diseases like syphilis. Although Benjamin Rush (1745–1813), a signer of the Declaration of Independence, as well as a physician, argued that tobacco smoke is harmful to health as early as 1798, it was not until 1948 that a British researcher named Richard Doll (1912–2005) published proof that smoking increases the risk of lung cancer and heart disease. In spite of antismoking campaigns since the 1970s, smoking remains a difficult habit to break. One reason is the addictive nature of nicotine itself; it is considered even more addictive than cocaine. When inhaled in tobacco smoke, nicotine reaches the brain within seconds. It stimulates the release of dopamine, a brain chemical that causes most people to feel good. Nicotine is also a stimulant—a drug that makes people feel more alert and awake. Thus people smoke in order to relieve stress, to wake up in the morning, to stay alert when tired, or as part of social get-togethers. The habits that build up around tobacco use are another reason why people find it hard to quit smoking. Smoking is harmful to health partly because of nicotine itself and partly because of the other chemicals contained in tobacco smoke along with nicotine. Nicotine increases a person’s risk of heart disease because UXL Encyclopedia of Diseases and Disorders

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The Great American Smokeout The American Cancer Society (ACS) sponsors a program called the Great American Smokeout every year on the third Thursday of November. The aim of the Smokeout is to get smokers to stay away from tobacco for just one day in hopes that they will make a permanent commitment to stop smoking. The Smokeout started as a local activity in 1974 when a newspaper editor in Minnesota started the state’s first Don’t Smoke Day, or D-Day. In 1976, the California chapter of the ACS took up the idea, and in 1977 the ACS took the Great Smokeout nationwide. The present program includes a Quitline that people can call for help in quitting twenty-four hours a day, a guide to quitting smoking successfully, a list of reasons to quit, and links to local Great American Smokeout activities. People who want help quitting can telephone 1-800-ACS-2345 to find a quitline or other science-based support group in their area. They can also ask for help via the Great American Smokeout’s website at http://www.cancer.org/ docroot/subsite/greatamericans/Smokeout.asp.

it raises blood pressure and speeds up the heart rate. It doubles a person’s risk of stroke. Because the tobacco in a cigarette or cigar does not burn completely, the smoke contains carbon monoxide. It also contains arsenic, cyanide, and at least sixty chemicals known to cause cancer. In addition to causing 90 percent of deaths from lung cancer, smoking also causes cancers of the bladder, oral cavity, pharynx, larynx (voice box), esophagus, cervix, kidney, lung, pancreas, and stomach. Women who smoke have an increased risk of giving birth prematurely or having the baby die before birth. They are also at increased risk of osteoporosis after menopause.

Demographics

Cigarette smoking is considered the leading cause of preventable illness and premature death worldwide. As of 2008, it is estimated that about 1.1 billion people around the world are smokers, more of them in the developing countries than in the West. The rates of smoking are increasing rapidly in China and India but decreasing in the United States. As of 2008, about 28 percent of American males and 24 percent of females smoke, down from 52 percent of males and 34 percent of females in 1965. Cigarette smoking costs the United States about $195 billion in health care costs each year, or an average of $4,300 per adult smoker. About 438,000 Americans die each year from smoking-related diseases. More deaths are caused each year by tobacco use than by all deaths from AIDS, illegal drug use, alcoholism, motor vehicle injuries, suicides, and murders combined. In addition to the death toll, about 8.6 million people in the United States as of 2008 had at least one serious illness caused by smoking. Risk factors for becoming a smoker include: • Low levels of education. Forty percent of men who did not complete high school smoke, compared to 17 percent of college graduates.

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• Low income. • Race. Forty percent of African American men and 30 percent of Hispanics smoke compared to 27 percent of Caucasian men. • Age at which a person starts smoking. People who begin to smoke before age eighteen are far more likely to be heavy smokers as adults than those who started after age twenty-one. As of 2008, the average age of first-time smokers had dropped to 14.5 years. • Having parents who smoke. Teens with parents who smoke are twice as likely to start smoking. • Depression. Depression is a common symptom of nicotine withdrawal. People who have become depressed may start smoking in order to soothe their feelings and then find themselves unable to quit. • Genetic factors. Recent research indicates that some people have a gene that influences the production of an enzyme that clears nicotine from the bloodstream fairly rapidly. These people tend to smoke more heavily and find it harder to quit.

Causes and Symptoms People start smoking as a result of a combination of social and individual psychological factors. They then become dependent on smoking because of the addictive qualities of nicotine and possible genetic factors that increase their dependency on nicotine. The symptoms of nicotine dependence include: • Inability to quit smoking in spite of one or more serious attempts. • Craving for a cigarette at certain times of day or in specific situations. • Continuing to smoke in spite of lung disease, heart disease, or other smoking-related health problems. • Withdrawal symptoms when trying to quit smoking. These may include anxiety, depression, headache, drowsiness, difficulty concentrating, diarrhea, irritability, insomnia, and weight gain.

Diagnosis Most visits to doctors about smoking are usually to ask for help with quitting rather than diagnosing that a person smokes, though nicotine UXL Encyclopedia of Diseases and Disorders

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withdrawal can be diagnosed on the basis of the patient’s smoking history and the presence of withdrawal symptoms. Doctors and dentists are, however, in a good position to give their patients the facts about the harmful effects of smoking and offer encouragement and advice about quitting.

Treatment Treatment of smoking is called smoking cessation. The goal is to help the smoker quit smoking permanently. There are a number of different approaches to smoking cessation: • Quitting cold turkey. This term refers to stopping without medications or other helps and relying on will power alone. About 90 percent of smokers try to stop cold turkey on their first attempt; however, only about 10 percent are able to stop for as long as six months this way. • Counseling and psychotherapy. This approach attempts to help smokers understand their reasons for smoking and identify situations or other triggers that increase the urge to smoke. It helps about 25 percent of smokers stay smoke-free for six months. • Antismoking medications. These include nicotine replacement gums, patches, and inhalers that work to reduce cravings for tobacco by supplying the body with nicotine in other forms. A newer drug called Chantix works by occupying the nicotine receptors in the brain even though it is not nicotine itself. Chantix reduces withdrawal symptoms and the satisfaction people get from smoking. Doctors usually suggest that smokers combine these medications with support group meetings, smoking cessation programs, or ongoing guidance from a health professional rather than relying on the drugs alone. • Antidepressants. A drug called Zyban is sometimes prescribed to help smokers quit. It helps some people stop smoking by increasing the level of dopamine in the brain. • Group therapy and support groups. Many smokers find support group meetings helpful in dealing with the social triggers of cigarette smoking. • Complementary and alternative treatments. Some smokers report that hypnosis, acupuncture, and massage therapy are useful in helping to quit. 994


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WORDS TO KNOW Nicotine: A chemical found in tobacco that acts as a stimulant in humans.

Stimulant: Any drug or chemical that temporarily increases the user’s awareness or alertness.

Smoking cessation: A term that refers to a product or program to help people quit smoking.

Withdrawal: A group of physical and emotional symptoms associated with stopping tobacco use.

Prognosis Quitting smoking is very difficult; it is much better never to start in the first place. According to the Surgeon General, only about 30 percent of attempts to quit last longer than six months. The average person who does succeed in quitting takes between seven and fifteen attempts to do so. The benefits of quitting at any age, however, make the effort worthwhile. A person who quits smoking before age thirty-five will avoid 90 percent of the health risks associated with smoking. A person who succeeds in quitting between the ages of thirty-five and fifty cuts his or her risk of dying before age sixty-five in half compared to people who continue smoking. Even someone who quits at age sixty-five will increase his or her lifespan by an average of three years.

Prevention Many programs to prevent smoking in the United States are aimed at teenagers, on the grounds that more than 90 percent of first-time tobacco use occurs before high school graduation, and about 40 percent of teenagers who smoke become addicted to nicotine. Among the specific measures to lower the rate of smoking among young people are: • Imposing legal penalties for food stores or supermarkets that sell tobacco products to anyone under 18. • Education programs in schools, patient handouts in doctors’ and dentists’ offices, and personal counseling by health care professionals about the dangers of smoking. • Limiting or forbidding smoking in restaurants, offices, stores, and other public places. • Limiting the advertising of cigarettes and other tobacco products. • Taxing tobacco products heavily. UXL Encyclopedia of Diseases and Disorders

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The Future As of 2008 there were several nicotine vaccines undergoing clinical trials as aids to smoking cessation. One is called NicVAX and is thought to work by stimulating the body to produce antibodies against nicotine. The antibodies block nicotine from reaching the brain, thus interfering with the pleasurable effects of smoking. Other nicotine vaccines being studied include one called TA-NIC and another called Nicotine-Qbeta. Both of these work like NicVAX in producing antibodies against nicotine. SEE ALSO

Alcoholism; Asthma; Bronchitis; Coronary artery disease; Depression; Emphysema; Heart attack; Heart failure; Hypertension; Laryngitis; Lung cancer; Marijuana use; Osteoporosis; Periodontal disease; Prematurity; Stroke; Tooth decay; Tuberculosis


Bellenir, Karen, Ed. Tobacco Information for Teens. Detroit, MI: Omnigraphics, 2007. Deboo, Ana. Tobacco. Chicago, IL: Heinemann Library, 2008. Kiesbye, Stefan, ed. Teen Smoking. Detroit, MI: Greenhaven Press, 2008. Price, Sean. Nicotine. New York: Chelsea House, 2008. PE R I O DI C A L S

Downs, Martin. “Taming that Overwhelming Urge to Smoke.” New York Times, December 17, 2007. Available online at http://health.nytimes.com/ ref/health/healthguide/esn-smoking-ess.html (accessed September 27, 2008). This article includes information about recent research into genetic factors that make it hard for people to quit smoking. WE B S IT E S

American Cancer Society (ACS). Smoking and Cancer. Available online at http:// www.cancer.org/docroot/PED/ped_10.asp (updated October 13, 2007; accessed September 27, 2008). American Lung Association (ALA). All about Smoking. Available online at http:// www.lungusa.org/site/c.dvLUK9O0E/b.22938/k.A4C8/All_About_ Smoking.htm (updated August 2008; accessed September 27, 2008). Centers for Disease Control and Prevention (CDC). Smoking and Tobacco Use Home Page. Available online at http://www.cdc.gov/tobacco/ (updated May 8, 2007; accessed September 27, 2008). Mayo Clinic. Nicotine Dependence. Available online at http://www.mayoclinic. com/health/nicotine-dependence/DS00307 (updated October 26, 2006; accessed September 27, 2008). National Institute on Drug Abuse (NIDA). InfoFacts: Cigarettes and Other Tobacco Products. Available online at http://www.nida.nih.gov/Infofacts/ tobacco.html (updated July 2006; accessed September 27, 2008). 996


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TeensHealth. Smoking. Available online at http://kidshealth.org/teen/ drug_alcohol/tobacco/smoking.html (updated August 2007; accessed September 27, 2008).

Sore Throat Definition Sore throat, also known as pharyngitis, is a common symptom associated with upper respiratory infections, surgical procedures, and other irritants that may inflame the tissues of the throat. It is not a separate disease.

Description The discomfort associated with a sore throat varies somewhat according to its cause. Most sore throats are caused by viruses, specifically the viruses that cause the common cold. A person with a viral sore throat will be sneezing and having a runny nose as well as coughing and feeling a mild headache. A sore throat caused by the flu, however, will usually be accompanied by a fever of 102°F (38.8°C) or higher, and muscle aches and general tiredness. A patient with a sore throat caused by the virus responsible for infectious mononucleosis may have swollen tonsils, swollen lymph glands in the neck, and be tired for several weeks after the sore throat goes away. A sore throat caused by bacteria, such as those that cause strep throat, may be very painful; the patient may drool or spit because swallowing is difficult. Bacterial sore throats also often come on suddenly. Sore throats caused by smoking, air pollution, allergies, or overuse of the voice are often characterized by a dry or scratchy feeling in the throat rather than an aching sensation. Some people also experience this type of sore throat during winter, particularly in the mornings, because dry heat from a furnace tends to irritate the tissues that line the throat. A sore throat caused by an injury to the lining of the throat—for example getting a fish bone caught in the throat or having a medical examination that requires putting an instrument down the throat— usually involves pain only in the area of the injury. It is not accompanied by fever, sneezing, or other symptoms of an infection. In rare cases, a sore throat is the first sign of throat cancer. Cancerous tumors in the throat are often accompanied by coughing up blood, pain UXL Encyclopedia of Diseases and Disorders

Also Known As Pharyngitis Cause Viruses, bacteria, allergies, tobacco smoke, air pollutants, surgery, swallowing a foreign object Symptoms Loss of voice, difficulty swallowing, fever and other symptoms of upper respiratory infections Duration A few days to two weeks, depending on the cause 997

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in the throat that does not go away with antibiotic treatment, difficulty in swallowing, and a hoarse voice.

Demographics Sore throats are one of the most common reasons for staying home from school or work. The National Institutes of Health (NIH) estimates that sore throats are responsible for forty million doctor visits every year in the United States. Children have an average of five upper respiratory infections causing sore throats every ear, and adults have between one and three. About 90 percent of sore throats are caused by one type of virus or another, with most of the remaining 10 percent being caused by bacterial infections. Sore throats caused by viruses are equally common in both sexes and in all racial and ethnic groups in the United States. People at increased risk of sore throats include:

A doctor uses a tongue depressor to check for a sore throat. SHUTTERSTOCK.

• • • •

•

• Smokers or those exposed to secondhand smoke • People whose jobs expose them to chemicals that irritate the throat People with seasonal allergies to plant pollen, or year-round allergies to household dust, pet dander, or molds People with diabetes People with weakened immune systems, including those with HIV infection and those receiving chemotherapy for cancer People who live or work in close quarters with others, such as college students, military personnel, child care workers, office workers, and hospital staff People with frequent sinus infections

Causes and Symptoms Sore throat can have many possible causes, ranging from viruses and bacteria to smoking, air pollution, allergies, swallowing a foreign body, dry 998


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air, and overuse of the voice; however, most cases of sore throat are caused by viruses. The different types of viral infection that may be accompanied by a sore throat include:

When to See the Doctor Most sore throats, particularly those caused by cold viruses, go away on their own after a few days without the need for a visit to the doctor. People should, however, see their doctor if they have any of the following symptoms, which could indicate a serious condition:

• Common cold (There are about 200 different viruses that can cause colds.) • Influenza • Infectious mononucleosis • Severe difficulty in swallowing or • Cold sores breathing • Measles • A sore throat that lasts longer than a • Chickenpox week, or hoarseness that lasts longer • HIV infection than two weeks • Problems sleeping because of pain in The most common bacterial cause of sore the throat throat is the bacterium that causes strep throat. • Fever of 102°F (38.8°C) or higher Other bacterial infections that can cause sore • Sunken eyes, weakness, low urine throat include gonorrhea, a sexually transmitted output, and other signs of dehydration disease, and diphtheria. Diphtheria is a poten• Pus in the back of the throat tially life-threatening infection of the upper • Skin rash respiratory tract that has been virtually wiped out in the developed countries since the develop• Lump in the neck ment of a vaccine against it in the 1980s. • Coughing up blood, or blood in the saliva The symptoms that accompany sore throat depend on its cause. In general, sore throat • Family member or acquaintance diagnosed with strep throat caused by a viral or bacterial infection will look • Pain in the abdomen or vomiting red or swollen when the doctor examines the patient’s upper respiratory tract, and the tonsils will often look enlarged and have a coating of pus. A sore throat caused by smoking, chemical irritants, tissue injury, or dry air will not be accompanied by swollen tonsils or pus. In the case of throat cancer, the tumor will often be visible when the doctor examines the inside of the patient’s throat.

Diagnosis In most cases, the doctor can diagnose the cause of the patient’s sore throat by taking a history (asking about recent exposure to people with colds, flu, mononucleosis, or strep throat; occupation; history of allergies; smoking habits; and similar questions), and by examining the inside of UXL Encyclopedia of Diseases and Disorders

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the patient’s mouth and throat. It is not always easy to distinguish between a sore throat caused by a virus and strep throat just by looking, however, so the doctor will take a sample of fluid from the patient’s throat on a cotton swab. The fluid can be sent to a laboratory for a throat culture, which is an accurate test that takes two days. The doctor may also perform what is called a rapid strep test in the office. A blood test called the monospot test can be performed if the doctor thinks that the patient may have mononucleosis. If there is a tumor in the throat, the doctor can take a sample of tissue to be analyzed for evidence of cancer. In addition, the patient will be given a computed tomography (CT) scan or magnetic resonance imaging (MRI) of the head and neck to see whether the tumor is limited to the throat or has started to spread to other parts of the body.

Treatment Antibiotics are not effective in treating a sore throat caused by a virus. Most doctors prefer to wait until they have the results of a throat culture to prescribe antibiotics. Adults or children with strep throat or a sore throat caused by colds or flu can also take ibuprofen, acetaminophen, or another nonaspirin pain reliever to bring down fever and relieve muscle cramps or headache. Gargling with salt water—a half teaspoon of salt in a glass of warm water— is recommended for easing the throat discomfort. Other remedies recommended by doctors for sore throats include: • Using a humidifier in the home to help keep the throat tissues moist • Drinking lots of liquids • Drinking warm tea with honey and a small amount of lemon juice • Getting enough sleep The doctor may recommend a tonsillectomy (surgical removal of the tonsils) for children with recurrent severe sore throats. Tumors in the throat are treated with surgery and radiation therapy.

Prognosis Sore throats caused by viral infections other than HIV usually clear up with no long-term complications once the person has recovered from the illness. Most people with strep throat also recover completely; however, about two patients per 1,000 who are not treated for strep throat will 1000


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develop rheumatic fever and another two per 1,000 will develop a severe infection of the tonsils. Other possible but rare complications of strep throat include ear infections, kidney or liver damage, pneumonia, inflammation of the bones or joints, or sinusitis. The prognosis of throat cancer depends on the stage of disease at the time of diagnosis. Early-stage throat cancers have a high cure rate.

Prevention It is difficult to completely prevent sore throat, particularly during cold and flu season, but people can reduce their risk by taking the following precautions: • Wash the hands frequently, and use hand sanitizers containing alcohol when soap and water are not available. • Do not share drinking glasses, food utensils, towels, or other personal items with others. • Avoid close contact with people who have colds or other upper respiratory infections. • Quit smoking (or do not start in the first place) and avoid exposure to secondhand smoke. • Use a humidifier in the home during the winter. • Stay indoors on high pollution or high pollen count days. • If the sore throat is related to overusing the voice, give the voice a rest for several days.

The Future Because of the many different possible causes of sore throat and the near impossibility of eliminating the common cold and other viral illnesses, the condition will continue to be a frequent health problem for children and adults alike. SEE ALSO

Allergies; Common cold; Infectious mononucleosis; Influenza; Laryngitis; Smoking; Strep throat; Tonsillitus


Blenkinsopp, Alison, Paul Paxton, and John Blenkinsopp. Symptoms in the Pharmacy: A Guide to the Management of Common Illness. 5th ed. Malden, MA: Blackwell Publishing, 2005. Powell, Jillian. Sore Throat. North Mankato, MN: Cherrytree Books, 2007. UXL Encyclopedia of Diseases and Disorders

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American Academy of Family Physicians (AAFP). Sore Throat: Easing the Pain of a Sore Throat. Available online at http://familydoctor.org/online/famdocen/ home/common/infections/cold-flu/163.html (accessed July 27, 2008). American Academy of Otolaryngology—Head and Neck Surgery. Sore Throats. Available online at http://www.entnet.org/HealthInformation/soreThroats. cfm (accessed July 27, 2008). JAMA Patient Page: Sore Throat. Journal of the American Medical Association 291 (April 7, 2004). Available online at http://jama.ama-assn.org/cgi/ reprint/291/13/1664.pdf (accessed July 27, 2008). Mayo Clinic. Sore Throat. Available online at http://www.mayoclinic.com/ health/sore-throat/DS00526 (accessed July 27, 2008).

Spina Bifida Definition Spina bifida (pronounced SPEYE-na BIFF-ih-da) is a birth defect in which the tissues and vertebrae that normally cover the spinal cord fail to close completely during the baby’s development before birth. The words spina bifida mean “split spine” in Latin. Spina bifida is also known as a neural tube defect (NTD). Neural tube is the medical term for the folds of tissue in a human embryo that eventually give rise to the brain and spinal cord. Also Known As Neural tube defect, NTD Cause Incomplete closure of the spinal column during fetal development Symptoms None (in mild cases); bowel and bladder problems, seizures, partial paralysis (severe cases) Duration Lifelong unless corrected by surgery 1002

Description Spina bifida is a birth defect that occurs during the first few weeks of pregnancy, before the mother knows she is pregnant. As the fertilized egg develops into the embryo, it forms three layers of tissue, one of which contains cells along the back of the embryo that eventually form the central nervous system. As this group of cells grows, it folds inward to form a sheath that eventually closes to form the brain and spinal cord. This closure usually takes place around the twenty-eighth day of pregnancy. If a portion of the neural tube fails to close properly, the baby’s spine may be weakened, or portions of the spinal cord and meninges (the membranes that cover the brain and spinal cord) may push through the opening in the vertebrae. UXL Encyclopedia of Diseases and Disorders

Spina Bifida Baby with spina bifida. © BIOPHOTO ASSOCIATES/ PHOTO RESEARCHERS, INC.

The severity of spina bifida varies from a mild form that may be discovered only by accident to a severe form that can lead to premature death if untreated. There are three main types: • Spina bifida occulta. This is the mildest form. Occulta means “hidden,” because the condition is not noticeable at birth. In this form, there is a small space or gap in one or several of the vertebrae in the spinal column. Because there is no damage to the spinal cord or other nerves, children with spina bifida occulta do not usually have symptoms. In many cases the gap in the vertebrae is discovered only during a routine x ray study in later life. Doctors estimate that between 5 and 30 percent of cases may fall into this group. • Meningocele. This is a relatively rare form. The meninges that cover the spinal cord may push outward through the gap in the vertebrae to form a lump or cyst. The spinal cord itself is not affected, and in most cases the cyst can be removed surgically without damage. • Myelomeningocele. This is the most severe form, also known as open spina bifida, which usually involves some type of permanent disability. A section of the spinal cord and the nerves leading outward from it protrude through the gap in the vertebrae and are exposed on the outside of the body. UXL Encyclopedia of Diseases and Disorders

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Spina Bifida

Demographics Spina Bifida and Euthanasia In 2004 a group of doctors in the Netherlands made headlines around the world with their publication of the Groningen Protocol, a document justifying the euthanasia, or mercy killing, of infants that the doctors regarded as involving “unbearable and hopeless suffering.” The doctors then published an article in the New England Journal of Medicine in 2005 defending their position and discussing the euthanasia of twenty-two newborns between 1997 and 2004 on the grounds that their cases were hopeless. All had spina bifida. The article disturbed many people because even severe spina bifida is not considered a fatal disability. None of the twenty-two infants died simply from allowing their birth defect to take its course; they were killed by administering an overdose of a sleeping medication. Another Dutch doctor openly questioned the Groningen Protocol’s reference to “unbearable suffering,” noting that the majority of patients with myelomeningocele can be treated surgically and have good prospects of a productive adult life. He concludes, “There is no reason whatsoever for active life-termination of these newborns.” An ongoing question remains: if spina bifida is considered a reason for ending a newborn’s life, might other diseases come to be regarded in the same way?

Spina bifida is the most common permanently disabling birth defect worldwide. It is estimated to affect one to two of every 1,000 newborns in the United States. In some parts of the world, the rates are higher: in Ireland and Wales, for example, there are three to four cases of myelomeningocele per 1,000 births. There are some variations in frequency among different ethnic groups in the United States, with Hispanics having the highest rate of spina bifida, followed by Caucasians, Native Americans, African Americans, and Asian Americans. The total number of Americans with severe spina bifida was estimated to be around 70,000 in the early 2000s. Spina bifida is slightly more common in girls than in boys, although the reason for this difference is not known.

Causes and Symptoms

The exact cause of NTD is not known, but is thought to be the result of interactions between genetic factors and the mother’s diet. The fact that the rates of NTD vary from country to country and among different races suggests that genes are involved in the disorder. In addition, researchers have found that a woman who has one child with NTD has a greater chance of having a second child with NTD. Diabetes and seizure disorders also increase a woman’s risk of having a baby with spina bifida. With regard to diet, it is known that adequate amounts of folic acid (a form of vitamin B9) in the mother’s food during pregnancy can help to prevent spina bifida, though scientists are not yet certain why the vitamin has this beneficial effect. Folic acid is found in green leafy vegetables, egg yolks, dried peas and beans, brewer’s yeast, fortified cereal products, and certain other fruits and vegetables. It can also be taken by itself as a dietary

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supplement. Since January 1998, following recommendations from the Food and Drug Administration (FDA), folic acid has been added to breads, breakfast cereals, and other grain products sold in the United States. The symptoms of spina bifida vary considerably according to the severity of the defect: • Spina bifida occulta: There are usually no symptoms of damage to the nervous system; sometimes a small birthmark or tuft of hair on the skin over the small opening in the affected vertebrae is visible. • Meningocele. A small fluid-filled sac, usually covered by a thin layer of skin, protrudes from the baby’s back. • Myelomeningocele. There may be a sac on the baby’s back at birth, but in most cases the nerves and other tissues are exposed, leaving them extremely vulnerable to infection. Open spina bifida is associated with a number of health problems and physical disabilities, depending on the location of the exposed part of the spinal cord. • There is usually some degree of paralysis below the level of the defect in the spinal cord. The closer the defect lies to the head and neck, the more difficulties the person will have with walking, coordination, deformities of the hips and knees, and loss of muscle tone. • A defect close to the lower back may lead to intense pain in the lower back, upper leg, and knee. • Defects occurring toward the base of the spinal cord often result in loss of bowel and bladder control. • About 90 percent of patients with open spina bifida develop hydrocephalus, or a buildup of fluid inside the skull caused by interference with the normal flow of cerebrospinal fluid, potentially lead to learning difficulties and problems with concentration as the child grows older. • Babies with open spina bifida are at increased risk of meningitis, an infection of the meninges that can be life-threatening. • Tethering of the spinal cord. With this complication, the spinal cord cannot move freely inside the vertebrae but is attached (tethered) to nearby tissues, which can lead to scoliosis (curvature of the spine), dislocation of the hip, and other deformities. • Latex allergies, depression, obesity, and stomach disorders. These complications occur as children with spina bifida grow older. UXL Encyclopedia of Diseases and Disorders

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Diagnosis Spina bifida can be diagnosed during pregnancy by testing the mother’s blood for a protein called alpha-fetoprotein, which is produced by the fetus and the placenta during pregnancy and enters the mother’s bloodstream in small amounts. Unusually high levels of this protein may indicate a neural tube defect. The doctor can order additional tests, including taking a sample of the amniotic fluid surrounding the baby and performing an ultrasound imaging study. Mild cases of spina bifida can be detected after the baby is born by an x-ray study, computed tomography (CT) scan, or magnetic resonance imaging (MRI). A CT scan may be ordered to check for fluid inside the skull if the doctor thinks that the baby may have hydrocephalus.

Treatment There is no cure for spina bifida. Treatment depends on the location and severity of the defect in the spine. Babies with spina bifida occulta may not need any treatment, and those with meningocele are usually treated by having the cyst on the back removed by surgery. They usually have no complications. Treatment of myelomeningocele is complex, as children with this severe form of spina bifida usually need extensive physical therapy and sometimes special education following surgery. In most cases newborns with open spina bifida are operated on as soon as possible after birth. They are given antibiotics to prevent infection of the exposed part of the spinal cord. The opening of the spinal cord is closed, and covered with skin and muscles taken from either side of the back. If the baby has hydrocephalus, a shunt system may be inserted to redirect excess fluid away from the brain to other parts of the body. As the child grows older, additional operations are usually needed to correct a tethered spinal cord or scoliosis or to replace the shunt for hydrocephalus. Physical therapy usually includes range-of-motion exercises as well as strength exercises to prepare the child for walking with braces or crutches.

Prognosis The prognosis for patients with spina bifida occulta and meningocele is good. The prognosis for patients with myelomeningocele depends on the location of the defect in the spinal column and the amount of spinal cord 1006


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WORDS TO KNOW Euthanasia: Sometimes called mercy killing; the act of killing a hopelessly ill human or pet in a painless way.

Neural tube: The medical term for the folds of tissue in the human embryo that eventually form the brain and spinal cord.

Folic acid: A form of vitamin B9 that helps to prevent spina bifida.

Shunt: A flexible plastic tube inserted by a surgeon to drain cerebrospinal fluid from the brain and redirect it to another part of the body.

Meninges (singular, meninx): The three layers of protective tissue that cover the central nervous system.

that was exposed. Advances in prenatal diagnosis and surgery mean that most patients survive; and early treatment of hydrocephalus prevents mental retardation in most cases. With appropriate follow-up surgery and physical therapy, most patients with open spina bifida can complete their education and live independently; many marry and have families of their own.

Prevention Although the genetic factors that may be involved in spina bifida have not been identified, adding folic acid to a mother’s diet has been found to reduce a the baby’s risk of spina bifida by 70 percent.

The Future New approaches to surgical treatment of spina bifida include fetal surgery or operating on the baby before delivery. This technique involves opening the mother’s abdomen and uterus and closing the opening over the baby’s spinal cord. Fetal surgery is usually performed between the nineteenth and twenty-fifth weeks of pregnancy. Some researchers think that this early surgery improves the baby’s chances of normal brain development as well as lowering the risk that the spinal cord may become infected; however, it also increases the risk of premature birth and the baby’s death. Other areas of research include the search for specific genes associated with spina bifida and studies that may shed light on why folic acid helps to prevent it. SEE ALSO

Hydrocephalus; Meningitis; Scoliosis


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Lutkenhoff, Marlene, ed. Children with Spina Bifida: A Parents’ Guide, 2nd ed. Bethesda, MD: Woodbine House, 2008. Watson, Stephanie. Spina Bifida. New York: Rosen Publishing Group, 2008. PE R I O DI C A L S

Verhagen, Eduard, and Pieter J. J. Sauer. “The Groningen Protocol— Euthanasia in Severely Ill Newborns.” New England Journal of Medicine 352 (March 10, 2005): 959–962. Available online at http://content.nejm.org/ cgi/content/full/352/10/959 (accessed July 26, 2008). This is the article that touched off a major controversy about intentionally ending the lives of newborns with spina bifida. WE B S IT E S

Centers for Disease Control and Prevention (CDC). The Basics about Spina Bifida. Available online at http://www.cdc.gov/ncbddd/folicacid/ spinabifidabasics.htm (updated October 16, 2007; acccessed July 27, 2008). Mayo Clinic. Spina Bifida. Available online at http://www.mayoclinic.com/ health/spina-bifida/DS00417 (updated October 4, 2007; accessed July 26, 2008). National Institute of Neurological Disorders and Stroke (NINDS). Spina Bifida Fact Sheet. Available online at http://www.ninds.nih.gov/disorders/spina_ bifida/detail_spina_bifida.htm (updated December 11, 2007; accessed July 26, 2008). Spina Bifida Association (SBA). FAQs about Spina Bifida. Available online at http://www.spinabifidaassociation.org/site/c.liKWL7PLLrF/b.2642327/ k.5899/FAQ_About_Spina_Bifida.htm (accessed July 26, 2008).

Also Known As Spinal cord trauma, SCI Cause Direct or indirect injury to the spinal cord Symptoms Weakness, numbness, pain, paralysis, loss of bowel and bladder control Duration Years 1008

Spinal Cord Injury Definition Spinal cord injury, or SCI, refers to damage caused either directly to the cord itself or indirectly by injury to the bones, muscles, or soft tissues surrounding the cord. Most spinal cord injuries are caused by accidents or other traumas, but some are the result of tumors, birth defects, or diseases that affect the spine or surrounding muscles. The spinal cord can be compressed by damage to the vertebrae surrounding it or by blood and tissue fluid accumulating inside the spinal column. The spinal cord can also be completely cut or torn in an accident or by a knife or gunshot wound. UXL Encyclopedia of Diseases and Disorders

Spinal Cord Injury

Spinal cord injuries can be classified in two ways, by degree of severity and by location. Some doctors refer to an SCI as either complete, meaning that the patient has no sensation or ability to move muscles below the injury; or incomplete, meaning that the patient has some degree of sensation or function in the parts of the body below the injury. The location of a spinal cord injury is identified by the number of the affected vertebra. The human spine is divided into four segments: cervical (the neck region, containing seven vertebrae); thoracic (the chest region, containing twelve vertebrae); lumbar (the lower back, containing five vertebrae); and sacral (the tailbone region, containing five vertebrae). Thus a C4 injury refers to the fourth cervical vertebra; T12 refers to an injury at the level of the twelfth thoracic vertebra; and so on.

Description Injury to the spinal cord at any point along its length involves a series of events that damage the nerve endings in the cord. The spinal cord contains two major types of neurons, or nerve cells: sensory neurons that carry messages from the skin, joints, and muscles upward to the brain; and motor neurons, which carry messages from the brain downward to the various parts of the body. Thus any injury to the cord interferes with both sensation and movement. When the spinal cord is compressed, torn, or cut, the cord swells to fill the entire inside of the spinal column, which cuts off the blood supply to the injured tissue. The patient’s blood pressure drops and the nerve endings lose their ability to transmit electrical impulses to or from the brain. This condition is called spinal shock. It is followed by a secondary phase of damage that includes inflammation, the overstimulation of injured nerve cells, and the self-destruction of these nerve cells.

Image of a spinal cord injury in a human neck. The spinal cord (pink) is pinched by the back bones at the center of the picture. LUNAGRAFIX / PHOTO RESEARCHERS, INC.

Demographics According to the National Institutes of Health, there are between 10,000 and 12,000 spinal cord injuries each year in the United States. As of UXL Encyclopedia of Diseases and Disorders

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First Aid for Spinal Cord Injuries A spinal cord injury is a medical emergency. It is important, however, not to move someone who may have an SCI as paralysis or permanent injury could result. A spinal cord injury should be assumed in any of the following circumstances • The person has a head injury and is drifting in and out of consciousness. • The injured person complains of pain in the neck or back. • The person cannot move their neck. • The injury to the head or neck was caused by significant force. • The person’s neck or back is twisted or is positioned oddly. • The person complains of weakness, numbness, or paralysis. • The person cannot control their limbs, bladder, or bowels. To help someone with a suspected SCI: • Call 911 at once. • Keep the person still. Put heavy towels on both sides of the neck or hold the head and neck to prevent movement. It is important to keep the person in the same position as they were in when found until emergency help arrives. • Give as much first aid as possible without moving the injured person’s head or neck. • If it is absolutely necessary to turn the injured person to one side because they are choking on blood or vomiting, get someone else to help turn them. Work together to keep the injured person’s head, neck and back in alignment while rolling them onto one side.

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2008, there were 255,000 Americans living with these injuries; their care costs the country about four billion dollars per year. Car accidents are the largest single cause of spinal cord injuries, being responsible for 42 percent. Another 27 percent result from falls; the remainder are caused by athletic accidents (8 percent), criminal violence (15 percent), and work-related injuries (7 percent). There are four times as many men with spinal cord injuries as women. Fifty-five percent of these men are between sixteen and thirty years old.

Causes and Symptoms Spinal cord injuries may be caused by transportation accidents, falls, workplace accidents, violence, or diseases that affect the bones or muscles of the spinal column. The symptoms of spinal cord injury include: • Pain or intense stinging sensations at the point of injury • Increased muscle tone or muscle spasms • Inability to feel heat, cold, or touch • Loss of bowel or bladder control • Loss of the ability to move parts of the body below the point of injury • Difficulty breathing or coughing • Problems with blood pressure or temperature regulation • Abnormal sweating The specific disabilities that may result from spinal cord injury depend on the location of the damage. In general, the higher the level of injury (closer to the head), the more extensive the paralysis. Some patterns of disability are as follows: • C1 through C3: Injuries to these neck vertebrae result in quadriplegia, or paralysis of UXL Encyclopedia of Diseases and Disorders

Spinal Cord Injury

• •

• • •

both arms and both legs. The patient will need to be placed on a respirator in order to breathe. C5 and C6: The person has some arm function but not the use of the hands. T1 through T8: The person has paraplegia; that is, he or she cannot use the legs or lower part of the trunk. The hands, arms, head, and breathing are usually not affected. T9 through T12: The person can control their abdominal muscles and sit upright. L1 through L5: The person will have difficulty bending or flexing the legs and hips. S1 through S5: The person may have some difficulty with bowel and bladder control.

Diagnosis A person with a suspected SCI must be moved carefully by a specially trained trauma team. The usual practice is to fit a stiff collar around the injured person’s neck and move him or her on a rigid board, to prevent further injury to the spinal cord. The injured person is taken to the hospital as quickly as possible, as it is critical not to delay treatment. If the injured person is able to talk, the doctor may be able to determine the location of the injury fairly rapidly by asking about pain and other sensations, lack of ability to move parts of the body, and so on. The doctor may also test the patient’s reflexes or use pinpricks or other forms of touch to determine whether sensation has been lost. If the patient is having difficulty breathing or has lost consciousness, the doctor will order one or more imaging studies, including x rays, computed tomography (CT) scans, and magnetic resonance imaging (MRI). Another imaging technique that is often used with spinal cord injuries is myelography. This test consists of injecting a contrast dye into the spinal column that will show up on an x ray or CT scans. Patients are usually given a second round of diagnostic tests and imaging studies a few days after the injury to evaluate the extent of the injury and the patient’s chances for recovering sensation and function.

Treatment Treatment of spinal cord injuries usually involves a combination of medications, surgery, traction or bracing, and long-term physical therapy and rehabilitation. UXL Encyclopedia of Diseases and Disorders

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• A medication called Medrol can be given to patients with a severe SCI. Medrol is a corticosteroid that reduces swelling and inflammation of the spinal cord. It must, however, be given within eight hours of the injury. • Surgery is performed to remove bone fragments, foreign objects, or vertebrae that are compressing the spinal cord. Surgeons differ as to whether it is better to perform surgery immediately or to wait until the extent of the patient’s injuries has been determined. • Traction and braces or a body harness are applied to bring the patient’s spine into proper alignment during healing. • Physical therapy and rehabilitation. These forms of therapy usually begin after the patient has left the hospital, which may take from a few days to several weeks. Rehabilitation includes learning to cope with bowel, bladder, or sexual functions (if any), self-care, and the use of a wheelchair or other assistive devices as well as regaining muscle strength and range of motion. Most patients also need psychotherapy and support groups to cope with depression and other emotional problems that often occur after a spinal cord injury, particularly if the patient is quadriplegic or paraplegic.

Prognosis The prognosis of a spinal cord injury varies. It may take several weeks or months for the patient’s doctors to determine the extent of possible recovery. In general, impairment that remains a year after the injury is likely to be permanent. Some studies indicate that age makes a difference in a patient’s ability to regain function; younger patients are more likely to improve than patients over fifty years of age. A common complication of spinal cord injuries is chronic pain. Two-thirds of patients with SCIs have ongoing pain, with half of these reporting that their pain is severe. There is no universally successful treatment for such pain. Most patients are given medications for the pain, usually antidepressants or antiseizure drugs. Spinal cord injury shortens most patients’ life spans, although people still live longer with such injuries than was the case in the 1960s. Pneumonia is a common cause of death in patients with quadriplegia. Another common cause of death is suicide; patients with spinal cord injuries have a suicide rate five times higher than the general population. 1012


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WORDS TO KNOW Paraplegia: Paralysis that affects only the lower body. Quadriplegia: Paralysis that affects both arms and both legs. It is also known as tetraplegia.

Traction: The use of braces, casts, or other devices to straighten broken bones and keep them aligned during the healing process.

Prevention Many spinal cord injuries can be prevented by taking basic safety precautions: • Practice safe driving. This includes the use of seat belts, keeping the car in good repair, and avoiding driving after drinking or taking drugs. • When swimming, check the depth of water before diving. Be particularly careful when diving in natural bodies of water because of the possibility of hidden rocks. • Use appropriate protective equipment when playing football or other contact sports. Avoid movements that put the head and neck at risk, such as sliding into a base headfirst. • Store firearms in a locked cabinet or safe, and store ammunition in a separate location. • Protect against falls by checking the house or apartment for safety hazards, wearing properly fitted shoes, and reducing the use of medications that cause drowsiness or loss of balance.

The Future As of 2008, Medrol was the only drug that is generally used to bring down inflammation following an SCI, although another medication called GM-1 ganglioside is being tested as a treatment for the damage to nerve tissue that follows spinal shock. Other areas of research include various ways to stimulate the regrowth of damaged nerve fibers; the use of computers combined with electrodes implanted in the injured person to restore function to paralyzed limbs; and better ways to control pain in survivors of SCIs. SEE ALSO

Fractures; Multiple sclerosis; Osteoporosis; Pneumonia; Spina

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Palmer, Sara, Kay Harris Kriegsman, and Jeffrey B. Palmer. Spinal Cord Injury: A Guide for Living. 2nd ed. Baltimore, MD: Johns Hopkins University Press, 2008. Wilder, Esther Isabelle. Wheeling and Dealing: Living with Spinal Cord Injury. Nashville, TN: Vanderbilt University Press, 2006. WE B S IT E S

Centers for Disease Control and Prevention (CDC). Spinal Cord Injury (SCI): Prevention Tips. Available online at http://www.cdc.gov/ncipc/factsheets/ sciprevention.htm (accessed August 25, 2008). Children’s Hospital Boston. My Child Has Spinal Cord Injury. Available online at http://www.childrenshospital.org/az/Site1150/mainpageS1150P0.html (accessed August 25, 2008). Mayo Clinic. Spinal Cord Injury. Available online at http://www.mayoclinic. com/health/spinal-cord-injury/DS00460 (accessed August 25, 2008). National Institute of Neurological Disorders and Stroke (NINDS). Spinal Cord Injury: Hope through Research. Available online at http://www.ninds.nih.gov/ disorders/sci/detail_sci.htm (accessed August 25, 2008). National Library of Medicine (NLM). Spinal Cord Injury. Available online at http://www.nlm.nih.gov/medlineplus/tutorials/spinalcordinjury/htm/index. htm (accessed August 25, 2008). This is an online tutorial with voiceover; viewers have the option of a self-playing version, a text version, or an interactive version with questions.

Also Known As Pulled muscles, twisted ankle Cause Direct or indirect blow to affected area; fall; muscle overuse; inadequate rest Symptoms Pain, swelling, bruising, difficulty using joint, muscle weakness or cramping Duration Days to months 1014

Sprains and Strains Definition Sprains and strains are commonplace injuries of the joints and muscles. A sprain is a stretching or tearing of a ligament—one of the tough bands of fibrous tissue that connects bones to other bones. A strain is an injury to a muscle or tendon. Both types of injury can occur in various parts of the body, depending on the location of an injury or the part of the body that has been overused. The most common locations for sprains are the ankle, knee, or thumb. The most common cause of an ankle sprain is called an inversion injury; it occurs when the foot turns inward when a person falls UXL Encyclopedia of Diseases and Disorders

Sprains and Strains A patient with a bruised and swollen sprained ankle. © PHOTOTAKE INC. / ALAMY.

on the ankle or lands on it after a jump. Less commonly, the ankle is injured when the foot turns outward suddenly; this is called an eversion injury. Knee sprains are most likely to occur as the result of a blow to the knee or falling on the knee. Thumb sprains are most likely to occur in skiers. Strains most commonly affect the muscles of the back; the hamstring muscle at the back of the thigh; the muscles of the hand and forearm; and the muscles of the upper arm and elbow. Sprains can be classified according to severity as well as location. Doctors usually distinguish three levels of sprains: • Mild (sometimes called first-degree sprain): The ligament is mildly stretched or has a minor tear. • Moderate (second-degree sprain): The ligament is torn but not completely ruptured. • Severe (third-degree sprain): One or more ligaments are completely ruptured. Strains can be categorized according to the type of damage caused to the injured muscle: • The muscle tissue may tear. • The area where the muscle joins its tendon may tear. • The tendon itself may tear or rupture. UXL Encyclopedia of Diseases and Disorders

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Description When to Call the Doctor for a Sprain Mild sprains and muscle strains can be treated at home using the PRICE therapy described in the body of the article. More severe injuries, however, require a doctor’s diagnosis and treatment. A person with any of the following symptoms should see a doctor or go to the emergency room quickly: • The person is in severe pain. • The person cannot put any weight on the affected joint, or walk more than four steps without severe pain. • The joint cannot be moved. • The limb buckles or collapses when the person tries to use the affected joint. • There is numbness in any part of the injured area. • The affected joint or muscle has been injured several times before. • There is redness spreading outward from the injury. • The person has any doubt about the severity of the injury or how to care for it.

The experience of a sprain may vary from mild discomfort lasting a few minutes or hours to inability to walk or use the affected joint. In many cases the person will feel a popping or tearing sensation in the joint: • First-degree sprain: The affected joint feels sore and hurts when it is moved, but there is not much swelling and the person can put weight on the joint. • Second-degree sprain: The affected joint is sore, swollen, and difficult to move. There may be bruising from blood leaking into the joint. The person may feel shaky or unsteady if they try to put weight on the joint. • Third-degree sprain: The affected joint is very painful, bruised, and swollen. The person may not be able to move it at all, and the injury may be difficult to distinguish from a bone fracture or dislocation. A strain is usually experienced as pain in the area of the injured muscle along with cramping or spasms in the muscle, limited range of motion, and weakness in the muscle. There may also be swelling and inflammation in the affected area.

Demographics Sprains and strains are very common injuries in the general population; according to the National Institutes of Health (NIH), there are about 25,000 ankle sprains each day in the United States. Although amateur and professional athletes are somewhat more likely to be injured, anyone whose occupation involves lifting heavy objects, repetitive movements, or the use of power tools may develop sprains or strains. Elderly people and others at risk of falls are also more likely to sprain the knee or ankle joints. 1016


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Sprains and strains are equally common in both sexes and in all races and ethnic groups. Some people are at increased risk of sprains and strains: • People who are in poor physical condition or who exercise when they are tired or unwell. • People who are obese. • People who are not using the proper techniques for their sport or occupation. Dancers, skaters, or skiers who have not been taught to jump and land properly, for example, are more likely to sprain an ankle or knee. • People who do not warm up before athletic activities. • People with diabetes. • People who take medications that make them drowsy or affect their sense of balance. • People with a history of repeated joint or muscle injuries.

Causes and Symptoms The causes of sprains and strains include accidental falls, sports injuries, overuse of weak or injured muscles, improper techniques for lifting or carrying heavy objects, repetitive use of muscles without adequate rest, or unusual stresses on a normally healthy joint or muscle. The symptoms of sprains and strains have already been described.

Diagnosis Mild sprains and strains can usually be diagnosed by a primary care doctor by taking the patient’s history and examining the affected joint and the tissues surrounding it. The doctor may refer the patient to an orthopaedics specialist for further evaluation of the injury. X rays may be taken to rule out broken bones but are not usually helpful in diagnosing soft tissue injuries. The doctor may order a magnetic resonance imaging (MRI) test for better evaluation of injuries to ligaments and muscles. Numbness in the affected joint may indicate nerve damage, while coldness may indicate a problem with circulation. Either of these symptoms, or the possibility that a bone is broken or dislocated, means that the patient should go to an emergency room as quickly as possible. UXL Encyclopedia of Diseases and Disorders

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Treatment Mild sprains and strains can be treated at home by using the PRICE approach for twenty-four to forty-eight hours: • Protection. Protecting the injured joint or muscle involves avoiding unnecessary movement of the affected area. • Rest. Rest means avoiding activities or body movements that make the pain or swelling in the joint worse; it doesn’t mean complete bed rest. • Ice. An ice pack can be applied to the affected area for fifteen to twenty minutes every four to six hours for one to two days. • Compression. Compression refers to the use of a wrap, air cast, or Ace bandage to keep swollen muscles from restricting movement in an injured joint. • Elevation. Raising the affected arm, leg, elbow, or wrist on a pillow or cushion (above heart level) is helpful in relieving swelling in the affected muscle or joint. Nonsteroidal anti-inflammatory drugs, or NSAIDs, can be used to relieve pain and inflammation in the sore joint or muscle. These drugs include aspirin as well as Tylenol and Advil. Moderate and severe injuries require a combination of immobilizing the affected joint with a splint or cast followed by physical therapy and rehabilitation to restore muscle strength and range of motion in the affected joint. In some cases, surgery may be needed to repair a ruptured ligament or muscle.

Prognosis The prognosis for recovery from sprains and strains is very good with appropriate medical treatment and self-care at home. It is important, however, for patients to follow the doctor or physical therapist’s recommendations carefully to avoid reinjury. A mild ankle sprain may require several weeks of rehabilitation; a moderate sprain could require two to three months. With a severe sprain, it can take as long as eight to twelve months to return to full activity. These time frames may be even longer in elderly patients.

Prevention People can reduce their risk of sprains and strains by taking the following precautions: • Avoiding sports or physical exercise when tired, ill, or in physical pain. 1018


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WORDS TO KNOW Eversion injury: An ankle injury caused when the foot is suddenly forced to roll outward. Inversion injury: A type of ankle injury caused when the foot is suddenly forced to roll inward. Ligament: A tough fibrous band of tissue that joins bones together.

Orthopaedics (also spelled orthopedics): The branch of medicine that diagnoses and treats disorders of or injuries to the bones, muscles, and joints. Tendon: A thick band or cord of dense white connective tissue that attaches a muscle to a bone.

• Maintaining a healthy weight and eating a nourishing diet that keeps muscles strong. • Wearing shoes that fit properly, and replacing athletic shoes as soon as the tread is worn or the heel wears unevenly. • Doing daily stretching exercises. Yoga is a good low-impact way to stretch muscles. • Warming up and stretching before participating in vigorous sports. • Wearing appropriate protective equipment for baseball, football, hockey, and other similar sports. • Being in good physical condition before playing sports. • If running, running on even rather than rough or irregular surfaces. • Putting safety measures in place to prevent falls, such as keeping stairways, walkways, yards, and driveways free of clutter and well lighted; making sure that rugs are anchored and electrical wires are secured; putting grab bars in shower stalls; and salting or sanding icy sidewalks and driveways in the winter.

The Future Sprains and strains are likely to continue to be commonplace health problems given that so many sports and occupations put people at risk for injuries to muscles and joints. SEE ALSO

Fractures; Obesity; Tendinitis


Bellenir, Karen, ed. Sports Injuries Information for Teens. 2nd ed. Detroit, MI: Omnigraphics, 2008. UXL Encyclopedia of Diseases and Disorders

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Griffith, H. Winter, and David A. Friscia. Complete Guide to Sports Injuries: How to Treat—Fractures, Bruises, Sprains, Strains, Dislocations, Head Injuries. 3rd ed. New York: Body Press/Perigee, 2004. Silverstein, Alvin, Virginia Silverstein, and Laura Silverstein Nunn. Pains and Strains. New York: Franklin Watts, 2003. WE B S IT E S

American Academy of Orthopaedic Surgeons (AAOS). Sprains and Strains: What’s the Difference? Available online at http://orthoinfo.aaos.org/topic.cfm? topic=A00111 (accessed August 2, 2008). Mayo Clinic. Sprains and Strains. Available online at http://www.mayoclinic. com/health/sprains-and-strains/DS00343 (accessed August 1, 2008). National Institute of Arthritis and Musculoskeletal and Skin Diseases (NIAMS). Questions and Answers about Sprains and Strains. Available online at http:// www.niams.nih.gov/Health_Info/Sprains_Strains/default.asp (accessed August 1, 2008). National Library of Medicine (NLM). Fractures and Sprains Available online at http://www.nlm.nih.gov/medlineplus/tutorials/fracturesandsprains/htm/ index.htm (accessed August 2, 2008). This is an online tutorial with voiceover; viewers have the option of a self-playing version, a text version, or an interactive version with questions. TeensHealth. Dealing with Sports Injuries. Available online at http://kidshealth. org/teen/exercise/safety/sports_injuries.html (accessed August 1, 2008).

Staph Infection Also Known As S. aureus infection, MRSA infection, staphylococcal infection Cause Bacteria belonging to the genus Staphylococcus Symptoms Depends on the part of the body infected Duration Days to months, depending on location and severity of the infection 1020

Definition Staphylococcus is the name of a group of bacteria responsible for a number of serious illnesses, although most species are harmless to humans. Staphylococci are widespread in all parts of the world. They are commonly found in the soil as well as on the bodies of humans and domestic animals. Staphylococci can live on or in humans without necessarily causing harm. They can, however, cause disease in humans and other animals either by direct destruction of tissue or by releasing toxins into the digestive tract or bloodstream. Under a microscope, these bacteria look like clumps or clusters of grapes.

Description There are four species of staphylococci that cause various types of infections in humans. The two most important of these are Staphylococcus UXL Encyclopedia of Diseases and Disorders

Staph Infection

aureus, a golden-yellow bacterium, and Staphylococcus epidermidis, a species that causes skin infections. S. aureus is generally considered the most dangerous species of staphylococcus, causing a range of infections from pneumonia and endocarditis to food poisoning and eye infections. Methicillin-resistant S. aureus, or MRSA, has become a major public health concern since the 1990s (see sidebar). The other two types of staph that cause disease in humans are responsible for urinary tract infections in sexually active women and infections of the bones and joints.

Demographics Staphylococci are commonplace organisms found on the scalp, skin (particularly the armpits and genital areas), or outer nasal passages of humans. Biologists refer to the formation of groups or clumps of bacteria on a human or animal as colonization. Staph is found in 80 percent of the general population from time to time and 20–30 percent of the population on an ongoing basis. People who harbor staphylococci most of the time are called “staph carriers.” An estimated 2 billion people are colonized by some form of S. aureus; of these persons, as many as 53 million, or 2.7 percent of carriers, are thought to carry MRSA, the drug-resistant form of S. aureus. It is possible for a person to carry staphylococci for many years without becoming sick. In addition, such domestic animals as cats, dogs, chickens, and horses can carry MRSA strains as well as less powerful staphylococci. As far as is known, people of either gender, any age group, or any race are equally likely to carry staphylococci. Newborns may be colonized by staphylococci from the mother during childbirth. Some groups, however, are more susceptible than others to staph infections, including diabetics, African Americans, gay men who practice anal intercourse, very young children, elderly adults, and persons with artificial joints or heart valves. UXL Encyclopedia of Diseases and Disorders

Methicillin resistant Staphylococcus aureus (MRSA) infection. © SCOTT CAMAZINE / ALAMY.

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Methicillin-resistant Staphylococcus aureus (MRSA) Methicillin-resistant Staphylococcus aureus (MRSA) is a strain of the bacterium responsible for severe and potentially fatal skin and soft-tissue infections. There are two major subgroups of MRSA, named for the locations where people can get infected: community-acquired MRSA (CAMRSA) and hospital-acquired (or healthcareacquired) MRSA (HA-MRSA). MRSA was first identified as a particular strain of S. aureus in 1961. Methicillin, an antibiotic similar to penicillin, was introduced in 1959 to treat penicillin-resistant strains of S. aureus, but only two years later, the first strains of MRSA were reported in the United Kingdom. MRSA infections were uncommon until the 1990s, however, when their rate shot upward, particularly in hospitals. CA-MRSA causes a boil or skin infection in about 75 percent of cases and is easily mistaken for a

spider bite. The affected area is red, swollen, and may ooze pus. CA-MRSA can be much more powerful than hospital-acquired MRSA, however, and can lead to sepsis (generalized infection of the entire body), bacteremia (infection of the bloodstream), or pneumonia. HA-MRSA is most commonly found in patients in healthcare settings, particularly those in dialysis centers, nursing homes, or other hospital settings. Patients with HA-MRSA are more likely to develop pneumonia, infected joints, or urinary tract infections than skin infections. MRSA infections cannot be treated with the antibiotics used for most staph infections. Newer drugs like vancomycin, linezolid, or tigecycline must be used instead. As of 2008 some 94,000 serious MRSA infections were reported in the United States annually and 19,000 deaths—more than are caused by AIDS.

Causes and Symptoms The causes and symptoms of staph infections vary somewhat depending on the species of staph involved and the specific tissues or organs affected: • Skin and soft tissue infections. These may be caused by either S. aureus or S. epidermidis. Skin infections caused by staph often look like spider or other insect bites. Infected wounds or surgical incisions typically ooze pus or another discharge. Many of these skin infections develop from scratching insect bites or patches of eczema. After the skin is broken, the bacteria can enter the tissues beneath the surface and form large pus-filled abscesses. In patients with weakened immune systems, the staphylococci can then enter the bloodstream. • Endocarditis. Endocarditis is an inflammation of the valves and other tissues lining the heart, caused when staphylococci form colonies on the surface of the valves. It is more common in patients 1022


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•

•

•

•

who have damaged or artificial heart valves. A patient with staphylococcal endocarditis will run a fever, and will have a heart murmur or some other abnormality of blood flow in the heart that can be detected on an echocardiogram. Pneumonia. Most cases of bacterial pneumonia are caused by streptococci, but about 3 percent of cases of pneumonia acquired outside hospitals are caused by S. aureus. These patients have the typical symptoms of pneumonia: fever, chest pain, cough, and production of sputum (mucus or phlegm from the lungs). Joint infections. Staphylococcal infections of the joints are common complications of patients who have artificial joints. S. aureus and S. epidermidis are the species usually involved in joint infections. The most common symptom of a joint infection is sudden swelling and pain due to pus and tissue fluid building up in the affected joint. The patient may or may not have a fever. Eye infections. People can get staph infections of the tissues on the inside of the eye following eye surgery or an injury to the eye. This type of eye infection is called endophthalmitis. The early symptoms of staphylococcal endophthalmitis include pain, swelling, and redness in the affected eye and partial loss of vision within a week of the injury or operation. The patient may also have a headache and be sensitive to bright light. Food poisoning. Staphylococcal food poisoning is the result of toxins secreted by the organisms rather than by tissue damage caused by the bacteria themselves. The foods most likely to be contaminated are those made by hand, those that require little or no cooking—such as sandwiches, cold cuts, and certain types of pastry—and those that have not been refrigerated. The symptoms of staphylococcal food poisoning include nausea, vomiting, and diarrhea, beginning between one and six hours after eating the contaminated food. Most people with staphylococcal food poisoning feel better in one to two days.

Diagnosis The diagnosis of a staphylococcal infection is based on a combination of the patient’s medical history, symptoms, an examination of the skin or other affected body parts, and a blood culture that is positive for a specific staphylococcus species. UXL Encyclopedia of Diseases and Disorders

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Samples for a staph culture may be obtained from a skin injury, from drawing a blood sample, from a urine sample, or by having the patient cough up sputum if pneumonia is suspected. Although a standard blood culture for a staph infection takes a day or two to yield results, rapid diagnostic methods using amplification and probe-based molecular techniques provide results in hours, thus allowing treatment to be started earlier and improving the patient’s chances of recovery. Although staph can be identified in stool samples or vomit from a patient with food poisoning, doctors do not usually test for the organism unless there is an outbreak involving several people. The diagnosis of staphylococcal food poisoning is usually made on the basis of the patient’s symptoms.

Treatment Treatment of a staph infection depends on its specific type and location. In most cases the doctor will start antibiotic therapy when a staphylococcal infection is suspected as soon as the sample of tissue, blood, sputum, or urine has been sent to the laboratory. Specific types of infections are treated as follows: • Skin infections: The doctor may make an incision to drain the pus and other infected fluid out of the wound. In some cases an antibiotic cream or lotion may be applied after the wound has been cleansed, or the patient may be given oral or intravenous antibiotics. • Staphylococcal pneumonia following influenza is usually treated with intravenous antibiotics following hospitalization. People who are seriously ill may need to be given supplemental oxygen in an intensive care unit (ICU). • If the infection is located in a joint with a prosthetic appliance, the artificial joint must be removed and the patient given a four- to six-week course of antibiotics. Infected joints without a prosthetic appliance are usually drained of fluid and the patient is given a four-week course of antibiotic therapy to clear the infection. • Infected artificial heart valves may or may not require removal. Endocarditis does, however, require long-term antibiotic therapy, particularly if the patient is over fifty-five. • Staphylococcal eye infections require emergency treatment. An ophthalmologist (specialist in eye disorders) usually injects antibiotics 1024


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into the tissues around the eye and also gives antibiotics by mouth or intravenously. In extreme cases the entire eye may need to be removed. Staphylococcal food poisoning is treated with bed rest, plenty of fluids, and anti-nausea drugs prescribed by the doctor. Antibiotics cannot be used to treat food poisoning caused by staphylococci because the toxins that cause the nausea and vomiting are not affected by these drugs. Severely ill patients may need to be hospitalized and given intravenous fluids.

Prognosis The prognosis of staphylococcal infections varies according to the specific illness. Untreated S. aureus infections of the bloodstream can have a mortality rate as high as 80 percent. Endocarditis and pneumonia caused by antibiotic-resistant staphylococci have mortality rates around 11 percent in patients without other diseases or disorders, but the rate may be as high as 44 percent in patients with diabetes, HIV infection, or other disorders that weaken the immune system. Elderly people with staphylococcal pneumonia have a worse prognosis than younger adults. In patients over the age of seventy, community-acquired staph infections are associated with a mortality rate of 21 percent in the year following diagnosis. Most patients with staphylococcal food poisoning or staphylococcal urinary tract infections recover completely; fatalities are rare except in the elderly or people with AIDS.

Prevention People can help to prevent staphylococcal infections by taking the following precautions: • Avoid scratching insect bites or other areas of irritated skin; see a doctor about a boil filled with pus or a similar skin lesion that will not heal. • Wash hands carefully before and after preparing food. • Cover infected skin or skin draining pus with waterproof dressings, and dispose of soiled dressings carefully. Clean cuts and scratches promptly and keep them bandaged. • People with infections on their hands or wrists should avoid preparing or serving food until the infection has been cleared. UXL Encyclopedia of Diseases and Disorders

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WORDS TO KNOW Bacteremia: The presence of bacteria in the bloodstream. Colonization: The process by which bacteria form colonies in or on the bodies of humans and other animals. Endocarditis: An inflammation of the tissues lining the inside of the heart and its valves. Endophthalmitis: Inflammation of the tissues inside the eyeball.

Sepsis: The presence of bacteria or their toxic products in the bloodstream or other tissues, leading to inflammation of the entire body. Sputum: Matter from the lungs or throat that is brought up by coughing. Strain: A genetic variant or subtype of a bacterium.

• Avoid sharing such personal items as combs, brushes, cosmetics, cell phones, razors, and towels. Be particularly careful in gyms and health clubs, as staphylococci prefer warm, moist environments. • Wipe down kitchen countertops, athletic equipment, and hospital equipment with alcohol-based sanitizers. • Avoid direct contact with other people’s wounds or injuries whenever possible.

The Future Staph infections are likely to be common for the foreseeable future because these bacteria are widespread in all countries. Research at present is focused on finding new drugs that will be effective against MRSA and improving techniques to prevent its spread outside as well as inside hospitals. SEE ALSO

Pneumonia; Toxic shock syndrome


Tilden, Thomasine E. Lewis. Help! What’s Eating My Flesh?: Runaway Staph and Strep Infections! New York: Franklin Watts, 2008. 1026


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eMedicine Health. Staphylococcus (Staph Infection). Available online at http:// www.emedicinehealth.com/staphylococcus/article_em.htm (accessed September 16, 2008). Mayo Clinic. Staph Infections. Available online at http://www.mayoclinic.com/ health/staph-infections/DS00973 (updated June 7, 2007; accessed September 16, 2008). National Institute of Allergy and Infectious Diseases (NIAID). MethicillinResistant Staphylococcus aureus (MRSA). Available online at http://www3. niaid.nih.gov/topics/antimicrobialResistance/Examples/mrsa/default.htm (updated June 16, 2008; accessed September 16, 2008). Nemours Foundation. Staph Infections. Available online at http://kidshealth.org/ parent/infections/bacterial_viral/staphylococcus.html (updated March 2008; accessed September 16, 2008).

Steroid Use Definition Steroid use usually refers to the abuse of synthetic hormones to build muscles, raise athletic performance, or improve one’s appearance. There are, however, two major types of steroids that are used in medicine. The synthetic hormones used to build muscles are called anabolic or androgenic steroids. They are human-made drugs related to male sex hormones or androgens. The other group of steroid medications are known as corticosteroids or glucocorticoids. They are synthetic forms of hormones that are produced naturally by the adrenal glands when the body is stressed. Corticosteroids are often prescribed to treat inflammation in disorders like eczema, arthritis, or asthma, or to treat immune system disorders like lupus or multiple sclerosis. Although corticosteroids are strong drugs with side effects and require a doctor’s prescription, they cannot be used for muscle building. The remainder of this entry will focus on anabolic steroids.

Description Anabolic steroids are synthetic drugs modeled on the chemical structure of male sex hormones. Anabolic steroids boost the rate of protein UXL Encyclopedia of Diseases and Disorders

Also Known As Steroid abuse Cause Abuse of anabolic steroids to improve one’s looks or athletic performance Symptoms Voice deepening, body hair growth (women); testicle shrinking (men); stunted growth; aggressiveness Duration As long as the user continues using, typically months to years 1027

Steroid Use Robert Hazelton, who claims he lost his legs due to steroid use. AP IMAGES.

formation in cells, which is why they are effective in building muscle tissue and increasing physical strength. These compounds were first made in European laboratories in the 1930s; they were recommended in bodybuilding magazines as early as 1938. Anabolic steroids were given to German soldiers during World War II (1939–1945) to increase their aggressiveness, and Adolf Hitler (1889–1945) asked his personal physician for steroid injections. Anabolic steroids do have legitimate uses in treating bone diseases in older men as well as the wasting of muscle tissue that occurs in AIDS and certain types of cancer. They are also given to boys with delayed puberty to help them mature. What is controversial about these drugs is their use (and abuse) in amateur and professional sports to improve performance. Anabolic steroids have serious psychological as well as physical side effects in females as well as males, and can lead to long-term damage to the heart and liver as well as unattractive changes in appearance. Anabolic steroids can be taken by mouth in the form of pills or by injections. More recently, some users have tried using steroids in the form of transdermal patches, which deliver the drug into the body through the skin. People who use anabolic steroids have several methods for trying to speed up the effects of the drugs on building muscle. One method, called 1028


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stacking, involves using several different steroids at the same time. The other method, called cycling, involves taking the drugs for six or twelve weeks at a time and not using the drugs for brief periods in between cycles. Neither stacking nor cycling makes steroids more effective, however.

Demographics One reason for concern in the early 2000s is the young age of steroid abusers, as well as their numbers. Although the average age of people who use anabolic steroids for nonmedical purposes is twenty-five, about 2.7 percent of high school students are reported to use these drugs. Boys are more likely than girls to use steroids, and athletes are more likely to use them than high schoolers who are not athletes. According to a study conducted by the National Institutes of Health (NIH) in 2002, 2.5 percent of eighth graders have tried steroids; 3.5 percent of tenth graders; and 4 percent of high school seniors. College students are less likely than high schoolers to use steroids—about 1 percent. Males between the ages of nineteen and forty are the heaviest users of anabolic steroids in the United States as of the early 2000s. The American College of Sports Medicine (ACSM) conducted a survey in 2005 of 500 young adults who use anabolic steroids. The survey found that most steroid users (78 percent) are noncompetitive bodybuilders and nonathletes who use the drugs to improve their appearance rather than to gain an edge in sports competitions. Thirteen percent of these users reported such unsafe injection practices as reusing needles, sharing needles, and sharing multidose vials of injectable steroids.

Causes and Symptoms The cause of nonmedical steroid use in adolescents and young adults is usually dissatisfaction with one’s appearance or a strong desire to excel at sports. One former user interviewed by an NIH researcher said, “When I walked into a room, I wanted heads to turn…. My whole priority was, I wanted people to say, ‘That guy’s huge’.” Another former user said, “Steroids were the easy way to get big and to be respected, especially at the gym and they were very easy to obtain…. I see all these people who are built up on TV and stuff and I’m always comparing myself to them all the time, like, ‘I’m bigger than him,’ or ‘I’m more cut up than he is.’” UXL Encyclopedia of Diseases and Disorders

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The symptoms of steroid use are different for males and females. In males, steroid use can lead to: • Loss of head hair • Shrinking of the testicles and lowered sperm count • Enlargement of the left ventricle of the heart, which can lead to heart problems in later life • Increased risk of heart attack and stroke • High blood pressure • High blood cholesterol levels • Weakening of joints and increased risk of rupturing tendons • Liver damage • Stunted growth • Depression, increased aggressiveness, and rapid mood changes Females who use anabolic steroids may undergo virilization, a process in which they develop certain physical characteristics associated with males: • • • • •

Growth of facial hair Deepening of the voice Irregular menstrual cycles and eventual loss of fertility Loss or thinning of scalp hair Shrinking of the breasts

Other risks related to steroid use include hepatitis or HIV infection from needle sharing; dangerous side effects from contaminated steroids or fakes (other substances sold as steroids) purchased over the Internet; and legal penalties for purchasing or possessing steroids without a prescription. Anabolic steroids are classified as Schedule III drugs, in the same group as narcotic painkillers and barbiturates. Simple possession of any Schedule III substance without a valid prescription is a federal offense punishable by up to one year in prison and/or a minimum fine of $1,000.

Diagnosis The diagnosis of steroid use may be based on changes in the person’s physical characteristics or behavior. A routine medical checkup may indicate liver damage or high blood pressure. Family members or others may notice oily skin or acne on the user’s upper back, needle marks, hair 1030


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falling out, jaundice or yellowing of the skin (a sign of liver damage), changes in the person’s figure, extreme mood swings, or angry outbursts. The most common medical test for steroid abuse is a urine sample. Other laboratory tests that the doctor may order are blood tests for blood sugar levels (higher than normal may indicate steroid abuse); cholesterol levels; and liver function.

Treatment It is important for someone who has been using steroids to talk to a doctor about quitting rather than simply stopping the drugs. Steroids are powerful hormones and can produce such side effects as nausea, vomiting, joint pain, abdominal cramps, dizziness, and low blood pressure when they are stopped abruptly. In many cases the doctor will work out a schedule to taper the patient’s use of steroids gradually. The user should be completely honest with the doctor about the following details: • All the drugs that were taken and where and how they were purchased. This information is important to help the doctor find out whether the drugs might have been contaminated or counterfeit. • The user’s dosing schedule. • Length of usage. • A description of any physical and mental side effects that were experienced. A person who is coming off steroids should not stop exercising or working out. Physical exercise helps in avoiding depression as well as maintaining good general health and fitness. A balanced diet is also important, as is drinking plenty of water. In some cases the doctor may recommend psychotherapy to treat the emotional dimension of steroid addiction.

Prognosis The prognosis of steroid use depends on the user’s gender, length of use, types and amounts of steroids used, and the age at which use began.

Prevention The most important preventive measure is good communication between parents and children, particularly during adolescence, when concerns about appearance and achievement become critical to many teens. In many cases athletic coaches or physical education teachers can help by UXL Encyclopedia of Diseases and Disorders

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WORDS TO KNOW Anabolic: Referring to tissue building. Anabolic steroids build up muscle and bone tissue. Androgens: Male sex hormones. Cycling: Using steroids in periods of several weeks or months (a time cycle) separated by short rest phases of not using the drugs.

Hormone: Any chemical produced by living cells that stimulates organs or tissues in parts of the body at some distance from where it is produced. Stacking: Using several different types of steroids at the same time. Virilization: The development of male sexual characteristics in females.

talking frankly about the dangers of steroids to young people who may be experimenting with them.

The Future Further research needs to be done about the long-term effects of anabolic steroids—including their psychological effects—at all stages of the life cycle. Beginning in 2005, a number of steroid activists began to push for decriminalization of anabolic steroids, claiming that they are not as harmful to mature adults as previous studies have indicated. It is difficult to see, however, how adults could be permitted to use steroids freely without the drugs becoming available to teenagers whose bodies are still developing and could be damaged by long-term steroid use. SEE ALSO

AIDS; Tendinitis


Fitzhugh, Karla. Steroids. Chicago, IL: Heinemann Library, 2005. Freedman, Jeri. Steroids: High-risk Performance Drugs. New York: Rosen Publishing Group, 2009. Schaefer, Adam Richard. Steroids. Ann Arbor, MI: Cherry Lake Publishing, 2008. PE R I O DI C A L S

American College of Sports Medicine. “Steroid Survey Reveals Dangerous Trends among Users.” News release, June 1, 2005 (accessed July 11, 2008). Mitchell, George. “The Steroids Era.” The New Atlantis 19 (Winter 2008): 139– 141. Available online at http://www.thenewatlantis.com/publications/thesteroids-era (accessed July 11, 2008). This article is a series of excerpts from a 1032


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former Senator’s testimony before a House Committee on the illegal use of steroids in major league baseball. Mitchell’s testimony was given on January 15, 2008. WE B S IT E S

Hormone Foundation. Hormone Abuse Prevention and What You Need to Know. Available online at http://www.hormone.org/Abuse/prevention.cfm (accessed July 11, 2008). National Institute on Drug Abuse (NIDA) InfoFacts. Steroids (Anabolic-Androgenic). Available online at http://www.nida.nih.gov/infofacts/steroids.html (accessed July 11, 2008). Nemours Foundation. Steroids. Available online at http://kidshealth.org/parent/ fitness/safety/steroids.html (accessed July 11, 2008). NIDA for Teens. Facts on Drugs: Anabolic Steroids. Available online at http:// teens.drugabuse.gov/facts/facts_ster1.asp (accessed July 11, 2008). PBS In the Mix. Steroids: The Hard Truth. Available online at http://www.pbs. org/inthemix/shows/show_steroids.html (accessed July 11, 2008). Page contains a link to four video clips from the television program. Each clip takes about a minute and a half to play.

Strabismus Definition Strabismus is a condition in which a person’s eyes are not properly aligned with each other. One eye is either constantly or occasionally turned inward, outward, upward, or downward. Someone looking at a person with strabismus may notice that their eyes are pointed in different directions. If one or both eyes are turned inward, the person is said to have crossed eyes; if either eye is turned outward, they are said to be wall-eyed. Ophthalmologists (doctors who specialize in treating eye disorders) classify strabismus as congenital, acquired, or secondary. Congenital strabismus is present at birth and affects about 1 percent of infants. Acquired strabismus develops in later life from injury to the eye, the brain, or such diseases as diabetes, while secondary strabismus results from another eye disorder, usually cataracts.

Also Known As Crossed eyes, squint eye, walleye Cause Lack or loss of coordination between the two eyes

Description

Symptoms Eye fatigue; seeing double; pulling sensation around the eye; loss of vision in one eye

Strabismus is an eye disorder in which the person’s eyes do not focus on a single point at the same time. The lack of coordination of the eyes

Duration Lifelong if not corrected


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Strabismus A young boy with strabismus. © IMAGEBROKER / ALAMY.

results from eye muscles that do not work together properly. One or both eyes may turn outward, inward, upward, or downward. Some people may have two different subtypes of strabismus, one in each eye. Strabismus may be constant or it may come and go. In children, strabismus may vary over the course of a few hours as well as from day to day. Although strabismus is not a life-threatening condition, it can have serious consequences for a child’s vision if it is not corrected. The reason is that unlike an adult’s fully developed brain, a child’s brain is still learning to coordinate the visual perceptions from both eyes. If the two eyes are focusing in different directions, the brain may start to ignore the input from one eye. This condition is called amblyopia, or lazy eye. Although the affected eye is completely normal in terms of its basic structures, it can lose its ability to see over time. Uncorrected amblyopia resulting from strabismus is the leading cause of blindness in one eye in American adults over the age of twenty. Some children have a condition called pseudostrabismus or false strabismus because their facial features make them look cross-eyed or walleyed. Children with eyes set unusually close together, a wide flat nose, or an extra fold of skin near the inner eye may look as if they have strabismus. False strabismus does not affect vision and usually goes away as the child grows older and his or her face lengthens. 1034


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Demographics According to the American Academy of Ophthalmology, about four in every one hundred adults in the United States have strabismus. About 2 percent of children have strabismus, half of them being born with the condition. Although strabismus can develop at any age, the age group most commonly affected is children between three and six years of age. Strabismus appears to run in some families, although no specific genes have yet been identified that are linked to strabismus. It is also not known whether strabismus itself is genetic or whether it is the underlying causes of the disorder (weakness of the eye muscles or cranial nerves controlling the eye muscles) that are inherited. Asian Americans appear to be at a slightly higher risk of strabismus than people of other races or ethnic backgrounds. As far as is known, males and females are equally affected. Other risk factors for strabismus include: farsightedness or hyperopia; premature birth; and developmental delays.

Causes and Symptoms

Abraham Lincoln’s Strabismus Abraham Lincoln (1809–1865) was ridiculed by many of his contemporaries for his “homely” and “misshapen” face. The left side of Lincoln’s face was noticeably smaller than the right side, a difference that can be clearly seen in photographs taken of him during his presidency. Some medical historians think that this difference was caused by a hereditary developmental defect—Lincoln had a first cousin with strabismus—while others think that the facial problem was caused by trauma. Lincoln had been kicked in the face by a horse when he was nine years old. Several people who knew Lincoln reported that his left eye sometimes moved upward independently of his right eye—a clear indication of strabismus. Lincoln himself noted that he saw double on occasion; however, he was not particularly troubled by this symptom. In 2007 a retired ophthalmologist and history buff made a laser scan of two facial masks that had been made of Lincoln during his lifetime. The threedimensional scan allowed the doctor to analyze the differences between the muscles in Lincoln’s left and right eyes, and to confirm the diagnosis of adult strabismus.

Strabismus in children can be caused by weakness of the eye muscles or defects in the baby’s developing nervous system. Children with cerebral palsy, Down syndrome, Edwards syndrome, or whose mother had rubella during pregnancy have a significant risk of congenital strabismus. In adults, acquired strabismus may result from a concussion, brain tumor, stroke, traumatic brain injury that affects the cranial nerve controlling the eye muscles, loss of vision in one eye, or diabetes. Symptoms of strabismus in a child may include:

• Eyes focusing in different directions when the child becomes interested in playing with a nearby object. • The child’s eyes roll or wander for no apparent reason. • The child does not seem to have normal depth perception. UXL Encyclopedia of Diseases and Disorders

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• The child covers one eye with the hand in order to focus the other eye. The symptoms of strabismus in adults are slightly different from those in children because the visual system in the adult’s brain is completely developed. Amblyopia is therefore unusual in adults with acquired strabismus. Common symptoms in adults include: • Seeing double. This is the most annoying symptom for most adults with acquired strabismus because it interferes significantly with reading, driving, and many other everyday tasks. • Having problems with depth perception. • Recurrent headaches or feelings of eyestrain. • Squinting or tilting the head to one side in order to focus the affected eye. • Eyes that appear crossed or walleyed to other people. This can be a cause of considerable social embarrassment; one study found that 70 percent of adults with strabismus had difficulties in school, work, or family life because of the impact of strabismus on their appearance.

Diagnosis Early diagnosis of strabismus in children is critical in order to prevent amblyopia and later loss of vision. The eyes of newborns cannot always focus directly on an object because the muscles of the eye are still developing. A baby should, however, be able to focus both eyes in parallel by the age of three to four months. If parents notice that the infant still looks cross-eyed or walleyed at four months, they should have the child examined by the child’s primary care doctor or by an ophthalmologist. The most common tests used to diagnose strabismus are the cover test and the Hirschsprung test. In the cover test, the examiner covers each of the patient’s eyes in turn with a handheld shield while asking the patient to focus on a small object at a distance. If a person has strabismus, the unaffected eye will not change focus when uncovered, while the strabismic eye will move or change its focus. In the Hirschsprung test, the examiner shines a small flashlight or penlight on the patient’s eyes. The examiner can see the light reflected on the front surface of the pupil. If the eyes are properly aligned, the reflection will be in the same spot on each eye. If the person has strabismus, the reflection from the light will appear on different areas of each eye. 1036


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The ophthalmologist may also perform other examinations to rule out the possibility that a brain tumor is causing the strabismus.

Treatment Treatment of strabismus in children may consist of one or more of the following measures: • Patch therapy and vision therapy. In patch therapy, the child’s stronger eye is covered with a patch, forcing the weaker eye to function at a higher level. Vision therapy consists of exercises performed in the eye doctor’s office under supervision to change the way the eyes process visual information. It is not concerned with strengthening the eye muscles. • Medications injected into the eye muscles to weaken overactive muscles. Interestingly, the drug most often used for this purpose—botox—is derived from the same organism that produces the deadly toxin of botulism food poisoning. • Corrective lenses. These are intended to improve the focusing of the patient’s eyes and redirect the line of sight. • Surgery. Surgery to realign the eye muscles may be done if corrective lenses and patch therapy are not successful. It is not usually performed on children younger than four years of age. Adults with strabismus may be treated with corrective lenses, botox injections in the eye muscles, or surgery on the eye muscles. Surgery is usually done to correct double vision, the most troublesome symptom of strabismus in adults.

Prognosis When strabismus in children is detected and treated early, the prognosis is good. The prognosis for strabismus in adults depends on the cause (trauma, brain tumor, other diseases) and its severity.

Prevention Congenital strabismus can be prevented in some cases by immunization against rubella in women planning a pregnancy. Acquired strabismus can be prevented in some cases by observing safety measures to lower the risk of head injuries in sports or the workplace and by avoiding UXL Encyclopedia of Diseases and Disorders

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WORDS TO KNOW Amblyopia: Dimness of sight in one eye without any change in the structure of the eye. It is also known as lazy eye. Botulism: A rare but potentially fatal paralytic illness caused by a bacterial toxin in contaminated food.

Congenital: Present at birth. Pseudostrabismus: A condition in which a child may seem to have strabismus because of certain facial features that change as the child’s face matures.

improperly canned foods (a common source of botulism) or poisonous shellfish.

The Future As of 2008, the National Institutes of Health (NIH) was conducting about 29 different clinical trials related to strabismus. Most are studies comparing the effectiveness of different types of treatment for the condition, but three of the trials are exploring genetic factors that may be linked to strabismus. SEE ALSO

Cataracts; Cerebral palsy; Concussion; Diabetes; Edwards syndrome; Hyperopia; Rubella; Stroke


Bakri, Sophie J., ed. Mayo Clinic Guide to Better Vision. Rochester, MN: Mayo Clinic, 2007. Ballard, Carol. Eyes. Chicago, IL: Heinemann Library, 2003. WE B S IT E S

Eye Care America. Strabismus. Available online at http://www.eyecareamerica. org/eyecare/conditions/strabismus/index.cfm (accessed July 4, 2008). National Eye Institute (NEI). Facts about Amblyopia. Available online at http:// www.nei.nih.gov/health/amblyopia/amblyopia_guide.asp (accessed July 4, 2008). Prevent Blindness America. Strabismus. Available online at http://www.preventblindness.org/children/strabismusFAQ.html (accessed July 4, 2008). Research to Prevent Blindness (RPB). Animation: Strabismus. Available online at http://www.rpbusa.org/rpb/eye_info/AmblyopiaStrabismus/ (accessed July 4, 2008). Clicking on the animation sidebar opens a series of three animations on the characteristics, symptoms, and treatments of strabismus. Each animation takes about a minute to play. 1038


Strep Throat

Strep Throat Definition Strep throat is an acute infection of the throat caused by the same type of bacterium (group A streptococcus) that causes scarlet fever.

Description Strep throat is an infectious disease that may affect adults as well as children. It is spread by fluids from the throat or nose of an infected person or by contact with a drinking glass, soiled tissue, or other object touched by an infected person. In a very few cases, the bacteria that cause strep throat have been spread by contaminated food. The incubation period of strep throat is short, usually between two and five days. The symptoms often come on rapidly, with the patient developing a sore throat that may make swallowing or speaking difficult. The fever is usually highest on the second day of illness.

Demographics The bacterium that causes strep throat is common around the world. It is responsible for 25–30 percent of the ten million cases of severe sore throat that doctors treat in the United States each year. Strep throat can occur at any time of the year but is most common in North America in the late winter and early spring. It is more likely to occur in children between the ages of five and fifteen than in adults; it is less common in children younger than two years of age. Strep throat affects males and females equally, and appears to be equally common in all races and ethnic groups.

Causes and Symptoms Strep throat is caused by a bacterium—a group A streptococcus that normally lives in the upper respiratory tract. As the bacteria grow in the tissues of the nose and throat, they may secrete toxins that may cause skin rashes in some patients with strep throat in addition to the fever and other symptoms. UXL Encyclopedia of Diseases and Disorders

Also Known As Streptococcal pharyngitis, streptococcal sore throat Cause Group A streptococcus; also called Streptococcus pyogenes Symptoms Sudden and severe sore throat, inflamed tonsils, fever of 101°F (38.3°C), difficulty swallowing Duration Symptom improvement in two to five days 1039

Strep Throat

In addition to a sore throat of sudden onset, the symptoms of strep throat include: • • • • • •

White areas in the back of this patient's throat signify a strep throat infection. © PHOTOTAKE INC. / ALAMY.

• • •

Fever of 101°F (38.3°C) or higher Headache Chills and cold sweats Nausea and vomiting (more common in children) Difficulty swallowing Red and swollen tonsils, sometimes with yellow or whitish-grey streaks of pus Bad breath Rash or hives Loss of appetite

• Abdominal cramps • Enlarged glands in the neck that are sore to the touch • Aching muscles or sore joints

Diagnosis Correct diagnosis of strep throat is important because most sore throats are caused by viruses rather than the bacteria that cause strep throat. Sore throat caused by viruses should not be treated with the antibiotics used for strep throat. The diagnosis of strep throat is usually based on a combination of the patient’s history—particularly recent exposure to other children with a streptococcal infection—and the doctor’s examination of the patient’s throat, neck glands, and skin. The doctor may also take a sample of fluid from the child’s throat on a cotton swab. The fluid can be sent to a laboratory for a throat culture, which is an accurate test that takes two days. The doctor may also perform what is called a rapid strep test. It can detect proteins produced by the streptococci in a few minutes in the doctor’s office. The rapid strep test, however, is not as accurate as a throat culture.

Treatment Patients with a known case of strep throat are treated with a course of antibiotics, most commonly penicillin, azithromycin, or a similar drug known to be effective in treating streptococcal infections. A child whose 1040


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throat is too sore to allow comfortable swallowing can be given penicillin by injection. A child with strep throat will usually not be contagious within a day or two of starting treatment and can return to school once the fever goes down. It is important, however, for anyone, child or adult, with strep throat to take the full course of antibiotics (usually ten days), even though he or she may start to feel better in a few days. Not taking the full course of antibiotics may lead to such later complications of strep throat as rheumatic fever or inflammation of the kidneys. The doctor should be consulted if the patient does not begin to feel better after a day or two of antibiotic treatment. Adults or children with strep throat can take ibuprofen, acetaminophen, or another nonaspirin pain reliever to bring down fever and relieve muscle cramps or headache. Gargling with salt water—one-half teaspoon of salt in a glass of warm water—is recommended for easing the throat discomfort. In some cases, the doctor may recommend a tonsillectomy to prevent recurrence of streptococcal infections. A study done in 2006 found that children with repeated episodes of strep throat whose tonsils are intact are more than three times as likely to develop additional episodes of strep throat than children whose tonsils were removed.

Prognosis The great majority of patients with strep throat recover completely with no complications even without antibiotic treatment. However, about two patients per 1,000 who are not treated will develop rheumatic fever and another two per 1,000 will develop a severe infection of the tonsils. Other possible but rare complications of strep throat include ear infections, kidney or liver damage, pneumonia, inflammation of the bones or joints, or sinusitis. Another possible complication of strep throat is the PANDAS syndrome, a term that stands for Pediatric Autoimmune Neuropsychiatric Disorders Associated with Streptococcal infections. Some children develop symptoms of obsessive-compulsive disorder or Tourette syndrome after a group A streptococcal infection; or they become moody, irritable, and anxious when separated from their parents. The connection between these symptoms and the infections is not clear, however, and many doctors think that further research is needed. UXL Encyclopedia of Diseases and Disorders

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Prevention Strep throat is difficult to prevent completely because of the close contact among children in schools and day care centers, particularly in the winter. In addition, some people can carry Group A streptococci in their throats without getting sick themselves. When anyone in a family is diagnosed with strep throat, doctors recommend protecting other members by washing the sick person’s eating utensils, drinking glasses, and bedding in hot soapy water separately from the rest of the family’s dishes and laundry. Children with strep throat should also be reminded to cover the nose and mouth when sneezing or coughing and to wash the hands thoroughly in warm soapy water afterward.

The Future As of 2008 the chief concern among doctors was the overuse of antibiotics in treating strep throat. Across the United States, 70 percent of children with sore throats who are seen by a doctor are treated with antibiotics even though 30 percent at most have strep infections. It can be difficult to distinguish between bacterial and viral infections of the throat even when a throat culture is performed because some people may be carriers of group A streptococci and have the bacteria in their throat at the same time that they have a sore throat caused by a virus. The chief danger of overuse of antibiotics is the creation and spread of drug-resistant disease organisms. In addition, some people can have severe allergic reactions to antibiotics. To guard against overprescribing antibiotics for sore throats that may not be caused by streptococci, many doctors now follow a two-step procedure for diagnosing strep throat before giving the patient a prescription for antibiotics. They give the patient a rapid strep test in the office; if the result is positive, the doctor then takes a throat swab and sends it for a culture. If that test too comes back positive, the patient is then given antibiotics. Waiting two days for antibiotic treatment will not increase the patient’s risk of developing complications from strep throat. SEE ALSO

Rheumatic fever; Scarlet fever


Glaser, Jason. Strep Throat. Mankato, MN: Capstone Press, 2007. Laskey, Elizabeth. Strep Throat. Chicago, IL: Heinemann Library, 2003. Smith, Tara C. Streptococcus (Group A). Philadelphia: Chelsea House Publishers, 2004. 1042


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WORDS TO KNOW Group A streptococcus: A sphere-shaped bacterium that grows in long chains and causes strep throat as well as scarlet fever. PANDAS disorders: A group of disorders with psychiatric symptoms that develop in some

children after strep throat or scarlet fever. The acronym stands for Pediatric Autoimmune Neuropsychiatric Disorders Associated with Streptococcal infections. Pharyngitis: The medical term for sore throat.

PE R I O DI C A L S

Brody, Jane. “Strep Symptoms: When to Use Antibiotics.” New York Times, October 10, 2006. Available online at http://www.nytimes.com/2006/10/ 10/health/10brody.html?_r=1&adxnnl=1&oref=slogin&adxnnlx= 1213344642-1KO2qaulFuPVyhJgLXpMrA (accessed June 12, 2008). WE B S IT E S

Centers for Disease Control and Prevention (CDC). Group A Streptococcal (GAS) Disease. Available online at http://www.cdc.gov/ncidod/dbmd/ diseaseinfo/groupastreptococcal_g.htm (accessed June 13, 2008). Mayo Clinic. Strep Throat. Available online at http://www.mayoclinic.com/ health/strep-throat/DS00260 (accessed June 12, 2008). National Institute of Allergy and Infectious Diseases (NIAID). Group A Streptococcal Infections. Available online at http://www3.niaid.nih.gov/ healthscience/healthtopics/streptococcal/overview.htm (accessed June 13, 2008). TeensHealth. Strep Throat. Available online at http://kidshealth.org/teen/ infections/bacterial_viral/strep_throat.html (accessed June 13, 2008).

Stress Definition Stress was originally defined by a Canadian biologist named Hans Selye (1907–1982) in the 1930s as a series of biochemical, nervous, digestive, and muscular responses in laboratory animals to a perceived threat, which he called a stressor. Selye later expanded the notion of stress to include humans trying to evaluate and respond to various stressors in their daily lives. Many people, however, use the word “stress” in casual UXL Encyclopedia of Diseases and Disorders

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conversation to refer to almost any event or situation that worries or upsets them. Some doctors distinguish several different types of stress according to whether the stress is positive or negative, or according to the length of time that the person experiences the stressor. In the 1970s, a psychologist named Richard Lazarus coined the term eustress to refer to stress that is good for health or leads to a sense of fulfillment. Increasing one’s strength or endurance through active exercise would be an example of eustress, as would completing a course of study or finishing a job assignment. Stress can also be categorized as acute, episodic acute, or chronic, according to the length of time the person feels stressed and whether the stress is a one-time event, repeated periodically, or long-term and unrelenting. An example of acute stress is facing a growling and aggressivelooking dog. Episodic acute stress includes the pressures that people place on themselves by taking on too many obligations or by not allowing enough time to complete tasks. Some jobs, such as police work or firefighting, involve episodic acute stress. Chronic stress is usually situational—the person is trapped in a bad marriage, a dead-end job, or living in a crime-ridden neighborhood.

Description

Also Known As Psychological stress, anxiety, tension Cause The body’s responses to any event or situation perceived as a stressor Symptoms Anxiety, trouble sleeping, moodiness, nausea, depression, overeating, drinking or doing drugs Duration Minutes to years 1044

In general, stress is a complicated set of physical and emotional responses to changes that occur in everyone’s life. On the biological level, stress begins with the “fight-or-flight” reaction—the activation of a section of the brain called the hypothalamic-pituitary-adrenal system, or HPA. When a human perceives a situation as stressful, the HPA system releases cortisol, a steroid hormone. The next stage in the stress reaction is the release of neurotransmitters, or brain chemicals, that activate parts of the brain that register the emotion of fear. The neurotransmitters also suppress activity in parts of the brain associated with short-term memory, concentration, and rational thinking. This limitation allows a human to react quickly to a stressful situation but it also lowers his or her ability to deal with intellectual or social factors that may be part of the situation. On the physical level, the person’s heart rate and blood pressure rise; he or she breathes more rapidly, which allows the lungs to take in more oxygen. Blood flow to the muscles, lungs, and brain may increase by 300–400 percent. The spleen releases more blood cells into the UXL Encyclopedia of Diseases and Disorders

Stress

circulation, which increases the blood’s ability to transport oxygen. The immune system redirects white blood cells to the skin, bone marrow, and lymph nodes. At the same time, nonessential body systems shut down. The skin becomes cool and sweaty as blood is drawn away from it toward the heart and muscles. The mouth becomes dry, and the digestive system slows down. After the crisis passes, the levels of stress hormones drop and the body’s various organ systems return to normal. This return is called the relaxation response. Some people are more vulnerable to stress than others because their hormone levels do not return to normal after a stressful event. In chronic stress, the organ systems of the body do not have the opportunity to return fully to normal levels. Different organs become under- or overactivated on a long-term basis. In time, these abnormal levels of activity can damage an organ or organ system. What complicates the experience of stress is that different people respond differently to stressors. Some people find driving a highly stressful experience, for example, while others enjoy it. Similarly, some people enjoy the intellectual challenges of certain fields of study, while others are bored by them. Personality differences are another factor that influences people’s response to stress. Some people are highly aggressive, inclined to worry, or easily irritated, while others are less competitive or more optimistic about life.

Demographics Almost everyone has experienced acute or episodic acute stressors. Some people, however, are more vulnerable than others to chronic stressrelated illnesses: • Children. Children have very little control over their environments. In addition, they are often unable to communicate their feelings accurately. • Elderly adults. Aging appears to affect the body’s response to stress, so that the relaxation response following a stressful event is slower and less complete. In addition, the elderly are often affected by such major stressors as health problems, the death of a spouse or close friends, and financial worries. • Caregivers of mentally or physically disabled family members. • Women in general. • People with less education. UXL Encyclopedia of Diseases and Disorders

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• People who belong to racial or ethnic groups that suffer discrimination. • People who live in cities. • People who are anger-prone. Chronic anger is associated with narrowing of the arteries, a factor in heart disease. • People who lack supportive relatives or friends.

Causes and Symptoms Stress is caused by the human body’s response to any event or situation perceived as a stressor. Perception is an important factor in a person’s reaction to stress because it can be modified or changed in some situations. The specific symptoms of stress-related illness vary from person to person depending on which organs or body systems are most vulnerable. Common symptoms of stress include: • Heart. Chronic stress raises blood pressure, triggers the release of cholesterol into the bloodstream, and causes the arteries to narrow. It also increases the possibility that a clot will form in the coronary arteries, thus increasing the person’s risk of heart attack or stroke. • Skin. Eczema and other allergic skin rashes can be triggered or made worse by stress. • Digestive tract. Stress leads to nausea, diarrhea, constipation, bloating, and irritable bowel syndrome in many people. It may also play a role in the onset of eating disorders. • Reproductive system. Stress can lead to loss of sexual desire in both men and women. In addition, stress during pregnancy is associated with a 50 percent higher risk of miscarriage. High stress levels on the mother during pregnancy are also related to higher rates of premature births and babies of lower than average birth weight; both are risk factors for infant mortality. • Bones, joints, and muscles. Stress intensifies the chronic pain of arthritis and other joint disorders. It also produces tension-type headaches, which are headaches caused by the tightening of the muscles in the neck and scalp. • Brain and central nervous system. Stress hormones released during acute stress interfere with memory and learning. People who are under severe stress become unable to concentrate; they may 1046


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become clumsy and accident-prone. Acute stress interferes with short-term memory, although this effect goes away after the stress is resolved. In children, however, the brain’s biochemical responses to stress clearly limit the ability to learn. • Immune system. Chronic stress increases a person’s risk of getting an infectious illness. Several research studies have shown that people under chronic stress have lower than normal white blood cell counts and are more vulnerable to colds and influenza. Men with HIV infection and high stress levels progress more rapidly to AIDS than infected men with lower stress levels.

Diagnosis There is no specific test or imaging study for diagnosing stress. People with specific mental disorders like posttraumatic stress disorder (PTSD) or panic disorder can be diagnosed by a psychiatrist qualified to evaluate these conditions. In most other cases, however, a person is diagnosed in the course of a checkup for a stress-related physical condition when the doctor asks about the stress level in their living situation, school, or job.

Treatment Treatment for stress depends on the parts of the person’s body that are affected and the sources of stress and types of stress in his or her life. Most people benefit from a combination of treatment approaches: • Medications. These can be prescribed to treat physical conditions related to stress like high blood pressure or high cholesterol levels, or to help relieve emotional anxiety. • Psychotherapy. The two approaches most often used in treating stress are interpersonal therapy and cognitive therapy. In interpersonal therapy, people learn about the events in their past and the triggers in their lives that set off the stress response, together with strategies for coping with stressors. Cognitive therapy works by teaching patients to change their ways of thinking about stressful situations or events. Many people have underlying negative assumptions about life that make them more vulnerable to stress. • Lifestyle changes. People who have used alcohol, drugs, or smoking are usually advised to quit. In some cases, people may have to change jobs or leave bad relationships in order to relieve chronic stress. UXL Encyclopedia of Diseases and Disorders

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• Physical exercise. Physical activity is a good way to work off tension in the muscles and joints, and to improve strength and endurance. • Stress management. Stress management refers to programs or techniques intended to help people deal more effectively with stress. Many of these are intended to help people handle job- or workplace-related stress. Stress management programs ask participants to identify the specific aspects of their jobs that they find stressful and then plan a course of positive action to lower their stress levels. • Complementary and alternative approaches. Acupuncture, yoga, relaxation training, meditation, prayer and religious practice, guided imagery, hypnosis, massage therapy, music therapy, humor, and pet therapy are alternative approaches that help many people cope with stress.

Prognosis The prognosis for stress depends on the patients’ overall health, their age, the specific stressors they confront, and the ways of coping that they have developed over time. Some people tend to focus on their feelings about the stressful situation while others focus on solving the problem. Still others react to stress by trying to escape from it through drugs or alcohol.

Prevention The National Institutes of Health (NIH) has compiled a list of ten things people can do to prevent stress: • Stay away from stressors that can be avoided. • Avoid making too many lifestyle changes too close together—such as trying to quit smoking while planning to move to a new city and take a new job. • Recognize limitations and not take on too many responsibilities at the same time. • Organize tasks according to priority and allow enough time to complete each one. • Learn to communicate effectively and politely with others. • Don’t isolate; share thoughts or feelings with friends, family, or appropriate others, and take their advice if it seems reasonable and helpful. 1048


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WORDS TO KNOW Eustress: A term that is sometimes used to refer to positive stress. Stress management: Any set of techniques intended to help people deal more effectively with stress in their lives by analyzing specific

stressors and taking positive actions to minimize their effects. Stressor: Any event or stimulus that provokes a stress response in a human or animal.

• Create a positive attitude toward life. • Set aside time for a break or a treat as a reward for overcoming a stressful situation. • Get regular physical exercise, at least thirty minutes each day. • Eat a healthy diet and get enough sleep.

The Future The stress level in people’s lives is likely to increase in the future rather than improve. One reason is the growing complexity and interconnectedness of the world; political, economic, and public health problems in almost any country can have an impact on others thousands of miles away. Another factor is the effect of the mass media and rapid communications. People are constantly bombarded with news about natural disasters and other frightening events. SEE ALSO

Depression; Eczema; Heart attack; Irritable bowel syndrome; Panic disorder; Posttraumatic stress disorder; Prematurity; Stroke


Hipp, Earl. Fighting Invisible Tigers: Stress Management for Teens. Minneapolis: Free Spirit Publishing, 2008. Hyde, Margaret O., and Elizabeth H. Forsyth. Stress 101: An Overview for Teens. Minneapolis: Twenty-First Century Books, 2008. Lawton, Sandra A., ed. Stress Information for Teens. Detroit: Omnigraphics, 2008. WE B S IT E S

American Academy of Family Physicians (AAFP). Stress: How to Cope Better with Life’s Challenges. Available online at http://familydoctor.org/online/ UXL Encyclopedia of Diseases and Disorders

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famdocen/home/common/mentalhealth/stress/167.html (updated December 2006; accessed September 29, 2008). American Heart Association (AHA). How Can I Manage Stress? Available online in PDF format at http://www.americanheart.org/downloadable/heart/ 110167971464923%20HowCanIManageStress.pdf (updated December 2004; accessed September 29, 2008). American Psychological Association Help Center. Stress: The Different Kinds of Stress. Available online at http://www.apahelpcenter.org/articles/article.php? id=21 (accessed September 29, 2008). National Institute for Occupational Safety and Health (NIOSH). Working with Stress. Available online at http://www.cdc.gov/niosh/docs/video/stress1.html (produced in 2002; accessed September 29, 2008). This is a seventeenminute video about job-related stress that can be downloaded as well as played online. National Library of Medicine (NLM). Managing Stress. Available online at http://www.nlm.nih.gov/medlineplus/tutorials/managingstress/htm/index. htm (accessed September 29, 2008). This is an online tutorial with voiceover. Viewers have the option of a self-playing version, an interactive version with questions, or a text version. TeensHealth. Stress. Available online at http://kidshealth.org/teen/your_mind/ emotions/stress.html (updated July 2007; accessed September 29, 2008).

Stroke Also Known As Apoplexy, brain attack, cerebrovascular accident Cause Shortage of blood supply to the brain Symptoms Weakness or paralysis on one side, headache, vision problems, confusion, difficulty speaking Duration Brain damage begins within minutes; may continue for days 1050

Definition Stroke is a life-threatening condition that occurs when the blood supply to a part of the brain is suddenly cut off or when brain tissue is damaged by bleeding into the brain. There are two main types of stroke. Ischemic stroke occurs when a clot formed in the artery or coming from elsewhere in the artery system blocks an artery to the brain; this type accounts for about 80 percent of strokes. The other type, hemorrhagic stroke, occurs when a blood vessel in the brain bursts, allowing blood to spill out into brain tissue. The blood upsets the chemical balance that the nerve cells in the brain need to function.

Description Stroke is usually a sudden occurrence. Some people have a warning event called a transient ischemic attack (TIA) or mini-stroke. A TIA has the UXL Encyclopedia of Diseases and Disorders

Stroke Elderly woman undergoing rehabilitation after a stroke. © DENNIS MACDONALD / ALAMY.

same symptoms as a full-blown stroke but goes away in a few minutes or hours, leaving no permanent effects. It is, however, an indication that the person is at risk of a major stroke and should see their doctor right away. A TIA offers the person an opportunity to take preventive action. Stroke has five major signs or symptoms. The American Stroke Association has a quick symptom checklist called “Give Me 5” • • • • •

Walk: Is the person having trouble with balance or coordination? Talk: Is speech difficult or slurred? Is the person’s face drooping? Reach: Is one side of the body weak or numb? See: Is vision partly or entirely lost? Feel: Does the person have a sudden severe headache with no obvious cause? A person with stroke can have more than one of these symptoms at the same time. The important feature to keep in mind is that the symptoms come on suddenly, which helps in distinguishing stroke from other causes of dizziness, vision problems, or headache.

Demographics According to the Centers for Disease Control and Prevention (CDC), stroke is the third leading cause of death in the United States as of 2008, being responsible for about 160,000 deaths each year. About 700,000 UXL Encyclopedia of Diseases and Disorders

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Americans have strokes each year, 500,000 for the first time and 200,000 having a second or First Aid for Stroke third stroke. The total cost of stroke to the American economy each year is about $43 billion. The most important first step is to call for emergency help at once. Stroke is a medical About 50,000 Americans have a TIA in an emergency; the sooner the person is evaluated average year; of this group, 35 percent will have and treated, the better their chances of a severe stroke at some point in the future. recovery. The drug presently considered most Strokes can affect people in any age group; howuseful in treating stroke must be given within ever, the risk increases sharply in people over fiftythree hours of the attack to be effective. five years of age. Seventy-five percent of all strokes Additional measures that can be taken while occur in people over sixty-four. Men are 1.25 times waiting for the emergency team: more likely to have strokes than women; however, • If the person stops breathing, give them women are more likely to die of stroke because they mouth-to-mouth resuscitation. are usually older when they have their first stroke. • If they are vomiting, tilt their head to African Americans have an increased risk of one side to prevent them from swalstroke compared to other racial and ethnic lowing the material. groups in the United States, and they are also • Do not give them anything to eat or more likely to suffer a stroke at younger ages. drink. African Americans between the ages of forty-five and fifty-five die from stroke 4–5 times more often that Caucasians in the same age group. Risk factors for stroke include: • Hypertension (high blood pressure). This is the most important single risk factor for stroke. • High blood cholesterol levels. • Being over age fifty-five. • A family history of stroke, TIA, or heart attack. • Diabetes. • Smoking. Smoking doubles a person’s risk of ischemic stroke. • Personal history of previous stroke or TIA. • Obesity. • Heavy use of cocaine. • Irregular heart rhythm. • Heavy drinking. Alcohol consumption raises a person’s blood pressure. • Use of birth control pills or hormone replacement therapy. 1052


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Causes and Symptoms Stroke is caused by a loss of blood supply to the brain resulting either from a clot blocking an artery or from bleeding into or around the brain. Ischemic stroke can result from two types of clots. The first is an embolus, which is a free-floating clot produced in the heart or somewhere else in the body that travels to a blood vessel in the brain. The second type of clot is formed within an artery in the head or neck and grows there until it is large enough to block the artery. Atherosclerosis, a disease of the blood vessels in which fatty deposits build up along the walls of the vessels, is a common cause of this type of clot. Hemorrhagic stroke can occur when an aneurysm—a weak spot in the wall of an artery—suddenly bursts. High blood pressure is the most common cause of this type of hemorrhagic stroke. Hemorrhagic stroke can also occur when the walls of an artery become thin and brittle; they can then break and leak blood into the brain. Hemorrhagic stroke can take one of two forms: the blood can leak directly into brain tissue from an artery in the brain, or it can leak from an artery near the surface of the brain into the space between the skull and the membranes covering the brain. The major symptoms of stroke have already been described. Other symptoms that some patients experience include drooling, uncontrollable eye movements, personality or mood changes, drowsiness, loss of memory, or loss of consciousness.

Diagnosis The diagnosis of stroke includes taking the patient’s history and obtaining an account of the patient’s symptoms, followed by a complete physical and a neurological examination to rule out the possibility that the patient’s symptoms are being caused by a brain tumor. The neurologist may use the National Institutes of Health Stroke Scale (NIHSS), which is a checklist that allows the doctor to record the patient’s level of consciousness; visual function; ability to move; ability to feel sensations; ability to move the facial muscles; and ability to talk. Other tests include: • Blood tests. These can reveal the existence of blood disorders that increase a person’s risk of stroke. • Computed tomography (CT) scan. This type of imaging test is one of the first tests given to a patient suspected of having a stroke. It UXL Encyclopedia of Diseases and Disorders

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• • •

•

helps the doctor determine the cause of the stroke and the extent of brain injury. Magnetic resonance imaging (MRI). This imaging test is useful in pinpointing the location of small or deep brain injuries. Electroencephalogram (EEG). This test measures the brain’s electrical activity. Blood flow tests. These are done to detect the location and size of any blockages in the blood vessels. One type of blood flow test uses ultrasound to produce an image of the arteries in the neck leading into the brain. Another type of blood flow test, called angiography, uses a special dye injected into blood vessels that will show up on an x ray. Echocardiography. This type of test uses ultrasound to produce an image of the heart. It can be useful in determining whether an embolus from the heart caused the patient’s stroke.

Treatment Treatment of stroke depends on whether it is ischemic or hemorrhagic. Ischemic stroke is treated first with blood thinners, often aspirin or another drug known as warfarin. If the patient is seen by a specialized stroke team within three hours of the attack, he or she may be treated with a drug called tissue plasminogen activator or tPA. It is critical, however, to be sure that the patient has an ischemic rather than a hemorrhagic stroke, as blood-thinning drugs can make a hemorrhagic stroke worse. Hemorrhagic stroke is treated by removing pooled blood from the brain and repairing damaged blood vessels. To prevent another hemorrhagic stroke, the surgeon may use a procedure called aneurysm clipping. In this procedure, the surgeon clamps the weak spot in the artery away from the rest of the blood vessel, which reduces the chances that it will burst and bleed. After emergency treatment in the hospital, most stroke patients need long-term recovery and rehabilitation. The type and length of therapy depend on the amount of function the patient has lost; some need to relearn language skills, while others may need to relearn bowel and bladder control, swallowing, and movement or balance. Most patients need a combination of physical therapy, occupational therapy, speech therapy, and psychotherapy. It is common for stroke patients to feel depressed during rehabilitation or to have trouble controlling their feelings. 1054


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Prognosis The prognosis of stroke depends on the person’s age, the type and location of the stroke, and the amount of time elapsed between diagnosis and treatment. In general, patients with ischemic stroke have a better prognosis than those with hemorrhagic stroke. In one study in the Boston area, 19 percent of patients with ischemic stroke died within the first thirty days of the attack compared to 35 percent with hemorrhagic stroke. About 10 percent of stroke patients recover enough function to live independently without help; another 50 percent can remain at home with outside assistance. The remaining 40 percent require long-term care in a nursing home.

Prevention People cannot change some risk factors for stroke, such as race, age, sex, or family history, but they can control several other risk factors: • They can quit smoking, drinking heavily, or using cocaine. • They can keep their weight at a healthy level. • They can exercise regularly, eat a healthy diet, and take medications for high blood pressure if they are diagnosed with it. • They can take steps to lower their risk of diabetes or high blood cholesterol levels. • They can lower the level of emotional stress in their life or learn to manage stress more effectively. • They can get regular checkups for abnormal heart rhythms if they have been diagnosed with such problems. • They can see their doctor at once if they have a TIA.

The Future Stroke is a disorder that has attracted researchers from a number of different fields because its costs to individuals are still high and doctors are increasingly recognizing that many strokes are preventable. In addition, the aging of the American population means that the number of stroke patients is likely to increase over the next several decades. As of 2008, the National Institutes of Health was sponsoring 1,800 separate studies of stroke prevention and treatment, ranging from new medications to treat UXL Encyclopedia of Diseases and Disorders

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Stroke

WORDS TO KNOW Aneurysm: A weak or thin spot on the wall of an artery.

Thrombus: A blood clot that forms inside an intact blood vessel and remains there.

Embolus: The medical term for a clot that forms in the heart and travels through the circulatory system to another part of the body.

Transient ischemic attack (TIA): A brief stroke lasting from a few minutes to twenty-four hours. TIAs are sometimes called mini-strokes.

Ischemia: Loss of blood supply to a tissue or organ resulting from the blockage of a blood vessel.

ischemic stroke to investigations of the genetic factors that increase people’s risk of stroke. A recent innovation is the use of computer technology to allow stroke experts in one hospital to evaluate and diagnose a patient in another hospital that might not have a specialist available. Called TeleStroke, the network allows a patient to be evaluated for ischemic stroke within the three-hour time limit for the effective use of tPA. S E E A L S O Coronary artery disease; Hypercholesterolemia; Hypertension; Sickle cell anemia; Smoking


Edlow, Jonathan A. Stroke. Westport, CT: Greenwood Press, 2008. Hreib, Kinan K. 100 Questions and Answers about Stroke: A Lahey Clinic Guide. Sudbury, MA: Jones and Bartlett Publishers, 2008. McEwen, Mark. Change in the Weather: Life after Stroke. New York: Gotham Books, 2008. PE R I O DI C A L S

Kolata, Gina. “Precious Hours, Then Lives, Lost in Stroke’s Wake.” New York Times, December 22, 2007. Available online at http://health.nytimes.com/ ref/health/healthguide/esn-stroke-ess.html (accessed on August 27, 2008). WE B S IT E S

American Stroke Association. What Is Stroke? Available online at http://www. strokeassociation.org/presenter.jhtml?identifier=3030066 (accessed on August 27, 2008). Centers for Disease Control and Prevention (CDC). Stroke Home Page. Available online at http://www.cdc.gov/stroke/ (updated October 10, 2007; accessed on August 27, 2008). 1056


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eMedicine Health. Stroke. Available online at http://www.emedicinehealth.com/ stroke/article_em.htm (accessed on August 27, 2008). National Institute of Neurological Disorders and Stroke (NINDS). Stroke: Hope through Research. Available online at http://www.ninds.nih.gov/disorders/ stroke/detail_stroke.htm (updated August 20, 2008; accessed on August 27, 2008).

Sudden Infant Death Syndrome Definition Sudden infant death syndrome, or SIDS, is the unexpected death of an apparently healthy baby. According to the Centers for Disease Control and Prevention (CDC), such a death “cannot be explained after a thorough investigation is conducted, including a complete autopsy, examination of the death scene, and review of the baby’s clinical history.”

Description In the typical SIDS case, the parents or caregivers put the baby to bed after feeding him or her. A check of the baby shortly after bedtime indicates that everything is normal. However, the baby is later found dead, usually in the position in which he or she had been placed at bedtime or naptime. In most cases of SIDS, the parents state that the child was apparently healthy. However, some parents of infants who died of SIDS state that their babies “were not themselves” in the hours before death. In a number of cases, the parents report that the baby had diarrhea and vomiting at some point in the two weeks prior to death. Currently, doctors do not know whether these digestive problems are related to SIDS in some way or are only coincidental.

Demographics According to the CDC, SIDS is the leading cause of death among American infants between the ages of one and twelve months, and is the third leading cause overall of infant mortality in the United States. SIDS is UXL Encyclopedia of Diseases and Disorders

Also Known As SIDS, crib death, cot death, sudden unexpected death in infancy Cause Unknown Symptoms Infant found dead after having gone to sleep in apparent normal health Duration A few hours 1057


“Back to Sleep” Campaign The “Back to Sleep” Campaign is a safety program promoted by the National Institute of Child Health and Human Development (NICHD) that recommends placing a baby on its back for naps and sleeping at night. The campaign was started in 1992 following a recommendation from the American Academy of Pediatrics that babies should not be placed on their stomachs to sleep—as had been common practice for many years. The Back to Sleep campaign emphasizes three central points: • Sleeping on the back reduces an infant’s risk of sudden infant death syndrome (SIDS).

responsible for about one death per 2,000 live births as of the early 2000s; however, this figure is more than 50 percent lower than the figures for 1990, largely as a result of the “Back to Sleep” campaign. Most SIDS deaths occur in babies between two and four months of age; only 1 percent occur in newborns. Boys are more likely than girls to die of SIDS; 60–70 percent of SIDS cases involve boys. According to NICHD, African American babies are twice as likely as Caucasian babies to die from SIDS, and Native American babies are three times as likely. The reason for these differences is not yet known but may be related to other risk factors listed below. Studies indicate that some mothers are at increased risk of having their child die of SIDS:

• The sleeping surface makes a difference. Babies who are put to bed on a soft surface are at increased risk of SIDS.

• Those who smoke during pregnancy and after childbirth. • Those who abuse drugs or alcohol. • Every sleep and nap time matters. • Those who are underweight or suffer from Babies should always be placed on the malnutrition. back for sleeping. According to the campaign, “Babies who usually sleep on • Those who have children less than one their backs but who are then placed on year apart. their stomachs are at very high risk for • Teenage mothers. The more children the SIDS.” mother has while still in her teens, the greater the risk of SIDS. • Those who are obese. Apart from sleeping position, some babies are at increased risk of SIDS: • • • • • • 1058

Babies Babies Babies Babies Babies Babies

who are born prematurely. who weigh 4 pounds (1800 grams) or less at birth. who are not breastfed. who are part of a set of twins, triplets, or quadruplets. who are exposed to tobacco smoke. put to sleep in an overheated room. UXL Encyclopedia of Diseases and Disorders


• Babies whose parents practice co-sleeping (the baby shares the parents’ bed at night). • Babies who are overdressed for sleep or covered with too many blankets.

Causes and Symptoms The cause of SIDS is not known with certainty. It is possible that some cases of SIDS are the result of a combination of factors. Doctors have proposed several different theories for SIDS: • Bacterial infections. A British study published in May 2008 reported that some cases of SIDS appear to result from previously undetected bacterial infections. • Abnormalities in the part of the brain stem that controls breathing. A study published in the Journal of the American Medical Association in the fall of 2007 is one of the strongest pieces of evidence so far that innate differences in brain structure may put some babies at increased risk of SIDS. • Smothering caused by sleeping on the stomach. This theory holds that babies put to sleep lying on the stomach may breathe in their own exhaled carbon dioxide because they do not have the same ability as older children to move their heads during sleep to get more oxygen. • Episodes of apnea (sudden cessation of breathing). Babies sometimes stop breathing periodically for reasons that are still not understood. • Abnormalities in heart rhythm. About 10 percent of babies who die of SIDS have been found to have a gene associated with sudden episodes of extremely rapid heartbeat. • Triple-risk theory. This theory proposes to explain SIDS as the end result of three factors: a biological vulnerability (such as a weakened heart or abnormal brain stem), an environmental problem (such as sleeping on the stomach), and being too young to regulate breathing and other vital functions as effectively as older children. Theories that are no longer accepted include the notion that SIDS is caused by vaccinations, by dust mites or other insects in the crib mattress, UXL Encyclopedia of Diseases and Disorders

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or by toxic gases released by materials used in the manufacture of crib mattresses. The symptoms of SIDS have already been described.

Diagnosis SIDS is a diagnosis of exclusion, which means that the doctor can list it as the cause of a baby’s death only after all other possible causes have been ruled out. It is particularly important to exclude the possibility that the baby had been abused. The American Academy of Pediatrics has drawn up a list of criteria that must be met in order to distinguish SIDS from child abuse: • There has been a complete autopsy of the baby, and the autopsy findings are consistent with a diagnosis of SIDS. • There is no evidence of head trauma or significant disease. • There is no evidence of trauma to the baby’s bones. • Other possible causes of death have been ruled out, including pneumonia, metabolic disorders, dehydration, severe birth defects, dehydration, massive infection, trauma to the abdomen, or carbon monoxide poisoning. • There is no evidence that the baby was given alcohol, drugs, or other toxic substances. • There is no evidence of foul play when the death scene is investigated. • The baby’s medical history does not indicate previous health problems.

Treatment There is nothing that can be done to treat the infant when SIDS occurs. Treatment of the parents includes support and understanding. However, the doctor and other health professionals must at the same time conduct a thorough investigation into the circumstances surrounding the baby’s death. There are some differences among the states as to the way in which the postmortem (after death) investigation is carried out, but all states require an investigation before the death can be defined as SIDS. It is difficult for many parents to accept the need for an autopsy and an evaluation of the bed and room in which the baby died when they are 1060



grieving. However, ruling out the possibility of abuse or intentional suffocation of the child is a legal necessity. Circumstances that concern doctors as well as law enforcement when a baby dies suddenly include: • The child was seven months of age or older. SIDS is unusual in this age group. • The pregnancy was unwanted. • There have been previous unexplained infant deaths in the family. • Family members have a history of arrests for violent behavior.

Prevention The CDC recommends the following precautions to reduce the risk of SIDS: • Infants should always be placed on their backs to sleep when they are left alone; they should be placed on their stomachs only when they are awake and supervised by someone responsible. • If the baby sleeps in a crib, the crib’s mattress should be firm and fit snugly into the crib frame. Such other firm sleeping surfaces as bassinets or cradles are also fine. • The baby should be dressed in a sleeper or pajama to keep it warm rather than being covered by a blanket. • Parents who co-sleep with a baby should never smoke, drink alcohol, or use drugs when sleeping with the baby. It is better to have the baby sleep in a crib or bassinet next to the parents’ bed rather than sharing the bed. • Parents should never put a baby on a couch, waterbed, or pillow for a nap. • Parents should never smoke in the same room as the baby or allow anyone else to do so. • Caregivers should never place the baby to sleep or nap with any pillows, stuffed toys, bumper pads, comforters, quilts, or sheepskins.

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WORDS TO KNOW Autopsy: The examination of a body after death to determine the cause of death. Brain stem: The lower part of the brain directly connected to the spinal cord. It controls breathing and other vital functions.

Co-sleeping: Allowing a baby to sleep in the same bed as its parents. It is also called bed sharing. Postmortem: Referring to the period following death.

a child’s risk of dying of SIDS. Some scientists are looking into possible genetic factors that may affect a child’s risk of SIDS. SEE ALSO

Child abuse; Obesity; Prematurity; Shaken baby syndrome;

Smoking


Horchler, Joani Nelson, and Robin Rice. SIDS and Infant Death Survival Guide: Information and Comfort for Grieving Family and Friends and Professionals Who Seek to Help Them, revised and updated. Cheverly, MD: SIDS Educational Services, 2003. WE B S IT E S

American Sudden Infant Death Syndrome Institute. Reducing the Risk of SIDS. Available online at http://sids.org/nprevent.htm (updated 2007; accessed July 9, 2008). Centers for Disease Control and Prevention (CDC). Sudden Infant Death Syndrome: Home. Available online at http://www.cdc.gov/SIDS/index.htm (updated April 7, 2008; accessed July 9, 2008). First Candle. When a Baby Has Died. Available online at http://www.firstcandle. org/whenababy/whenababy.html (accessed July 9, 2008). First Candle is a charity that offers support and counseling to families that have lost a baby. It has a toll-free bilingual crisis counseling hotline staffed twenty-four hours a day, seven days a week at (800) 221-7437. Mayo Clinic. Sudden Infant Death Syndrome (SIDS). Available online at http:// www.mayoclinic.com/health/sudden-infant-death-syndrome/DS00145 (updated June 13, 2007; accessed July 9, 2008). National Institute of Child Health and Human Development (NICHD). SIDS: “Back to Sleep” Campaign. Available online at http://www.nichd.nih. gov/sids/sids.cfm (updated February 22, 2008; accessed July 9, 2008). 1062


Sunburn

Sunburn Definition Sunburn is an inflammation of the skin caused by overexposure to ultraviolet (UV) radiation, usually from the sun.

Description Sunburn is an uncomfortable skin condition marked by reddening and soreness in its milder forms and peeling or blistering with longer periods of exposure to sunlight or tanning lamps. The skin is hot and painful to the touch. Sunburn can also affect the eyes, causing a dry or gritty feeling inside the eyelid.

Demographics Sunburn is very common in the general population in North America. According to a survey carried out by the Skin Cancer Foundation, 42 percent of the people who answered the survey reported getting sunburned at least once in the preceding year. Some people are at greater risk of sunburn than others. Risk factors include: • Fair skin. Fair-skinned people with red or blond hair and lightcolored eyes are at particularly high risk of sunburn. • Infants and children of all races. • People with diabetes or thyroid disease. • People who live at high altitudes or close to the tropics, and people who are traveling to those parts of the world. • People who take certain types of antibiotics, tranquilizers, or birth control pills; these drugs make the skin more sensitive to sunlight. • People who enjoy swimming or boating in the summer or skiing in the winter. Sunlight reflected from water or snow can damage the skin as well as sunlight falling directly on the skin. • People whose work requires them to spend a lot of time in the sun. UXL Encyclopedia of Diseases and Disorders

Also Known As Sun overexposure, photodermatitis Cause Exposure to ultraviolet rays from sun or tanning devices Symptoms Reddened skin painful to touch, blisters, skin peeling Duration A week to several weeks following exposure 1063

Sunburn Severe blister due to sunburn. © TONY WATSON / ALAMY

Causes and Symptoms Sunburn is caused by ultraviolet (UV) radiation from the sun or a tanning lamp. The UV radiation causes damage to the DNA (genetic material) in the cells of the skin. The body responds to this damage by repairing the DNA and by increasing production of melanin, a brownish-black pigment that protects the skin from further sun damage. Melanin is responsible for the changes in skin color known as a suntan. Over time, repeated episodes of sunburn can lead to dry skin, premature wrinkling of the skin, patches of scaly skin known as actinic keratosis, and various types of skin cancer. Repeated exposure to sunlight over a period of years can also lead to changes in the lens of the eye known as a cataract. The symptoms of mild sunburn are: • Redness and pain in the affected skin. The intensity of the pain is directly proportional to the length of time the person was exposed to UV radiation and the intensity of the radiation. A person can get sunburned in as little as fifteen minutes. The redness usually develops within thiry minutes to six hours after exposure. The pain is most intense from six to forty-eight hours after exposure. • The skin becomes swollen. 1064


Sunburn

• The skin becomes itchy. • The skin is hot to the touch. This warmth is caused by the dilation of blood vessels in the injured area. • The area may exhibit peeling after several days. More severe sunburn causes the formation of blisters on the affected skin. Skin usually begins to peel about three days after exposure and may continue for another week or ten days. People who are severely sunburned sometimes develop a condition called sun poisoning. The symptoms of sun poisoning include fever, chills, dizziness, fluid loss, extreme tiredness, and a skin rash as well as the sunburn.

Diagnosis Most people do not need to consult a doctor to diagnose sunburn. Mild sunburn can be treated at home (see sidebar). However, people who notice any of the following symptoms should see a dermatologist (a doctor who specializes in skin problems) because they may be early signs of skin cancer: • A growth on the skin that was not there before the sunburn. • A sore that bleeds, crusts over, keeps reopening, and does not heal within two weeks. • A change in the size, color, or texture of a mole. • A dark flat spot on the skin that is gradually enlarging.

Treatment

First Aid for Sunburn The discomfort of sunburn can be relieved at home by the following treatments: • Taking a cool (not cold) bath or shower, adding baking soda to the water if desired. • Soothing the skin with a washcloth soaked in cold skim milk. The skim milk contains protein that helps to ease the pain. • Applying a non-greasy lotion moisturizing lotion to the burned area. Products containing aloe vera gel are a good choice. • A non-aspirin pain reliever like Advil or Motrin helps relieve the irritation. There are also some home remedies and cosmetic cover-ups that should be avoided: • Do not apply a self-tanning lotion to sunburned or peeling skin; it will stick to the injured skin and make it look worse. • Do not use petroleum jelly, butter, or products containing local anesthetics to the burned area. They will make the discomfort worse and slow healing. • Do not use harsh soap to wash sunburned skin. • If blisters form, do not cover them with ointments; allow them to heal in the open air. If they break open to form sores, cover them lightly with clean gauze and apply an antibacterial lotion to prevent infection. • Do not give aspirin to children or teenagers to relieve the inflammation of sunburned skin; use a non-aspirin pain reliever instead.

Home treatment of mild sunburn is described in the sidebar. Most mild cases of sunburn UXL Encyclopedia of Diseases and Disorders

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eventually heal without special attention from a doctor. Blisters, however, may require medical treatment if they break open and become infected. A person with sunburn blisters that are oozing, hot, red, swollen, and painful should see their doctor. A patient with any of the following symptoms may be suffering from sun poisoning, heat exhaustion, or shock as well as sunburn. A doctor should be contacted at once: • • • • • • •

Dizziness or a faint feeling A fast pulse or rapid breathing Sunken eyes, no urine output, extreme thirst Pale, cool, or clammy skin Severe or painful blisters Eyes hurt or are sensitive to light Nausea, fever, chills, or a skin rash

Prognosis Most mild cases of sunburn heal without problems in the short term. Blisters that become infected usually heal completely once the infection is treated. The long-term prognosis is of greater concern, as a history of repeated sunburn increases a person’s risk of melanoma (the most serious form of skin cancer) as well as cataracts and other eye disorders.

Prevention Sunburn can be prevented by taking the following steps: • Avoiding tanning booths and sun lamps. • Staying out of the sun between 10 a.m. and 4 p.m. • Using a sunscreen with a sun protection factor (SPF) of 15 or higher every day. People with very fair skin should use a product with an SPF of 30 or higher. • Applying sunscreen over the entire body thirty minutes before going outside, and reapplying the product every two hours. • Using a lip balm that contains sunscreen. • Wearing clothing that covers as much of the body as possible, including a broad-brimmed hat and sunglasses to protect the eyes. • Keeping infants under six months out of the sun altogether, and using sunscreen on infants older than six months. 1066


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WORDS TO KNOW Actinic keratosis: A patch of thickened or scaly skin caused by sun exposure. It is not itself a form of skin cancer but may develop progressively into a skin cancer. Dermatology: The branch of medicine that deals with skin problems and disorders.

Melanin: A brownish-black skin pigment. Melanoma: The most serious form of skin cancer. Sunburn increases the risk of melanoma. Sun poisoning: A term sometimes used to refer to a severe reaction to sunburn, consisting of fever, chills, fluid loss, dizziness, and nausea.

The Future Sunburn is a common health problem that is not likely to go away any time soon. One reason is that it can easily happen accidentally to someone who may not have planned to be outside in the sun for more than a few minutes. Another reason is that the long-term risks of sunburn, such as skin cancer and cataracts, usually take years to appear. This time lag means that a teenager who wants a glamorous tan right now may not think much about what will happen to his or her skin twenty or thirty years in the future. Prevention of sunburn is an important health measure for people of all ages. SEE ALSO

Burns and scalds; Cataracts; Dermatitis; Heat exhaustion


Gordon, Sharon. Sunburn. Danbury, CT: Children’s Press, 2002. Royston, Angela. Why Do I Get Sunburn? And Other Questions about Skin. Chicago: Heinemann Library, 2002. WE B S IT E S

American Academy of Dermatology (AAD). Public Center: Sun Safety. http:// www.aad.org/public/# (accessed April 17, 2008). This is a gateway to several sets of skin care tips and articles about the long-term health risks of sunburn. American Academy of Dermatology (AAD). SkinCancerNet. http://www.skincarephysicians.com/skincancernet/index.html (accessed April 17, 2008). This is a gateway to many articles on types of skin cancer, prevention methods, and treatment options. Nemours Foundation. Kids Health: How to Be Safe When You’re in the Sun. Available online at http://www.kidshealth.org/kid/watch/out/summer_ safety.html (accessed April 17, 2008.) UXL Encyclopedia of Diseases and Disorders

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Syphilis

Skin Cancer Foundation. Preventing and Treating Sunburn. Available online at http://www.skincancer.org/preventing-&-treating-sunburn/ (accessed April 17, 2008).

Syphilis Definition Syphilis is a sexually transmitted disease (STD) caused by a spiral-shaped bacterium, Treponema pallidum. It can be transmitted by an infected mother to her unborn child as well as by genital, oral, or anal sexual contact. Although the disease has been known for centuries, the organism that causes it was not identified until 1913. The discoverer was Hideyo Noguchi (1878–1928), a Japanese bacteriologist who was working at the Rockefeller Institute in New York as a research assistant.

Description

Also Known As Treponema pallidum infection, lues Cause Treponema pallidum bacteria Symptoms Chancres, flu-like symptoms, skin rash, fever; if untreated, dementia, heart failure, bone pain Duration Years, unless treated early 1068

Syphilis was for many years one of the deadliest STDs, not only because there was no effective treatment for it before the twentieth century, but also because its symptoms are difficult to distinguish from those of other diseases. Syphilis was nicknamed the “Great Imitator” because it could be easily confused with leprosy, infectious mononucleosis, fungal infections of the skin, meningitis, genital herpes, lymphoma, and many other diseases. To add to the diagnostic confusion, the symptoms of syphilis have changed somewhat since the first recorded European outbreak in 1494. French troops fighting in Italy were stricken with an STD that caused death within a few months. Medical historians think that this first epidemic, called the great pox to distinguish it from smallpox, was so severe because the disease was either new to Europe or that the spirochete that causes syphilis had mutated over the centuries. Some researchers hold that syphilis was brought to Europe by Columbus’s sailors, while others maintain that skeletons from the Middle Ages found in both Italy and England show evidence of late-stage syphilis. In either case, syphilis as it is known in the twenty-first century is rarely fatal unless it is not treated. UXL Encyclopedia of Diseases and Disorders

Syphilis A secondary syphilis rash on the back. CNRI/PHOTO RESEARCHERS, INC.

Syphilis is a disease that attacks the body in stages: • Primary syphilis: Acquired by direct sexual contact with an infected person, this stage usually appears after about ten days after the spirochete is transmitted, but can take several months to appear. Its major symptom is the chancre (pronounced SHANKer), a painless skin ulcer that appears at the location of exposure to the bacterium, usually on the penis, anal area, or vagina. There may be one or several chancres. The patient may also develop swollen lymph nodes, but there are rarely any other symptoms in this stage. Chancres go away after about a week or two even if untreated, but the disease does not. • Secondary syphilis: This stage develops about six to eight weeks after the primary infection. Its symptoms are the reason syphilis has been called the great pretender—they range from fever, loss of appetite, joint pains, and other flu-like symptoms to a reddish-pink skin rash, hair loss, headache, and swollen lymph nodes. The disease is most contagious in this stage. • Latent syphilis: Also known as dormant syphilis, in this stage the patient may have no symptoms or occasional flare-ups of the symptoms of secondary syphilis. The patient is not usually infectious but will still test positive for the disease if given a blood test. UXL Encyclopedia of Diseases and Disorders

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Syphilis

Dr. Hinton’s Blood Test The first modern treatment for syphilis, a drug containing a form of arsenic, was developed in Germany in 1908. Although not as effective as penicillin later proved to be, this useful drug prompted researchers to look for better ways to diagnose syphilis. In the early 1930s, a blood test more accurate than the previously accepted tests was developed by Walter Augustus Hinton (1883–1959), a graduate of Harvard Medical School and the first African American to become a full professor in any department at Harvard. Hinton, the son of two former slaves, acquired an international reputation as a public health expert in the prevention and treatment of syphilis. Hinton’s blood test was not only more accurate, but simpler and less expensive than former tests. It was officially endorsed as the diagnostic standard by the U.S. Public Health Service in 1934. In 1936 Hinton published the first medical school textbook written by an African American; it was on syphilis and its treatment. Hinton continued teaching at Harvard until 1950. After his retirement he worked as a staff physician at a hospital for crippled children in Canton, Massachusetts.

A woman in this stage of syphilis can still transmit syphilis to her unborn child. • Tertiary syphilis: Between a third and a half of patients with latent syphilis will progress to third-stage, or tertiary, syphilis. This stage can occur as early as one year after the initial infection or as late as fifty years afterward. It is marked by the development of gummas, large noncancerous tissue growths that may occur anywhere on the skin or inside the body, including the skeleton. Untreated tertiary syphilis, which is rarely seen in the 2000s, can lead to movement disorders, heart failure, dementia, and other disorders of the central nervous system. Patients with dementia caused by syphilis usually die within two to three years.

Demographics

Syphilis has been on the increase in the United States in recent years. The number of cases dropped after the introduction of penicillin as an effective treatment in the 1940s. In the 1980s, however, the number of cases began to rise again as a result of the growing use of crack cocaine and intravenous drugs, the exchange of sex for drugs, and the increase in the number of people with multiple sexual partners. According to the Centers for Disease Control and Prevention (CDC), the number of reported cases of primary and secondary syphilis rose 12 percent between 2005 and 2006. In 2006, there were 36,000 cases of syphilis reported in the United States; most of these occurred in adults between the ages of twenty and thirty-nine. The rates for syphilis were highest in women twenty to twenty-four years of age and in men thirtyfive to thirty-nine years of age. There were 349 cases of congenital syphilis reported in 2006. In the same year, 64 percent of the reported syphilis cases in males were among men who have sex with men (MSM).

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The rates of syphilis vary in different parts of the United States. The CDC reports that half of all cases of syphilis in the country are found in twenty counties and two cities. Syphilis also disproportionately affects African Americans, who accounted for 41 percent of all cases of the disease in 2006. Some people are at increased risk of becoming infected with syphilis: • Men who have sex with men. The highest rates of syphilis in the United States as of 2008 were in this group. • Those who are HIV-positive. About 50 percent of men diagnosed with syphilis since the early 2000s are also HIV-positive. • People who drink heavily or use mood-altering drugs. These substances do not cause syphilis, but they do affect a person’s ability to think clearly and practice safe sex. • People who have many different sexual partners or have sex with strangers.

Causes and Symptoms Syphilis is caused by Treponema pallidum, a bacterium that is usually transmitted by direct oral, anal, or vaginal contact with an infected person but can also be transmitted by an infected mother to her baby before birth. The bacteria can cross the mucous tissues lining the mouth and the genitals; they can also enter the body through a crack or break in the skin elsewhere on the body. In addition, the disease can be transmitted through transfusion with infected blood. Syphilis cannot be spread, however, through casual contact with toilet seats, doorknobs, swimming pools, hot tubs, bathtubs, shared clothing, drinking glasses, or food utensils. As has been noted earlier, the symptoms of syphilis vary depending on the stage of the infection: • Primary syphilis: one or more chancres, possibly swollen lymph nodes. • Secondary syphilis: Skin rashes, flu-like symptoms, headache, loss of appetite, fever, fatigue. • Latent (dormant) syphilis: Flare-ups of symptoms of secondary syphilis or no symptoms at all. • Tertiary syphilis: Difficulty coordinating muscle movements, paralysis, numbness, gradual blindness, and dementia, possibly ending in death. UXL Encyclopedia of Diseases and Disorders

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Diagnosis Primary syphilis is diagnosed by taking a sample of chancre cells and sending it to a laboratory for examination under a microscope to look for Treponema pallidum. This test is also useful in distinguishing the spirochete that causes syphilis from those that cause Lyme disease or yaws, a tropical disease. Blood tests are more effective in diagnosing secondary than primary syphilis. The two blood tests most commonly used as screeners are called the Venereal Disease Research laboratory Test (VDRL), and the rapid plasma reagin test (RPR). These tests work by showing the presence of antibodies stimulated by the bacteria in the patient’s blood. Some other diseases, such as lupus, infectious mononucleosis, and rheumatoid arthritis can give a positive result on these tests, however. For this reason a patient who has a positive test result on either the VDRL or the RPR is usually given another test that is specific for T. pallidum. Patients with tertiary syphilis have their cerebrospinal fluid checked periodically by a spinal tap in order to monitor the progress of treatment for the disease.

Treatment Syphilis can be treated with a single injection of penicillin (or another antibiotic if the patient is allergic to penicillin) during its primary and secondary stages. Patients in the later part of the latency stage or those diagnosed with tertiary syphilis are given three injections of penicillin, each one week apart. Patients with tertiary syphilis that has affected the brain may require intravenous penicillin every four hours for ten to fourteen days. Some patients, especially with secondary syphilis, have a brief reaction to treatment marked by fever, chills, and headache. This reaction is caused by the death of large numbers of spirochetes in a short period of time. It usually lasts only a day and can be treated at home with aspirin or acetaminophen. Having syphilis does not make a person immune to it; it is possible to become reinfected with the disease after having been successfully treated for it. People being treated for syphilis should not have sex with anyone until the doctor confirms that they are no longer infectious, which may take 2–3 months. The usual schedule for follow-up is blood tests at three, six, and twelve months after treatment to make sure that the spirochete has been 1072


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WORDS TO KNOW Chancre: A painless ulcer that forms on the skin during the early stage of syphilis.

Gumma: A soft noncancerous growth of tissue found in patients with tertiary syphilis.

Congenital: Present at birth.

Yaws: A spirochete-caused tropical infection of the skin, bones, and joints.

eliminated. Patients with tertiary syphilis should have repeat blood tests and tests of spinal fluid every six months for at least three years.

Prognosis Antibiotic treatment for primary and secondary syphilis has a very high cure rate. As of 2008, there were no reports of penicillin-resistant strains of T. pallidum. Untreated primary or secondary syphilis has a one in two or one in three chance of progressing to tertiary syphilis and possible death.

Prevention Syphilis can be prevented by: • Abstaining from sexual intercourse, or having sex with only one partner who is uninfected and faithful. • Using latex condoms when having sex with someone whose health status is not known. • Avoiding excessive drinking and drug use.

The Future Researchers are looking into newer oral antibiotics as effective ways of treating syphilis, particularly in developing countries where injectable penicillin is difficult to obtain or to keep refrigerated. Other areas of research include the development of effective diagnostic tests based on urine or saliva samples rather than blood. Last, the sequencing of the genome (genetic code) of T. pallidum in 1998 has encouraged scientists to work on developing a vaccine against syphilis, although such a vaccine lies at least several years in the future. SEE ALSO

AIDS; Chlamydia; Genital herpes; Gonorrhea


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Sherman, Irwin W. Twelve Diseases That Changed Our World. Washington, DC: ASM Press, 2007. Syphilis is the subject of Chapter 6, “The Great Pox.” Silverstein, Alvin, Virginia Silverstein, and Laura Silverstein Nunn. The STDs Update. Berkeley Heights, NJ: Enslow Elementary, 2006. Winters, Adam. Syphilis. New York: Rosen Publishing Group, 2007. WE B S IT E S

American Academy of Family Physicians (AAFP). Syphilis. Available online at http://familydoctor.org/online/famdocen/home/common/sexinfections/sti/ 380.html (updated April 2008; accessed September 2, 2008). Centers for Disease Control and Prevention (CDC). Sexually Transmitted Diseases: Syphilis. Available online at http://www.cdc.gov/std/syphilis/default. htm (updated July 23, 2008; accessed September 2, 2008). eMedicine Health. Syphilis. Available online at http://www.emedicinehealth. com/syphilis/article_em.htm (accessed September 2, 2008). National Institute of Allergy and Infectious Diseases (NIAID). Syphilis. Available online at http://www3.niaid.nih.gov/topics/syphilis/default.htm (updated November 13, 2006; accessed September 2, 2008). TeensHealth. Syphilis. Available online at http://kidshealth.org/teen/infections/ stds/std_syphilis.html (updated March 2007; accessed September 2, 2008).

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Tendinitis Definition Tendinitis (also spelled tendonitis) is inflammation or irritation of a tendon—one of the thick cords of white connective tissue that attach muscle to bone. Tendons are less elastic than muscle; they transmit the force of a muscle’s expansion or contraction to the bone or joint to cause movement. A tendon becomes inflamed when it is overused or injured by a blow or some other trauma, resulting in warmth, pain, swelling in the affected joint, and some loss of motion in the joint. Also Known As Tendinopathy Cause Overuse of certain muscles, aging process Symptoms Pain, warmth, and swelling in affected tendon; pain worsened by activity Duration Days to weeks

Description Tendons are located all over the body and range in size from the very small tendons in the hands to large tendons like the Achilles tendon at the back of the heel. The most common locations where tendinitis develops are the shoulders, elbows, knees, wrists, and heels. Some forms of tendinitis are named for the athletic activities that are known to cause them, such as golfer’s elbow (inner tendon of the elbow), tennis elbow (outer tendon of the elbow), pitcher’s shoulder (rotator cuff tendinitis), and jumper’s knee (quadriceps or patellar tendons of the knee). Although these types of tendinitis are associated with sports, they can also develop in people whose occupations require repetitive movements of the hands, arms, or legs. 1075

Tendinitis Illustration of tendinitis in the Achilles tendon. © PHOTOTAKE INC. / ALAMY.

Tendinitis begins when microscopically small tears develop in the tissue of the tendon as a result of overuse. In some cases the tendon may have been previously weakened by normal aging or by such diseases as rheumatoid arthritis. If the activity that has caused the first small tears in the tendon is continued, the tendon becomes irritated and inflamed, leading to swelling and pain in the soft tissues surrounding the joint. In most cases, the pain becomes noticeably worse when the joint is moved or used.

Demographics Tendinitis is a very common health problem in the general population. No exact statistics are kept because many people treat mild tendinitis at home without going to their doctor. It is known, however, that middle-aged adults are the age group most likely to develop tendinitis. People who are most at risk of developing tendinitis are: • Those over forty-five years of age. • People whose occupations require repetitive movements of the upper arm, wrist, or shoulder. These include carpenters, gardeners, painters, musicians, dancers, manicurists, dental hygienists, and dentists (tennis elbow and golfer’s elbow); construction work, electrical repair, or other jobs requiring reaching overhead (pitcher’s shoulder); and typing or data entry (wrist tendinitis). 1076


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• People with rheumatoid arthritis, osteoarthritis, thyroid disorders, diabetes, or gout. • People who take a type of prescription antibiotic known as fluoroquinolones. • People who have been recently injured in an accident or are recovering from burns. • People who abuse steroids for muscle building.

Causes and Symptoms Tendinitis is caused primarily by overuse of specific muscles; however, the aging process and diseases associated with joint inflammation may speed up the development of tendinitis or make the symptoms worse. In general, the symptoms of tendinitis include pain and swelling of the soft tissues near the affected tendon. Symptoms in specific tendons are as follows: • Golfer’s elbow: Pain when the wrist is flexed or turned outward, as when shaking hands or using certain kinds of handheld tools. • Tennis elbow: Pain spreading into the upper arm or lower arm when the patient grips an object or extends the wrist (as when pouring liquid from a pitcher). • Achilles tendinitis: Pain in the heel as the foot is flexed while running. • Tendinitis in the knee: Pain in the side of the knee during downhill running, or pain just below the kneecap during or after physical activity. • Rotator cuff tendinitis: Pain when the arm is raised above the head; pain worsened when the arm is lowered across the chest. UXL Encyclopedia of Diseases and Disorders

Home Care for Tendinitis There are five points to keep in mind in treating tendinitis at home. The word PRICE is a good way to remember them: • Protection. Protecting the injured tendon involves the use of slings, splints, crutches, or elastic bandages to prevent unnecessary movement of the affected area. • Rest. Rest means avoiding activities or body movements that make the pain or swelling worse; it does not mean complete bed rest. Swimming or exercising in a pool is often a good way to keep active without harming the injured tendon. • Ice. An ice pack can be applied to the affected area for fifteen to twenty minutes every four to six hours for three to five days, or a few days longer if the doctor recommends it. • Compression. Compression refers to the use of a wrap or Ace bandage to keep swollen muscles from restricting movement in an injured joint. • Elevation. Raising the affected arm or leg on a pillow or cushion is helpful in relieving swelling in the affected joint. Although rest is an important part of self-care at home for tendinitis, gentle movement of the affected joint after a few days of complete rest is necessary to prevent stiffness. Doctors recommend moving the sore area slowly and gently through its full range of motion or doing slow stretching exercises. Nonsteroidal anti-inflammatory drugs, or NSAIDs, can be used to relieve pain and inflammation in the sore joint. These drugs include aspirin as well as Advil and Motrin.

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Diagnosis It is important to have tendinitis diagnosed and treated promptly because continued overuse of a damaged tendon can lead to complete rupture (tearing) of the tendon. The doctor will begin by taking a patient history, noting any recent injuries and medications taken as well as any previously diagnosed conditions like diabetes or rheumatoid arthritis. The next step is a physical examination of the painful joint. This part of the examination involves asking the patient to hold or move the affected limb or joint according to the doctor’s instructions while the doctor puts pressure on the muscles and tendons. For example, to detect golfer’s elbow, the doctor will ask the patient to place the forearm on the examining table with the inside of the wrist upward. The patient is then asked to make a fist while the doctor holds the forearm down. If the patient has golfer’s elbow, he or she will feel pain in the elbow. There are similar tests for the tendons in the shoulder, knee, wrist, and heel. Imaging tests are not usually necessary unless the doctor wants to check for bone chips or fractures in addition to the tendinitis. If the patient does not get better after rest and medications for the tendinitis, the doctor may order an ultrasound or magnetic resonance imaging (MRI) test. A blood test is usually performed only when the doctor needs to rule out rheumatoid arthritis as the cause of the pain and swelling.

Treatment Treatment of tendinitis is conservative, usually consisting of pain relievers, rest, ice applications, and limiting the movement of the affected joint by splints or a sling (for rotator cuff tendinitis). After recovering from the acute pain, the patient should consider a program of physical therapy and exercise to increase muscle strength and range of motion in the affected joint. For severe pain that is not helped by NSAIDs, the doctor may inject steroid drugs to decrease pain and inflammation. Steroid injections should not, however, be used more than a few times because they may weaken tendons and increase the risk of a ruptured tendon. Ruptured tendons require prompt surgical treatment to prevent permanent disability. Other treatments for tendinitis that are currently considered experimental include ultrasound therapy, vitamin E, nitric oxide, and extracorporeal 1078


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shockwave therapy or ESWT. ESWT was originally developed to treat kidney stones but has been approved by the Food and Drug Administration (FDA) for the treatment of tennis elbow.

Prognosis The prognosis for recovery from tendinitis is very good with appropriate medical treatment and self-care at home.

Prevention The National Institute for Arthritis and Musculoskeletal and Skin Diseases (NIAMS) recommends the following steps to prevent tendinitis: • Warm up or stretch before exercising. • Stop and rest if there is pain during a particular exercise or body movement. • Try different types of exercise; alternate high-impact sports like running or tennis with lower-impact activities like swimming or yoga. • Make sure that the technique involved in the sport or occupational activity is correct. An improper stance or swing, or poor posture when typing or practicing music, can contribute to tendinitis. If necessary, consult a doctor or physical therapist for guidance. • Begin slowly when starting a new form of exercise or other physical activity and work up gradually to longer workouts. • Take frequent breaks from repetitive jobs or chores. • Cushion joints at risk of tendinitis; use pads for the knees when gardening, padded gloves for heavy tools, and additional grips on golf clubs. • Use a two-handed grip for heavy tools. • Do stretching exercises after a workout as well as before, to maintain full range of motion in the joints.

The Future New treatments for the pain of tendinitis are currently being studied. One treatment is an NSAID patch that could be applied to the skin and allow the drug to relieve pain in the affected joint without upsetting the UXL Encyclopedia of Diseases and Disorders

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WORDS TO KNOW Achilles tendon: The tendon that connects the calf muscle to the back of the heel. Tendinitis in the Achilles tendon is common in sports that involve running and jumping.

Tendon: A thick band or cord of dense white connective tissue that attaches a muscle to a bone.

Rotator cuff: A group of four muscles that attach the arm to the shoulder blade.

stomach, which oral NSAIDs often do. Another experimental treatment for tendinitis is injections with tissue plasminogen activator (tPA) factor, an enzyme that is presently used primarily to treat heart disease and stroke by breaking up blood clots. SEE ALSO

Diabetes; Rheumatoid arthritis; Sprains and strains; Steroid

use


Bellenir, Karen, ed. Sports Injuries Information for Teens. Detroit, MI: Omnigraphics, 2008. Leonard-Brown, Sarah. Sports Injuries. Chicago, IL: Raintree, 2005. WE B S IT E S

American College of Rheumatology (ACR). Fact Sheet: Tendonitis/Bursitis. Available online at http://www.rheumatology.org/public/factsheets/ tendonitis_new.asp? (accessed June 19, 2008). How Stuff Works. How to Ease Tendinitis. Available online at http://health. howstuffworks.com/how-to-deal-with-tendinitis.htm/printable (accessed June 19, 2008). Mayo Clinic. Tendinitis. Available online at http://www.mayoclinic.com/health/ tendinitis/DS00153 (accessed cited June 18, 2008). National Institute of Arthritis and Musculoskeletal and Skin Diseases (NIAMS). Questions and Answers about Bursitis and Tendinitis. Available online at http://www.niams.nih.gov/Health_Info/Bursitis/default.asp (accessed June 19, 2008). National Library of Medicine (NLM). Tennis Elbow. Available online at http:// www.nlm.nih.gov/medlineplus/tutorials/tenniselbow/htm/index.htm (accessed June 19, 2008). This is an online tutorial with voiceover; viewers have the option of a self-playing version, a text version, or an interactive version with questions. 1080


Tetanus

Tetanus Definition Tetanus is an infectious disease that, by the production of a potent toxin, affects the muscles of the body, causing stiffness, spasms, difficulty breathing, and a risk of death. It is caused by a bacterium called Clostridium tetani, which lives in the soil.

Description Tetanus has been familiar to doctors for centuries; it was described by Hippocrates around 400 BCE as a common but frequently fatal disease. He was the first medical writer to list the characteristic symptoms of the disease, including the tightening of the jaw muscles that gave tetanus its common name of lockjaw. Tetanus is caused by an anaerobic bacterium that exists in the soil as a spore and gains entrance to the body through a wound, often a puncture or a crushing wound. There are four basic forms of tetanus: neonatal, which affects newborns; cephalic, which is limited to the head; local, which affects the muscles closest to the infected wound; and generalized, which affects the entire body and can lead to death.

Demographics Tetanus was a fairly common disease until the twentieth century. The bacterium that causes tetanus was first identified in 1885, and an effective vaccine was developed in the 1940s. This vaccine helped to make tetanus a rare disease in the United States; only twelve cases of tetanus were diagnosed in American soldiers during World War II, compared to thousands of deaths from tetanus among unimmunized German and Italian troops. The annual number of cases of tetanus among civilians in the United States fell from 600 in 1940 to forty-three in 2000. As of the early 2000s, the rate of tetanus in the United States is 0.16 cases per 1 million population. Most cases of tetanus in the United States are cases of generalized tetanus; neonatal tetanus is very rare in North America. The adults at greatest risk include intravenous drug users, Hispanics, people over sixty UXL Encyclopedia of Diseases and Disorders

Also Known As Lockjaw Cause Clostridium tetani bacteria Symptoms Muscle stiffness and spasms, fever, difficulty breathing, irregular heartbeat, death Duration Several weeks 1081

Tetanus Baby with muscle stiffness from tetanus in a Vietnamese hospital. SUE FORD/PHOTO RESEARCHERS, INC.

who have allowed their immunization to lapse, and older adults with diabetes. In the developing world, however, neonatal tetanus is a major killer of newborns, responsible for thousands of deaths. It occurs when the stump of the baby’s umbilical cord becomes infected by dirt containing tetanus spores. There are about a million cases of tetanus reported around the world each year, causing between 300,000 and 500,000 deaths. The countries that have the highest rates of tetanus are those with hot, damp climates and soils containing large amounts of animal manure.

Causes and Symptoms The bacterium that causes tetanus is anaerobic, which means that it only thrives in the absence of oxygen. It is found in the soil, in dust, in the manure produced by farm animals and household pets, and in the digestive tracts of 10–25 percent of humans. The bacterium forms spores (an inactive stage) that can remain dormant outdoors for years. When the spores get into the body through a puncture wound, an injury that crushes tissue, or a drug injection, they germinate (start to grow) in dead or dying tissue, which lacks oxygen. Germination usually occurs between three days and three weeks after the spores are introduced into the body. The bacteria secrete two toxins, one of which affects the nervous system 1082


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The Bridge Builder John Augustus Roebling (1806–1869) was one of the greatest civil engineers of the nineteenth century, famous for the beauty as well as the strength of the bridges he designed. Roebling left his native Germany in 1831 to seek new opportunities in the United States. Settling near Pittsburgh, Pennsylvania, he began to work for the state as a designer of railroad bridges. He built several suspension bridges over the Allegheny and Monongahela Rivers, using wire ropes and cables that he invented himself. New bridges were a vital part of efficient troop movement during the Civil War, and Roebling began work on a bridge across the Ohio River at Cincinnati, Ohio, in 1863. It was the longest suspension bridge in the world when completed in 1867. A few months later, Roebling began work on his last project—the Brooklyn Bridge across the East River in New York. The bridge, a worldfamous landmark, cost Roebling his life in 1869. He believed in supervising the construction work himself rather than giving the job to others, and as he stood at the edge of a dock near the construction site a ferry crushed his foot against the dock. Roebling allowed doctors to amputate his crushed toes but refused further medical treatment.

John Augustus Roebling.

COURTESY OF THE LIBRARY OF

CONGRESS.

Twenty-four days later he was dead of tetanus, a disease for which the cause would not be identified for another sixteen years and an effective treatment would not be available for another half century.

and causes the muscle stiffening and spasms that are characteristic of tetanus. The first symptoms of tetanus usually appear about eight days after infection. The patient typically has a sore throat with difficulty swallowing, headache, stiffness in the jaw muscles known as trismus (lockjaw), followed by stiffness of the neck, heavy sweating, fever, stiffness in the muscles of the abdomen, and spasms in the muscles close to the site of the cut or other injury. In severe tetanus, the patient has spasms of the arms, legs, and back muscles that can be violent enough to dislocate or break bones. The spasms can also affect the vocal cords and the muscles that control UXL Encyclopedia of Diseases and Disorders

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breathing. The patient’s blood pressure may alternate between being too high and too low, and the heart rhythm may change from a fast heartbeat to an overly slow heartbeat. Without treatment, the patient may die from respiratory failure or the heart suddenly stopping.

Diagnosis The diagnosis of tetanus is usually based on the patient’s history, particularly a recent crushing or penetrating injury, and such symptoms as fever, muscle stiffness, and changes in blood pressure and heart rhythm. The doctor will also check the patient’s record of immunization against tetanus. There are no laboratory tests or imaging studies that are helpful in diagnosing the disease, although the doctor may order a blood test to rule out certain types of poisons.

Treatment Treatment can begin at home with cleaning a wound carefully with soap and running water. A clean cloth can be applied to stop the bleeding. If the wound was caused by a farm tool or other object left outdoors, or resulted from a crushing injury, the injured person should consult their doctor, particularly if they have not had a tetanus booster shot within the past ten years. Medical treatment begins with prevention, using debridement (surgical removal of any dead or dying tissue that may contain tetanus bacteria). The next step in treatment consists of administering human tetanus immune globulin (TIG), a form of immunization that neutralizes the toxin already produced by the bacteria. TIG produces temporary protection against tetanus in patients who have not been vaccinated against the disease or who have not had a booster shot in the last ten years. Other drugs that are given to treat severe tetanus include various antibiotics to kill the bacteria directly, muscle relaxants and tranquilizers to prevent muscle spasms, sedatives to help the patient sleep, and painkillers to relieve the pain caused by the muscle spasms. Patients who are having trouble breathing may be placed on a ventilator and given fluids intravenously to prevent dehydration and provide extra nutrition. The extra calories are needed because the muscle spasms of severe tetanus use up large amounts of the body’s energy stores. 1084


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WORDS TO KNOW Anaerobic: Capable of living in the absence of oxygen.

Spore: The dormant stage of a bacterium.

Debridement: Surgical removal of dead or dying tissue.

Trismus: The medical name for the spasms of the jaw muscles caused by tetanus.

Prognosis The prognosis of tetanus depends partly on the form of the disease. Cephalic and local tetanus have very high recovery rates. Neonatal tetanus, however, has a mortality rate of close to 90 percent. Generalized tetanus causes about five deaths per year in the United States; the overall mortality rate is about 30 percent but is close to 50 percent in people over the age of sixty. If the patient recovers, however, he or she usually recovers completely, without lasting damage to the nervous system.

Prevention Prevention is the most effective defense against tetanus. Children are usually immunized against tetanus by a combination vaccine that also protects against diphtheria and whooping cough. They are usually given five doses of the combination vaccine, at two, four, six, and fifteen months of age, and a final dose at four to six years. They should then have a booster shot every ten years. Adults who have not had a booster shot within the last ten years should be given a booster shot as well as TIG if they see their doctor about a wound that might be infected by tetanus spores.

The Future Tetanus is unlikely to ever be completely eradicated because the spores that cause the disease are so widely distributed in soils around the world and in the digestive systems of humans and animals. The best hope for lowering the worldwide death toll from this disease is universal immunization and greater availability of appropriate treatments. SEE ALSO

Whooping cough


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Guilfoile, Patrick. Tetanus. New York: Chelsea House Publishers, 2008. PE R I O DI C A L S

Centers for Disease Control and Prevention (CDC). “Tetanus Surveillance— United States, 1998–2000.” Morbidity and Mortality Weekly Report 52 (June 20, 2003). Available online at http://www.cdc.gov/mmwr/preview/ mmwrhtml/ss5203a1.htm (accessed April 21, 2008). Includes maps and graphs at the bottom of the page that give the number of cases per state and rates of survival. WE B S IT E S

Centers for Disease Control and Prevention (CDC). Tetanus Disease In-Short (Lockjaw). Available online at http://www.cdc.gov/vaccines/vpd-vac/tetanus/ in-short-both.htm (updated July 2007; accessed April 21, 2008). Mayo Clinic. Tetanus. Available online at http://www.mayoclinic.com/health/ tetanus/DS00227/DSECTION=1 (updated September 21, 2006; accessed April 21, 2008). National Network for Immunization Information Fact Sheet. Important Facts for Parents to Know about the DTaP Vaccine. Available online in PDF format at http://www.immunizationinfo.org/assets/files/pdfs/2_DTAP_facts.pdf (updated October 2000; accessed April 21, 2008). TeensHealth. Tetanus. Available online at http://www.kidshealth.org/teen/ infections/bacterial_viral/tetanus.html (updated April 2007; accessed April 21, 2008).

Also Known As Mediterranean anemia, Cooley’s anemia, hemoglobin H disease, hydrops fetalis Cause Genetic mutations on chromosome 11 or chromosome 16 Symptoms Anemia, childhood jaundice, bone abnormalities, fetal or newborn death Duration Lifelong 1086

Thalassemia Definition Thalassemia is the name of a group of inherited blood disorders caused by various mutations in the genes that affect the body’s ability to produce hemoglobin, the oxygen-carrying pigment in red blood cells. Some doctors prefer to speak of the thalassemias (in the plural) to underscore the fact that they are a group of blood disorders rather than a single disease.

Description There are two major types of thalassemia, categorized according to the part of the hemoglobin molecule that is affected by the genetic UXL Encyclopedia of Diseases and Disorders

Thalassemia

mutations. The hemoglobin molecule has four protein chains, two called alpha chains and two called beta chains. Thalassemias are classified as alpha thalassemias if the genetic mutation damages the alpha chain, and beta thalassemias if the genetic mutation affects the beta chain. Four genes are needed to make the proteins in the alpha chains of the hemoglobin molecule. If one or two of these genes are defective, the person has what is called thalassemia trait. They will not have the symptoms of thalassemia but will carry the genetic mutation. A child who inherits two thalassemia trait genes (one from each parent) will have the symptoms of the disease. A child of two carriers has a 25 percent chance of receiving two trait genes and developing the disease and a 50 percent chance of being a thalassemia trait carrier. On the other hand, if the person has defects in more than two of the four genes needed to make the proteins in the alpha chain, they will have moderate to severe anemia. The most severe form of alpha thalassemia is known as alpha thalassemia major or hydrops fetalis. Babies with hydrops fetalis usually die before or shortly after birth. In beta thalassemia, the person has mutations in one or both of the genes needed to form the beta chain of the hemoglobin molecule. The severity of beta thalassemia depends on the extent of the changes in one or both genes. If both genes are affected, the result is moderate to severe anemia. The severe form of beta thalassemia is sometimes called thalassemia major or Cooley’s anemia.

X ray of the hand of a patient with thalassemia. The lighter areas show weakened bones. CNRI / PHOTO RESEARCHERS, INC.

Demographics The demographic distribution of alpha thalassemia is different from that of beta thalassemia. The rate of alpha thalassemia in the United States is rising due to immigration from countries where the mutations that UXL Encyclopedia of Diseases and Disorders

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cause this type of thalassemia are relatively common. These include countries in Africa, the Middle East, India, Southeast Asia, southern China, and occasionally the countries around the Mediterranean Sea. About 300,000–400,000 severely affected infants are born worldwide every year; more than 95 percent of these births occur in Asia, India, and the Middle East. Doctors estimate that about 15 percent of African Americans are silent carriers of alpha thalassemia. In addition, thalassemia trait (minor) occurs in 3 percent of African Americans and in 1–15 percent of persons from Mediterranean countries. Beta thalassemia is more common in Africa, Southeast Asia, Iran, Arabia, Central Asia, and the countries around the Mediterranean than it is in northern Europe or North America. It may affect as many as 10 percent of the population in Southeast Asia and Africa. Males and females are equally affected by both alpha and beta thalassemia.

Causes and Symptoms Both alpha and beta thalassemia are caused by mutations in genes that affect the structure of the hemoglobin molecule. In alpha thalassemia, one or more of four genes (two from each parent) located on chromosome 16 are defective. In beta thalassemia, the mutation is located in the HBB gene on chromosome 11. The symptoms of alpha thalassemia range from no symptoms in carriers of the thalassemia trait to mild or severe symptoms of the disease, depending on the number of genes that are defective. • Thalassemia trait. This is a mild form of alpha thalassemia in which the person has red blood cells that are smaller than normal and a mild anemia, but no major health problems. It is often misdiagnosed by doctors as iron deficiency anemia. • Hemoglobin H disease. This is a form of alpha thalassemia in which the lack of alpha protein is great enough to cause severe anemia and such serious health problems as an enlarged spleen, deformed bones, leg ulcers, gallstones, and fatigue. It is named for the abnormal type of hemoglobin that is formed by the beta proteins in the hemoglobin molecule. Children with hemoglobin H disease are often born with jaundice and anemia; the condition is usually detected shortly after birth. 1088


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• Alpha thalassemia major or hydrops fetalis. In this condition there are no functional alpha proteins at all in the patient’s hemoglobin. Babies with hydrops fetalis die before or shortly after birth. Beta thalassemia is classified into three types, thalassemia minor, thalassemia intermedia, and thalassemia major (Cooley’s anemia) depending on the severity of symptoms. • Thalassemia minor: Persons with this form of beta thalassemia usually experience no health problems except for an occasional mild anemia. Their condition is usually discovered only through a routine blood test. • Thalassemia intermedia: Children with this form of beta thalassemia may require occasional blood transfusions to treat their anemia. Bone deformities and enlargement of the spleen are common. • Thalassemia major: This is a potentially life-threatening form of beta thalassemia. Children with Cooley’s anemia must receive regular blood transfusions and extensive medical care in order to survive past childhood.

Diagnosis Both major types of thalassemia are diagnosed by blood tests and genetic testing. Genetic testing can determine whether a person is a carrier of thalassemia even though they may not have symptoms. Genetic testing can be done before a baby is born, around the eleventh week of pregnancy. The doctor can remove a small amount of tissue from the placenta for analysis. Amniocentesis, which involves taking a sample of the fluid surrounding the baby in the uterus, can be performed around the sixteenth week of pregnancy.

Treatment Treatment depends on the severity of thalassemia. People with trait thalassemia may not have symptoms that need treatment. Patients with hemoglobin H disease and Cooley’s anemia typically require frequent blood transfusions for the rest of their lives along with a type of therapy called chelation therapy. Most patients with a major form of thalassemia are given red blood cell transfusions every two to three weeks, as much as fifty-two pints of blood per year. These transfusions are necessary to UXL Encyclopedia of Diseases and Disorders

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make sure that the patient’s blood is delivering enough oxygen to the tissues to meet energy needs. Chelation therapy consists of a medication administered to help the body get rid of the iron that builds up in tissues as a result of frequent blood transfusions. If the excess iron is not removed, it will eventually damage the patient’s liver and heart and lead to early death from organ failure. Chelation therapy for severe thalassemia involves the use of Desferal, a drug that is infused into the body through a pump worn under the skin of the stomach or legs five to seven times a week for as long as twelve hours. A newer drug for chelation therapy was approved by the Food and Drug Administration (FDA) in 2005. It can be taken by mouth just once a day. Both drugs work by changing the iron into a form that the body can excrete through the urine or stool. Patients with beta thalassemia major (Cooley’s anemia) usually have the spleen removed by surgery after they are six or seven years of age to prevent later complications and lower the frequency of blood transfusions required. Another treatment that is effective if a good donor match can be found is transplantation of bone marrow. Transplantation, however, is possible only for a small minority of patients who have a suitable bone marrow donor. The transplant procedure itself is still risky and can result in the patient’s death.

Prognosis The prognosis of thalassemia depends on the type and the severity. Carriers of alpha thalassemia who do not have symptoms have a normal life expectancy and usually enjoy good health, although they should consider genetic counseling before starting a family. Patients with hemoglobin H generally survive into adulthood, although some have a lowered quality of life because of the disease. Hydrops fetalis is almost always fatal. Patients with mild beta thalassemia have a normal life expectancy with generally good health, although like patients with alpha thalassemia, they should be informed about the hereditary nature of their condition. The prognosis for patients with Cooley’s anemia depends on their compliance with frequent transfusions and chelation therapy. Some people find Desferal therapy so troublesome and painful that they give up on treatment. Untreated, Cooley’s anemia usually leads to death from heart failure or infection before age twenty. 1090


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WORDS TO KNOW Anemia: A condition in which there are not enough red cells in the blood or enough hemoglobin in the red blood cells. Chelation therapy: A form of treatment to reduce overly high levels of iron (or other metals) in the body by giving the patient a chemical that allows the body to get rid of the excess metal in urine or stool. Cooley’s anemia: Another name for the most severe form of beta-thalassemia.

Hemoglobin: A pigment in red blood cells that contains iron and transports oxygen from the lungs to other body tissues. Hydrops fetalis: The most severe form of alpha thalassemia, leading to death before or shortly after birth. Thalassemia trait: A condition in which a person is missing one or two genes required to make the proteins in the alpha chains of the hemoglobin molecule. The person does not have the symptoms of thalassemia but can pass the genetic deficiency to their children.

Prevention There is no way to prevent either alpha or beta thalassemia.

The Future Researchers are hoping to develop a form of gene therapy to treat patients with beta thalassemia. This type of treatment would involve inserting normal HBB genes into immature bone marrow cells. These are the cells that produce red blood cells; thus gene substitution would lead to the eventual production of normal red blood cells. SEE ALSO

Anemias


Thalassemia. San Diego, CA: ICON Health Publications, 2004. WE B S IT E S

Cooley’s Anemia Foundation. What Is Thalassemia? Available online at http:// www.cooleysanemia.org/sections.php?sec=1 (accessed May 30, 2008). Genetics Home Reference. Beta Thalassemia. Available online at http://ghr.nlm. nih.gov/condition=betathalassemia (accessed May 30, 2008). National Center for Biotechnology Information (NCBI). Genes and Disease: Thalassemia. Available online at http://www.ncbi.nlm.nih.gov/books/bv.fcgi? call=bv.View..ShowSection&rid=gnd.section.250 (accessed May 30, 2008). UXL Encyclopedia of Diseases and Disorders

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Tick-borne Diseases

National Heart, Lung, and Blood Institute (NHLBI). What Are Thalassemias? Available online at http://www.nhlbi.nih.gov/health/dci/Diseases/ Thalassemia/Thalassemia_WhatIs.html (accessed January 2008; cited May 29, 2008). National Human Genome Research Institute (NHGRI). Learning about Thalassemia. Available online at http://www.genome.gov/page.cfm?pageID= 10001221 (accessed November 25, 2007; cited May 29, 2008). Nemours Foundation. Thalassemias. Available online at http://www.kidshealth. org/parent/medical/heart/thalassemias.html (accessed May 30, 2008).

Tick-borne Diseases Tick-borne diseases are infectious diseases carried by small eight-legged insects belonging to the spider family. Ticks are parasites that feed on blood and usually live in weeds, shrubs, or tall grass. They cannot fly and must attach themselves directly to a deer, human, dog, or other animal passing through the grassy area. Ticks have a harpoon-like structure in their mouths that enables them to attach to their host and feed for several hours or even days. Tick-borne diseases include those caused by bacteria (Lyme disease), viruses (various forms of encephalitis), and rickettsiae (Rocky Mountain spotted fever), which are a type of bacterium. These diseases can be difficult to diagnose because a tick may carry more than one disease organism, thus infecting a human with two diseases at the same time. Most tick-borne diseases are treated with antibiotics before the specific disease organism is identified because delayed treatment can lead to such complications as arthritis and severe fatigue. Rocky Mountain spotted fever is potentially fatal. Tick-borne diseases are becoming increasingly common in the United States as people build homes and move into areas that were recently wilderness. Controlling the deer population, wearing protective clothing, and clearing brush and tall grass where possible are important preventive strategies. SEE ALSO

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Encephalitis; Lyme disease UXL Encyclopedia of Diseases and Disorders

Tonsillitis

Tonsillitis Definition Tonsillitis is an inflammation of the tonsils at the back of the throat caused by infection by a virus or bacterium. The tonsils themselves are two areas of lymphoid tissue; they are part of the lymphatic system and act as part of the immune system. Tonsillitis may be caused by either viruses (about 75 percent of cases) or bacteria (the remaining 25 percent). Recurrent tonsillitis is defined as seven episodes of tonsillitis in one year; five episodes in two successive years; or three infections per year for three straight years.

Description The tonsils are part of the immune system protecting the body against infections of the throat and upper respiratory tract. These areas of tissue normally function to neutralize disease organisms before they reach the lower throat; however, they can be overwhelmed by a virus or bacterium. At that point the tonsils become red and swollen, and may develop abscesses, which are pus-filled pockets. Whether caused by viruses or bacteria, all forms of tonsillitis are contagious. Tonsillitis usually spreads from person to person by contact with discharges from the nose or throat of an infected child or adult. It is often spread by carriers—children or adults who carry a disease agent but do not have any of the symptoms of the disease.

Demographics Tonsillitis is a common illness among children in the United States; nearly all have at least one episode of tonsillitis by the time they reach the teen years, although tonsillitis is rare in children younger than two. Recurrent tonsillitis is less common, occurring in 11–13 percent of children. Tonsillitis caused by bacteria is most common in children between the ages of five and fifteen, while children younger than five are more likely to have viral tonsillitis. As far as is known, tonsillitis affects boys UXL Encyclopedia of Diseases and Disorders

Also Known As Tonsillar sore throat, infection of the tonsils Cause Infection by viruses or by streptococcal bacteria Symptoms Sore throat, painful swallowing, fever, “hot potato” voice, sore lymph nodes in neck Duration Three to twelve days 1093

Tonsillitis Enlarged, reddened tonsils due to tonsillitus. © MEDICAL-ONLINE / ALAMY.

and girls equally, and is equally common in all races and ethnic groups in the United States. Children at increased risk of tonsillitis include those with malnutrition or weakened immune systems as well as those who attend schools or day care centers with other children who may be carriers.

Causes and Symptoms About three-quarters of all cases of tonsillitis are caused by viruses, with the remaining quarter caused by bacteria. The most common virus that causes tonsillitis is the Epstein-Barr virus (EBV), often as part of infectious mononucleosis. Viral tonsillitis can also be caused by the measles virus, herpes virus (the virus that causes cold sores), or adenoviruses (viruses that also cause stomach flu). The most common organisms responsible for bacterial tonsillitis are group A streptococci, the bacteria that cause strep throat and scarlet fever. The symptoms of tonsillitis may include: • • • • • 1094

Sore throat Pain in the ears Fever and chills Red, swollen tonsils White or yellow patches on the tonsils UXL Encyclopedia of Diseases and Disorders

Tonsillitis

• • • • •

Pain or difficulty in swallowing Bad breath Swollen lymph nodes in the neck Tiredness and overall sick feeling Difficulty breathing or disturbed sleep, if the tonsils are extremely swollen

Diagnosis

Did You Know? Tonsillectomy, or removal of the tonsils, is one of the oldest surgical procedures in Western medicine. The earliest description we have of a tonsillectomy was written between 30 and 50 A.D. by Celsus, a Roman doctor, who invented a hook for grasping tonsils. After hooking the infected tonsil, Celsus removed it with a sharp knife or scalpel. His patient was then given a mixture of vinegar and herbs to stop the bleeding, cleanse the throat, and lower the risk of infection. By the seventeenth century, European doctors had invented an instrument called the tonsillotome, which allowed the doctor to grasp the tonsil and remove it in one motion. The doctor needed an assistant to hold the patient still, however, as anesthesia would not be developed for another two centuries.

The diagnosis of tonsillitis is made in the doctor’s office by a physical examination of the patient’s mouth and throat followed by a rapid strep test or culture to identify the disease organism that is causing the infection. During the physical examination, the doctor will feel the lymph nodes in the patient’s neck as well as taking the temperature and looking into the throat with the help of a tongue depressor. Redness and swelling of the tonsils, along with pus or other discharges, will be visible to the doctor Surgeons in the United States generally remove tonsils with forceps and scissors after the without the need for special equipment. patient has been put under general anesthesia. To see whether the infection is caused by strep Several new techniques for tonsillectomy have throat bacteria, the doctor will take a throat swab been developed, however, that include the use and send the sample of the patient’s throat secretions of ultrasonic scalpels, lasers, and radiofreto a laboratory for culture. The doctor may also perquency ablation. Radiofrequency ablation is a form a rapid strep test in the office. This test is faster method that uses radiofrequency energy to shrink or destroy the tissue of the tonsils than a throat culture but is slightly less accurate. without the need for cutting. The doctor may also order a blood test to check for signs of a viral infection. An unusually high number of certain white blood cells called atypical lymphocytes in the sample may indicate that the tonsillitis is caused by the mononucleosis (Epstein-Barr) virus.

Treatment It is important for the doctor to know whether the tonsillitis is caused by strep throat bacteria or viruses because the treatments are different. If the child has viral tonsillitis, treatment consists largely of self-care at home: drinking plenty of warm fluids, taking nonaspirin pain relievers (Tylenol UXL Encyclopedia of Diseases and Disorders

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or Advil) to bring down the fever, and gargling with salt water to relieve the sore throat. It may take a week or so for the child to feel better. Antibiotics do not help in treating viral infections. If the doctor determines that the tonsillitis is caused by a bacterium (almost always the group A streptococcus), he or she will prescribe a course of antibiotics, usually for ten days. If the child has trouble swallowing, the antibiotic may be given by injection, or the doctor may also prescribe a steroid medication to bring down the throat swelling. The child should not return to school or day care for twenty-four to fortyeight hours after beginning antibiotic treatment, to prevent spreading the infection to others. In addition, it is important for the child to take the full course of antibiotics even though he or she may feel better in a day or two. The doctor may recommend tonsillectomy (surgical removal of the tonsils) for patients with recurrent tonsillitis. Tonsillectomies are not performed nearly as often as they were in the 1950s and 1960s; the number of tonsillectomies performed each year in the United States has dropped from several million in the 1970s to approximately 600,000 in the late 1990s. Tonsillectomies are still recommended, however, to treat severe cases of recurrent tonsillitis accompanied by airway obstruction, and to reduce the risk of ear infections and other potential complications of tonsillitis.

Prognosis Most children and teenagers with tonsillitis recover without any longterm problems. In a few cases, however, the infection can spread from the tonsils to the deeper tissues of the neck or chest. If the tonsillitis is caused by streptococci, it can lead to such complications as inflammation of the kidney or rheumatic fever. For this reason, children with a sore throat and other symptoms of tonsillitis should see the doctor at once. Tonsillectomy is the second most common operation performed on school-age children and is an extremely safe procedure. It is often done as an outpatient procedure; however, the child may need to recover at home for a week or two afterward.

Prevention People can lower their risk of tonsillitis by washing their hands frequently, avoiding sharing drinking glasses and food utensils, covering the 1096


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WORDS TO KNOW Group A streptococcus: A sphere-shaped bacterium that grows in long chains and causes strep throat as well as scarlet fever and some forms of tonsillitis.

Tonsillectomy: Surgical removal of the tonsils.

nose and mouth when coughing or sneezing, and avoiding close contact with others who have upper respiratory infections.

The Future A major concern among doctors is the overuse of antibiotics in treating tonsillitis and other throat infections. Across the United States, 70 percent of children with sore throats who are seen by a doctor are treated with antibiotics even though 30 percent at most have bacterial infections. It can be difficult to distinguish between bacterial and viral infections of the throat even when a throat culture is performed because some people may be carriers of group A streptococci and have the bacteria in their throat at the same time that they have tonsillitis caused by a virus. The chief danger from the overuse of antibiotics is the creation and spread of drug-resistant disease organisms. SEE ALSO

Infectious mononucleosis; Scarlet fever; Sore throat; Strep

throat


Powell, Jillian. Sore Throat. North Mankato, MN: Cherrytree Publishing, 2007. Silverstein, Alvin, Virginia Silverstein, and Laurie Silverstein Nunn. Sore Throats and Tonsillitis. Danbury, CT: Fraklin Watts, 2000. PE R I O DI C A L S

Brody, Jane. “Personal Health: The Telltale Signs of Sore Throat Danger.” New York Times, February 21, 2000. Available online at http://query.nytimes. com/gst/fullpage.html?res=9E0DE1D71430F931A15751C0A9669C8B63 (accessed June 21, 2008). WE B S IT E S

American Academy of Family Physicians (AAFP). Sore Throat: Easing the Pain of a Sore Throat. Available online at http://familydoctor.org/online/famdocen/ UXL Encyclopedia of Diseases and Disorders

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home/common/infections/cold-flu/163.html (updated July 2005; accessed June 22, 2008). American Academy of Otolaryngology—Head and Neck Surgery. Tonsils and Adenoids. Available online at http://www.entnet.org/HealthInformation/ tonsilsAdenoids.cfm (accessed June 22, 2008). KidsHealth. Tonsillitis. Available online at http://kidshealth.org/kid/ill_injure/ sick/tonsillitis.html (updated November 2007; accessed June 22, 2008). Mayo Clinic. Tonsillitis. Available online at http://www.mayoclinic.com/health/ tonsillitis/DS00273 (updated May 10, 2008; accessed June 22, 2008). National Library of Medicine (NLM). Tonsillectomy and Adenoidectomy. Available online at http://www.nlm.nih.gov/medlineplus/tutorials/tonsillecto myadenoidectomy/htm/index.htm (accessed June 22, 2008). This is an online tutorial with voiceover; viewers have the option of a self-playing version, a text version, or an interactive version with questions.

Tooth Decay Definition

Also Known As Dental caries, tooth cavities Cause Acids produced by bacteria living in the mouth Symptoms None (in early stages); pain on eating or chewing, tooth sensitivity, toothache (later stages) Duration Months to years, or until treated 1098

Tooth decay, also known as dental caries, is a disorder of the mouth in which bacteria living in the mouth break down carbohydrates in food. The bacteria produce acids that eat away at the enamel—the hard smooth outer surface of the tooth—eventually producing cavities in the enamel. If untreated, cavities can lead to toothache, loss of the tooth, and bacterial infections spreading to the gums and other tissues.

Description Tooth decay begins with plaque, a thin film that is a mixture of saliva, bacteria, and dead cells from the tissues that line the mouth. When a person eats foods rich in carbohydrates—sugary or starchy foods—the bacteria in the plaque ferment the sugars in these foods, forming lactic acid. Plaque builds up on teeth if it is not removed by regular flossing and brushing, eventually hardening into a whitish substance called tartar. The surfaces of human teeth are basically composed of minerals that are sensitive to acid. Under normal circumstances, minerals lost from the tooth surface are replaced by the saliva. But when plaque is not removed from the teeth by brushing or flossing, the acid formed by the bacteria begins to remove enamel from the surface of the tooth faster than the UXL Encyclopedia of Diseases and Disorders

Tooth Decay A wisdom tooth showing decay. © DAVE JEPSON / ALAMY.

saliva can restore it. At this point the surface of the tooth begins to develop small pits or cavities. If these are not attended to, they can grow larger and move inward to affect the dentin, a layer of hard tissue below the enamel. Dentin is softer than enamel and protects the pulp at the center of the tooth. When the cavity cuts through the enamel into the dentin, it speeds up the decay process. The pulp contains nerve endings that become inflamed when the bacteria from the mouth are able to gain entry. Once the tooth decay reaches the pulp, the person may experience pain when biting down on food or the more severe toothache. If the inflammation has spread to affect the jawbone underlying the tooth, the person may develop a pus-filled hollow known as an abscess. In extreme cases, the bacteria may spread to other parts of the face or enter the bloodstream and spread infection to other parts of the body.

Demographics Tooth decay is one of the most common health problems around the world. It is also one of the oldest. Prehistoric humans appear to have had dental problems dating from the time that they first began to cultivate grains for food, since bread and flour are rich in carbohydrates. Skulls found in Asia dating from 7000 BCE have teeth that contain holes created by early dental drills. Ancient Egyptian, Indian, and Sumerian medical UXL Encyclopedia of Diseases and Disorders

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The Dentist Who Discovered the Cause of Tooth Decay The bacterium that causes tooth decay was identified in the early 1920s by military dentist Fernando Rodríguez Vargas (188–1932). Born in Puerto Rico, Rodríguez Vargas graduated from the dental school of Georgetown University in Washington, D.C. in 1913. He began to investigate the cause of tooth decay in 1915 while working for the federal government’s Indian Medical Service in Tucson, Arizona. There he noticed that the Native Americans he was treating had badly discolored teeth as well as a high number of cavities. His early research was interrupted when the United States entered World War I in 1917, and he was sent overseas to examine and treat American soldiers for dental problems. In 1921, Rodríguez Vargas was working as a bacteriologist in Washington, D.C., for the Army Dental Corps when he discovered that three species of Lactobacillus bacterium are responsible for producing the acids that cause tooth decay. He published his findings in a military medical journal. In 1928 he wrote an article for the Journal of the American Medical Association on the usefulness of various antiseptics in cleansing the mouth and preventing tooth decay. Rodríguez Vargas died of pneumonia in 1932. He has been honored for his pioneering work in dentistry by the Walter Reed Army Institute of Research and the Puerto Rico College of Dental Surgeons.

texts attributed tooth decay and cavities to a “tooth worm.” The rate of tooth decay among humans increased rapidly after 1850 CE, when people began to eat larger quantities of refined sugar, refined flour, and other sweet and sticky foods. According to the Centers for Disease Control and Prevention (CDC), tooth decay is the most common chronic health disorder among children in the United States between the ages of five and seventeen. Fifty-nine percent of children in this age group have one or more cavities. Many adults also have untreated tooth decay—27 percent of those between the ages of thirty-five and fortyfour, and 30 percent of those over sixty-five. Worldwide, about 90 percent of schoolchildren and 95 percent of adults have had at least one dental cavity. The rates are highest in Asia and Latin America and lowest in Africa. Males and females are equally likely to develop tooth decay. In developed countries, the rates of dental cavities have dropped since the 1950s; this decrease is attributed to improved patient education about care of the mouth and teeth, and to such preventive practices as adding fluoride to the water supply. On the other hand, however, the reduction in the number of cavities is not equally distributed throughout the population. Studies in Western Europe, Canada, and the United States indicate that 20 percent of the population in these countries has 70 percent of the cavities. People at increased risk of tooth decay include:

• Babies who are given sweetened juices or other liquids to drink. “Baby bottle tooth decay” is a common pattern of cavities in the front of the mouth found in very young children. 1100


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• People who abuse methamphetamine, an addictive stimulant drug. Methamphetamine dries out the tissues of the mouth, contributing to outright tooth loss as well as tooth decay. • People with diabetes or Sjögren syndrome. These disorders reduce the amount of saliva in the mouth. • People with eating disorders. People with bulimia who force themselves to vomit repeatedly weaken the enamel on their teeth by exposing the tooth surfaces to stomach acids. • Smokers. Smoking causes the gums to recede, thus exposing more of the tooth surface to bacteria in the mouth and the acid they produce.

Causes and Symptoms Tooth decay is caused by acid-forming bacteria in the mouth that live in plaque that has not been removed from the surfaces of the teeth. Decay is more likely to affect the teeth in the back of the mouth (the molars and premolars). These teeth have pits and grooves on their upper surfaces that make it more difficult to remove plaque completely. Tooth decay can develop over a period of months or even years without any obvious symptoms. When the decay begins to affect the dentin or the pulp beneath the enamel, however, the patient may begin to notice such symptoms as: • Sensitivity when eating or drinking sweet, very hot, or very cold foods • Pain when biting on something firm or tough • Pus around a tooth, which indicates that at abscess has formed • Pain that lasts after the person has finished eating • Visible pits or holes in the tooth • Bad breath or a bad taste in the mouth • Intense toothache

Diagnosis The diagnosis of tooth decay is made by a dentist rather than a primary care doctor in most cases. The dentist will ask the patient about tooth sensitivity or pain. In some cases he or she can see signs of tooth decay just by looking inside the patient’s mouth with an angled mirror. Another tool that is used is UXL Encyclopedia of Diseases and Disorders

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a hook-shaped instrument called an explorer, which allows the dentist to probe soft spots or areas of discoloration in the teeth. Last, the dentist will take x-ray films of the patient’s mouth to get a clearer picture of whether and how far the areas of decay have penetrated the tooth.

Treatment The treatment of tooth decay depends on the extent and severity of the problem. If the decay has just begun, the dentist may apply a solution of fluoride to stop the decay process. If the decay has progressed further, the dentist may need to drill away the decayed material or even remove the tooth. A small area of tooth decay is filled with a silver alloy, a composite resin, gold, or porcelain. Dentists call a filling a dental restoration. If much of the tooth must be removed, the dentist will drill away the top of the tooth and replace it with what is called a crown or a cap. If the tooth decay has affected the pulp in the center of the tooth and destroyed the nerve endings, the dentist removes the pulp along with any decayed portions of the tooth and fills the center of the tooth with a sealing material. This procedure is called a root canal. If the tooth is badly decayed, was broken in an accident, or is likely to cause trouble in the future, the dentist will perform an extraction. The tooth is lifted with a tool called an elevator and removed from its socket with dental forceps. The dentist will apply a material called gelfoam to speed clotting, or close up the socket with sutures if the wound is large. The patient is given antibiotics to take for several days to prevent infection.

Prognosis The prognosis of tooth decay depends on the stage at which it is discovered and treated. Dental fillings usually last for years with proper care, although they often need replacement when the patient is middle-aged. It is rare for tooth decay to lead to serious complications other than the loss of teeth; however, in a few cases bacteria from a tooth abscess can spread to the tissues of the floor of the mouth or to a hollow space within the brain that lies behind the upper jaw. These infections are potentially life-threatening.

Prevention Tooth decay is one of the most easily prevented health problems. There are several known ways to lower the risk of dental cavities: 1102


Tooth Decay

WORDS TO KNOW Abscess: A collection of pus that has formed in a body cavity or hollow. Caries: The medical name for tooth cavities.

Plaque: A film that forms on the surface of teeth containing bacteria, saliva, and dead cells.

Dentin: A firm tissue that lies between the enamel and the pulp of a tooth.

Pulp: The soft living material in the center of a tooth that contains blood vessels and nerve endings.

Enamel: The hard, smooth, white outer surface of a tooth.

Tartar: Hardened plaque.

• Brushing the teeth after each meal or snack and using dental floss once a day. Brushing is important because plaque starts to form within twenty minutes of finishing a meal. Flossing helps to remove food particles trapped between teeth. • Limiting sweets and sugary drinks like soda or sweetened tea. • Quitting smoking. • Using a toothpaste that contains fluoride or having the dentist apply a fluoride solution to the teeth during a checkup. Fluoride is a chemical that helps to prevent tooth decay by protecting the minerals in tooth enamel. According to the CDC, people in communities that have added fluoride to their drinking water have 29 percent fewer cavities. • Sealants. Sealants are protective plastic coatings applied to the surfaces of the back teeth that are most likely to develop cavities. They need to be replaced every few years. • Antibacterial mouthwashes. Dentists sometimes recommend these for people who are vulnerable to tooth decay because of their medical conditions. • Having regular dental checkups and necessary treatments.

The Future Newer methods for the prevention of tooth decay include the use of argon lasers to remove early signs of the erosion of tooth enamel and the development of a vaccine against tooth decay. Clinical trials for such a vaccine started in May 2006, but the vaccine has not yet been approved for use. SEE ALSO

Bulimia; Periodontal disease; Sjögren syndrome


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Kemper, Bitsy. Out and About at the Dentist. Minneapolis, MN: Picture Window Books, 2007. Mestman, Sadie S., and Ariella D. Herman. What to Do for Healthy Teeth: Easy to Read, Easy to Use. La Habra, CA: Institute for Healthcare Advancement, 2004. Sutton, Amy L., ed. Dental Care and Oral Health Sourcebook. Detroit, MI: Omnigraphics, 2003. WE B S IT E S

American Dental Association (ADA). Tooth Decay (Cavities/Caries). Available online at http://www.ada.org/public/topics/decay_faq.asp (updated January 2008; accessed August 23, 2008). Centers for Disease Control and Prevention (CDC). Preventing Dental Caries. Available online at http://www.cdc.gov/nccdphp/publications/factsheets/ Prevention/oh.htm (updated November 25, 2005; accessed August 23, 2008). KidsHealth. What’s a Cavity? Available online at http://kidshealth.org/kid/talk/ qa/cavity.html (updated April 2008; accessed August 23, 2008). Mayo Clinic. Cavities/Tooth Decay. Available online at http://www.mayoclinic. com/health/cavities/DS00896 (updated April 27, 2007; accessed August 23, 2008). National Institute of Dental and Craniofacial Research (NIDCR). Plaque: What It Is and How to Get Rid of It. Available online in PDF format at http://www. nidcr.nih.gov/NR/rdonlyres/0C900F9D-C582-4609-A62CCF4AB53E84A0/0/Plaque_brochure.pdf (accessed August 23, 2008). National Maternal and Child Oral Health Resource Center. What Is Tooth Decay? Available online at http://www.mchoralhealth.org/OpenWide/ mod1_1.htm (accessed August 23, 2008). This is a Flash animation about tooth decay; click on icon at right to start the animation.

Tourette Syndrome Definition Tourette syndrome (TS) is a disorder of the nervous system characterized by tics, which are involuntary repetitive movements or sounds. It is named for a French neurologist, Georges Gilles de la Tourette (1859– 1904), who first described it in a group of nine patients in 1885. 1104


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Description Tourette syndrome is a disorder of the nervous system known for the motor and vocal tics of patients diagnosed with the syndrome. It can affect adults as well as children, but is most commonly diagnosed in children around age seven or slightly older. In most cases TS improves as the child matures and disappears completely by adulthood. Tourette syndrome is considered a spectrum disorder because the symptoms vary in severity from patient to patient; in fact, some doctors think that the diagnosis of Tourette syndrome is often missed because the patient’s symptoms are very mild and not noticed by other people. For example, parents often attribute such tics as eye blinking or sniffing noises to vision problems, colds, or allergies. The tics that characterize TS are sudden, rapid, repeated movements or voice sounds that the person cannot control. The most common first tic in children is a facial tic like eye blinking or grimacing. Motor (movement) tics usually occur before vocal tics, and usually affect the face and neck before moving downward to the arms, chest, or legs. Other common tics include throat clearing, grunting, barking, sniffing, tongue clicking, arm thrusting, shoulder shrugging, jumping, twirling, or kicking. Contrary to popular depictions of TS in the media, the repetition of dirty words, ethnic insults, or curses—known as coprolalia—occurs in only a small minority (about 15 percent) of patients with TS. The tics may increase or decrease in both number and severity, often disappearing for weeks and months and returning when the person is under stress. Although tics are involuntary, some patients are able to suppress them or manage them for brief periods of time. These patients often feel tension building up when they try to control their tics, however, and will often say that they feel they must release the tension at some point and express the tic. Tics do not go away completely when the patient is sleeping but are usually much less noticeable during sleep.

Demographics At one time TS was thought to be a rare condition but is now diagnosed in 1–2 percent of children and adults in the United States. According to the National Institute of Neurological Disorders and Stroke (NINDS), about 200,000 Americans have the most severe form of TS. Some doctors think that as many as 10 percent of Americans may have mild TS. UXL Encyclopedia of Diseases and Disorders

Also Known As TS, Gilles de la Tourette syndrome Cause Possibly genetic Symptoms Motor and vocal tics Duration Years 1105

Tourette Syndrome These boys both have Tourette syndrome, but in most ways are typical teenagers. AP IMAGES.

Babies born prematurely appear to be at increased risk of developing Tourette syndrome in childhood, although the reasons for the connection are not yet clear. TS appears to be equally common in all racial and ethnic groups; however, boys are four to ten times more likely to develop TS than are girls. The reasons for the gender difference are not known. 1106


Tourette Syndrome

Causes and Symptoms The cause of Tourette syndrome is not known. At one time, the disorder was thought to be a psychiatric illness, but most researchers now believe that TS results from a combination of genetic factors and differences in brain functioning. It is known that the disorder runs in families; however, no specific genes associated with the syndrome have been identified. Brain imaging studies suggest that children with TS have brains that are unusually sensitive to a neurotransmitter (brain chemical) called dopamine, and that the chemical activates parts of the brain that are responsible for the movements involved in tics. One finding that supports this theory is that medications that block the brain’s uptake of dopamine are helpful in controlling tics. Tourette syndrome often coexists with other neurological disorders like attention-deficit hyperactivity disorder (ADHD) and obsessive-compulsive disorder (OCD). About 40 percent of children diagnosed with TS have only TS; the remaining 60 percent have either TS plus ADHD, or TS plus OCD. A few children with Tourette syndrome also suffer from disorders of impulse control, which may include aggressiveness, sexual acting out, or rage attacks. The tics characteristic of TS are sometimes categorized as simple or complex tics as well as motor or vocal tics. A simple tic is sudden, brief, and involves only a few muscles. A complex tic is a pattern of movement that involves several groups of muscles and takes slightly longer to perform than a simple tic. Examples of simple tics would be eye blinking (motor) or barking (vocal); examples of complex tics would be flapping the arms (motor) and repeating someone else’s words (vocal).

Diagnosis There are no laboratory or imaging tests that can be used to diagnose Tourette syndrome, although the patient’s doctor may order an ECG or a blood test to rule out seizure disorders or thyroid problems. The doctor will base the diagnosis of Tourette syndrome on a combination of the patient’s symptom history, a history of other family members with TS, and the patient’s age. The diagnostic criteria used by the American Psychiatric Association specify that the patient must: • Have several motor tics and at least one vocal tic for a period of a year, with no more than three consecutive months without a tic. • Have been under eighteen years of age when the tics started. UXL Encyclopedia of Diseases and Disorders

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• Not be abusing alcohol or drugs, or have any other disease or disorder that could be causing the tics. It is not unusual for people with mild TS to go undiagnosed for years, read about the syndrome and recognize that they have tics, and visit their doctor to have the diagnosis confirmed.

Treatment Mild TS may not need any treatment. Although there are medications that can be prescribed to control severe tics, most doctors prefer to wait for a few months rather than prescribe medications right away. One reason is that the drugs given to control tics all have side effects, particularly weight gain, drowsiness, and difficulty concentrating in school. Another reason is that many children with TS have periods when the tics are less severe. Many doctors recommend psychotherapy for children with TS to help them cope with the social embarrassment and difficulties with schoolwork that they may be facing. Although TS does not cause depression or learning problems, children may become depressed because of rejection by classmates due to the tics, or they may have trouble learning their lessons in school because their attention is focused on controlling the tics.

Prognosis Tourette syndrome is not usually a disabling condition, although it can cause social embarrassment to affected children and teenagers. TS is often most severe in the patient’s early teens, with symptoms improving in the later teens and improvement continuing into adult life. About a third of adults find that their tics eventually go away; about 10 percent, however, do not experience significant improvement in their thirties or even in their forties. People with Tourette syndrome have a normal life expectancy. The disorder does not affect a person’s basic intelligence or prevent them from completing their education once they are diagnosed; in fact, many people with Tourette syndrome have above-average intelligence. One follow-up study of thirty-one adults with TS found that all the patients finished high school; 52 percent finished at least two years of college, and 71 percent were employed full time or were pursuing advanced degrees. The chief problem confronting people with TS in adult life is an 1108


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WORDS TO KNOW Coprolalia: The medical term for uncontrollable cursing or use of dirty words.

Tic: A sudden repetitive movement or utterance. Tourette syndrome is considered a tic disorder.

Involuntary: Not under the control of the will. Neurotransmitters: Chemicals produced by the body that transmit nerve impulses across the gaps between nerve cells.

increased risk of depression, mood swings, and panic attacks compared to the general population.

Prevention There is no known way to prevent Tourette syndrome because its causes are not yet fully understood.

The Future A newer form of treatment for TS that is considered experimental as of 2008 is deep brain stimulation or DBS. In DBS, a battery-operated device is implanted in the brain to deliver carefully targeted electrical stimulation to the parts of the brain that control movement. In addition to clinical trials of DBS and some newer drugs as treatments for Tourette syndrome, other researchers are using advanced imaging techniques to study the parts of the brain involved in tics. Still other scientists are looking for specific genes that may be linked to TS. S E E A L S O Attention-deficit hyperactivity disorder; Obsessive-compulsive disorder; Prematurity


Chowdhury, Uttom, and Mary Robertson. Why Do You Do That?: A Book about Tourette Syndrome for Children and Young People. Philadelphia: Jessica Kingsley Publishers, 2006. Haerle, Tracy, ed. Children with Tourette Syndrome: A Parents’ Guide. 2nd ed. Bethesda, MD: Woodbine House, 2007. Shimberg, Elaine Fantle. Tourette Syndrome: What Families Should Know. Yarmouth, ME: Abernathy House Publishing, 2008. UXL Encyclopedia of Diseases and Disorders

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Toxic Shock Syndrome WE B S IT E S

Mayo Clinic. Tourette Syndrome. Available online at http://www.mayoclinic. com/health/tourette-syndrome/DS00541 (accessed June 29, 2008). National Institute of Neurological Disorders and Stroke (NINDS). Tourette Syndrome Fact Sheet. Available online at http://www.ninds.nih.gov/disorders/ tourette/detail_tourette.htm (accessed June 29, 2008). Tourette Syndrome Association. Facts about Tourette Syndrome. Available online in PDF format at http://tsa-usa.org/People/LivingWithTS/Images/ Fact_Sheet.pdf (accessed June 29, 2008). Tourette Syndrome Association video clip. “I Have Tourette’s, But Tourette’s Doesn’t Have Me”. Available online at http://www.tsa-usa.org/news/ HBO_Release_apr06_update.htm (accessed June 29, 2008).

Toxic Shock Syndrome Definition

Also Known As TSS Cause Toxin produced by Staphylococcus aureus bacteria Symptoms High fever, low blood pressure, sunburn-like skin rash, seizures, multiple organ failure Duration One to two weeks for initial episode; recurrences may occur four to six months later 1110

Toxic shock syndrome, or TSS, is a life-threatening illness caused by a bacterium called Staphylococcus aureus. A similar illness called toxic shock-like syndrome, or TSLS, is caused by another bacterium called Streptococcus pyogenes. Both illnesses are forms of sepsis, an inflammatory response of the entire body to severe infection.

Description Toxic shock syndrome, or TSS, was first given its present name by a pediatrician in Denver, Colorado, in 1978. He had been studying a case series of a severe illness caused by Staphylococcus aureus in a group of three boys and four girls between the ages of eight and seventeen. The doctor had been able to identify the bacterium in the tissues lining the noses, throats, or vaginas of the patients but not in their blood or urine samples. This finding led him to suspect that the symptoms of the illness— sudden high fever, shock, and a reddish rash resembling sunburn—were caused by a toxin produced by the bacteria. The doctor did not, however, suspect a connection between the illness and menstruation even though three of the four girls in his series had been using tampons at the time they fell ill. UXL Encyclopedia of Diseases and Disorders

Toxic Shock Syndrome

The link between TSS in women and menstruation became clear in late 1979 and early 1980 following the introduction of a new type of tampon made from a superabsorbent type of cotton fiber combined with compressed beads of polyester. The new product was able to absorb 20 times its weight in fluid. By January 1980, doctors in Wisconsin and Minnesota were reporting cases of toxic shock syndrome in women using the new tampons, and doctors in other parts of the United States were reporting cases of TSS in women using other brands of highly absorbent tampons. The Centers for Disease Control and Prevention (CDC) began to investigate the reports and had the new tampon withdrawn from the market. By September 1980 the number of cases of TSS began to decline as women began to use sanitary napkins in place of tampons. According to CDC statistics, 942 women were diagnosed with tampon-related TSS in the United States from March 1980 to March 1981; forty of the women died. It is now known that TSS can develop in males and in women who are not menstruating if they become infected with S. aureus following surgery or injury to the nasal passages. Patients with TSS develop a sudden high fever, a skin rash that looks like sunburn, a drop in blood pressure, and failure of multiple organ systems in the body. Patients with toxic shock-like syndrome, caused by S. pyogenes, the same organism that causes strep throat, have similar symptoms. They are more likely to fall sick following a skin infection caused by S. pyogenes.

Skin peeling on the hands from toxic shock syndrome. © MEDICAL-ON-LINE / ALAMY.

Demographics TSS related to menstruation is much less common in the United States than it was in the early 1980s. According to the Centers for Disease Control and Prevention (CDC), there were only five documented cases of toxic shock syndrome related to menstruation in 1997, compared to 814 in 1980. As of the early 2000s, the CDC estimates that between one and seventeen of every 100,000 menstruating women will get TSS. Some people are at increased risk of TSS: • Women who are menstruating • Women who use diaphragms or other barrier methods of birth control UXL Encyclopedia of Diseases and Disorders

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A Survivor’s Story A Canadian woman thought that frequent changes of the high-absorbency tampons she used would be an adequate safeguard against toxic shock syndrome (TSS). However, the first Saturday in November 2004, she fell ill, stating, “[F]or some odd reason I knew it was TSS. I was vomiting all the time and knew it was more than a stomach bug. . . . My husband was taking care of me, following the doctor’s instructions to keep me hydrated; give me nausea medication; and not to treat the diarrhea. . . . I don’t remember much of that night, except extreme muscle pain, high fever and my mouth was so sore that I couldn’t move my tongue without extreme pain. Every time I sat up I would black out. The next seven days were a blur of pokes, prods and doctors shaking their heads in confusion.” She continued, “After a week in intensive care and recovery I was well enough to go home. Even though the skin was peeling off my palms and the soles of my feet (typical symptoms of TSS), the doctors still were ‘not sure’ what I’d had!” Her recovery was slow: she gained 40 pounds due to the fluid treatment, had decreased energy, weakness in her hands, extreme pain in her arms and wrists, her hair fell out in handfuls, and she needed antidepressants. In an update from 2006, her hair had finally grown back after a year of complete baldness, she was back to her normal weight, and she no longer needed antidepressants.

• • • • 1112

• • • •

People who are having surgery on the nose People with diabetes People with a weakened immune system People who have developed a staphylococcal infection following surgery

Causes and Symptoms The cause of toxic shock syndrome is infection with S. aureus, while TSLS is caused by S. pyogenes. In both illnesses, the bacteria produce exotoxins—toxic substances released into the bloodstream—that overstimulate the body’s immune system. As the immune system overreacts to the exotoxins, the person goes into shock, a medical emergency in which the circulatory system starts to shut down and deprives the body’s tissues of blood. Without the oxygen and nutrients carried by the blood, the body’s organs and tissues begin to fail. The symptoms of toxic shock syndrome include:

• Sudden high fever of 102°F (38.8°C) or higher • Nausea and vomiting • Low blood pressure • Confusion and disorientation • Sunburn-like rash that leads to peeling of the skin on the hands and feet after a week or so • Sore, aching muscles • Lightheadedness or dizziness when standing up Cramping or pain in the abdomen Redness in the eyes, mouth, and throat Headaches Seizures UXL Encyclopedia of Diseases and Disorders


• Large amounts of watery diarrhea • Shock occurring about two days after the fever and other symptoms begin The symptoms of TSLS are similar to those of toxic shock syndrome. In addition, patients with TSLS may have severe pain at the location of the skin infection that precedes TSLS.

Diagnosis There is no single test that is used to diagnose TSS or TSLS. The doctor will base the diagnosis on the patient’s recent history and a set of criteria drawn up by the CDC to distinguish toxic shock syndrome from measles, Rocky Mountain spotted fever, or other similar diseases: • Fever of 102.2°F (39°C) or higher. • Systolic blood pressure below 90 mmHg (Systolic is the top number in a blood pressure reading.) • Reddish rash followed by skin peeling • Involvement of three or more of the following organs or organ systems: digestive tract; kidneys; liver; soft tissues lining the throat, nasal passages, or vagina; central nervous system; or the blood

Treatment TSS and TSLS are medical emergencies. The patient is taken at once to the hospital emergency department and tampons, nasal packing, or dressings covering a skin infection are removed. The doctor will usually order a blood test to evaluate liver function, kidney function, and the number of white blood cells present. A high white blood cell count, a high level of liver enzymes, and signs of abnormal kidney function suggest a diagnosis of TSS. The doctor will also check the patient’s blood pressure, temperature, and heart rate. A female patient will usually be given a pelvic examination. Treatment begins with locating the source of the infection (vagina, nose, throat, skin) and administering intravenous antibiotics. Depending on the patient’s condition, he or she may be placed in an intensive care unit and given one or more of the following: • Intravenous fluids to raise blood pressure and prevent dehydration • Monitoring of kidney and liver function UXL Encyclopedia of Diseases and Disorders

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• Dialysis in case of kidney failure • Oxygen in case of breathing difficulties or lung failure

Prognosis The prognosis for TSS is better than it was in the 1980s, partly because of earlier diagnosis and treatment. In 1980 the mortality rate for women with menstrual-related toxic shock syndrome was 13 percent; as of 2005, it was 3–5 percent. The mortality rate in other patient groups, however, can run as high as 30 percent, particularly if the infection is caused by S. pyogenes rather than by S. aureus. Most patients with toxic shock syndrome or TSLS are sent home from the hospital after a week and recover fully in two to three weeks. The condition can be fatal within a few hours, however, if it is not treated promptly. About half of patients lose their hair and nails within two or three months after the illness, but these will usually grow back on their own. About 50 percent of people treated for TSS or TSLS will develop recurrences between four and six months after the acute illness. These recurrences are not usually as serious as the first episode but must still be treated in the hospital.

Prevention The CDC recommends the following precautions to lower the risk of toxic shock syndrome or TSLS: • Women of childbearing age should use low-absorbency tampons during their menstrual periods, change them every four to eight hours, or use sanitary napkins rather than tampons. Women who have had TSS or any serious staph or strep infection should not use tampons at all. • People who have had nasal surgery should watch carefully for signs of infection, particularly if the nose has been packed with gauze or surgical dressings. • Skin infections should be treated promptly. • People who have had abdominal surgery, or women who have recently given birth, should also be monitored for signs of infection. 1114



WORDS TO KNOW Dialysis: A process in which the blood of a patient with kidney failure is cleansed of the body’s waste products by being pumped through a machine that filters the blood and then returns it to the body.

Sepsis: The medical term for blood poisoning. Shock: A medical emergency in which the body’s tissues do not receive enough blood due to problems with the circulatory system.

Exotoxin: A toxin secreted by a bacterium or other disease organism into the body tissues of an infected individual.

The Future TSS and TSLS are fortunately very rare illnesses. Research is currently focused on understanding why some people develop toxic shock syndrome when most people exposed to S. pyogenes and S. aureus do not. These bacteria are very common in all parts of the world and can be found in the throats or on the skin of people who are not sick. Recent studies indicate that the majority of adults have antibodies in the blood that protect them against the bacterial exotoxins that cause TSS and TSLS, but scientists do not yet understand why a small number of people lack these antibodies. SEE ALSO

Scarlet fever; Staph infection; Strep throat


Sheen, Barbara. Toxic Shock Syndrome. San Diego, CA: Lucent Books, 2006. Sommers, Michael A. Yeast Infections, Trichomoniasis, and Toxic Shock Syndrome. New York: Rosen Central, 2008. PE R I O DI C A L S

Centers for Disease Control and Prevention (CDC). “Epidemiologic Notes and Reports: Toxic Shock Syndrome—United States.” Morbidity and Mortality Weekly Report 46 (June 6, 1997): 492–495. Available online at http://www. cdc.gov/mmwr/preview/mmwrhtml/00047818.htm (accessed July 14, 2008). This is a reprint of the first article published by the CDC on toxic shock syndrome on May 23, 1980. It was reprinted as part of the CDC’s fiftieth anniversary commemoration. Ray, C. Claiborne. “Q and A: Runaway Germs.” New York Times, November 26, 2002. Available online at http://query.nytimes.com/gst/fullpage.html?res= 9B02E7D61239F935A15752C1A9649C8B63 (accessed July 14, 2008). UXL Encyclopedia of Diseases and Disorders

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Toxoplasmosis WE B S IT E S

Centers for Disease Control and Prevention (CDC). Toxic Shock Syndrome. Available online at http://www.cdc.gov/ncidod/dbmd/diseaseinfo/ toxicshock_t.htm (updated October 24, 2005; accessed July 14, 2008). Mayo Clinic. Toxic Shock Syndrome. Available online at http://www.mayoclinic. com/health/toxic-shock-syndrome/DS00221 (updated April 25, 2007; accessed July 14, 2008).

Toxoplasmosis Definition Toxoplasmosis is an infectious disease caused by a one-celled parasitic protozoon. It gets its name from the scientific name of the parasite, Toxoplasma gondii. It is classified as a zoonosis because it can be transmitted from animals to people.

Description

Also Known As Toxoplasma infection Cause Protozoa (single-celled animal-like organisms) Symptoms None in most people; flulike illness in some; brain, lung, or eye damage in a few Duration About a month 1116

Toxoplasmosis is an infectious disease caused by a one-celled parasite called Toxoplasma gondii. Although the parasite reproduces sexually only inside cats, it is widespread in many other animals, including rats, mice, birds, deer, and pigs. Most humans who become infected get toxoplasmosis from eating raw or undercooked meat or drinking water containing the parasite rather than from pet cats. About 90 percent of people who have been infected by the parasite have no symptoms at all; some people develop a flu-like illness that lasts about a month; and a few people with weakened immune systems develop severe disease that can particularly affect the brain. It is also possible for a pregnant woman who is infected by the parasite for the first time during pregnancy to pass the infection to her unborn baby.

Demographics Toxoplasmosis is very common in the developed world, particularly in countries where people like to eat raw or undercooked meat. It is UXL Encyclopedia of Diseases and Disorders

Toxoplasmosis Scar (center) on the retina of a patient with toxoplasmosis. © PHOTOTAKE INC. / ALAMY.

estimated that about 20 percent of the population of the United States, or 60 million people, have been infected by the parasite. Around the world, the average rate of infection is about 30 percent, but in some countries like France, the rate hovers around 75 percent because so many people prefer undercooked meat. Toxoplasmosis is the third most common cause of fatalities from food-related illnesses in the United States; it causes about 250,000 cases each year, resulting in 5,000 hospitalizations and about 750 deaths. About 3,500 babies are born each year in the United States with toxoplasmosis. The rate of illness is high among patients with AIDS because of their weakened immune systems. Florida has a particularly high rate of toxoplasmosis in AIDS patients; as many as 40 percent are infected. Between 1 and 5 percent of AIDS patients in the United States eventually develop encephalitis (inflammation of the brain) from toxoplasmosis. Toxoplasmosis affects both sexes and all races equally, as far as is known.

Causes and Symptoms The protozoon that causes toxoplasmosis has a complex life cycle but reproduces sexually only inside cats. When a cat eats a dead mouse, rat, UXL Encyclopedia of Diseases and Disorders

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Keeping Kitty Healthy Although cats are carriers of the toxoplasmosis parasite, people do not get the disease from petting or playing with a pet cat, since cats do not carry the parasite on their fur. They also do not pass the parasite to humans by scratching them. People who enjoy having cats as pets do not have to give them up even if they have AIDS, are pregnant, or are being treated for cancer. The American Veterinary Medical Association (AVMA) recommends the following steps to lower the risk of getting toxoplasmosis from a cat: • Keep the cat indoors. In addition to lowering the cat’s risk of getting the parasite by eating dead animals, keeping kitty indoors protects him or her from automobiles, coyotes and other predators, and other parasitic infections. • Do not feed the cat raw or undercooked meat. Feed only well-cooked meat or processed cat foods. • Scoop the cat’s litter box every day. Disposing of feces as soon as possible prevents toxoplasmosis cysts from maturing. • Pregnant women should ask another family member to clean the cat’s box, or wear disposable gloves and wash the hands well in hot soapy water afterward. • Have a sick cat checked by a veterinarian. Most cats with toxoplasmosis, like most humans, have no signs of infection at all and recover completely even without treatment.

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bird, or raw meat that contains cysts (a capsule containing the parasite in its resting stage), the cysts open up within the cat’s digestive tract. There they reproduce and form new cysts, which are expelled in the cat’s feces. Cats shed these cysts for only one or two weeks, after which they cannot spread the infection further. It takes the cysts in the cat’s feces between one and five days to mature. This delay is the reason why cleaning a cat’s litter box on a daily basis helps to prevent toxoplasmosis in humans. The parasite’s cysts are hardy; they can live for a year in garden soil. They can survive freezing temperatures as low as 10°F and cannot be killed by household bleach or detergents. The cysts can, however, be killed by freezing at temperatures below 0°F ( 18°C) or by heating food containing them to temperatures above 150°F (66°C). People can get toxoplasmosis in one of several ways: from eating uncooked meat containing cysts; by eating unwashed vegetables that have been contaminated with cysts from garden soil; by drinking water contaminated by the parasite; by failing to wash hands after handling cat feces and getting cysts into the mouth accidentally; by direct transmission from mother to child; and by receiving an infected organ by transplantation or infected blood through transfusion (very rare). People cannot get the disease from touching or being close to an infected child or adult or from petting an infected cat. Once inside the human body, the cysts release the parasite, which forms new cysts, especially in the muscles and brain. In people with healthy immune systems, the cysts usually remain dormant for the rest of the person’s life. In persons with immune systems weakened by AIDS or chemotherapy for cancer, however, the parasites may cause a flu-like illness or severe infections of the central nervous system. UXL Encyclopedia of Diseases and Disorders

Toxoplasmosis

People with the mild form of toxoplasmosis typically have the following symptoms: • Headache • Fever and sore throat • Sore aching muscles • Swollen lymph nodes • Night sweats Patients with a severe toxoplasmosis infection may have: • • • • • •

Lung infections resembling pneumonia Headache Loss of coordination Seizures Mental confusion and disorientation Blurred vision (in people with normal or weakened immune systems) The risk of harm to an unborn baby from toxoplasmosis is highest if the mother becomes infected during the last three months of pregnancy. Toxoplasmosis can cause a pregnant woman to lose her baby before birth. The baby may also be born with seizures, disorders of the liver, or a severe eye infection. Some babies who are infected with toxoplasmosis before birth may have normal health for several years and then develop hearing loss, eye disorders, or mental retardation in the early teen years.

Diagnosis People are not routinely screened for toxoplasmosis because most who are infected do not develop symptoms. Those with a mild case of the disease may be thought to have an illness with similar symptoms like flu or mononucleosis. The diagnosis of toxoplasmosis can be made, however, by taking samples of the patient’s blood and sending them to a laboratory for analysis. A pregnant woman who thinks she may have been infected can be tested for toxoplasmosis by having a small sample of the fluid surrounding the baby in the womb withdrawn through a needle and tested for the parasite. This test increases the risk of losing the baby, however. The Centers for Disease Control and Prevention (CDC) advises women UXL Encyclopedia of Diseases and Disorders

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Toxoplasmosis

who are planning to become pregnant or have recently become pregnant to have a blood test for toxoplasmosis. A patient who has symptoms of a brain disorder caused by the parasite can be evaluated by magnetic resonance imaging or a CT scan, as the infection produces characteristic patterns of damage to brain tissue that can be distinguished from brain tumors or other disorders.

Treatment No treatment is needed for patients who have no symptoms of infection. Patients who have a mild case of the disease are treated with a combination of an antibiotic and a drug that was originally developed to treat malaria. People with AIDS might need to take this drug combination for an extended period to prevent symptoms from recurring. Pregnant women are given an antibiotic by itself, as the antimalarial drug can have serious side effects for both mother and child.

Prognosis The prognosis of toxoplasmosis depends on the severity of the infection. Most people never know they have been infected. People with a mild form of illness usually recover completely in a few weeks. Those with severe toxoplasmosis may have lifelong eye disorders, personality changes, or seizures; about 15 percent will die from the infection.

Prevention The CDC recommends the following steps to lower the risk of getting toxoplasmosis: • Cook foods thoroughly, especially meats. Cook beef, lamb, and veal to 145°F (63°C), pork and venison (deer meat) to 160°F (71°C), and poultry to 180°F (82°C). • Do not eat raw or undercooked meat. • Wash knives and cutting boards in hot soapy water after use. • Do not eat raw unwashed fruits and vegetables. • Freeze meat for several days before cooking. • Avoid drinking unpasteurized milk or untreated drinking water, particularly when traveling abroad. • Wear gloves when working in the garden. • Take proper care of pet cats (see sidebar). 1120


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WORDS TO KNOW Cyst: A capsule or sac containing a parasite in its resting stage. Encephalitis: Inflammation of the brain. Protozoon (plural, protozoa): A one-celled animal-like organism with a central nucleus

enclosed by a membrane. Many protozoa are parasites that can cause disease in humans. Zoonosis: A disease that animals can transmit to humans.

The Future There is no vaccine to prevent toxoplasmosis in either humans or other animals. Although an effective vaccine may be developed in the future, the best protection against toxoplasmosis at present is prevention. SEE ALSO

AIDS; Encephalitis; Food poisoning


Flynn, Jason. Cat Care. Avon, MA: Adams Media, 2005. Parker, James N., MD. The Official Patient’s Sourcebook on Toxoplasmosis. San Diego, CA: ICON Health Publications, 2002. PE R I O DI C A L S

Adam, David. “Can a Parasite Carried by Cats Change Your Personality?” Guardian, September 25, 2003. Available online at http://www.guardian.co. uk/science/2003/sep/25/medicineandhealth.thisweekssciencequestions1 (accessed April 13, 2008). WE B S IT E S

American Veterinary Medical Association (AVMA). What You Should Know about Toxoplasmosis. Available online at http://www.avma.org/ communications/brochures/toxoplasmosis/toxoplasmosis_brochure.asp (updated April 2008; accessed April 12, 2008). Centers for Disease Control and Prevention (CDC). Toxoplasmosis Fact Sheet. Available online at http://www.cdc.gov/toxoplasmosis/factsheet.html (updated January 16, 2008; accessed April 12, 2008). Cornell Feline Health Center. Toxoplasmosis in Cats. Available online at http:// www.vet.cornell.edu/fhc/brochures/toxo.html (updated April 8, 2008; accessed April 12, 2008). UXL Encyclopedia of Diseases and Disorders

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Triple X Syndrome

Triple X Syndrome Definition Triple X syndrome is a condition in which a female is born with an extra X chromosome in each cell of the body. Those who have the extra chromosome in only some of their body cells are said to have triple X mosaicism.

Description Triple X syndrome is caused by the presence of an extra X chromosome in the cells of a female’s body. It was discovered in 1959 by Patricia Jacobs, a researcher working in a hospital in Scotland. The patient was a thirty-five-year-old woman who had undergone premature menopause. Although some girls with triple X syndrome have learning disabilities or developmental delays, many do not. There are no unusual physical or medical disabilities associated with the syndrome; many girls with very mild symptoms may never be diagnosed. Researchers do not know why the extra copy of the X chromosome causes an increase in height and learning problems in some girls with the syndrome.

Also Known As Trisomy XXX, XXX syndrome, 47, XXX aneuploidy Cause An extra X chromosome in some or all cells of a female’s body Symptoms No symptoms unique to syndrome; some girls have none at all Duration Lifelong 1122

Demographics Triple X syndrome occurs in about one of every 900–1,000 girls born in the United States. It is estimated that between five and ten girls are born with the condition each day. As far as is known, the syndrome is equally common in all racial and ethnic groups. The only known risk factor for the syndrome is the mother’s age; women who are thirty-five or older when they become pregnant are at increased risk of having a daughter with triple X syndrome.

Causes and Symptoms The most common cause of triple X syndrome occurs when an egg carrying two copies of the X chromosome is involved in conception. The reason for the extra copy in the abnormal germ cell is a genetic error called nondisjunction. Nondisjunction is a random event and is UXL Encyclopedia of Diseases and Disorders

Triple X Syndrome

not caused by anything either of the baby’s parents did or by any medications they may have taken. During the normal process of germ cell formation, the paired chromosomes in the cell divide so that each daughter cell has only one member of the pair. In nondisjunction, one daughter cell gets both members of the chromosome pair and the other cell has none. If a germ cell carrying two copies of the X chromosome is fertilized by a normal germ cell from the other parent, the child will have three copies of the X chromosome. This genetic error is called a full trisomy X. Some girls affected by triple X syndrome children have some body cells with the extra copy of the X chromosome and some body cells without the extra copy. This condition is called mosaic trisomy X. About half of women with triple X syndrome have the full trisomy X and the other half have mosaic trisomy X. Not all girls born with triple X syndrome have noticeable symptoms of the condition, which is why they may not be diagnosed for some years. In addition, girls with the normal number of X chromosomes may also have these features that are symptomatic of triple X syndrome:

A Mother’s Concern The mother of a girl who was diagnosed with triple X syndrome at age ten remarks that one of the major difficulties in coping with the disorder is that little has been written about the syndrome, possibly because the symptoms are so mild in many girls. Her own daughter was diagnosed as the result of learning difficulties, particularly language skills. “Although our numbers are smaller than some of the other X and Y chromosome variations, I can’t help but wonder where are all the other girls? According to the scientific literature, trisomy X occurs in approximately one out of 900 to 1,000 live female births. And yet our numbers have hovered in the hundreds of individuals for a condition that affects millions worldwide.…While we all hope for the best, in part because the symptoms can be so mild and there is such a small amount of literature concerning treatments, we eventually become resigned to accept that the problems we experience are just an unavoidable given that we have to deal with.” The first national conference on triple X syndrome in the United States was held in October 2006. It is hoped that regular meetings will lead to new research and better understanding of the syndrome.

• Slightly lower weight at birth • Taller than other girls and women in the family • Less coordinated; somewhat higher risk of developing back problems • Development of language skills may be slowed • Less assertive and quieter than most girls • Increased risk of depression • Intelligence that may be slightly lower than that of other girls and women in the patient’s family (Mental retardation is unusual.) UXL Encyclopedia of Diseases and Disorders

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Girls with trisomy X go through puberty at the same age as girls with two X chromosomes and develop all the normal sexual characteristics of adult women. They are able to marry and have children, and do not need hormone treatments in order to become sexually mature. It is not yet known whether adult women with triple X syndrome undergo menopause at an earlier age than most women because the condition has not been studied long enough for researchers to follow a significant number of subjects through adult life into menopause.

Diagnosis Triple X syndrome may never be diagnosed if the girl has no obvious symptoms. It can, however, be detected by amniocentesis before birth. Amniocentesis is a procedure in which the doctor withdraws a small amount of fluid from the sac that surrounds the baby in the mother’s uterus and examines cells from the baby’s tissues for genetic abnormalities. Triple X syndrome is sometimes discovered after birth if the girl has developmental delays or learning difficulties and is given a genetic evaluation.

Treatment There is no specific treatment for triple X syndrome; many doctors do not consider it a major disability. Girls with the syndrome who do have learning disabilities or emotional problems are given the same types of therapy as other children with the same conditions. An individualized treatment plan can be drawn up with the help of the girl’s doctor and teachers. The most important aspect of treatment for the syndrome is love and support from the patient’s family. According to a Danish researcher who started one of the first triple X support groups in the world, “If conditions at home are good, stable and stimulating…learning problems rarely have any serious consequences. However, most triple X girls need remedial teaching at school at one time or another, and it is important that they get this help if and when they need it.”

Prognosis The prognosis for girls with triple X syndrome is generally good, particularly if their parents are loving and supportive. They are not at increased risk of other diseases as far as is known and have a normal life 1124


Triple X Syndrome

WORDS TO KNOW Mosaicism: A condition in which a person has some body cells containing an abnormal number of chromosomes and other cells containing the normal number. Mosaicism results from random errors during the process of cell division that follows conception. Nondisjunction: A genetic error in which one or more pairs of chromosomes fail to separate during the formation of germ cells, with the result that both chromosomes are carried to one

daughter cell and none to the other. If an egg or sperm with a paired set of chromosomes is involved in the conception of a child, the child will have three chromosomes in its genetic makeup, two from one parent and one from the other. Trisomy: A type of genetic disorder in which a cell contains three copies of a particular chromosome instead of the normal two.

expectancy. They are less likely to complete college than other girls, but almost all can finish high school with speech therapy or other additional help. While a few girls with triple X syndrome have some social difficulties, most are able to join the workforce, marry, and start families in adult life.

Prevention Because triple X syndrome is thought to be caused by a spontaneous genetic mutation rather than an inherited genetic defect, there is no way to prevent it.

The Future It is possible that the increasing numbers of women having children in their thirties or forties will lead to an increase in the number of girls born with triple X syndrome. Little research has been done on triple X syndrome considering the numbers of girls affected by it; however, the conference hosted by the University of California, Davis, in 2006 offered some possible new directions. Papers were presented on the treatment of language difficulties, depression, anxiety, and developmental differences in girls with triple X syndrome. Another presenter discussed the use of medications as part of treatment plans for these girls. S E E A L S O Down syndrome; Dyslexia; Edwards syndrome; Klinefelter syndrome; Patau syndrome UXL Encyclopedia of Diseases and Disorders

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Trisomy 13

For more information WE B S IT E S

Genetics Home Reference. Triple X Syndrome. Available online at http://ghr. nlm.nih.gov/condition=triplexsyndrome (updated January 2006; cited June 10, 2008.) Klinefelter Syndrome and Associates. Brief Introduction to Trisomy X. Available online at http://www.genetic.org/knowledge/support/action/200#Brief% 20Introduction%20to%20Trisomy%20X (updated February 28, 2007; accessed June 11, 2008). Mayo Clinic. Triple X Syndrome: What Causes It? Available online at http:// www.mayoclinic.com/health/triple-x-syndrome/AN00351 (updated July 27, 2006; accessed June 11, 2008). Pacific Northwest Regional Genetics Group. Sex Chromosome Problems Discovered through Prenatal Diagnosis: 47,XXX Syndrome. Available online in PDF format at http://mchneighborhood.ichp.edu/pacnorgg/media/Sex_Chrom/ xxx_eng.pdf (updated July 2007; accessed June 11, 2008). Turner Center, Risskov, Denmark. Triple-X Females: An Orientation. Available online at http://www.aaa.dk/TURNER/ENGELSK/TRIPLEX.HTM (accessed November 6, 2008).

Trisomy 13 See Patau syndrome.

Trisomy 18

See Edwards syndrome.

Trisomy 21 See Down syndrome.

Tuberculosis Definition Tuberculosis, or TB, is an infectious disease caused by rod-shaped bacteria called Mycobacterium tuberculosis. It mostly attacks the lungs but can also infect other organs. TB has been known for centuries and was first 1126


Tuberculosis

recognized as a contagious disease in the eleventh century by Ibn Sina (980–1037), a Persian doctor. TB was not recognized as a single illness until the 1820s, however. Robert Koch (1843–1910), the German doctor considered the father of microbiology, identified M. tuberculosis as the cause of tuberculosis in 1882. He received the Nobel Prize in physiology or medicine for this discovery in 1905.

Description Although it is no longer the leading cause of death in the United States, TB is a leading cause of infection-related death worldwide. The World Health Organization (WHO) estimates that 3 million people die of TB each year around the world. TB is spread by droplets coughed or sneezed into the air. Other people can become infected if they breathe in these droplets. TB is not known to affect any species other than humans. After the tuberculosis bacteria enter the body, they pass down through the airway to the lungs, with one of three outcomes: • The bacteria multiply and cause primary tuberculosis. This condition is also called active TB. • The bacteria may become dormant (inactive) and the patient will not feel sick or be able to spread the disease. This condition is called latent TB, because the patient will test positive for the bacterium if they have a skin test. About 90 percent of people infected with TB have the latent form of the disease. • The bacteria are dormant for a while, but then begin to multiply again and the patient feels sick. This condition is called reactivation TB. About 10 percent of people with latent TB will eventually develop reactivation TB during their lifetimes, half of these cases occur in the first two years. A person with active TB may first notice a cough lasting three weeks or longer with bloody sputum (mucus or phlegm). The coughing or even breathing may cause pain. Night sweats and a low-grade fever usually appear. Another common symptom is loss of appetite and unintended weight loss; in fact, TB used to be called consumption because the patient’s body looked as if it were being consumed, or eaten up, from within. In addition to the lungs, tuberculosis can spread through the bloodstream and affect the spine, bones and bone marrow, joints, kidneys, muscles, and central nervous system, which might create symptoms such UXL Encyclopedia of Diseases and Disorders

Also Known As TB, consumption Cause Bacterium Symptoms Long-lasting cough with bloody sputum, low-grade fever, drenching night sweats, weight loss, painful breathing or coughing Duration Months to years 1127

Tuberculosis Magnified image of the bacteria that cause tuberculosis. © MEDICAL-ON-LINE / ALAMY.

as severe back pain, blood in the urine, abdominal pain, swollen lymph nodes, or skin ulcers. These manifestations of TB are usually part of reactivation TB and can occur without any evidence of lung TB.

Demographics The frequency of active TB dropped in the United States even before the introduction of antibiotics in the 1950s, a decrease related to better living conditions and nutrition. It began to rise again in the 1980s among ethnic minorities and persons with HIV infection. In 1993 there were 25,200 cases of TB reported in the United States; that number declined again to 13,300 cases in 2007. There are about 4.4 cases of active TB in the United States for every 100,000 people. Over half these cases involve immigrants from four countries: Mexico, the Philippines, India, and Vietnam. The Centers for Disease Control and Prevention (CDC) estimates that 10–15 million people in the United States have latent TB as of 2008. In general, it is difficult to become infected with the TB bacillus unless one lives in close long-term contact with a person with active TB. There is increased risk of infection for these groups: • The elderly • Those who have immune systems weakened by such diseases as AIDS, diabetes, rheumatoid arthritis, kidney disease, or Crohn disease 1128


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• Those who are malnourished or severely underweight • Patients who have developed silicosis (a lung disease caused by breathing in rock dust produced by blasting and drilling) • Homeless people • People living in refugee camps or other crowded conditions • Drug or alcohol abusers • Patients being treated for cancer with chemotherapy, or who have received organ transplants • Those who work or live in hospitals, nursing homes, prisons, and other institutions for long-term care • People who come from countries with high rates of active TB

Causes and Symptoms

Drug-Resistant Tuberculosis Bacteria Beginning in the 1980s, doctors began to notice that people who failed to take medications for active TB were developing strains of the TB bacillus that are resistant to treatment. The two drugs that are considered most effective in treating TB are isoniazid (INH) and rifampin. A patient is considered to have multiple drug-resistant tuberculosis (MDR-TB) if a laboratory test shows that the bacteria in the sample are resistant to those two specific drugs. Patients diagnosed with MDR-TB must be treated for twice as long as those with ordinary TB. The drugs used to treat MDR-TB are less effective, often much more expensive, some have to be injected rather than taken by mouth, and they can produce severe side effects. Public health doctors insist that patients with MDR-TB be treated by the DOT method described in the main entry. An even more severe form of drug-resistant TB

TB is caused by a bacterium, Mycobacterium is known as extremely drug-resistant TB or XDR-TB. It is diagnosed when a sputum test tuberculosis. The bacteria enter a person’s respirashows resistance to an injectable drug and a tory tract through the nose or throat, then travel drug called levofloxacin as well as rifampin and to the lungs, where they multiply within the tiny isoniazid. XDR-TB is much more difficult to air sacs known as alveoli. In the alveoli, the bactreat with the drugs available and has a very teria are picked up by cells that carry them to nearby lymph nodes in the chest cavity. The TB bacteria can then spread into the bloodstream and other organs or tissues. The most common symptoms of active TB (that is still limited to the lungs) include: • • • • •

A cough that lasts longer than three weeks Pain when coughing or even breathing Loss of appetite and weight loss Pale complexion Fatigue


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• Wheezing • Low-grade fever and night sweats • Clubbing of the fingers or toes

Diagnosis The diagnosis of TB can be difficult because the disease does not produce symptoms immediately even with an active infection. People exposed to a person with active TB and are at high risk to become infected should check with their doctor even if they do not feel sick. The doctor will perform a physical examination. Some people with active TB develop noises in the lungs known as crackles that can be heard through a stethoscope. The doctor will also feel the lymph nodes in the patient’s neck and look for such other signs as clubbing of the finger tips. A skin test known as the Mantoux test (also called the PPD test) is used to screen patients for infection with TB. The doctor injects a fluid derived from the TB bacteria under the top layer of the patient’s skin. If the person has been infected with TB, a raised hard flat area will develop within forty-eight to seventy-two hours at the site of the injection. The patient’s risk factors are used to determine how large the bump must be to be considered a positive reaction. A newer test is a blood test approved by the Food and Drug Administration (FDA). Called the QuantiFERON-TB Gold (QFT) test, it detects the presence of TB bacteria in the patient’s blood and gives results in a day. As of 2008, it was not yet available in all parts of the United States, however. A patient who tests positive on either the Mantoux or the QFT test will then be given a chest x ray and a sputum test. A sample of sputum is sent to a laboratory where it is cultured, to see whether the person has active TB and to see whether the TB bacteria respond to standard antibiotics. If not, the patient has multidrug-resistant TB (MDR-TB) and will need special treatment.

Treatment Patients who are found to have latent TB may be treated with a drug called isoniazid or INH. This drug is given to destroy dormant bacteria so that they cannot reactivate in the future. The patient usually takes INH for six to nine months. 1130


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Patients with active TB are treated with INH plus a combination of three other drugs to make sure that all the TB bacteria are destroyed. The doctor may change one of the drugs during therapy if it turns out that the patient has a form of the TB bacillus resistant to that particular drug. Drug treatment for TB is a long-term process that can take anywhere from six months to a year for non-drug resistant TB; MDR-TB may require two full years of drug therapy. The patient may be admitted to the hospital for the first two weeks of treatment or until tests show that they are no longer contagious. It is very important for patients with active TB to take all their drugs exactly as directed for the full course of therapy even though they will usually start to feel better in a few weeks. If they do not, TB bacteria may survive and develop resistance to the drugs. MDR-TB is much more difficult to treat and is very dangerous. To make sure that patients take their medications correctly, some doctors or clinics use an approach called directly observed therapy or DOT. In DOT, a nurse or other health care worker gives the patient their drugs in the clinic so that they do not have to remember to take their medications at home. Some patients with severe MDR-TB may need surgery as well as medications. Removing part of an infected lung reduces the number of active bacteria in the patient’s body; it may also increase the effectiveness of drug therapy.

Prognosis The prognosis of active tuberculosis depends on the patient’s age, overall health, and whether he or she has a drug-resistant strain of TB. About 4 percent of patients in the United States with active TB die from the disease; this is much lower than the 50 percent death rate in the 1920s. In general, people with MDR-TB have a worse prognoses than those who do not; patients with HIV infection as well as MDR-TB have poor prognoses.

Prevention Tuberculosis is a preventable disease. In addition to diagnosing and treating people with latent TB before they develop active infection, people can lower their risk of getting TB in several ways: • Keep the immune system healthy. • Get an annual skin test if one is frequently exposed to TB or if one has a weakened immune system. UXL Encyclopedia of Diseases and Disorders

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WORDS TO KNOW Alveoli (singular, alveolus): Tiny air sacs in the lungs where the exchange of oxygen for carbon dioxide in the blood takes place.

medications to patients in a clinic or doctor’s office to make sure that the patients take the drugs correctly.

Clubbing: Thickening of the tips of the fingers or toes.

Latent: Referring to a disease that is inactive.

Directly observed therapy (DOT): Treatment in which nurses or health care workers administer

Sputum: Mucus that comes up when a person coughs.

• Get treatment for latent TB if infected. • Patients diagnosed with active TB should stay home, avoid close contact with others, and cover their mouths when they sneeze or cough. • A vaccine against TB, known as BCG, is widely used in Europe. It is not very effective in adults, however, and is not widely used in the United States because it can cause a false-positive result on the Mantoux test.

The Future Before the 1980s, it was hoped that tuberculosis could be wiped out completely. The emergence of MDR-TB in the 1980s, however, destroyed that hope. In 1993 WHO declared the resurgence of TB as a global health emergency. Researchers are trying to develop a more effective vaccine than BCG and find new antibiotics to treat MDR-TB and XDR-TB. They are also testing fixed-dose combination tablets of antiTB drugs to simplify patients’ medications. SEE ALSO

AIDS; Pneumonia


Dormandy, Thomas. The White Death: A History of Tuberculosis. New York: New York University Press, 2000. Reichman, Lee B., and Janice Hopkins Tanne. Timebomb: The Global Epidemic of Multi-Drug-Resistant Tuberculosis. New York: McGraw-Hill, 2002. 1132


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American Lung Association (ALA). Tuberculosis (TB). Available online at http:// www.lungusa.org/site/apps/nlnet/content3.aspx?c=dvLUK9O0E&b= 4294229&ct=3052615 (updated May 2007; accessed September 14, 2008). The ALA was founded in 1904 as the National Tuberculosis Association. Centers for Disease Control and Prevention (CDC). Questions and Answers about TB, 2007. Available online at http://www.cdc.gov/tb/faqs/default.htm (updated June 26, 2008; accessed September 14, 2008). Mayo Clinic. Tuberculosis. Available online at http://www.mayoclinic.com/ health/tuberculosis/DS00372 (updated December 21, 2006; accessed September 14, 2008). National Institute of Allergy and Infectious Diseases (NIAID). Drug-Resistant TB—A Visual Tour. Available online at http://www3.niaid.nih.gov/topics/ tuberculosis/Understanding/WhatIsTB/VisualTour/firstLine.htm (updated May 18, 2007; accessed September 14, 2008). This is a slide show illustrating the various treatment options for drug-resistant TB. National Institute of Allergy and Infectious Diseases (NIAID). Tuberculosis (TB). Available online at http://www3.niaid.nih.gov/topics/tuberculosis/ default.htm (updated June 25, 2008; accessed September 14, 2008). TeensHealth. Tuberculosis. Available online at http://kidshealth.org/teen/ infections/bacterial_viral/tuberculosis.html (updated October 2007; accessed September 14, 2008).

Turner Syndrome Definition Turner syndrome is a genetic disorder in which the cells in a girl’s body are missing all or part of one of the two X chromosomes. The syndrome occurs only in girls. It is named for Henry Turner (1892–1970), a doctor in Oklahoma who first described the syndrome at a conference in 1938.

Description Turner syndrome is a genetic disorder in which a girl is missing one or part of one of the two X chromosomes that define a person’s sex as female. Women with Turner syndrome are shorter than average and cannot have children because their ovaries do not develop normally. They may also have some abnormal physical features, such as extra skin around the neck that gives the neck a webbed appearance; swollen hands UXL Encyclopedia of Diseases and Disorders

Also Known As Ullrich-Turner syndrome, monosomy X, TS Cause Absent or damaged X chromosome Symptoms Growth problems; infertility; kidney or heart disorders; learning difficulties Duration Lifelong 1133

Turner Syndrome Image of the set of chromosomes of a patient with Turner syndrome. Women with the disease have only one X chromosome. GJLP / PHOTO RESEARCHERS, INC.

and feet; heart or kidney problems; and scoliosis (abnormal sideways curvature of the spine). They are also at increased risk of high blood pressure and osteoporosis (brittle bones) in later life. Turner syndrome may result either from a complete lack of the second X chromosome—a condition called monosomy X—or from damage to or partial rearrangement of the second X chromosome. About half of all women with Turner syndrome have monosomy X; two-thirds of these patients lack the father’s X chromosome and the remaining third lack the mother’s X. The other half of patients with Turner syndrome have a damaged or incomplete second X chromosome. Although geneticists are not certain how many genes on the X chromosome are responsible for some of the characteristics of the syndrome, they have identified one gene known as SHOX, which is responsible for the production of a protein involved in bone growth. A missing or abnormal SHOX gene is thought to cause the short stature and skeletal abnormalities of women with Turner syndrome.

Demographics Turner syndrome occurs in one in every 2,000–2,500 newborn girls in the United States. Most female fetuses with Turner syndrome, however, do not survive until birth; doctors estimate that 98 percent die before birth or are miscarried. 1134


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The rate of Turner syndrome appears to be the same in all countries around the world and in all races and ethnic groups. No risk factors have been identified that increase the likelihood of parents having a daughter with the syndrome; as far as is known, the genetic errors that cause the disorder occur at random.

Causes and Symptoms

An Academy Award Winner Linda Hunt (1945–), is a film and television actress who won an Oscar in 1983 for her portrayal of a male Chinese-Australian photographer in a film called The Year of Living Dangerously. She is the first star to win an Academy Award for playing a character of the opposite sex.

Diagnosed with Turner syndrome in adolesTurner syndrome involves genetic errors that cence, Hunt is short for an adult woman at 4 occur during the formation of germ cells (eggs feet 9 inches (1.45 meters). She has a rich and and sperm) or during cell division shortly after deep speaking voice that has made her a popthe egg is fertilized by the sperm. The more ular choice as a narrator for such television series as American Experience and California common form of the syndrome occurs when and the American Dream. One of Hunt’s bestan egg or sperm lacking an X chromosome is known film roles is the voice of Grandmother involved in conception. The reason for the Willow in the 1997 Disney animated feature missing copy in the abnormal germ cell is a Pocahontas. genetic error called nondisjunction. During the normal process of germ cell formation, the paired chromosomes in the cell divide so that each daughter cell has one member of the pair. In nondisjunction, one daughter cell gets both members of the chromosome pair and the other cell has none. If a germ cell lacking an X chromosome is fertilized by a normal germ cell from the other parent, the child will have only one X chromosome. This genetic error is called monosomy X. Some cases of Turner syndrome occur in girls who have some body cells with two X chromosomes and some body cells without the second X. This condition is called mosaic Turner’s. It is thought to result from random errors in cell division during the early stages of fetal development. The symptoms of Turner syndrome include:

• Short height in adult life. The average height of an adult woman with Turner syndrome is 4 feet 7 inches (1.4 meters). • Flat, shield-shaped chest with widely spaced nipples. • Wide neck with webbing (extra skin) at the base. • Swelling of the hands and feet. UXL Encyclopedia of Diseases and Disorders

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• Kidney abnormalities, including a single horseshoe-shaped kidney on one side of the body or poor blood flow to the kidneys. • Low hairline and low-set ears. • Drooping eyelids. • Turned-out elbows. • Frequent ear infections and hearing loss. • Abnormalities in the structure of the heart. These may include damaged heart valves or a weakened aorta, which is the large artery that leaves the left side of the heart and carries oxygenated blood to all parts of the body. Women with Turner syndrome are at increased risk of a ruptured aorta. • Hypothyroidism (low levels of thyroid hormone). About a third of women with Turner syndrome develop Hashimoto’s disease. • Increased risk of both type 1 and type 2 diabetes. • Absence of menstrual periods and inability to have children. • Specific learning difficulties, most commonly with mathematics and with spatial perception.

Diagnosis Turner syndrome can be detected by amniocentesis before birth. Amniocentesis is a procedure in which the doctor withdraws a small amount of fluid from the sac that surrounds the baby in the mother’s uterus and examines cells from the baby’s tissues for genetic abnormalities. It may also be diagnosed after the baby is born when the doctor and parents notice such features as a webbed neck, broad flat chest, swollen hands and feet, and heart defects. The diagnosis can be confirmed by a karyotype, which is a blood test used to obtain cells for examination of their chromosomes under a microscope. In some cases Turner syndrome is not diagnosed until the girl’s growth slows down in early childhood or until she fails to reach puberty. At that time that doctor may order a karyotype (a photomicrograph of the chromosomes in a single human cell).

Treatment Turner syndrome cannot be cured because it is a genetic condition. However, growth hormone started early and estrogen replacement treatment in adolescence can help girls with the disorder grow to a normal height 1136


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and achieve normal sexual development. Early diagnosis of Turner syndrome is important because growth hormone treatment should be started in childhood. Estrogen replacement therapy is not started until the girl is twelve to fifteen years old, as it will slow down her growth in height if given earlier. Girls with Turner syndrome should continue to receive estrogen until they reach the normal age of menopause in order to prevent osteoporosis. Patients with Turner syndrome require careful monitoring throughout life for such possible complications as recurrent ear infections and possible hearing loss; kidney or thyroid disorders; heart problems; diabetes; and high blood pressure. They should have annual blood tests as part of routine physical checkups. In addition, they should watch their weight carefully because obesity increases their already high risk of diabetes. Although women with Turner syndrome are infertile because their ovaries do not develop normally, they can become pregnant with the help of assisted reproductive techniques. They should, however, consult a heart specialist before considering pregnancy because of the risk of aortic rupture or other heart complications. Most girls with Turner syndrome have normal intelligence, and many are intellectually gifted. Those who have difficulty with mathematics or related areas of study may need special tutoring in those fields. In general, however, TS should not interfere with patients’ ability to complete schooling and be successful in a wide variety of occupations. Several studies have shown that many women with Turner syndrome have higher-than-average educational achievements.

Prognosis The prognosis of Turner syndrome depends partly on whether the patient has monosomy X, a damaged second X chromosome, or mosaic Turner syndrome. In general, patients with monosomy X have a greater chance of developing heart or kidney problems than those with other forms of Turner syndrome and require more careful monitoring of their health. Most patients have an overall good prognosis with a slightly shorter than average life expectancy.

Prevention Since Turner syndrome is thought to be caused by a random genetic mutation rather than an inherited genetic defect, there is no way to UXL Encyclopedia of Diseases and Disorders

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WORDS TO KNOW Karyotype: A photomicrograph of the chromosomes in a single human cell. Making a karyotype is one way to test for genetic disorders. Monosomy: A type of genetic disorder in which a cell contains only one copy of a particular chromosome instead of the normal two. Mosaicism: A condition in which a person has some body cells containing an abnormal

number of chromosomes and other cells containing the normal number. Mosaicism results from random errors during the process of cell division that follows conception. Nondisjunction: A genetic error in which one or more pairs of chromosomes fail to separate during the formation of germ cells, with the result that both chromosomes are carried to one daughter cell and none to the other.

prevent it. Parents of a daughter with Turner syndrome are unlikely to have other daughters with the disorder.

The Future Turner syndrome is not likely to become more common in the general population in the future. In terms of treatments, as of 2008 the National Institutes of Health (NIH) was recruiting patients with Turner syndrome for clinical trials to evaluate the long-term effects of growth hormone therapy and estrogen replacement therapy. Research is ongoing to look for other genes on the X chromosome that may be involved in Turner syndrome. SEE

ALSO

Hashimoto disease; Osteoporosis; Scoliosis; Triple X

syndrome


Gizel, Kayli. All about Me: Growing Up with Turner Syndrome and Nonverbal Learning Disabilities. Wallingford, VT: Maple Leaf Center, 2004. WE B S IT E S

Genetics Home Reference. Turner Syndrome. Available online at http://ghr.nlm. nih.gov/condition=turnersyndrome (updated May 2008; accessed June 21, 2008). National Human Genome Research Institute (NHGRI). Learning about Turner Syndrome. Available online at http://www.genome.gov/19519119 (updated May 29, 2008; accessed June 21, 2008). 1138


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National Institute of Child Health and Human Development (NICHD). Turner Syndrome. Available online at http://www.nichd.nih.gov/health/ topics/Turner_Syndrome.cfm (updated February 21, 2007; accessed June 21, 2008). TeensHealth. Turner Syndrome. Available online at http://kidshealth.org/teen/ diseases_conditions/genetic/turner.html (updated January 2005; accessed June 21, 2008).


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Ulcerative colitis Definition

Also Known As UC, inflammatory bowel disease, IBD Cause Unknown; possibly genetic factors combined with environmental triggers Symptoms Cramping in lower abdomen, diarrhea, bloody diarrhea, bleeding from rectum, fever, weight loss Duration Years

Ulcerative colitis, or UC, is a form of inflammatory bowel disease or IBD. Unlike Crohn disease, which is another form of IBD, ulcerative colitis affects only the large bowel or colon. It does not affect the small intestine or other parts of the digestive tract. Ulcerative colitis that is limited to the rectum (the lowermost portion of the colon) is sometimes called proctitis. Ulcerative colitis that affects the entire colon, from the rectum to the point where the colon joins the small intestine, is called pancolitis. It is important to distinguish IBD from irritable bowel syndrome, or IBS. IBS does not involve inflammation of the bowel and is a less serious disease than IBD.

Description Ulcerative colitis is a disorder of the digestive tract that usually begins slowly rather than suddenly. In response to inflammation of the tissues lining the colon, small sores or ulcers form on the surface of these tissues and produce pus and bloody mucus that the body then expels. The patient typically experiences cramps in the lower abdomen and bloodor mucus-streaked diarrhea several times a day. In the early stages of the disease the patient notices that the stools gradually become looser. As the 1141

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View of the colon of an elderly woman with ulcerative colitis. Yellow areas show inflammation. DAVID M. MARTIN, M.D. / PHOTO RESEARCHERS, INC.

disease progresses, the patient may have more frequent stools and a more urgent need to defecate. Ulcerative colitis does not affect all patients with equal severity. About half of patients with UC have only mild diarrhea (fewer than four stools per day) and cramping whereas the other half may have six or more stools per day with fever, anemia, and complications that affect the eyes or other organs. In addition, the symptoms of ulcerative colitis often come and go; periods of few or no symptoms are called remissions. A potentially life-threatening but rare form of ulcerative colitis is known as fulminant colitis. In fulminant colitis, the patient has ten or more bowel movements per day, involvement of the entire colon, and the potential for rupture of the colon. Ulcerative colitis differs from Crohn disease in two important respects: first, the affected portion of the bowel is continuous; there is no pattern of alternation between diseased portions of the bowel and normal portions. Second, unlike Crohn disease, ulcerative colitis is usually limited to the innermost layer of tissue lining the colon, whereas Crohn disease can penetrate to deeper layers of intestinal tissue.

Demographics Ulcerative colitis affects between 500,000 and 700,000 people in the United States, with another 500,000 suffering from Crohn disease. Ulcerative colitis is almost entirely a disorder of older adolescents or adults, with two peak age groups: people between fifteen and thirty years of age, and people between fifty and seventy. It can, however, occur in other age groups. In the developing world, UC primarily affects the upper classes. It is less common in Asia and Africa than in Europe and North America. In the United States, it is more common among Caucasian Jews of Eastern European ancestry than among other racial and ethnic groups, and more common in the northern states than in other parts of the country. Ulcerative colitis is slightly more common among women than men; there are three females for every two males affected. 1142


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Having a family member with ulcerative colitis increases a person’s risk of developing the disease, but only slightly. An identical twin of a patient diagnosed with UC has a 10 percent chance of developing it.

Causes and Symptoms The causes of ulcerative colitis are not completely understood. The most widely accepted theory holds that the disease is caused by the patient’s immune system mistaking bacteria that normally live in the intestine as foreign substances that must be attacked. When the immune system overreacts, white blood cells move in large numbers to the intestines, where they accumulate and eventually cause swelling and destruction of tissue. Another theory holds that ulcerative colitis is an inherited bowel disorder. There are certain regions of the human genome on chromosomes 1, 3, 5, 6, 12, 14, 16, and 19 that have been linked to UC; however, no single gene from any of these regions has been shown to be consistently associated with ulcerative colitis. Researchers think that a combination of several genes is necessary to trigger the disorder. At one time it was thought that diet or emotional stress played a role in the development of UC, but these theories are no longer accepted by most doctors. In contrast to Crohn disease, smoking does not increase a person’s likelihood of developing ulcerative colitis. The most common symptoms of ulcerative colitis are bloody or mucus-streaked diarrhea, abdominal cramps, rectal bleeding, and fever or unintended weight loss. Some patients also experience a feeling of fullness in the rectum even when it is empty; night sweats; nausea or vomiting; fatigue; and loss of appetite. It is not known why some patients with UC have symptoms in other organs or parts of the body, although researchers think that these complications are the result of inflammation triggered by the patient’s immune system. Complications outside the digestive tract may include: • • • • • •

Inflammation of the iris of the eye Pains in the joints Mouth ulcers Liver disease Osteoporosis Skin rashes


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Diagnosis The diagnosis of ulcerative colitis can be complicated because of the need to rule out Crohn disease, irritable bowel syndrome, and intestinal infections. Most primary care doctors will refer the patient to a gastroenterologist, who is a doctor who specializes in diagnosing and treating disorders of the stomach and intestines. The gastroenterologist will take a history of the patient’s symptoms and order one or more of the following tests: • Blood tests. These may be ordered to check for anemia or signs of infection. A high white blood cell count typically indicates infection somewhere in the patient’s body. • Stool sample. This test can be done to rule out intestinal parasites or bacteria or viruses that may be causing bloody stools. • Sigmoidoscopy or colonoscopy. A sigmoidoscope is a flexible lighted tube that can be inserted into the rectum and used to examine the last two feet of the colon. A colonoscope is a long flexible tube attached to a video camera and monitor that allows the doctor to examine the entire length of the patient’s colon and rectum. The patient must take a laxative the night before a colonoscopy to cleanse the bowel and may be given a sedative in the doctor’s office to make them more comfortable. The doctor will remove a small sample of tissue for biopsy; this is done to rule out Crohn disease. • Barium enema. A barium enema is an enema that contains a chalky substance that coats the lining of the rectum and upper colon. X-ray photographs are then taken as the patient lies on a table. • Computed tomography (CT) scan. The CT scan is an imaging tool to view internal organs.

Treatment There is no cure for ulcerative colitis. Treatment of the disease depends on the severity of the patient’s symptoms and the amount of the bowel that is involved. Some patients do well with one or more drugs given to reduce inflammation and encourage remission. There are three groups of drugs commonly prescribed for ulcerative colitis: • Aminosalicylates. These include drugs like sulfasalazine and mesalamine. They can be taken by mouth or as rectal suppositories, depending on the location of the inflammation. 1144


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• Corticosteroids. These include prednisone and hydrocortisone. Steroid medications are effective in reducing inflammation but are usually given only for short periods of time because they have potentially serious side effects. • Azathioprine and mercaptopurine. These are drugs that work to lower inflammation by suppressing the patient’s immune system. Patients who are having a severe attack of ulcerative colitis may need to be hospitalized for treatment of dehydration and blood loss. They may need a special diet for a few weeks or intensive treatment with steroid medications to bring down the inflammation. Patients at risk of fulminant colitis or who do not respond to medications can be treated with surgery to remove the inflamed portion of the colon. The surgeon can remove the entire colon and rectum and create an artificial opening to the outside of the abdomen called a stoma. The patient’s digestive wastes are passed into an ostomy bag attached to the stoma with adhesive. A newer surgical technique involves the creation of a pouch inside the abdomen by joining the lower end of the small intestine to the inside of the rectum and the anus. The patient may still have watery or loose bowel movements but will not need to wear an ostomy bag.

Prognosis In general, patients with proctitis have a milder course of the disease than those whose colitis affects a larger portion of the colon; they are also more likely to have long periods of remission. Between 25 and 40 percent of patients eventually need surgery for the disease. Ulcerative colitis does not, however, appear to shorten a person’s life span. Patients with ulcerative colitis have an increased risk of colorectal cancer except for those with proctitis only. About 5 percent of patients will eventually develop colon cancer. The risk increases after 10 years of the disease, particularly if the entire colon is involved. Most doctors recommend having a colonoscopy eight years after diagnosis of UC and every one to two years after that to check for signs of colorectal cancer.

Prevention There is no known way to prevent ulcerative colitis, because the causes of the disorder are not yet known. UXL Encyclopedia of Diseases and Disorders

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WORDS TO KNOW Fulminant: Referring to any disease or condition that strikes rapidly and is severe to the point of being life-threatening.

Rectum: The lowermost portion of the large intestine, about 6 inches (15.2 centimeters) long in adults.

Gastroenterologist: A doctor who specializes in diagnosing and treating diseases of the digestive system.

Remission: A period in the course of a disease when symptoms disappear for a time.

Pancolitis: Ulcerative colitis that affects the entire colon. Proctitis: The medical term for ulcerative colitis limited to the rectum.

Stoma: An opening made in the abdomen following surgery for digestive disorders that allows wastes to pass from the body.

The Future Ulcerative colitis is not likely to become more common in the general American population. Current research is focused on learning more about the role of the immune system in triggering the disease and the effectiveness of newer drugs in treating symptoms. SEE ALSO

Colorectal cancer; Crohn disease; Irritable bowel syndrome


Bonci, Leslie. American Dietetic Association Guide to Better Digestion. New York: John Wiley and Sons, 2003. King, John, ed. Mayo Clinic on Digestive Health. Rochester, MN: Mayo Clinic, 2004. Sklar, Jill. Crohn Disease and Ulcerative Colitis: An Essential Guide for the Newly Diagnosed, 2nd ed. New York: Marlowe and Co., 2007. PE R I O DI C A L S

Berlin, Loren. “Surgery for Ulcerative Colitis Is a Difficult Choice.” New York Times, February 20, 2008. Available online at http://health.nytimes.com/ref/ health/healthguide/esn-ulcerativecolitis-ess.html (accessed August 24, 2008). WE B S IT E S

American Gastroenterological Association (AGA). What Is Ulcerative Colitis? Available online at http://www.gastro.org/wmspage.cfm?parm1=4024 (click on link in middle of page) (accessed August 25, 2008). This webcast takes about six minutes to play. 1146


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Crohn and Colitis Foundation of America (CCFA). About Ulcerative Colitis and Proctitis. Available online at http://www.ccfa.org/info/about/ucp (updated July 25, 2008; accessed August 25, 2008). Mayo Clinic. Ulcerative Colitis. Available online at http://www.mayoclinic.com/ health/ulcerative-colitis/DS00598 (updated May 9, 2008; accessed August 24, 2008). National Institute of Diabetes and Digestive and Kidney Diseases (NIDDK). Ulcerative Colitis. Available online at http://digestive.niddk.nih.gov/ ddiseases/pubs/colitis/index.htm (updated February 2006; accessed August 24, 2008).

Ulcers Definition An ulcer is an open sore that forms in the skin or the lining of the mouth or digestive tract (esophagus, stomach, and intestines). It may be caused by pressure that cuts off circulation in the skin over bony parts of the body in bedridden patients; by complications of diabetes; or by infections that inflame the skin or mucous membranes (soft tissues that line the digestive and respiratory tracts) and lead to erosion of tissue. Ulcers can occur in different parts of the body. Ulcers in the digestive tract are called peptic ulcers.

Description Peptic ulcers are sores in the soft tissues that line the esophagus, the stomach, and the duodenum (the first part of the small intestine). They develop when tissues have been eaten away by stomach acid and digestive juices. As the tissues break down, the person experiences a burning or gnawing pain in the upper part of the abdomen. Although most peptic ulcers are small in size, the high acidity of the digestive juices in the stomach can cause intense pain when the acid in the juices touches the open sores.

Also Known As Bedsores, canker sores, diabetic ulcers, peptic ulcer disease, PUD Cause Infections or loss of blood circulation in affected parts of the body

Demographics

Symptoms Open painful areas in the mouth, digestive tract, skin, or eyes; heartburn, nausea, chest pain, vomiting blood, dark tarry stools (peptic ulcers)

Peptic ulcer disease, or PUD, is a very common disorder of the digestive system in developed countries. In the United States, treatments for PUD

Duration Days to months


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Ulcers A human stomach with a gastric ulcer that perforated, or burned a hole through the wall of the stomach. CNRI / PHOTO RESEARCHERS, INC.

account for 10 percent of the health care costs for digestive diseases. About 4.5 million Americans have PUD at any given time, and one person in ten will develop a peptic ulcer at some point in his or her life. There are approximately 350,000–500,000 new cases of PUD and more than 1 million ulcer-related hospitalizations each year in the United States. About 6,000 people die each year of complications from peptic ulcers. Peptic ulcers are largely a disease of adults; they are relatively rare in children and adolescents. The location of peptic ulcers varies somewhat according to age and sex, however; duodenal ulcers are more common in adults between the ages of thirty and sixty and are twice as common in men as in women. Gastric (stomach) ulcers are more common in adults over sixty and are more common in women than in men. Peptic ulcers are somewhat more common among African Americans and Hispanics than among Caucasians and Asian Americans in the United States.

Causes and Symptoms Most peptic ulcers are caused either by infection by a bacterium called Helicobacter pylori or by heavy use of over-the-counter nonsteroidal antiinflammatory drugs, or NSAIDs. About 61 percent of all duodenal ulcers and 63 percent of gastric ulcers are caused by H. pylori. This spiral-shaped bacterium is found in the digestive tracts of about 50 percent of the 1148


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world’s population; however, most people who have H. pylori in their digestive systems do not have any ulcer symptoms. In about 20 percent of people infected with H. pylori, the bacterium is able to weaken the mucous tissues that protect the deeper layers of stomach and intestinal muscle. Once H. pylori burrows through the mucous tissues, the acid in the digestive juices irritates the tissues further and eventually produces an ulcer. The next most common cause of peptic ulcers is NSAIDs. These are pain relievers that include such drugs as aspirin, ibuprofen, naproxen, and newer anti-arthritis drugs like celecoxib. NSAIDs can weaken the protective lining of the stomach, causing peptic ulcers directly or making it easier for H. pylori to penetrate the lining. Elderly people are at increased risk of PUD caused by NSAIDs because many of them take these drugs routinely for arthritis or headaches. Before H. pylori was identified as a major cause of PUD in 1982, doctors thought that ulcers were caused by eating spicy foods or having a stressful job, but these theories are no longer accepted. A small proportion of peptic ulcers are caused by: • Stress related to recovery from severe burns • Zollinger-Ellison syndrome, a rare disease that produces tumors that cause the stomach to secrete abnormally high levels of acid • Excessive alcohol drinking • Smoking • Being treated with radiation therapy for cancer The most noticeable symptom of PUD is a burning or gnawing pain behind the breastbone or in the upper middle portion of the abdomen several hours after a meal. The pain is often worse in the early morning or at night, and can last anywhere from a few minutes to several hours. It may also come and go over a period of a few days or weeks. The pain of a peptic ulcer is usually relieved by eating a small amount of bland food, by taking antacids, or by vomiting. Other symptoms of PUD include: • • • • • •

Nausea and vomiting Black or tarry-looking stools Vomiting up blood Chest pain Unintended weight loss Loss of energy


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Diagnosis Peptic ulcers are usually diagnosed by a series of tests: • Upper GI (gastrointestinal) series: This is the medical term for an imaging study in which the patient drinks a chalky liquid containing barium, a substance that coats the lining of the esophagus, stomach, and small intestine and shows up on an x ray. Most ulcers, though not all, will be visible on the x-ray photograph. • Endoscopy. An endoscope is a thin, flexible tube with a light and a miniature camera at one end. The doctor threads the endoscope down through the esophagus into the stomach. The instrument can be used to remove a small sample of the stomach lining for biopsy as well as to take photographs of the inside of the digestive tract. • Tests for H. pylori. If the doctor detects a peptic ulcer through an upper GI series or an endoscopy, further testing must be done to see whether the ulcer is caused by H. pylori, because the treatment is different from that for ulcers caused by NSAIDs or other factors. H. pylori can be detected by a blood test that measures antibodies to the bacterium, by a biopsy of stomach tissue removed during an endoscopy, or by a breath test. The breath test is done by having the patient drink a solution of urea (a watery compound containing nitrogen) combined with radioactive carbon. If H. pylori is present in the patient’s stomach, the bacterium will break down the urea and release the carbon, which the patient will exhale in the form of carbon dioxide. The patient breathes into a plastic bag about thirty minutes after drinking the urea and carbon solution, and the amount of carbon dioxide in the breath is measured.

Treatment Treatment of PUD depends on whether the ulcer is caused by H. pylori, by NSAIDs, or by lifestyle factors. Ulcers caused by NSAIDs, by smoking, or by heavy drinking can be treated by quitting smoking, cutting back on alcohol, and by substituting other painkilling medications for NSAIDs. These ulcers can also be treated by prescription medications that coat the lining of the stomach until the ulcer heals, or other medications that block the production of stomach acid. 1150


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Peptic ulcers caused by H. pylori are treated by a combination of two or more medications. The goal of this type of therapy is to eliminate the bacterium. • Antibiotics. Two or three different antibiotics are given together to eliminate H. pylori because one antibiotic alone will not kill the bacterium. There are now two combination drugs available for H. pylori infection, each drug combining two antibiotics plus a drug to block acid production. These combination medications are called Prevpac and Helidac. • Pepto-Bismol plus antibiotics. The combination of Pepto-Bismol with two antibiotics works for 80–95 percent of people infected with H. pylori. • Medications that block the production of stomach acid. • Antacids. Antacids work by neutralizing stomach acid rather than preventing its production; they also provide rapid relief from the pain of a peptic ulcer. Most peptic ulcers respond to treatment with medications. In rare cases, the doctor may recommend surgery to treat the ulcer. The most common surgical procedures done to treat PUD are cutting part of the nerve from the brain to the stomach that controls the production of stomach acid and removing the portion of the stomach that produces a hormone that stimulates acid production.

Prognosis The prognosis for peptic ulcers is excellent; almost all patients can be treated successfully by avoiding NSAIDs, taking appropriate medications, and getting treatment for H. pylori infection.

Prevention People can do several things to lower their risk of peptic ulcers: • To avoid infection with H. pylori, people should stay away from contaminated food and water and observe strict standards of personal hygiene. They should wash hands carefully with warm water and soap every time they use bathroom, change a diaper, and before and after they prepare food. • They should use lower doses of NSAIDs, use acetaminophen (Tylenol) in place of NSAIDs, or consult their doctor about pain relievers that are easier on the stomach. UXL Encyclopedia of Diseases and Disorders

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WORDS TO KNOW Duodenum: The first part of the small intestine. Gastric: Related to the stomach.

Peptic ulcer: The medical term for an ulcer in the digestive tract.

• They should quit smoking. • They should lower the amount of alcohol, tea, and coffee that they drink.

The Future Peptic ulcers caused by H. pylori appear to be decreasing in frequency in the United States, while those caused by NSAIDs are increasing, particularly among the elderly. This increase is not surprising given the aging of the general population and the number of age-related health problems that are treated with NSAIDs. Considerable research is presently directed toward finding pain-relieving drugs that would be easier on the digestive system. One experimental drug in clinical trials is a combination of ibuprofen, an NSAID, with a drug that blocks acid production. The researchers are investigating whether the combination medication will reduce the rate of ulcer development in patients who need a daily dose of ibuprofen over long periods of time. S E E A L S O Alcoholism; Burns and scalds; Canker sores; Diabetes; Gangrene; Irritable bowel syndrome; Smoking; Stress


Jacoby, David B., and Robert M. Youngson. Encyclopedia of Family Health, 3rd ed. Tarrytown, NY: Marshall Cavendish, 2004. Miskovitz, Paul, and Marian Betancourt. The Doctor’s Guide to Gastrointestinal Health. Hoboken, NJ: Wiley, 2005. PE R I O DI C A L S

Brody, Jane E. “Personal Health: Canker Sores.” New York Times, June 10, 1987. Available online at http://query.nytimes.com/gst/fullpage.html?res= 9B0DE5DA1138F933A25755C0A961948260&sec=&spon=&pagewanted= all (accessed October 1, 2008). 1152


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American Academy of Family Physicians (AAFP). Ulcers and H. pylori Infection. Available online at http://familydoctor.org/online/famdocen/home/ common/digestive/disorders/271.html (updated December 2006; accessed October 1, 2008). American College of Gastroenterology (ACG). Peptic Ulcer Disease. Available online at http://www.acg.gi.org/patients/gihealth/peptic.asp (accessed October 1, 2008). American Dental Association (ADA). Common Mouth Sores. Available online at http://www.ada.org/public/topics/mouth_sores.asp#faq (accessed May 13, 2008). Mayo Clinic. Peptic Ulcer. Available online at http://www.mayoclinic.com/ health/peptic-ulcer/DS00242 (updated May 15, 2007; accessed September 30, 2008). National Institute of Diabetes and Digestive and Kidney Diseases (NIDDK). H. pylori and Peptic Ulcer. Available online at http://digestive.niddk.nih.gov/ ddiseases/pubs/hpylori/index.htm (updated October 2004; accessed October 1, 2008). TeensHealth. Ulcers. Available online at http://kidshealth.org/teen/diseases_ conditions/digestive/ulcers.html (updated May 2006; accessed September 30, 2006).

Urinary tract infection Definition Urinary tract infections, or UTIs, are disorders caused by infections, mostly bacterial but sometimes fungal or viral, of the urinary bladder, the urethra, the ureters, or the kidneys themselves. Infection of the bladder by itself is called cystitis; infection that has moved upward to the kidneys from the bladder or ureters is called pyelonephritis. UTIs can be caused by several different types of bacteria, but the most common offenders are bacteria that live in the intestines and get into the urinary tract because of poor cleansing after using the toilet. Other organisms that may be involved in a UTI include those that cause herpes, gonorrhea, and other sexually transmitted diseases.

Description The human urinary tract is usually free of bacteria, as is the urine it produces. Bacterial infections usually start when bacteria from the outside of UXL Encyclopedia of Diseases and Disorders

Also Known As UTI, bladder infection, cystitis Cause Bacteria in the kidneys, bladder, ureters, or urethra Symptoms Fever; pain on urination; need to urinate frequently; cloudy, smelly, or reddish urine Duration Three to ten days in most cases 1153

Urinary tract infection Computer image of bacteria (blue) in the urinary tract. Normally no bacteria are in the urinary tract. DAVID MACK / PHOTO RESEARCHERS, INC

the body enter through the urethra, a thin tube that connects the urinary bladder in the lower abdomen to the outside. The urethra in adult women is only about 1.5–2 inches (3.8–5.1 centimeters) long, whereas the adult male urethra is about 8 inches (20.3 centimeters) long. This difference helps to explain why adult women are the group at greatest risk of UTIs. Bacteria from the area around the anus or the vagina can enter the female urethra during sexual intercourse, or they can be introduced into the opening of the urethra by wiping from back to front after using the toilet. In men, bacteria are most likely to get into the urethra following surgery or insertion of a urinary catheter. Once the bacteria have entered the body through the urethra, they travel upward into the bladder, a hollow muscular organ in the lower abdomen that collects and stores urine. In the bladder, the bacteria may cause an inflammation known as cystitis, which is characterized by pain on urination, a need to urinate frequently, and cloudy, bloody, or foulsmelling urine. If the infection is not treated, it may spread upward past the bladder through the ureters into the kidneys. The ureters are two tubes about 10 inches (25.4 centimeters) long in human adults that connect the kidneys to the bladder. A bacterial infection of the kidneys is more serious than a bladder infection because of the possibility of long-term damage to the kidneys. Patients with pyelonephritis may experience vomiting, 1154


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severe pain in the abdomen, night sweats, and a high fever as well as painful urination.

Demographics UTIs are largely an adult disorder, although between 1 and 2 percent of children are affected by them. According to the American Urological Association, urinary tract infections are responsible for more than 7 million visits to doctors each year in the United States and about 5 percent of all visits to primary care doctors. About 40 percent of women and 12 percent of men will experience at least one UTI during their lifetime. Although UTIs are less common in boys and men than in girls and women, they are also more serious when they do occur. As far as is known, race or ethnicity does not affect a person’s risk of UTIs. Factors that do increase risk, however, include:

UTIs in Children Most people think of urinary tract infections (UTIs) as an adult problem, but between 1 and 2 percent of children develop UTIs. These can be serious, because small children are much more likely than older children or adults to suffer lasting kidney damage from UTIs, and children may be too young to tell an adult when and where they are having pain; they may have only a fever, smelly urine in a diaper, diarrhea, or no symptoms at all. It is best to take a small child to the doctor if he or she is running a high fever and there is no other obvious explanation for it such as an ear infection or a cold. As with an adult, the diagnosis of a UTI in a small child is based on a urine sample. After the infection clears, the doctor may recommend additional tests to check for abnormalities in the structure of the child’s ureters or urethra. In some cases children get recurrent UTIs because they are born with abnormally narrow passages in one or more parts of their urinary tract, which can prevent the normal passage of urine out of the body and encourage the growth of bacteria in the urine. Doctors usually recommend x-rays or other imaging studies for children with UTIs when the child is:

• Female sex. The female urethra is only a quarter as long as the male urethra, which makes it easier for bacteria to enter the female bladder. • Sexual activity. Sexual intercourse can irritate the opening of the urethra in women and allow bacteria to enter. • Pregnancy. • A girl over age five who has had two or • Age. Older men are more likely to develop more UTIs UTIs because the swelling of the prostate • A boy of any age who has his first UTI gland may make it more difficult to empty • Younger than five the bladder completely. Women past • Running a high fever menopause have an increased risk of UTIs because of the weakening of the muscles surrounding the bladder. • Women who use diaphragms as a method of birth control. The rigid frame on the outside of a diaphragm can irritate the urethra or put pressure on it. • People with diabetes. UXL Encyclopedia of Diseases and Disorders

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• People who have become dehydrated or are not drinking enough fluids. • People with anatomical abnormalities of the urinary tract. • People with a history of kidney stones. • People who have had surgery that requires the placement of a urinary catheter.

Causes and Symptoms The cause of urinary tract infections is the introduction of bacteria into the urinary tract. If the bacteria are not washed out by urine, they may multiply in the tissues lining the urethra and the bladder, causing inflammation, fever, pus in the urine, and other symptoms of infection. It is possible for a person to have a UTI without noticeable symptoms of illness; however, most people will feel sick fairly rapidly after the infection begins. The symptoms of a bladder infection include: • Burning or painful urination • A low fever (below 101°F/38.3°C) • Feeling a need to urinate frequently • Cloudy, bloody, or foul-smelling urine • Need to urinate at night • A feeling of pressure in the lower part of the pelvis If the infection has spread to the kidneys, the patient may also have: • • • • •

A high fever (over 101°F/38.3°C) and chills Night sweats Severe pain in the side around waist level or in the lower back Nausea and vomiting Mental confusion (more common in the elderly)

Diagnosis Diagnosis of a urinary tract infection is based on the patient’s symptoms and the results of a urine test. Urine is usually obtained via a clean-catch midstream urine specimen: after cleansing the area around the urethral opening and urinating a small amount into the toilet, the patient then urinates into a small cup or container. If the patient is a small child or 1156



an adult who cannot urinate, the doctor may obtain a sample by inserting a catheter into the bladder through the urethra. The doctor can perform a simple urine test to determine whether an infection is present by looking for an increased number of white blood cells in the urine or for the bacteria themselves. To determine which specific bacterium is causing the infection, the doctor can send the urine sample to a laboratory for culture. The doctor may order imaging tests if there is evidence that the infection is related to structural abnormalities in the patient’s urinary tract. Imaging tests are most commonly ordered for patients who have recurrent UTIs (three or more in a year); young children with UTIs, particularly boys; and patients of any age who have blood in the urine.

Treatment Treatment of an uncomplicated urinary tract infection in most women is a three- to seven-day course of an antibiotic given by mouth. Adult males usually require two weeks of antibiotic treatment, and children are usually given a ten-day course of antibiotics. The doctor may also prescribe a medication that numbs the pain of urination while the infection is being treated. These drugs may discolor the urine either blue or bright orange. If the patient has pyelonephritis, intravenous antibiotics may be needed, along with intravenous fluids if the patient is vomiting and cannot keep anything in the stomach. The patient will usually be given oral antibiotics for ten to fourteen days after the intravenous antibiotics are stopped. A patient who is very sick with pyelonephritis, is pregnant, or has kidney stones may be admitted to the hospital for treatment. The doctor may recommend surgery for children or adults with anatomical abnormalities of the urinary tract in order to reduce the risk of recurrent UTIs and permanent damage to the kidneys.

Prognosis Most people with uncomplicated cystitis recover in a few days without any long-term complications. About 1 percent of patients with pyelonephritis die following the spread of the infection from the kidneys to the bloodstream. Those most at risk of death from a severe urinary tract infection are the elderly, people with sickle cell anemia, people with cancer, and people with chronic kidney disease. UXL Encyclopedia of Diseases and Disorders

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Prevention There are several precautions to reduce their risk of urinary tract infections: • Drink plenty of water and other fluids. There is some evidence that cranberry juice is particularly beneficial because it prevents bacteria from attaching to the cells of the tissues lining the bladder. • Empty the bladder regularly, particularly after sexual intercourse. • Women using the diaphragm as a method of birth control may wish to consider another method. • Cleanse the genital area from front to back after using the toilet. This helps to prevent bacteria from the area around the anus from getting into the urethra. • Urinate promptly when the bladder begins to feel full rather than holding in the urine for long periods of time. In addition, empty the bladder as completely as possible. • Avoid the use of deodorant sprays or other feminine hygiene products that can irritate the urethral opening; change tampons or napkins frequently during menstrual periods. • Wear underwear made of cotton rather than nylon or other synthetic fabrics. In some cases the doctor may prescribe a low-dose antibiotic to be taken after sexual intercourse to prevent a urinary tract infection.

The Future UTIs are likely to continue to be commonplace illnesses in the general population. Current research includes studies of electrochemical chips and other new technologies for rapid identification of the bacteria that cause UTIs. SEE ALSO

Diabetes


Litin, Scott C., ed. Mayo Clinic Family Health Book, 3rd ed. New York: HarperResource, 2003. WE B S IT E S

American Urological Association. Urinary Tract Infections in Adults. Available online at http://www.urologyhealth.org/adult/index.cfm?cat=07&topic=147 (updated December 2002; accessed July 15, 2008). 1158



WORDS TO KNOW Bladder: A hollow organ in the lower abdomen that collects urine from the kidneys and stores it prior to urination. Catheter: A thin tube inserted into the urethra to drain urine from the bladder. Cystitis: The medical term for an infection of the urinary bladder. Pyelonephritis: The medical term for a urinary tract infection that has spread from the bladder

or other parts of the urinary tract upward to the kidneys. Ureter: A muscular tube that carries urine from the kidney to the bladder. Urethra: The thin tube that connects the bladder to the outside of the body. Urologist: A doctor who specializes in diagnosing and treating disorders of the kidneys and urinary tract.

Mayo Clinic. Urinary Tract Infection. Available online at http://www .mayoclinic.com/health/urinary-tract-infection/DS00286 (updated June 27, 2008; accessed July 15, 2008). National Institute of Child Health and Human Development (NICHD). Urinary Tract Infections (UTI). Available online at http://www.nichd.nih .gov/health/topics/urinary_tract_infections.cfm (updated August 25, 2006; accessed July 15, 2008). National Institute of Diabetes and Digestive and Kidney Diseases. Urinary Tract Infections in Adults. Available online at http://kidney.niddk.nih.gov/kudiseases/ pubs/utiadult/index.htm (updated December 2005; accessed July 15, 2008). TeensHealth. Urinary Tract Infections. Available online at http://kidshealth.org/ teen/infections/common/uti.html (updated August 2006; accessed July 15, 2008).


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Vision Disorders Vision disorders are a group of diseases and disorders that affect the sense of sight. Some are caused by infections or allergies, like conjunctivitis, but most are caused by abnormalities in the structure of the eye or changes in the eye over time as a result of aging. Some diseases that affect the whole body, like diabetes, may eventually cause vision problems in addition to other symptoms. Refractive errors are a type of vision disorder in which the person cannot see clearly because the eye cannot properly focus the light that enters the eye. Hyperopia (farsightedness), astigmatism, and myopia (nearsightedness) are types of refractive error. They develop when the lens of the eye is too strong or too weak for the length of the person’s eyeball or when the cornea (the transparent front part of the eye) has an abnormal curvature. Strabismus is a vision disorder in which the eyes are not aligned because the muscles that control the movements of the eyes are weak and uncoordinated. Cataracts and glaucoma are vision disorders associated with the aging process. A cataract is a yellowish or cloudy discoloration of the lens of the eye, while glaucoma can lead to permanent damage to the optic nerve and eventual blindness. SEE ALSO

Astigmatism; Cataracts; Conjunctivitis; Glaucoma; Hyperopia; Myopia; Strabismus 1161

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Vitiligo Definition Vitiligo (pronounced vittle-EYE-go) is a skin disorder in which patches of skin—most commonly on parts of the body that are exposed to sunlight— lose their pigmentation. The patches of depigmented tissue may involve the soft tissues that line the nose and mouth.

Description Vitiligo is a skin disorder in which patches of skin, soft tissues lining the nose and mouth, and/or hair gradually lose their color. This loss of color takes place when melanin, a dark brown or reddish pigment produced by cells in the skin called melanocytes, is either destroyed or not produced in the first place. The patches of depigmented skin may grow, shrink, or stay the same size. They usually appear first on the parts of the body that are exposed to the sun, such as the hands, feet, face, lips, and arms. They may spread later to the armpits, genitals, groin area, and the soft tissues that line the nose and mouth. In some cases the white patches may eventually cover the patient’s entire body. Doctors classify vitiligo into three types according to the pattern of the skin patches: Also Known As Leukoderma Cause Unknown; possibly a combination of autoimmune and genetic factors Symptoms Patches of depigmented skin on various parts of the body Duration Years 1162

• Focal. The areas of depigmented skin are limited to one or a few parts of the body. • Segmental. The loss of color occurs on only one part of the body. • Generalized. There are many patches of white skin on many different parts of the body. This is the most common of the three patterns.

Demographics Vitiligo is thought to affect between 0.5 and 2 percent of people around the world, as many as 65 million adults. There are between 1 and 2 million people in the United States with the disorder. Vitiligo can start at any age, but roughly half of patients develop it before age twenty and most patients before age forty. It affects men and women equally, although women are more likely to notice the disorder at an earlier age than men. It also affects people of all races equally; UXL Encyclopedia of Diseases and Disorders

Vitiligo Discoloration on the hands of a woman with vitiligo. © ROB / ALAMY.

however, the depigmented areas of skin are more noticeable on people with darker skin. In addition to humans, vitiligo is found in some animals, particularly certain breeds of dogs and horses.

Causes and Symptoms The causes of vitiligo are not completely understood. One reason some researchers think that genetic factors may be involved is that about 30 percent of cases run in families. Another theory is that vitiligo is either an autoimmune disorder or caused by one. Still other researchers think that vitiligo may be stress-related, because some people develop their first symptoms of it following a severe case of sunburn or an emotional shock. None of these theories have been proved so far, however. In addition to the patches of depigmented skin, the symptoms of vitiligo may include: • Premature graying (before age thirty) of scalp hair, pubic hair, and eyebrows. • Uveitis. This is an inflammation of the interior of the eye. • Depigmented areas on the soft tissues lining the mouth and nose. • Change in color of the retina of the eye. UXL Encyclopedia of Diseases and Disorders

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In the Public Eye: A Television Reporter’s Story Lee Thomas, a television anchor in Detroit, first noticed his vitiligo in 1992, when he was 25 and working for a news station in Louisville, Kentucky. After a haircut he noticed a white spot about the size of a quarter on one side of his scalp. Looking closely, he found other patches on the other side of the scalp, one hand, and inside his mouth. He immediately went to a doctor and was told he had vitiligo. He decided not to let the disease interfere with his goals, though his career depends in part on appearance. On camera, he wears makeup to even out the different colors of his facial skin. “I’m a black man turning white on television and people can see it…If you’ve watched me over the years, you’ve seen my hands completely change from brown to white.” Thomas no longer wears makeup outside the studio, a decision made partly for the sake of patients with vitiligo who fear rude or unkind reactions from the public. He admits that he himself went through “times when I would not come out of the house. I call it a mental war. It was me saying, ‘I don’t want to deal with it today.’” Thomas wrote a book about his experiences and credits the disease with strengthening his inner qualities: “Having this disease forces me to focus on what I am: kind, caring, honest. There are [other] people who have diseases that will kill them.”

• Itching of the affected skin. This symptom is usually limited to the early stages of the disorder. • Increased sensitivity to sun exposure. Although vitiligo is a skin disorder and not a psychiatric condition, many patients do have strong psychological reactions to the impact of the disorder on their appearance, particularly if the face is affected. In some cultures, people with vitiligo are thought to be evil or infected with leprosy and may be rejected by other members of the community. Many people with vitiligo in the United States become depressed or socially isolated because they are afraid of being stared at or teased.

Diagnosis The diagnosis of vitiligo is based on the patient’s history, including a family history of vitiligo. The doctor will also ask about autoimmune disorders, recent sunburns or other injuries to the skin, unusual sensitivity to the sun, or a history of diabetes. In most cases the doctor can diagnose vitiligo by looking at the patient’s skin with a Wood lamp, a special device that uses ultraviolet light to diagnose skin infections and other abnormalities. Another diagnostic technique that can be used is the skin biopsy. To perform a biopsy, the doctor removes a small piece of the affected skin to examine under a microscope. If the patient has vitiligo, the skin sample will usually show a complete absence of melanocytes.

Treatment There is no cure for vitiligo. Medical or surgical treatment is not necessary; some people choose to manage the condition with special cosmetics that cover the white areas and even out the person’s skin tone. Even patients who choose medical or surgical therapies may wish to use 1164


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camouflage cosmetics during their treatment, as it takes between six to eighteen months to complete treatment. No treatment that is presently available for vitiligo will work for all patients. The choice of treatment depends partly on the number, size, and location of the white patches. Medical treatments for vitiligo are aimed at reducing the contrast between the pigmented and depigmented areas of skin. They include: • Corticosteroids. These medications are applied directly to the depigmented skin; they work by restoring the color to the white areas. They take about three months for the skin to show improvement. • PUVA (psoralen/ultraviolet A) therapy. In this type of treatment, the patient takes a drug called psoralen either by mouth or by applying it to the skin as a cream. The patient is then exposed to carefully timed ultraviolet light in the doctor’s office. Psoralen reacts with ultraviolet light to darken the skin. Major drawbacks of PUVA therapy are its side effects (chiefly sunburn and too much darkening of the skin) and an increased risk of skin cancer. • Depigmentation. A drug called Benoquin is applied twice a day to the pigmented areas of the body to lighten them to match the areas that are already white. Depigmentation may be the best choice for people who have vitiligo on more than 50 percent of the body. Its chief drawback is that the person’s skin will always be unusually sensitive to sunlight afterward. In addition, this form of treatment is irreversible. Surgical treatments for vitiligo include: • Skin grafts. The surgeon removes skin from pigmented areas of the patient’s body and places it on depigmented areas. This procedure has a number of drawbacks: it is time-consuming, expensive, painful, and carries some risk of scarring and infection. • Micropigmentation (tattooing). In this procedure, the doctor implants pigment into the skin with a special surgical instrument. It is usually used only in the area around the lips. One drawback is that it is usually difficult to match the patient’s natural skin color. • Autologous melanocyte transplantation. This procedure is still considered experimental. The doctor removes a sample of the patient’s normal pigmented skin and places it in a special culture medium to grow melanocytes. After the melanocytes have UXL Encyclopedia of Diseases and Disorders

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WORDS TO KNOW Melanin: A brownish or dark reddish pigment that is the primary determinant of skin, hair, and eye color in humans. Melanocyte: A type of skin cell that produces melanin.

Retina: The layer of light-sensitive cells at the back of the eyeball. Uveitis: Inflammation of the interior of the eye. Wood lamp: A special lamp that uses ultraviolet light to detect certain types of skin infections and other disorders, including vitiligo.

multiplied, the doctor transplants them into the areas of depigmented skin. As of 2008, this treatment was very expensive and impractical for most people with vitiligo. Patients with vitiligo are encouraged to join support groups or seek counseling in order to cope with the emotional effects of the disease.

Prognosis It is very difficult to predict the spread of vitiligo on any patient’s body or the outcome of any specific type of treatment.

Prevention There is no known way to prevent vitiligo, because the causes of the disorder are not yet understood.

The Future It is not likely that vitiligo will become either more or less common in the general population than it is at present. Research into the disorder is focused on looking for specific genes that may be related to vitiligo and examining the role of stress in triggering the onset of the disorder. Some evidence has been recently found of a link between vitiligo and variants of a gene called FOXD3. SEE ALSO

Stress; Sunburn


Thomas, Lee. Turning White: A Memoir of Change. Troy, MI: Momentum Books, 2007. 1166


Vitiligo PE R I O DI C A L S

Associated Press. “Fox TV Reporter Refuses to Give In to Skin Disorder Turning Him White.” Fox News, December 17, 2007. Available online at http://www.foxnews.com/story/0,2933,317065,00.html (cited June 15, 2008). WE B S IT E S

American Vitiligo Research Foundation. Vitiligo Facts. Available online at http://www.avrf.org/facts/facts.htm (accessed June 15, 2008). Mayo Clinic. Vitiligo. Available online at http://www.mayoclinic.com/health/ vitiligo/DS00586 (updated April 20, 2007; accessed June 15, 2008). National Institute of Arthritis and Musculoskeletal and Skin Diseases (NIAMS). Questions and Answers about Vitiligo. Available online at http://www.niams .nih.gov/Health_Info/Vitiligo/default.asp (updated October 2006; accessed June 15, 2008). National Vitiligo Foundation (NVF). Vitiligo Patient Handbook. Available online at http://nvfi.org/pages/info_patient_handbook.php (updated February 2008; accessed June 15, 2008).


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Warts Definition Warts are small benign (noncancerous) growths of tissue on the surface of the skin caused by the human papillomavirus (HPV). Most are skincolored but some are darker than the surrounding skin. Dermatologists (doctors who specialize in treating skin disorders) classify warts into four main types according to their location on the body:

Also Known As Verrucae Cause Human papillomavirus (HPV) Symptoms Small rough benign tissue swellings on the hands, feet, or genitals Duration A few months to several years

• Common warts: Usually found on the fingers, fingernails, and backs of the hands. • Plantar warts: Found on the soles of the feet. Plantar warts that form in groups are sometimes called mosaic warts. • Flat warts: Located on the face or (in men) the beard area. • Genital warts: Found on the external genital areas or around the anus.

Description Warts are small growths on the surface of the skin that result from one or more strains of human papillomavirus infecting the skin through small breaks in the outer surface of the skin. The virus can be transmitted from one person to another; genital warts are highly contagious, whereas the risk of getting common, plantar, or flat warts directly from another person is relatively small. 1169

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Warts on a thumb. © MEDICALON-LINE / ALAMY.

The external appearance of warts varies somewhat according to location. Common warts are usually the same color as the surrounding skin and may occur around the edges of the nails where the person has chewed on or cut off a hangnail. The blood vessels inside the wart may look like black dots or seeds. Plantar warts are usually flat because of the pressure of walking or running. They usually are grayish-yellow in color and may also have black dots inside them like common warts. Plantar warts typically form on parts of the foot that are under pressure from shoes, like the heel or ball of the foot. These warts can be painful as well as unattractive. Flat warts are smaller (about one-quarter inch [0.64 centimeter]) and smoother than common warts. They are most likely to occur on parts of the body where the skin may be cut or broken by shaving, like the face in men or the legs in women. Genital warts are a sexually transmitted infection. They usually appear in clusters, which may be very small or may develop into large masses of tissue around the anus or the exterior genitals. In women, genital warts can grow inside the vagina as well as outside it. Genital warts are not cancerous.

Demographics Warts are widespread in the general American population. Between 7 and 10 percent of people develop plantar warts. Flat warts and plantar warts are more common in children and teenagers than adults. Women are slightly more likely than men to develop plantar warts.

Causes and Symptoms Warts are caused by infection with the human papillomavirus. There are over 130 strains of this virus that have been identified as of the early 2000s. The virus thrives in warm, moist environments like shower stalls or locker rooms, which is why it can be transmitted indirectly from one 1170


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person to another. It takes between one and eight months for a wart to appear after the virus has entered a person’s body through a break in the skin. Some people are more susceptible to warts than others, most likely because of genetic factors. No specific genes, however, have been associated with warts. The symptoms of warts have already been described. Plantar warts are the only type of wart that are usually painful.

When to Call the Doctor about Warts A person should see their doctor about warts if they notice any of the following: • The wart is bleeding heavily or has such signs of infection as red streaks, pus, or a discharge. • The patient develops a fever of 101°F (38.3°C) or higher. • The wart is painful.

Diagnosis

• The wart is in the anal or genital area.

• The wart has changed its color or Warts can usually be diagnosed by looking at overall appearance. them. When in doubt, a person should consult • The patient has diabetes, HIV infectheir doctor to make sure the growth of tissue tion, or an immune system weais really a wart. The doctor can diagnose a wart kened by cancer chemotherapy. by scraping off some of the tissue and sending the sample to a laboratory for analysis. Another technique, which involves injecting a local anesthetic beforehand, is called a punch biopsy. The doctor takes an instrument called a punch and removes a disk-shaped piece of tissue to send to the laboratory.

Treatment Common or flat warts do not always need treatment. About 30 percent of warts will disappear by themselves within six months. Most will disappear without any treatment within three years. Since warts are not cancerous, most people choose to treat them either because they are unattractive or because (like plantar warts) they cause discomfort when walking. People can treat common or flat warts at home in several different ways: • Using over-the-counter preparations containing salicylic acid. It comes in two forms, a liquid to be painted directly on the wart or a sticky plaster to be cut and pasted on the wart. Salicylic acid should not be applied to normal tissue surrounding the wart. It can take as long as twelve weeks to remove warts by this method. • Covering the wart with adhesive tape or duct tape. This technique works because it forms an airtight environment. The tape is left on UXL Encyclopedia of Diseases and Disorders

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for a week, then removed, and the wart is scraped with an emery board or pumice stone. • If home treatment does not work, it is best to see the doctor, because the skin growth may be a mole or something other than a wart. • Genital warts should never be treated with home remedies. These warts require professional medical care. Doctors can treat warts with various medical or surgical techniques: • Cryotherapy. Cryotherapy uses liquid nitrogen to freeze the warts. The dead tissue in the wart falls away from the skin beneath in about a week. • Imiquimod. Imiquimod is a topical cream that gets rid of warts by stimulating the body’s immune system to fight the virus that causes the warts. • Cantharidin. Cantharidin is a substance derived from blister beetles. It is a liquid that the doctor applies directly to the skin and covers with a bandage. The cantharidin causes the skin to blister, which lifts the wart from the skin surface and allows the doctor to remove the wart surgically. • Surgery. The doctor can remove the wart by treating it with an electric needle, then scraping the tissue with a sharp instrument called a curette. Lasers can also be used to remove warts. Both types of surgery can leave scars, however, and are usually used only for warts that have not responded to other types of treatment.

Prognosis As has already been mentioned, about a third of warts will go away without treatment in a few months. Warts often regrow after the skin has healed because the virus that causes them remains in the body; plantar warts are especially likely to reappear. Salicylic acid is about 75 percent effective in removing warts even though it is a slow method.

Prevention People can lower their risk of getting or spreading warts by: • Avoiding cutting, shaving, brushing, or picking at warts. These actions can spread the virus that causes warts into other areas of nearby skin. 1172


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WORDS TO KNOW Benign: Not cancerous. Cryotherapy: The use of liquid nitrogen or other forms of extreme cold to treat a skin disorder. Plantar: Located on or referring to the sole of the foot.

Topical: Referring to a type of medication applied directly to the skin or outside of the body. Verruca (plural, verrucae): The medical term for a wart.

• Avoiding biting their fingernails. The virus that causes common warts often enters the skin of the hands through bitten areas of skin. • Wearing shower shoes in locker rooms or public showers. • Washing the hands carefully after touching a wart. • Keeping the hands and feet as dry as possible, since the HPV virus grows and spreads in warm, moist environments. • Avoiding sexual contact with anyone known to have genital warts. There is also a vaccine for women that prevents infection with the strains of HPV that cause cervical cancer.

The Future Common, flat, and plantar warts are widespread minor health problems that are likely to continue to affect children as well as adults. It is possible that researchers may eventually identify specific genes that make some people more susceptible to getting warts. SEE ALSO

HPV infection


Kinch, Michael P. Warts. New York: Franklin Watts, 2000. Royston, Angela. Warts. Chicago, IL: Heinemann Library, 2002. PE R I O DI C A L S

O’Neil, John. “Remedies: A Clear Winner in Curing Warts.” New York Times, September 3, 2002. Available online at http://query.nytimes.com/gst/ fullpage.html?res=9C0DE5DE163AF930A3575AC0A9649C8B63 (accessed June 28, 2008). UXL Encyclopedia of Diseases and Disorders

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O’Neil, John. “Treatments: For Warts, the Duct Tape Cure.” New York Times, October 15, 2002. Available online at http://query.nytimes.com/gst/ fullpage.html?res=9C00E3DC153AF936A25753C1A9649C8B63 (accessed June 28, 2008). WE B S IT E S

American Academy of Dermatology (AAD). Warts. Available online at http:// www.aad.org/public/publications/pamphlets/common_warts.html (accessed June 28, 2008). American Academy of Family Physicians (AAFP). Warts. Available online at http://familydoctor.org/online/famdocen/home/common/skin/disorders/ 209.html (updated May 2008; accessed June 28, 2008). Mayo Clinic. Common Warts. Available online at http://www.mayoclinic.com/ health/common-warts/DS00370 (updated February 16, 2008; accessed June 28, 2008). TeensHealth.Warts. Available online at http://kidshealth.org/teen/your_body/ skin_stuff/warts.html (updated November 2007; accessed June 28, 2008).

West Nile Virus Infection Definition West Nile virus (WNV) infection is a disease spread by mosquitoes. Severe forms of the infection may be called West Nile encephalitis (if brain tissue is inflamed) or West Nile meningitis (if the membranes covering the brain become inflamed). Also Known As WNV, West Nile fever Cause Virus from infected birds transmitted by mosquitoes Symptoms Chills, fever, drowsiness, sweating, headache, weakness, nausea and vomiting Duration Three to ten days 1174

Description West Nile virus infection is caused by a virus related to those that cause yellow fever and dengue. It can be classified as a zoonosis because it is a disease that can be spread to humans from animals. It is also called an emerging infectious disease (EID) because it has become more widespread in the last 20 years and is likely to become more common in the future. Most people who become infected with the virus have no noticeable symptoms; about 20 percent develop a mild flu-like illness that lasts about a week; a few people develop a serious illness as a result of WNV causing inflammation of the central nervous system (the brain and spinal cord). UXL Encyclopedia of Diseases and Disorders


Demographics WNV is increasingly widespread in both tropical and temperate regions of the globe. In North America, epidemics of WNV are most likely to occur in August and September, when mosquitoes are most active. The disease is not a serious infection in 80 percent of people exposed to it; out of 151 people who become infected with the virus, 110 will not notice any symptoms at all; forty will be sick for about a week; and one person will become severely ill. The risk of severe illness in North America is greatest among people over fifty, pregnant women, people who have recently had cancer chemotherapy, people with diabetes, and people with weakened immune systems. As far as is known, WNV affects all races and both sexes equally. The West Nile virus is thought to have developed in Uganda about a thousand years ago. It was first identified as a distinct cause of disease in 1937 in a feverish woman in central Africa by researchers who were studying yellow fever. WNV was not described as a cause of severe disease in older adults until an outbreak took place in Israel in 1957. The virus reached North America some time in the 1990s; the first outbreak that attracted public attention occurred in New York, New Jersey, and Connecticut in 1999. The disease has since been reported across the United States. According to the Centers for Disease Control and Prevention (CDC), the total number of deaths in the United States from WNV between 1999 and 2007 is 1,060; most have been in elderly people.

Magnified image of the West Nile virus. © SCOTT CAMAZINE / ALAMY.

Causes and Symptoms West Nile virus infection is caused by a virus transmitted from infected birds to humans through mosquitoes that first bite the birds and then bite people. Crows, ravens, robins, and blue jays are the birds most likely to carry the virus; the CDC reported in 2007 that at least 138 different species of birds in North America have been found to carry WNV, and forty-three different species of mosquitoes. The first major outbreak of West Nile infection in the United States was preceded by the sudden death of large numbers of birds in the New York City area. UXL Encyclopedia of Diseases and Disorders

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The Mysterious Death of Alexander the Great One medical puzzle of ancient history is the death of Alexander the Great (356–323 BCE) at the young age of thirty-two. Alexander returned to Babylon in the spring of 323 BCE after his conquest of India. He fell sick with a fever and died after a two-week illness, which has been variously attributed to typhoid, influenza, liver failure caused by heavy drinking, and poisoning by enemies in his court. In 2003, however, two researchers in Virginia and Colorado suggested that Alexander might have died from West Nile encephalitis. They noticed an interesting detail recorded by the Greek historian Plutarch: “When [Alexander] arrived before the walls of [Babylon], he saw a large number of

Statue of Alexander the Great.

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ravens flying about and pecking one another, and some of them fell dead in front of him.” Epidemics of WNV are often preceded by the death of infected birds, so the American researchers thought that Alexander’s symptoms might have been related. Others disagree, saying that the time course of West Nile encephalitis does not fit what is known of Alexander’s last days. The mystery is not likely to yield a final solution, however, as doctors in the ancient world did not use the same terms that are used today to describe symptoms of illness, and translators of ancient Greek documents do not always agree about the meaning of specific words.

SHUTTERSTOCK.



The virus can be transmitted by mosquitoes to bats, horses, dogs, cats, squirrels, skunks, and rabbits as well as to people. The mosquitoes that carry the virus are called vectors, and the infected animals that harbor the virus are called hosts. The virus can also be transmitted by blood transfusions, organ transplants, and from a nursing mother to her baby through breast milk. People cannot get WNV, however, by touching or kissing someone with the virus; there are also no reported cases of people getting West Nile infections from household pets. When a mosquito carrying WNV bites a human, the virus is transmitted directly into the bloodstream. Once in the bloodstream, WNV multiplies for an incubation period of three to fourteen days. The 20 percent of people who feel symptoms of WNV infection typically have chills, a low-grade fever, headache, sore throat, and nausea and vomiting. About half these patients will also develop a mild rash on the upper chest. In most cases the illness lasts about a week, although the person may feel tired for several weeks afterward. West Nile encephalitis or meningitis develops when the virus reaches the tissues of the brain or the tissues that cover the brain and the spinal cord and multiplies there. People with this severe form of West Nile infection develop a stiff neck, severe headaches, and feel mentally confused. They have weak or partially paralyzed muscles and may lose consciousness.

Diagnosis The symptoms of WNV are similar to those of other viral infections. A definite diagnosis can be provided by testing blood or spinal fluid for antibodies against the virus. Since 2003, the Food and Drug Administration (FDA) has approved two rapid diagnostic tests for detecting the West Nile virus; one, developed in Australia, gives results in two hours. The other test was developed in Canada and was approved for use in the summer of 2007; it gives results in only fifteen minutes.

Treatment There is no specific treatment for West Nile virus. Most people who develop fever, nausea, or other symptoms recover without seeing a doctor because the symptoms are similar to those of other mild viral infections. The National Institute of Allergy and Infectious Diseases (NIAID) is currently testing a new drug treatment for WNV that was expected to complete its Phase I clinical trial by the end of 2008. UXL Encyclopedia of Diseases and Disorders

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People who develop West Nile encephalitis or West Nile meningitis should be taken to the hospital for specialized treatment to help them breathe. They may also be given intravenous fluids to prevent dehydration and intensive nursing care.

Prognosis Most people who have a mild form of West Nile virus infection recover in about a week with no long-term health problems. Those with severe infections, however, have a 10 percent risk of dying. Those who survive may suffer permanent brain damage or paralysis similar to that caused by polio.

Prevention There is no vaccine against WNV for humans that has completed clinical trials, although a vaccine for horses has been developed and approved for use. The most important precautions that humans can take are controlling mosquitoes and preventing themselves from being bitten by mosquitoes. The CDC recommends the following steps: • Once a week, drain water from birdbaths, outdoor buckets, flower pots, swimming pool covers, and other water-filled containers where mosquitoes can lay their eggs and breed. Empty children’s wading pools when they are not being used. • Use insect repellent when outdoors; apply it to exposed skin and spray clothing with repellent. • Wear long-sleeved shirts and long pants when the weather permits. • Try to stay indoors in early morning and early evening, because mosquitoes are most active at those times of day. • Keep window and door screens in good repair so that mosquitoes cannot get inside the house. • Cover baby strollers or carriers with mosquito netting when taking the baby for a walk outdoors. • Do not handle any dead birds found outside. Contact the local health department first and ask for instructions on reporting and disposing of them.

The Future It is likely that a vaccine for humans and a specific treatment for West Nile virus will be approved by the FDA within the next few years. About 1178



WORDS TO KNOW Dengue: A tropical disease caused by a virus similar to the virus that causes West Nile infection. It is also spread by mosquitoes.

Host: An organism that is infected by a virus, bacterium, or parasite. Birds, humans, and other animals may be hosts of West Nile virus.

Emerging infectious disease (EID): A disease that has become more widespread around the world in the last twenty years and is expected to become more common in the future.

Meningitis: Inflammation of the membranes that cover the brain and line the brain and spinal cord.

Encephalitis: Inflammation of the brain.

Vector: An animal that carries a disease from one host to another.

450 different chemicals that appear to be effective against viruses have been identified since 2003 as promising enough to justify further testing. There were also two potential vaccines against WNV undergoing clinical trials at the NIAID Vaccine Research Center in Maryland in 2008. SEE ALSO

Encephalitis; Meningitis


Abramovitz, Melissa. West Nile Virus. San Diego, CA: Lucent Books, 2004. Bernard, Amy B. West Nile Virus. Brockton, MA: Western Schools, 2005. PE R I O DI C A L S

Marr, J.S., and C.H. Calisher. “Alexander the Great and West Nile Virus Encephalitis.” Emerging Infectious Diseases 9 (December 2003): 1599–1603. Available online at http://www.cdc.gov/ncidod/EID/vol9no12/03-0288.htm (accessed April 10, 2008). “Patient Handout: West Nile Virus.” American Family Physician 68 (August 15, 2003): 671. Available online at http://www.aafp.org/afp/20030815/671ph . html (accessed April 9, 2008). Pearson, Helen. “West Nile Virus May Have Felled Alexander the Great.” Nature News Service, November 28, 2003. http://www.gideononline.com/ reviews/nature.htm (accessed April 11, 2008). WE B S IT E S

Centers for Disease Control and Prevention (CDC) BAM! (Body and Mind) website. The Buzz-z-z on West Nile Virus. http://www.bam.gov/sub_diseases/ diseases_westnile.html (accessed April 10, 2008). BAM! Is the CDC’s website for children in elementary school and junior high. Centers for Disease Control and Prevention (CDC). West Nile Virus Home Page. http://www.cdc.gov/ncidod/dvbid/westnile/index.htm (accessed April 10, 2008). UXL Encyclopedia of Diseases and Disorders

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United States Geological Survey (USGS). West Nile Virus Disease Map, Human. http://diseasemaps.usgs.gov/wnv_us_human.html (accessed April 9, 2008). Viewers can click on their state on the map of the United States to obtain updated information about reported cases of West Nile virus in their area. There is also a link to a disease surveillance map of Canada.

Whiplash Definition Whiplash is a general term for injuries to the neck caused by stretching of the spine and the soft tissues in the neck when the head is moved sharply forward and then snapped back. It is not a formal medical term; doctors are more likely to use phrases like “cervical sprain” to describe whiplash.

Description

Also Known As Whiplash-associated disorders, WAD, hyperextension injury, cervical sprain Cause Rear-end collisions, falls, sports injuries, criminal assault Symptoms Neck soreness, headaches, shoulder pain, ringing in the ears, dizziness, tiredness Duration A few days or weeks 1180

Whiplash injuries most commonly occur when a person is in a car or amusement park ride and is struck from behind. The impact pushes the car forward, which in turn throws the occupant’s head forward suddenly and then sharply backward, causing overstrain on the muscles or tearing of other soft tissues in the neck and shoulders. Some people feel pain at the time of the accident, while others may not feel the effect of the whiplash injury until several days later. Symptoms may range from soreness or stiffness in the neck and shoulders for a few days to severe pain and disability from injuries to the vertebrae in the neck.

Demographics Whiplash injuries are quite common in the United States and Canada, particularly those related to auto accidents. The National Highway Traffic Safety Administration (NHTSA) estimates that there are between 750,000 and 900,000 whiplash injuries related to automobile travel each year in the United States; about 40 percent of these are caused by rearimpact collisions. They are among the most frequently reported injuries in insurance claims, amounting to about $8.5 billion in insurance payouts each year. UXL Encyclopedia of Diseases and Disorders

Whiplash Illustration of how the brain is forced against the back and front of the skull during whiplash. © NUCLEUS MEDICAL ART, INC. / ALAMY.

Females tend to be at greater risk of whiplash injury than males regardless of whether they are driving the car or riding as a passenger. Apart from gender, drivers are more likely to get a whiplash injury than a front-seat passenger, possibly because drivers are more likely to move forward to try to control the car when hit from behind whereas passengers are more likely to be leaning further back in their seats. Passengers in the rear seats of a car have a slightly lower risk of whiplash injury than drivers or front-seat passengers.

Causes and Symptoms Although most whiplash injuries are caused by rear-end auto collisions, they can also be caused by: • Amusement park rides, particularly roller coasters and bumper-car rides • Falling from a horse, bicycle, or motorcycle • Railroad and airplane accidents • Contact injuries in sports like football, wrestling, or judo • Being hit on the head by a falling object • Being shaken or hit on the head by an abusive parent or other attacker Doctors do not agree, however, on exactly what causes the pain of whiplash in terms of the structures of the human neck. Some think that whiplash injury is caused by hyperextension of the neck, which is the medical term for stretching the neck beyond its normal range of motion. Other doctors think that the biological cause of whiplash injuries is damage to nerve endings in the neck. UXL Encyclopedia of Diseases and Disorders

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Home Treatment for Whiplash Home care for whiplash includes applying heat or cold to the neck and taking mild over-thecounter pain relievers. A common recommendation is to apply ice to the patient’s neck for twenty minutes at a time each hour for the first twenty-four hours while the patient is awake. The ice should not be applied directly to the skin but placed inside an ice pack or wrapped in a towel. After the first day or two of recovery, the patient should use a heating pad or other method of applying heat to warm and loosen the neck muscles for stretching exercises.

There is no clear relationship between an automobile’s speed at the time of an accident and a passenger’s risk of a whiplash injury; people have reported whiplash injuries when their car was traveling at no more than 15 miles per hour (24 kilometers per hour). Some doctors use a four-level scale for assessing the symptoms of a whiplash injury. The scale was first drawn up by a task force in Quebec in 1995.

• Level 1: Soreness or stiffness in the neck but there are no physical signs that can be detected by a doctor. • Level 2: The patient complains of pain Acetaminophen or ibuprofen are recommended and the doctor finds a decreased range of instead of aspirin for pain relief and to bring motion in the neck. down inflammation in the soft tissues of the • Level 3: The person has pain moving neck. If the pain is severe, the doctor may prefrom the neck into the shoulders and arms scribe a pain reliever containing codeine or a muscle relaxant. These medications should be plus such symptoms as insomnia, weaktaken at bedtime as they often cause drowsiness. ness, headache, blurred vision, or ringing in the ears. • Level 4: In addition to the patient’s symptoms, the doctor can detect dislocations or fractures of the bones in the neck, or injury to the spinal cord.

Diagnosis People with only mild whiplash injuries may simply treat themselves at home (see sidebar). While it is not always necessary to see a doctor for whiplash, people who notice tingling or numbness in their arms or legs, loss of function in their limbs, severe pain when trying to move the neck, pain moving from the neck into the shoulders, headache, or dizziness should see their doctor or go to a hospital emergency department as soon as possible. Doctors diagnose the seriousness of whiplash injuries by gently moving the patient’s head to see how far the neck can move in different directions. They will also press on different parts of the neck to see whether there are any localized sore spots. X rays and other imaging 1182


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studies may be ordered to check for bone fractures or other signs of serious injury to soft tissues.

Treatment Treatment for mild whiplash injuries may involve massage therapy and heat application in addition to treatment at home with bed rest, ice, and mild pain relievers. Within three to four days of the injury, the patient will be asked to start range-of-motion exercises to keep the neck flexible. These exercises usually involve gently rolling the head from side to side or bending the neck backward and forward. If the pain persists for several months, the doctor may recommend physical therapy to strengthen the neck muscles. The doctor may also inject a local anesthetic to reduce muscle spasms before the patient begins the range-of-motion exercises. Cervical (neck) collars are not used as often now as they were some years ago. The reason for this change is that wearing a collar for several weeks or months causes the muscles in the neck to lose their strength. People who have trouble sleeping because of whiplash pain, however, may be given a cervical collar to wear while they are sleeping. Some people are helped by alternative and complementary treatments for whiplash injuries. The approaches that have been found helpful include acupuncture, massage therapy, and chiropractic.

Prognosis Most people feel better within a few days or weeks after a whiplash injury. Severe damage to the bones in the neck or to the spinal cord, however, can result in permanent disability and chronic pain. There is a 40 percent chance of having some symptoms as long as three months after a whiplash injury, and an 18 percent chance that the symptoms will last for as long as two years, but there is no reliable way to predict a specific individual’s risk of falling into one of these two groups.

Prevention Head restraints have been mandated in new passenger cars manufactured in the United States since 1969. The effectiveness of these restraints in preventing whiplash injuries is debated by specialists who study the effects of whiplash injuries on the human body, however. One problem is that people do not always adjust their head restraint to the proper height for the size of their head and neck. The head restraint should be UXL Encyclopedia of Diseases and Disorders

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WORDS TO KNOW Acupuncture: A form of alternative medicine in which very fine needles are inserted into the skin at specific points on the body for pain relief. Chiropractic: A form of alternative medicine that treats disorders of the joints and

muscles by adjusting the patient’s spine or other joints. Hyperextension: Stretching or moving a part of the body beyond its normal range of motion.

adjusted so that the middle of the headrest is even with the upper tips of the ears. Another problem is that the stiffness of a car seat affects the likelihood of a whiplash injury as much as the quality of the head restraint and its proper adjustment. Safety engineers are still working on designing better head restraints, including some that adjust their position automatically when the driver moves the seat forward or backward.

The Future Some causes of whiplash injury, such as abusive or criminal attacks or accidents involving public transportation, would be difficult to prevent entirely. The risk of sports injuries to the neck can be lowered somewhat by redesigning shoulder pads and other protective equipment and by teaching athletes to minimize their risk of neck injuries. Better automobile design might help also, but even the best-designed seat or head restraint will not be effective if drivers and passengers fail to wear seat belts and adjust their head restraints correctly. SEE ALSO

Shaken baby syndrome


Ferrari, Robert. The Whiplash Encyclopedia: The Facts and Myths of Whiplash, 2nd ed. Sudbury, MA: Jones and Bartlett Publishers, 2006. WE B S IT E S

Insurance Institute for Highway Safety (IIHS). Q&As: Neck Injury. Available online at http://www.iihs.org/research/qanda/neck_injury.html#1 (posted December 2007; accessed April 26, 2008). Mayo Clinic. Whiplash. Available online at http://www.mayoclinic.com/health/ whiplash/DS01037 (updated December 19, 2007; accessed April 25, 2008). 1184


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Nemours Foundation. Dealing with Sports Injuries. Available online at http:// www.kidshealth.org/teen/exercise/safety/sports_injuries.html (updated June 2007; accessed April 27, 2008). Advice for teens on whiplash and other sports-related neck injuries. SpineUniverse. Whiplash Animation. Available online at http://www.spineuni verse.com/videos/whiplash/ (accessed April 26, 2008). This is a two-minute animation with voiceover that describes the structure of the neck and spinal column as well as explaining what happens in whiplash injuries. The transcript of the voiceover is printed beneath the animation.

Whooping Cough Definition Whooping cough is a highly contagious and potentially fatal bacterial infection of the upper respiratory tract.

Description Whooping cough, or pertussis, is a potentially severe upper respiratory infection characterized by spells of intense coughing that end in a whooping sound when the person is finally able to catch their breath. It can affect people in any age group, but is most common (and most serious) in infants and young children. The organism that causes whooping cough affects only humans; it is not spread by animals. The early symptoms of whooping cough resemble those of the common cold—runny nose, sneezing, general unwell feeling—and the disease is often mistaken for an ordinary cold. After about a week of cold-like symptoms, however, the patient develops episodes of severe coughing that can bring up thick phlegm (mucus) from the throat. The coughing may be intense and spasmotic enough to cause vomiting or cause the patient to turn red or blue in the face. At the end of the coughing attack, the patient may make a whooping or crowing sound as they gasp to take in their next breath of air.

Also Known As Pertussis Cause A bacterium

Demographics

Symptoms Runny nose, sneezing, fever, coughing episodes ending in a whooping sound

At one time whooping cough was a leading cause of death in infants and toddlers, causing 3,000 to 5,000 deaths in the United States

Duration Three to six weeks


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Whooping Cough Image of whooping cough bacteria. CNRI / PHOTO RESEARCHERS, INC.

every year. Even though vaccines against whooping cough have been available since the 1940s, the disease is still one of the leading causes of vaccine-preventable deaths worldwide. The World Health Organization (WHO) estimates that there are between 30 and 50 million cases of pertussis each year around the world, and 300,000 deaths. Ninety percent of cases of whooping cough occur in the developing world. Widespread vaccination against the disease, however, has lowered the death rate in the United States to fewer than thirty cases per year. In the United States, cases of whooping cough tend to cluster in cycles, with peaks every three to four years. Outbreaks of whooping cough are seasonal, with most cases occurring between June and September. On average there are about 2.7 cases of whooping cough per 100,000 in the general population in North America. Most people who get whooping cough in the United States are unimmunized children or older teenagers and adults whose full immunity has faded. The classic symptoms of whooping cough are not often seen in this latter group, who are likely to have cough for more than three weeks. According to the Centers for Disease Control and Prevention (CDC), 29 percent of patients with whooping cough are younger than one year; 12 percent are aged one to four years; 10 percent are aged 1186


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five to nine years; 29 percent are aged ten to nineteen years; and 20 percent are older than twenty years. As far as is known, males and females are equally affected by the disease. Caucasians appear to be more likely to get whooping cough than either African Americans or Native Americans.

Causes and Symptoms Whooping cough is caused by a bacterium known as Bordetella pertussis, an organism that appears to live only in humans. The organism is spread primarily by droplets in the coughing of infected individuals. When someone breathes in some of these droplets, the bacterium attaches itself to the tissues that line the throat and upper respiratory tract and multiplies. The patient usually begins to feel sick within three to twelve days after being infected. The symptoms of whooping cough depend on the stage of the illness:

Opposition to Vaccination Since the early 1990s public health doctors have become increasingly concerned about a growing trend among parents in some parts of the United States to refuse to have their children vaccinated against whooping cough and other childhood diseases. Most of these parents are too young to remember when such diseases as smallpox, polio, diphtheria, and whooping cough were real threats to children’s lives, but because they have heard rumors that vaccines can cause such disorders as autism and multiple sclerosis, they choose not to have their children vaccinated. They think that the risks of side effects from the vaccine are greater than the risks that their children will get a potentially lifethreatening disease. The problem is that when the rate of vaccination in a community drops below a certain point, diseases that were once rare begin to make a comeback. In parts of Colorado the rate of whooping cough has nearly doubled since the mid-1990s. Over the long term, the children who are not vaccinated are likely to come down with a serious illness themselves as well as putting others in their communities at risk. It may take a major outbreak of whooping cough or another vaccine-preventable disease to change some parents’ minds about the benefits of vaccination.

• Early phase (lasts one to two weeks). The patient appears to have an ordinary cold, with runny nose, sneezing, and nasal congestion. There may be low-grade fever and runny eyes. The disease is most likely to be spread to others at this stage. • Coughing stage (one to two weeks). The patient has spells of intense coughing that may last for several minutes and end in a whooping sound as the child struggles for breath. Infants younger than six months do not usually make the whooping sound but may become completely exhausted. The child may turn red in the face and vomit at the end of the coughing spell. Adults with whooping cough may get headaches during this stage. The coughing is usually worse at night. In some cases the patient develops pinpoint-sized red marks in the upper chest or the whites of the eyes caused by the breaking of tiny blood UXL Encyclopedia of Diseases and Disorders

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vessels during the coughing spells. These little marks are called petechiae. • Recovery stage (one to two weeks). The child begins to feel better but continues to cough occasionally.

Diagnosis In most cases the doctor will make the diagnosis on the basis of the patient’s physical symptoms, a history of exposure to others with whooping cough, and the patient’s record of immunization against whooping cough. The doctor may take a blood test to see whether the patient has a higher than normal number of lymphocyte white blood cells or order a chest x ray to see whether the patient has developed pneumonia, but neither of these tests is specific for whooping cough. To make the diagnosis definite, the doctor can take a sample of fluid from the patient’s nose or throat on a cotton swab and send it to a laboratory for analysis.

Treatment Treatment of whooping cough depends partly on the patient’s age and partly on the severity of the disease. Infants younger than six months often need hospitalization so that they can be given oxygen, have mucus removed from their airway, and fed intravenously if necessary. Very young infants are at greatest risk of ear infections, seizures, or other complications of whooping cough. Older children, teenagers, and adults should stay home from school or work in order not to give the disease to other people. They should rest in bed if at all possible. In most cases the doctor will prescribe an antibiotic medication, usually for two or three weeks. Antibiotics can shorten the duration of the illness and also shorten the length of time that the patient is contagious. In some cases the doctor will prescribe antibiotics for other members of the patient’s family to reduce their risk of getting the disease. Over-the counter cough medicines are not usually very helpful in relieving the sore throat and coughing spells of whooping cough. A coolmist vaporizer and drinking lots of fluids are usually more effective.

Prognosis Older children, adolescents, and adults usually recover from whooping cough in five to six weeks without any lasting effects. Infants who have not been immunized against whooping cough and older adults with heart 1188


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problems or lung disease are at greatest risk of developing pneumonia or other complications of whooping cough. About two-thirds of infants who develop whooping cough will need hospital treatment; the average length of stay for a baby with whooping cough in 2004 was seven days. Of the deaths caused by whooping cough in the United States in the early 2000s, 99 percent were in infants.

Prevention The best protection against whooping cough is immunization. Since the 1940s, the vaccine that protects against pertussis has been combined with vaccines against diphtheria and tetanus in a single vaccine. The American Academy of Pediatrics (AAP) recommends a total of five doses of the combined vaccine in children between the ages of two months and six years. Neither the vaccine nor getting the disease confers permanent immunity against whooping cough, however; the effectiveness of the vaccine fades away in three to five years after the last shot. Because an increasing number of cases of whooping cough are being diagnosed in teenagers, in 2005 the AAP recommended that all teenagers receive an additional booster shot of vaccine. This measure is intended to protect younger children as well as the adolescents, because the evidence indicates that many cases of whooping cough in infants are caused by the infection being transmitted to them by older family members. For adults less than sxity-five years of age, one booster of whooping cough vaccine should be given combined with the once every ten years tetanus/ diphtheria booster. This is especially important in prospective parents and grandparents and those health care workers who work in pediatrics.

The Future Whooping cough is likely to be a major public health problem even in developed countries for the foreseeable future because of some people’s opposition to vaccination. In the 1970s there were a number of lawsuits filed by people who felt that they had been injured by the diphtheria/ tetanus/pertussis vaccine. While it was not clear in many of these cases that the person’s health problems were caused by the vaccine, Congress passed a law in 1986 that requires doctors to give a child’s parents an information sheet about a vaccine before giving the child the shot. The doctor is also required to report any side effects of the vaccination to a national reporting system. UXL Encyclopedia of Diseases and Disorders

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Whooping Cough

WORDS TO KNOW Pertussis: The medical name for whooping cough. Petechiae: Tiny reddish or purplish spots in the skin caused by the breaking of small

blood vessels during intense coughing or vomiting. Phlegm: Thick mucus secreted in the throat and lungs during an upper respiratory infection.

Vaccines licensed for use in the United States must go through a three-stage process of clinical trials that often takes ten years or even longer before the new vaccine is approved. A newer form of the diphtheria/tetanus/pertussis vaccine was developed in 1991 and replaced the older vaccine completely by 2002. It is reported to have lowered the rate of side effects from vaccination in the United States by 90 percent. SEE ALSO

Common cold; Tetanus


Laskey, Elizabeth. Whooping Cough. Chicago, IL: Heinemann Library, 2003. PE R I O DI C A L S

Allen, Arthur. “Bucking the Herd.” Atlantic Monthly, September 2002. Available online at http://www.theatlantic.com/doc/200209/allen_a (accessed April 22, 2008). This is an article about the reappearance of whooping cough in Colorado as the result of parents’ opposition to vaccination. American Academy of Family Physicians (AAFP). “Whooping Cough: What You Should Know.” American Family Physician 74 (August 1, 2006): 427. Available online at http://www.aafp.org/afp/20060801/427ph.html (accessed April 22, 2008). WE B S IT E S

Centers for Disease Control and Prevention (CDC). History of Vaccine Safety. Available online at http://www.cdc.gov/vaccinesafety/basic/history.htm (updated February 26, 2008; accessed April 22, 2008). Centers for Disease Control and Prevention (CDC) Fact Sheet. Pertussis. Available online at http://www.cdc.gov/ncidod/dbmd/diseaseinfo/pertus sis_t.htm (updated October 13, 2005; accessed April 22, 2008). National Network for Immunization Information Fact Sheet. Important Facts for Parents to Know about the DTaP Vaccine. Available online in PDF format at http://www.immunizationinfo.org/assets/files/pdfs/2_DTAP_facts.pdf (updated October 2000; accessed April 21, 2008). Nemours Foundation. Whooping Cough (Pertussis). Available online at http:// www.kidshealth.org/parent/infections/lung/whooping_cough.html (updated December 2005; accessed April 22, 2008). 1190


X

Xeroderma Pigmentosum Definition Xeroderma pigmentosum, or XP, is a rare condition in which skin cells are not able to repair damage caused by exposure to the ultraviolet portion of sunlight. It was first described in 1874 by two Austrian dermatologists, Ferdinand von Hebra (1816–1880) and Moritz Kaposi (1837–1902). Dr. Kaposi gave the disorder its name, which means “dry discolored skin,” in 1882. XP was not understood to be caused by genetic mutations until 1968, however.

Also Known As XP Cause Defects in several genes Symptoms Sunburn after minimal sun exposure; dry, thin skin; discolored patches of skin; eye problems Duration Lifelong

Description Xeroderma pigmentosum is a rare skin disorder caused by mutations in any of eight different genes that govern the ability of skin cells to repair damage to DNA (the genetic material inside a cell) caused by exposure to sunlight. In a normal person, exposure to the ultraviolet radiation in sunlight causes damage to the DNA of the cells in the upper layer of the skin. This damage is fixed by a mechanism known as nucleotide excision repair, or NER. In patients with XP, however, the enzymes that carry out NER are either reduced in effectiveness or missing entirely. When the damage to the cell’s DNA cannot be repaired, the DNA itself may mutate, leading to the death of skin cells or to skin cancer. The average child with XP develops the first signs of skin cancer around age eight. 1191

Xeroderma Pigmentosum This student with xeroderma pigmentosum has gym classes in the auditorium of her local school because she cannot be exposed to sunlight. AP IMAGES.

Xeroderma pigmentosa progresses in three stages: • Stage 1. The child’s skin is healthy at birth but around six months of age the skin develops reddish, scaly patches with heavy freckling or sunburn after even short exposure to sunlight. At first only the 1192


Xeroderma Pigmentosum

face and other areas exposed to direct sun are affected, but gradually the skin changes appear on the neck, lower legs, and even the chest. • Stage 2. The skin develops irregular patches of lightened or darkened skin with spidery patterns of blood vessels appearing underneath. The skin also becomes much thinner. • Stage 3. This stage begins when the child is four to five years old. Skin cancers and scaly patches known as solar keratoses appear. About 80 percent of patients with XP develop eye problems related to sun exposure. The eyes may become bloodshot and painfully sensitive to light. Both cancerous and noncancerous growths may appear near the eyes. In a few cases the eyelids may shrink or even disappear entirely. Between 20 and 30 percent of patients with XP develop symptoms affecting the nervous system in late childhood or early adolescence. These symptoms range from the loss of tendon reflexes and poor coordination to hearing loss and mental retardation. The child’s growth may also slow down. These neurologic symptoms tend to get worse over time.

Demographics

A Very Special Summer Camp In 1996 the parents of a child with xeroderma pigmentosum had the idea of creating a nighttime camp for patients with XP that would allow them to enjoy the typical activities of a summer camp experience but without the dangers of exposure to sunlight. By 2005 the couple was able to open a permanent retreat house for Camp Sundown, as they named it, in Craryville, New York. The camp’s sessions in recent years include a retreat for family members combined with a medical conference that brings researchers from around the world to the camp to share new information with the families and to offer support for living with the limitations that the disorder imposes on family members. The campers themselves enjoy outdoor sports under artificial lights after dark, including an adventure course. Camp Sundown provides lodging, meals, and supplies to each camper and one family member completely free of charge. Other family members are charged only nominal fees for staying at the camp. In 2007 the camp ran six sessions through the summer and into October, including one week just for teens. Any person or organization can sponsor a camper for one full session with a donation of $350. That sum offsets the cost of the camper’s food, utilities, activities, insurance and transportation.

The frequency of xeroderma pigmentosum varies from country to country. In the United States, it is estimated to affect between one person in 250,000 and one in 1,000,000. In Japan, however, XP is much more common, striking one person in every 22,000. It is also more common in the Middle East and North Africa than in Europe or North America. The reason for these geographical differences is not yet known for certain but is thought to be associated with the high rates of marriages within extended families in some of these countries. UXL Encyclopedia of Diseases and Disorders

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In all countries, XP affects men and women equally. Within the United States, it affects all races and ethnic groups equally.

Causes and Symptoms The cause of xeroderma pigmentosum is a mutation in any of eight genes (on eight different chromosomes) known to affect the production of the enzymes responsible for the repair of DNA in sunlight-damaged skin cells. There are eight subtypes of XP that vary somewhat in the severity of symptoms depending on which of the eight genes has been affected by a mutation. The most common subtype, known as XPA, is also the type most likely to be associated with neurologic symptoms. A child must inherit a defective gene from both parents in order to develop XP. A person who has only one copy of the gene mutation is called a carrier. When both parents are carriers of a recessive gene mutation, there is a 25 percent chance that a child will inherit two mutations and develop XP. In addition to the symptoms that have already been described, children with xeroderma pigmentosum may also have: • • • • •

Raw patches of broken skin oozing tissue fluid Premature aging of the lips, eyes, mouth, and tongue Cancer developing on the tip of the tongue Limited growth of body hair on the chest and legs Increased vulnerability to infectious diseases

Diagnosis The diagnosis of xeroderma pigmentosa is usually made during the baby’s first or second year of life, often following a history of severe and long-lasting sunburn following only brief exposure to sunlight, or heavy freckling on the baby’s face. There is usually no family history of the disorder. The doctor will, however, ask the parents about a family history of intermarriage among relatives in the extended families on both sides, as kinship marriages are a risk factor for genetic disorders. The doctor will examine the baby for signs of eye problems, including clouding of the cornea (the transparent covering of the front of the eyeball that admits light) and skin tumors growing near the eyes. The baby’s reflexes and coordination may also be tested. The diagnosis of XP can be confirmed by genetic testing or by tests on skin cells that 1194



evaluate whether the cells are unusually sensitive to ultraviolet light. These tests can be performed only in highly specialized laboratories, however. XP can be diagnosed before birth by amniocentesis or by chorionic villus sampling (CVS). CVS is a test in which the doctor takes a small sample of tissue from the placenta, the organ that forms inside the uterus during pregnancy and links the mother’s blood supply with the baby’s blood supply. The tissue sample can then be analyzed for evidence of a genetic disorder.

Treatment There is no cure for xeroderma pigmentosum. In addition, any damage that occurs to the skin from sun exposure is permanent and irreversible. The main goals of treatment are therefore to protect the patient from sun exposure and monitor the development of symptoms affecting the eyes and nervous system. Avoiding sun exposure includes: • Wearing protective clothing (long-sleeved shirts and full-length pants, shirts with collars, tightly-woven fabrics that don’t let light through); wide-brimmed hats; and eyewear specifically made to screen out ultraviolet rays. • Applying sunscreens of SPF 30 or higher to all exposed areas of skin. • Avoiding going outdoors during daylight hours as much as possible. • Limiting outdoor activities to nighttime only. • Avoiding the use of halogen or fluorescent bulbs indoors; these give off enough ultraviolet radiation to affect people with XP. • Applying special film that blocks ultraviolet rays to house and car windows. Monitoring patients with xeroderma pigmentosum includes: • Regular visits to a dermatologist—at least every three to five months—to check for changes in the skin or early signs of skin cancer. • Yearly testing of the patient’s nervous system. • Frequent visits to an ophthalmologist (eye specialist) to check for clouding of the cornea, tumors near the eye, or other problems. Skin cancers are usually removed by surgery as soon as they appear. Solar keratoses are treated with a cream containing a drug called 5-fluorouracil. UXL Encyclopedia of Diseases and Disorders

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Prognosis The prognosis of xeroderma pigmentosum depends on the subtype that the patient belongs to; however, all patients with XP have over a thousand times greater risk of developing skin cancer than people without the disorder. Those with subtype XPA typically develop skin cancer before they are ten years old. Only 40 percent of people with XP live into their twenties. A small percentage of patients with milder symptoms live into middle age. In general, XP reduces a patient’s life expectancy by at least thirty years.

Prevention Parents of a child with XP have a 25 percent chance of having another child with the disorder in later pregnancies. They should consult a genetic counselor before considering having other children. In addition, people who have a relative with XP should consider having a genetic test before starting a family.

The Future Researchers are trying to better understand the gene mutations responsible for XP and to see whether there are any other genes associated with the condition that have not yet been identified. Treatments being investigated in 2008 included the use of a drug called isotretinoin in preventing skin cancer in patients with XP and a lotion called T4N5 liposome lotion in protecting against skin damage caused by ultraviolet radiation. SEE ALSO

Skin cancer; Sunburn

For more information PE R I O DI C A L S

Foderaro, Lisa J. “Hudson Journal: Where Daylight’s a Risk, Dark Is a Time to Shine.” New York Times, July 21, 2002. Available online at http://query. nytimes.com/gst/fullpage.html?res=9C01E1D91638F932A15754 C0A9649C8B63&sec=&spon=&pagewanted=all (accessed August 7, 2008). This news report is about Camp Sundown, a special outdoor camp in upstate New York for people with XP. WE B S IT E S

Cancer Net. Xeroderma Pigmentosum. Available online at http://www.cancer.net/ patient/Cancer+Types/Xeroderma+Pigmentosa#mainContent%20idmain% Content (updated October 2006; accessed August 7, 2008). 1196



WORDS TO KNOW Chorionic villus sampling (CVS): A prenatal test that involves taking a small sample of the placenta, the organ that forms inside the uterus during pregnancy and supplies the baby with oxygen and nutrients carried by the blood. Dermatologist: A doctor who specializes in diagnosing and treating skin disorders.

Neurologic: Pertaining to the nervous system. Nucleotide excision repair (NER): A mechanism that allows cells to remove damage caused by ultraviolet light to the cell’s DNA. Solar keratoses (singular, keratosis): Rough scaly patches that appear on sun-damaged skin. They are considered precancerous.

DermNet NZ. Xeroderma Pigmentosum. Available online at http://dermnetnz. org/systemic/xeroderma-pigmentosum.html (updated March 18, 2008; accessed August 7, 2008). National Organization for Rare Disorders (NORD). Xeroderma Pigmentosum. Available online at http://www.rarediseases.org/search/rdbdetail_abstract. html?disname=Xeroderma%20Pigmentosum (accessed August 7, 2008). Sloan Science and Film. XP. Available online at http://www.scienceandfilm.org/ films.php?film_id=18 (film made in 2002; accessed August 7, 2008). This 11-minute movie was made by David Barba about a young boy with XP. Barba was moved to make the short movie after reading an article about children with XP. Xeroderma Pigmentosum Society (XPS). XPS Tips for Students. Available online at http://www.xps.org/student_tips.htm (accessed August 7, 2008).


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Z

Zoonoses Zoonoses (singular, zoonosis) are infectious diseases that can be transmitted from wild or domestic animals to humans. Some zoonoses can also be transmitted from humans to other animals. The disease agents that can cause zoonoses include prions (abnormal proteins), bacteria, viruses, fungi, and parasites. A wide variety of animals can serve as vectors, or carriers, of zoonoses. Wild animals and insects that can spread zoonoses include bats, birds, chimpanzees, fleas, flies, mosquitoes, mice and rats, monkeys, opossums, rabbits, snails, and ticks. Domestic and farm animals that can transmit zoonoses include cats, dogs, cattle, goats, horses, pigs, and sheep. Animals can transmit zoonoses through biting humans (plague, Lyme disease, rabies), leaving droppings that contain the disease organism (hantavirus infection, toxoplasmosis), or harboring the organism in their tissues or hair (anthrax). Zoonoses range from mild diseases like cat scratch fever and cowpox to highly fatal illnesses like Ebola and Marburg hemorrhagic fevers. Some zoonoses, like rabies, appear as isolated cases in humans, while others, like AIDS and plague, can spread directly from one human to another and cause worldwide epidemics. Some doctors think that many diseases that are now spread directly among humans, like measles, tuberculosis, influenza, and the common cold, may have started out as zoonoses thousands of years ago. 1199

Zoonoses SEE ALSO

AIDS; Anthrax; Avian influenza; Creutzfeldt-Jakob disease; Ebola and Marburg hemorrhagic fevers; Hantavirus infection; Lyme disease; Plague; Rabies; Toxoplasmosis; West Nile virus infection

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Where to Learn More

Books Abramovitz, Melissa. Lupus. Detroit, MI: Lucent Books, 2008. American Cancer Society (ACS). Quick Facts Lung Cancer: What You Need to Know—Now / from the Experts at the American Cancer Society. Atlanta, GA: American Cancer Society, 2007. Bernard, Amy B. West Nile Virus. Brockton, MA: Western Schools, 2005. Bloom, Ona, and Jennifer Morgan. Encephalitis. Philadelphia: Chelsea House Publishers, 2006. Currie-McGhee, Leanne K. AIDS. Detroit, MI: Lucent Books, 2009. Davidson, Tish. Influenza. San Diego, CA: Lucent Books, 2006. Decker, Janet, and Alan Hecht. Anthrax, 2nd ed. New York: Chelsea House, 2008. Germ Wars: Battling Killer Bacteria and Microbes. New York: Rosen Publishing Group, 2008. Goldsmith, Connie. Meningitis. Minneapolis, MN: Twenty-First Century Books, 2008. Jones, Phill. Sickle Cell Disease. New York: Chelsea House, 2008. Kiesbye, Stefan, ed. Teen Smoking. Detroit, MI: Greenhaven Press, 2008. Marcovitz, Hal. Infectious Mononucleosis. Detroit, MI: Lucent Books, 2008. Marcus, Bernard A. Malaria. Philadelphia: Chelsea House Publishers, 2004. Marr, Lisa. Sexually Transmitted Diseases: A Physician Tells You What You Need to Know, 2nd ed. Baltimore, MD: Johns Hopkins University Press, 2007. Michaud, Christopher. Gonorrhea. New York: Rosen Publishing Group, 2007. Nardo, Don. Human Papillomavirus (HPV). Detroit, MI: Lucent Books, 2007. Peirce, Jeremy. Attention-Deficit/Hyperactivity Disorder. New York: Chelsea House, 2008. lxiii

Where to Learn More

Raabe, Michelle. Hemophilia. New York: Chelsea House, 2008. Saffer, Barbara. Measles and Rubella. Detroit: Lucent Books, 2006. Sheen, Barbara. Allergies. Detroit: Lucent Books, 2008. Sheen, Barbara. Food Poisoning. Detroit, MI: Lucent Books, 2005. Sheen, Barbara. Toxic Shock Syndrome. San Diego, CA: Lucent Books, 2006. Sherman, Irwin W. Twelve Diseases That Changed Our World. Washington, DC: ASM Press, 2007. So, Po-Lin. Skin Cancer. New York: Chelsea House, 2008. Stewart, Gail B. Fetal Alcohol Syndrome. Detroit, MI: Lucent Books, 2005. Winheld, Josh. Worth the Ride: My Journey with Duchenne Muscular Dystrophy. Beach Haven, NJ: Little Treasure Books, 2008. Wyborny, Sheila. Alcoholism. Detroit, MI: Lucent Books, 2008. Web Sites Alliance for a Healthier Generation. Healthy Schools Program. http://www. healthiergeneration.org/schools.aspx (accessed December 15, 2008). Alzheimer’s Association. Just for Kids & Teens. http://www.alz.org/living_ with_alzheimers_just_for_kids_and_teens.asp (accessed December 15, 2008). American Cancer Society. Learn About Cancer. http://www.cancer.org/docroot/ LRN/lrn_0.asp (accessed December 15, 2008). American Hearth Association. For Kids. http://www.americanheart.org/ presenter.jhtml?identifier=3028650 (accessed December 15, 2008). American Lung Association. Sudden Infant Death Syndrome Fact Sheet (SIDS). http://www.lungusa.org/site/apps/nlnet/content3.aspx?c=dvLUK9O0E &b=2060727&content_id={DD8EAC73-1371-4129-9D82-0220D 296D5E9}¬oc=1 (accessed December 15, 2008). Asthma Society of Canada. About Asthma. http://www.asthma.ca/adults/about/ (accessed December 15, 2008). Centers for Disease Control and Prevention. BAM! Body and Mind. http://www. bam.gov/ (accessed December 15, 2008). Centers for Disease Control and Prevention. Rabies. http://www.cdc.gov/ ncidod/dvrd/kidsrabies/ (accessed December 15, 2008). KidsHealth, The Nemours Foundation. About Sexually Transmitted Diseases (STDs). http://kidshealth.org/teen/sexual_health/stds/std.html (accessed December 15, 2008). KidsHealth, The Nemours Foundation. Diseases and Conditions. http://kids health.org/teen/diseases_conditions/ (accessed December 15, 2008). KidsHealth, The Nemours Foundation. Everyday Illnesses and Injuries. http:// kidshealth.org/kid/ill_injure/index.html (accessed December 15, 2008). lxiv


Where to Learn More

KidsHealth, The Nemours Foundation. Health Problems of Grown-Ups. http:// kidshealth.org/kid/grownup/index.html (accessed December 15, 2008). KidsHealth, The Nemours Foundation. Kids’s Health Problems. http://kids health.org/kid/health_problems/index.html (accessed December 15, 2008). MedlinePlus. Infectious Diseases. http://www.nlm.nih.gov/medlineplus/infectious diseases.html (accessed December 15, 2008). MedlinePlus. Obesity in Children. http://www.nlm.nih.gov/medlineplus/obesity inchildren.html (accessed December 15, 2008). MedlinePlus. Severe Acute Respiratory Syndrome (SARS). http://www.nlm.nih. gov/medlineplus/severeacuterespiratorysyndrome.html (accessed December 15, 2008). National Center for Chronic Disease Prevention and Health Promotion Diabetes Public Health Resource: The Eagle’s Nest. http://www.cdc.gov/diabetes/eagle/ (accessed December 15, 2008). National Institute of Arthritis and Musculoskeletal and Skin Diseases. Arthritis. http://www.niams.nih.gov/Health_Info/Arthritis/arthritis_rheumatic_qa. asp (accessed December 15, 2008). Office on Women’s Health, U.S. Department of Health and Human Services. girlshealth.gov. http://www.girlshealth.gov/index.cfm (accessed December 15, 2008). Providence Health and Services. Childhood Diseases. http://www.providence.org/ healthlibrary/contentViewer.aspx?hwid=hn-3564009&serviceArea= generic (accessed December 15, 2008). U.S. Food and Drug Administration. Health Information for Teens. http://www. fda.gov/oc/opacom/kids/html/7teens.htm (accessed December 15, 2008). U.S. Food and Drug Administration. Preventing Tick-borne Disease. http://www. fda.gov/fdac/features/696_flea.html#prevent (accessed December 15, 2008).


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List of Organizations

Academy for Eating Disorders

111 Deer Lake Rd., Ste. 100 Deerfield, IL 60015 Phone: (847) 498-4274 Fax: (847) 480-9282 E-mail: [email protected] Internet: http://www.aedweb.org/ American Academy of Child and Adolescent Psychiatry

3615 Wisconsin Ave. NW Washington, DC 20016-3007 Phone: (202) 966-7300 Fax: (202) 966-2891 Internet: http://www.aacap.org/ American Academy of Pediatrics

141 Northwest Point Blvd. Elk Grove Village, IL 60007-1098 Phone: (847) 434-4000 Fax: (847) 434-8000 E-mail: [email protected] Internet: http://www.aap.org/ Alzheimer's Association

225 N. Michigan Ave., 17th Floor Chicago, IL 60601-7633 Phone: (312) 335-8700 Fax: (866) 699-1246

E-mail: [email protected] Internet: http://www.alz.org/ American Academy of Sleep Medicine

One Westbrook Corporate Center, Ste. 920 Westchester, IL 60154 Phone: (708) 492-0930 Fax: (708) 492-0943 Internet: http://www.aasmnet.org/ American Cancer Society

1599 Clifton Rd. NE Atlanta, GA 30329 Phone: (800) ACS-2345 Internet: http://www.cancer.org/ American Diabetes Association

1701 N. Beauregard St. Alexandria, VA 22311 Phone: (800) 342-2383 E-mail: [email protected] Internet: http://www.diabetes.org/ American Foundation for AIDS Research

120 Wall St., 13th Fl. New York, NY 10005-3908 Phone: (212) 806-1600 Fax: (212) 806-1601 Internet: http://www.amfar.org/ lxvii


American Heart Association

7272 Greenville Ave. Dallas, TX 75231 Phone: (800) 242-8721 Internet: http://www.americanheart.org/ American Lung Association

61 Broadway, 6th Fl. New York, NY 10006 Phone: (212) 315-8700 Phone: (800) 586-4872 Internet: http://www.lungusa.org/ American Medical Association

515 N. State St. Chicago, IL 60610 Phone: (800) 621-8335 Internet: http://www.ama-assn.org/ American Obesity Association

8630 Fenton St., Ste. 814 Silver Spring, MD 20910 Phone: (301) 563-6526 Fax: (301) 563-6595 Internet: http://www.obesity.org/ American Parkinson Disease Association

135 Parkinson Ave. Staten Island, NY 10305 Phone: (718) 981-8001 Phone: (800) 223-2732 Fax: (718) 981-4399 E-mail: [email protected] Internet: http://www.apdaparkinson.org/ Arthritis Foundation

PO Box 7669 Atlanta, GA 30357-0669 Phone: (800) 283-7800 Internet: http://www.arthritis.org/ Autism Society of America

7910 Woodmont Ave., Ste. 300 Bethesda, MD 20814-3067 Phone: (301) 657-0881 lxviii

Phone: (800) 328-8476 Internet: http://www.autism-society.org/ Centers for Disease Control and Prevention (CDC)

1600 Clifton Rd. Atlanta, GA 30333 Phone: (800) 232-4636 Internet: http://www.cdc.gov/ Cystic Fibrosis Foundation

6931 Arlington Rd. Bethesda, MD 20814 Phone: (301) 951-4422 Phone: (800) 344-4823 Fax: (301) 951-6378 E-mail: [email protected] Internet: http://www.cff.org/ Epilepsy Foundation

8301 Professional Place Landover, MD 20785 Phone: (800) 332-1000 Internet: http://www.epilepsyfoundation. org/ Huntington's Disease Society of America

505 Eighth Ave., Ste. 902 New York, NY 10018 Phone: (212) 242-1968 Fax: (212) 239-3430 E-mail: [email protected] Internet: http://www.hdsa.org/ March of Dimes Birth Defects Foundation

1275 Mamaroneck Ave. White Plains, NY 10605 Phone: (914) 997-4488 Internet: http://www.modimes.org/ Muscular Dystrophy Association–USA

National Headquarters 3300 E. Sunrise Dr. Tucson, AZ 85718 Phone: (800) 572-1717



E-mail: [email protected] Internet: http://www.mdausa.org/ National Center for Complementary and Alternative Medicine

9000 Rockville Pike Bethesda, MD 20892 Phone: (301) 519-3153 Phone: (888) 644-6226 Fax: (866) 464-3616 E-mail: [email protected] Internet: http://www.nccam.nih.gov/ National Diabetes Information Clearinghouse

1 Information Way Bethesda, MD 20892-3560 Phone: (800) 860-8747 Fax: (703) 738-4929 E-mail: [email protected] Internet: http://diabetes.niddk.nih.gov/ National Digestive Diseases Information Clearinghouse

2 Information Way Bethesda, MD 20892-3570 Phone: (800) 891-5389 Fax: (703) 738-4929 E-mail: [email protected] Internet: http://digestive.niddk.nih.gov/ about/ National Down Syndrome Society

666 Broadway, 8th Fl. New York, NY 10012 Phone: (800) 221-4602 E-mail: [email protected] Internet: http://www.ndss.org/ National Eating Disorders Association

603 Stewart St., Ste. 803 Seattle, WA 98101 Phone: (206) 382-3587 Phone: (800) 931-2237 Fax: (206) 829-8501 UXL Encyclopedia of Diseases and Disorders

E-mail: [email protected] Internet: http://www.nationaleating disorders.org/ National Fibromyalgia Association

2121 S. Towne Centre Place, Ste. 300 Anaheim, CA 92806 Phone: (714) 921-0150 Internet: http://www.fmaware.org/ National Heart, Lung, and Blood Institute Health Information Center

PO Box 30105 Bethesda, MD 20824-0105 Phone: (301) 592-8573 Fax: (240) 629-3246 E-mail: [email protected] Internet: http://www.nhlbi.nih.gov/ National Hemophilia Foundation

116 W. 32nd St., 11 Fl. New York, NY 10001 Phone: (212) 328-3700 Phone: (800) 424-2634 Fax: (212) 328-3777 E-mail: [email protected] Internet: http://www.hemophilia.org/ National Institute of Allergy and Infectious Diseases

6610 Rockledge Dr., MSC 6612 Bethesda, MD 20892-6612 Phone: (301) 496-5717 Phone: (866) 284-4107 Fax: (301) 402-3573 Internet: http://www.niaid.nih.gov/ National Institute of Diabetes and Digestive and Kidney Diseases

Bldg. 31, Rm. 9A04, 31 Center Dr., MSC 2560 Bethesda, MD 20892-2560 Phone: (301) 496-3583 Internet: http://www.niddk.nih.gov/ lxix


National Multiple Sclerosis Society

733 Third Ave. New York, NY 10017 Phone: (212) 986-3240 Phone: (800) 344-4867 Internet: http://www.nmss.org/ National Osteoporosis Foundation

1232 Twenty-second St. NW Washington, DC 20037-1202 Phone: (202) 223-2226 Phone: (800) 231-4222 Internet: http://www.nof.org/ Sickle Cell Disease Association of America

231 E. Baltimore St., Ste. 800

lxx

Baltimore, MD 21202 Phone: (410) 528-1555 Phone: (800) 421-8453 Fax: (410) 528-1495 E-mail: [email protected] Internet: http://www.sicklecelldisease.org/ World Health Organization

Avenue Appia 20 Geneva 27, 1211 Switzerland Phone: (011-41-22) 791-2111 Fax: (011-41-22) 791-3111 E-mail: [email protected] Internet: http://www.who.int


Index Note: Bold page numbers indicate main essays. Italic page numbers indicate figures.

Abusive head trauma. See Shaken baby syndrome ACE inhibitors, 2:261, 3:497, 587 Achondroplasia, 1:1–6 causes and symptoms, 1:1, 2 definition, 1:1 demographics, 1:1–2 description, 1:1 diagnosis, 1:2, 3 the future, 1:5 gene mutation, 1:1, 2, 4–5 hydrocephalus, 1:4 Little People of America (LPA), 1:3, 4 prevention, 1:4–5 prognosis, 1:4 treatment, 1:4 Acid reflux. See Gastroesophageal reflux disease Acne, 1:6–12 Accutane, 1:10 causes and symptoms, 1:6, 7–8 comedones, 1:7, 11 definition, 1:6 demographics, 1:7 description, 1:6–7 diagnosis, 1:8, 9 the future, 1:10 hair follicle irritation, 1:6–7, 7, 8 prevention, 1:10 prognosis, 1:10 Propionibacterium acnes, 1:8, 10

sebum, 1:6–7, 8, 9–10, 11 treatment, 1:9–10 Acquired immunodeficiency syndrome. See AIDS Acromegaly. See Gigantism Acute gastroenteritis. See Food poisoning Acute noninflammatory encephalopathy. See Reye syndrome Acute viral nasopharyngitis. See Common cold ADD. See Attention-deficit hyperactivity disorder ADHD. See Attention-deficit hyperactivity disorder AIDS, 1:12–19 causes and symptoms, 1:12, 15 definition, 1:12 demographics, 1:12, 13–14 description, 1:12–13 diagnosis, 1:15–16 the future, 1:17–18 and hemophilia, 3:517, 519 highly active antiretroviral therapy (HAART), 1:16–17, 18 infection of hemophilia patients from contaminated blood, 3:517 Kaposi sarcoma, 1:13, 15 and medical marijuana, 4:713 opportunistic infections, 1:12, 15, 18 pandemic, 1:12, 13, 18 Pneumocystis carinii pneumonia, 1:15, 4:833 prevention, 1:17 prognosis, 1:17 toxoplasmosis, 1:15, 5:1117, 1118, 1120 treatment, 1:16–17 lxxi

Index

viral load, 1:16, 18 window period, 1:16, 18 Airsickness. See Motion sickness Alcohol abuse. See Alcoholism Alcohol dependence. See Alcoholism Alcohol in pregnancy. See Fetal alcohol syndrome Alcoholism, 1:19–26 alcohol abuse, 1:19 Alcohol Use Disorders Identification Test (AUDIT) questionnaire, 1:21, 23 binge drinking, 1:19 blackouts, 1:23, 26 CAGE questionnaire, 1:21, 23 causes and symptoms, 1:19, 22–23 definition, 1:19 delirium tremens (DTs), 1:24, 26 demographics, 1:22 description, 1:20–21 detoxification (detox), 1:24, 26 diagnosis, 1:21, 23–24 fibrosis in the liver, 1:20 the future, 1:25 intervention, 1:24 medications, 1:24 prevention, 1:25 prognosis, 1:25 rehabilitation, 1:24 treatment, 1:24–25 Alexander the Great, 5:1176, 1176 Allen, Sandy, 2:423 Allergic rhinitis. See Hay fever Allergies, 1:26–32 causes and symptoms, 1:26, 28–29 contact dermatitis, 1:28 definition, 1:26 demographics, 1:28 description, 1:26–28 diagnosis, 1:27, 29 food allergies, 1:28, 30, 146, 3:643 the future, 1:30–31 histamine release, 1:27 immunoglobulin E (IgE) antibodies, 1:26, 27, 29, 31 prevention, 1:30 prognosis, 1:30 lxxii

radioallergosorbent test (RAST), 1:29 treatment, 1:28, 29–30 Allergy shots, 3:469–470, 471 Alzheimer disease, 1:32–39 causes and symptoms, 1:32, 34 concussion, 2:235, 237 definition, 1:32 demographics, 1:33–34 description, 1:32–33, 33 diagnosis, 1:36 Down syndrome, 2:314 early-onset (familial) Alzheimer disease, 1:33, 34–35 famous people affected, 1:34 the future, 1:37–38 prevention, 1:37 prognosis, 1:37 stages of disease, 1:35 treatment, 1:36 Amblyopia, 3:581, 582, 5:1034, 1036, 1038 Amenorrhea, 1:48, 50 Anabolic steroids. See Steroid use Anaphylactic shock. See Anaphylaxis Anaphylaxis, 1:39–45 angioedema, 1:42, 44 causes and symptoms, 1:28, 39, 41–42 definition, 1:31, 39 demographics, 1:28, 41 description, 1:39–41 diagnosis, 1:42 EpiPen, 1:40, 41, 43 first aid, 1:41 the future, 1:43 histamine release, 1:39, 41–42 immunoglobulin E (IgE) antibodies, 1:39 prevention, 1:43 prognosis, 1:43 treatment, 1:29, 40, 41, 42–43 triggers, 1:40–41 André the Giant (Roussimoff, André), 2:424, 424 Anemias, 1:45, 3:624 See also specific diseases Aneurysms, 3:585, 589, 4:707, 709, 5:1053, 1054, 1056 Angioedema, 1:42, 44, 3:539, 541, 542, 543 UXL Encyclopedia of Diseases and Disorders

Index

Anorexia, 1:46–51 amenorrhea, 1:48, 50 and athletes, 1:48 causes and symptoms, 1:46, 47–48 cognitive behavioral therapy (CBT), 1:49, 50 definition, 1:46 demographics, 1:46–47 description, 1:46 diagnosis, 1:48–49 distorted body image, 1:46, 47, 48, 2:332 diuretics abuse, 1:46, 50 the future, 1:50 prevention, 1:49–50 prognosis, 1:49 treatment, 1:49 Anorexia nervosa. See Anorexia Anthrax, 1:51–57 Bacillus anthracis, 1:51, 54, 55 causes and symptoms, 1:52, 54, 5:1199 cutaneous (skin-related) anthrax, 1:52, 52, 54 definition, 1:51–52 demographics, 1:53–54 description, 1:52–53 diagnosis, 1:55 the future, 1:56 gastrointestinal anthrax, 1:52, 54 inhalation anthrax, 1:52–53, 54 mailings of anthrax spores in 2001, 1:53 prevention, 1:55, 56 prognosis, 1:52–53, 55 treatment, 1:55 vaccine, 1:56 Anxiety. See Stress Anxiety disorder. See Panic disorder Aortic stenosis, 2:241, 243 Aphthous stomatitis. See Canker sores Aphthous ulcers. See Canker sores Apoplexy. See Stroke Appendicitis, 1:58–63 appendectomy, 1:60, 61–62 causes and symptoms, 1:59–60 Crohn disease, 1:59, 60 definition, 1:58 demographics, 1:58–59 description, 1:58, 59 UXL Encyclopedia of Diseases and Disorders

diagnosis, 1:60–61 the future, 1:62–63 guarding, 1:61, 62 peritonitis, 1:58, 62 prevention, 1:62 prognosis, 1:62 rebound tenderness, 1:60, 62 treatment, 1:60, 61–62 wartime appendectomy on a submarine, 1:60 Arthritis, 1:63–64 See also Osteoarthritis; Rheumatoid arthritis Asperger, Hans, 1:66, 90 Asperger syndrome, 1:64–69 autistic rights or autistic pride community, 1:68–69 causes and symptoms, 1:64, 66–67 definition, 1:64 demographics, 1:65, 96 description, 1:64–65 diagnosis, 1:67 the future, 1:68–69 Morris, Craig, 1:65 as pervasive developmental disorder, 1:64 prevention, 1:68 prognosis, 1:68 as spectrum disorder, 1:95–96 treatment, 1:67–68 Asthma, 1:70–77 athletes with asthma, 1:72 bronchial challenge test, 1:74 categories of severity, 1:70 causes and symptoms, 1:70, 72–73 definition, 1:70 demographics, 1:28, 70–72 description, 1:70 diagnosis, 1:73–74 the future, 1:75 long-term medications, 1:74 peak flow meters, 1:74, 76 prevention, 1:75 prognosis, 1:75 quick-relief or rescue medications, 1:74 spirometry, 1:74, 76 treatment, 1:71, 74 triggers, 1:73 lxxiii

Index

Astigmatism, 1:77–82 against-the-rule astigmatism, 1:77, 80, 81 causes and symptoms, 1:77, 78 compound myopic astigmatism, 1:78 contact lenses, 1:79, 80 corneal topography, 1:79 corrective lenses, 1:78, 80 definition, 1:77, 81 demographics, 1:77 description, 1:77, 5:1161 diagnosis, 1:78, 78–79 eyeglasses, 1:80, 4:752 the future, 1:81 keratoconus, 1:78, 81 keratometers, 1:79 laser surgery, 1:80 mixed astigmatism, 1:78 orthokeratology (Ortho-K), 1:80, 81 prevention, 1:81 prognosis, 1:80–81 simple astigmatism, 1:78 treatment, 1:78, 80 videokeratoscope, 1:79 with-the-rule astigmatism, 1:77, 81 Atopic dermatitis (AD). See Eczema Atrial septal defect (ASD), 2:241, 243 Attention-deficit hyperactivity disorder, 1:82–89 adult symptoms, 1:84 causes and symptoms, 1:82, 84–86 definition, 1:82–83 demographics, 1:84 description, 1:83 diagnosis, 1:86–87 the future, 1:88 hyperactive or impulsive ADHD, 1:84, 85–86 inattentive ADHD, 1:83, 85 prevention, 1:88 prognosis, 1:88 psychostimulants, 1:87, 88 treatment, 1:87 Wender Utah Rating Scale, 1:86–87 Autism, 1:89–95 autistic rights or autistic pride community, 1:68–69 causes and symptoms, 1:90, 91, 92–93 lxxiv

definition, 1:69, 89–90 demographics, 1:91, 96, 2:299 description, 1:90–91 diagnosis, 1:93 the future, 1:94 MMR vaccine, 1:92, 4:721–722 as pervasive developmental disorder, 1:89 prevention, 1:94 prognosis, 1:94 as spectrum disorder, 1:90, 95–96 treatment, 1:90, 93–94 Autism spectrum disorders, 1:95–96 definition, 1:90 demographics, 1:91, 96 description, 1:95–96 pervasive developmental disorder not otherwise specified (PDD-NOS), 1:96 treatment, 1:96 See also Asperger syndrome; Autism Autistic psychopathy. See Asperger syndrome Avian influenza, 1:96–101 avian influenza virus, 1:96–97, 97, 3:620 causes and symptoms, 1:96, 98 definition, 1:96–97 demographics, 1:97–98 description, 1:97 diagnosis, 1:98–99 the future, 1:100 H1N1 subtype of influenza A virus, 1:97 H5N1 subtype of influenza A virus, 1:97, 98, 99, 100 prevention, 1:99–100 prognosis, 1:99 treatment, 1:99 viral pneumonia, 1:97, 4:834

Balanchine, George, 2:266, 2:266 Banting, Frederick, 2:305 Bartholin-Patau syndrome. See Patau syndrome Barty, Billy, 1:3, 3 Basedow disease. See Graves disease Battered child syndrome. See Child abuse UXL Encyclopedia of Diseases and Disorders

Index

Bedsores, 2:403, 406, 409 See also Ulcers Best, Charles, 2:305 Beta blockers coronary artery disease, 2:261 heart attack, 3:489, 490 heart failure, 3:497 hypertension, 3:587 Marfan syndrome, 4:708, 709 Binge eating, 1:131, 2:332 Bipolar disorder, 1:103–109 bipolar disorder I (BPI), 1:103 bipolar disorder II (BPII), 1:103 causes and symptoms, 1:103, 106 cyclothymia, 1:103, 109 definition, 1:103 demographics, 1:105–106 depressive phase and depression, 1:103–105, 106, 108 description, 1:103–105 diagnosis, 1:107 electroconvulsive therapy (ECT), 1:108, 109 the future, 1:108 hypomania, 1:103, 109 manic phase and mania, 1:103–105, 106, 109 mixed state, 1:104, 109 prevention, 1:108 prognosis, 1:108 rapid cycling, 1:105, 109 scopolamine patch, 1:104 suicide, 1:104, 105, 106, 108 treatment, 1:104, 107–108 Bird flu. See Avian influenza Black death. See Plague Black, Francis, 4:719 Blackwater fever. See Malaria Bladder infection. See Urinary tract infections Bleeder’s disease. See Hemophilia Blemishes. See Acne Blood pressure. See Hypertension Body mass index (BMI), 1:185, 191, 4:769, 772, 773, 774 Bone marrow transplant (BMT), 5:955, 956 Boom. See Marijuana use Borreliosis. See Lyme disease UXL Encyclopedia of Diseases and Disorders

Brain cancers. See Brain tumors Brain tumors, 1:110–117 causes and symptoms, 1:110, 112–113 definition, 1:110 demographics, 1:112 description, 1:110–112 diagnosis, 1:111, 113–114, 3:479 the future, 1:115 gliomas, 1:110, 116 grading of tumors, 1:110–112 medulloblastomas, 1:112, 116 meningiomas, 1:110, 112, 116 prevention, 1:115 primary tumors, 1:110, 112–113, 115 prognosis, 1:115 secondary or metastatic tumors, 1:110, 112, 113, 114, 115 treatment, 1:114 Breast cancer, 1:117–124 biological therapy, 1:122 BRCA1 and BRCA2 genes, 1:119, 122 carcinoma in situ, 1:119, 121, 122, 123 causes and symptoms, 1:117, 120 chemotherapy, 1:122 definition, 1:117 demographics, 1:118–120 description, 1:117 diagnosis, 1:118, 120 ductal carcinoma, 1:117 the future, 1:123 genetic testing, 1:122 lobular carcinoma, 1:117, 122 lumpectomy, 1:121 mastectomy, 1:121, 122, 123 in men, 1:117, 119 prevention, 1:122–123 prognosis, 1:122 radiation therapy, 1:121 reconstruction, 1:121 stages and staging, 1:119, 120–121, 123 treatment, 1:120–122 Brittle bone syndrome. See Osteoporosis Broken bones. See Fractures Bronchitis, 1:124–130 acute bronchitis, 1:124–126, 126, 127–129 lxxv

Index

causes and symptoms, 1:124, 126, 127 chronic bronchitis, 1:124–125, 126, 127, 128–129 definition, 1:124 demographics, 1:126 description, 1:124–126 diagnosis, 1:125, 127 the future, 1:129 prevention, 1:128–129 prognosis, 1:128 smoking, 1:125, 128 treatment, 1:128 when to call the doctor, 1:126 Bronchogenic carcinoma. See Lung cancer Bronchopneumonia. See Pneumonia Bubonic plague. See Plague Bulimia, 1:130–135 binge eating, 1:131, 2:332 causes and symptoms, 1:130, 132–133 cognitive behavioral therapy (CBT), 1:133–135 definition, 1:130 demographics, 1:131–132 description, 1:130–131 diagnosis, 1:133 diuretic abuse, 1:130, 131, 133, 135 the future, 1:134 laxative abuse, 1:130–131 nonpurging subtype, 1:131 prevention, 1:134 prognosis, 1:134 purging, 1:131 treatment, 1:133–134 vomiting, 1:130–131, 132–133 Bulimia nervosa (BN). See Bulimia Burns, Robert, 3:668 Burns and scalds, 1:135–142 body surface area (BSA) estimates, 1:136, 139 causes and symptoms, 1:136, 138–139 chemical burns, 1:137 contact burns, 1:136 debridement, 1:140, 142 definition, 1:135–137 degrees of burns, 1:136, 137 demographics, 1:137–138 description, 1:137 diagnosis, 1:136, 139 lxxvi

electrical burns, 1:136 flame burns, 1:136 and frostbite, 1:137 the future, 1:141 prevention, 1:140–141 prognosis, 1:140 radiation burns, 1:137 rule of nines, 1:136, 139 and smoke inhalation, 1:137 thermal burns, 1:136–137 treatment, 1:139–140 Bush, Barbara, 2:442, 442 Bush, George H. W., 2:442, 442 Byron, George Gordon (Lord Byron), 1:210, 210

Caffey, John, 5:947, 950 CAGE questionnaire, 1:21, 23 Cancer, 1:143 Cancer of the blood. See Leukemia Cancer of the large bowel. See Colorectal cancer Cancer staging breast cancer, 1:119, 120–121, 123 lung cancer, 3:674–675 lymphoma, 3:693–694 prostate cancer, 4:868 Canker sores, 1:144–148 causes and symptoms, 1:144, 145–146 definition, 1:144 demographics, 1:144 description, 1:144 diagnosis, 1:145, 146 the future, 1:148 prevention, 1:147–148 prognosis, 1:146 treatment, 1:146–147 when to call the dentist, 1:146 See also Ulcers Cannabis. See Marijuana use Carbon monoxide poisoning, 1:149–154 causes and symptoms, 1:149, 151–152 definition, 1:149 demographics, 1:150–151 UXL Encyclopedia of Diseases and Disorders

Index

description, 1:149–150 diagnosis, 1:152 entry into bloodstream, 1:150, 151 the future, 1:153 hyperbaric oxygen (HBO) chambers, 1:152, 153 prevention, 1:151, 153 prognosis, 1:152–153 safety tips, 1:151 treatment, 1:152 typical levels of carbon monoxide, 1:150 Carbon monoxide toxicity. See Carbon monoxide poisoning Carcinoma of the breast. See Breast cancer Carcinoma of the skin. See Skin cancer Cardiac failure. See Heart failure Carsickness. See Motion sickness Cassatt, Mary, 1:157 Cataracts, 1:155–161 causes and symptoms, 1:155, 156–157 congenital cataracts, 1:155 cortical cataracts, 1:155 definition, 1:155, 5:1161 demographics, 1:156 description, 1:155 diagnosis, 1:156, 157–158 extracapsular surgery, 1:158 the future, 1:160 intraocular lens (IOL), 1:158 nuclear cataracts, 1:155 phacoemulsification, 1:158, 159 posterior capsular cataracts, 1:155 prevention, 1:159–160 prognosis, 1:159 secondary cataracts, 1:155 small incision surgery, 1:158 smoking, 1:156, 159 and sunburn, 5:1066, 1067 traumatic cataracts, 1:155 treatment, 1:157 Cavities. See Tooth decay Celiac disease, 1:161–166 anemia, 1:45 autoantibody tests, 1:164 causes and symptoms, 1:161, 162–164 definition, 1:161 UXL Encyclopedia of Diseases and Disorders

demographics, 1:162 description, 1:161–162 diagnosis, 1:164 Down syndrome, 1:162 the future, 1:165–166 gluten-free diet, 1:163, 165–166 prevention, 1:165 prognosis, 1:165 skin rash, 1:162, 163, 164 treatment, 1:163, 164–165 unresponsive celiac disease, 1:165 Celiac sprue. See Celiac disease Cephalagia. See Headache Cerebral palsy, 1:166–173 ataxic cerebral palsy, 1:167 athetoid (dyskinetic) cerebral palsy, 1:167 causes and symptoms, 1:167, 168–169 definition, 1:166 demographics, 1:167–168, 2:299 description, 1:167 diagnosis, 1:169–170 the future, 1:172 mixed cerebral palsy, 1:167 occupational therapy, 1:170 prevention, 1:171–172 prognosis, 1:171 rehabilitation and physical therapy, 1:170 scoliosis, 1:167, 172, 4:924 spastic cerebral palsy, 1:167 special education programs, 1:171 speech and language therapy, 1:171 treatment, 1:170–171 Cerebrovascular accident. See Stroke Cervical sprain. See Whiplash CF. See Cystic fibrosis Chickenpox, 1:173–178 acyclovir (Zovirax), 1:176, 177 causes and symptoms, 1:173, 175 definition, 1:173 demographics, 1:174–175 description, 1:173–174 diagnosis, 1:174, 176, 5:980–981 differences from smallpox, 5:980–981 the future, 1:177–178 history of name, 1:175 lxxvii

Index

prevention, 1:173, 177–178 prognosis, 1:177 treatment, 1:176 vaccine, 1:173, 177–178 varicella-zoster immune globulin (VZIG), 1:177 varicella-zoster virus (VZV), 1:173, 175 Child abuse, 1:179–185 causes and symptoms, 1:179, 181–182 definition, 1:179 demographics, 1:179, 180–181 description, 1:179–180 diagnosis, 1:182 emotional abuse, 1:179, 180 the future, 1:183–184 incest, 1:179, 184 neglect, 1:179, 184 physical abuse, 1:179, 180 prevention, 1:183 prognosis, 1:183 sexual abuse, 1:179 treatment, 1:183 Child maltreatment. See Child abuse Childhood obesity, 1:185–191 body mass index (BMI), 1:185, 191, 4:769, 772, 773, 774 causes and symptoms, 1:185, 187–188 definition, 1:185 demographics, 1:186–187 description, 1:186 diagnosis, 1:188 the future, 1:190 overweight vs. obesity, 1:185 prevention, 1:190 prognosis, 1:189–190 treatment, 1:186, 189 Childhood overweight. See Childhood obesity Children with special needs. See Developmental disability Chlamydia, 1:192–196 causes and symptoms, 1:192, 193–194 Chlamydia trachomatis, 1:192, 193 definition, 1:192, 2:256 demographics, 1:192–193 description, 1:192 diagnosis, 1:194 lxxviii

the future, 1:195–196 ophthalmia neonatorum, 2:252, 253, 255, 256 pelvic inflammatory disease (PID), 1:195 prevention, 1:195 prognosis, 1:195 Reiter’s syndrome, 1:192, 195 trachoma, 1:192, 193, 195 treatment, 1:194 Chlamydia trachomatis infection. See Chlamydia Cholesterol. See Hypercholesterolemia Chorionic villus sampling (CVS), 2:303, 315, 5:1195, 1197 Christie, Agatha, 4:904 Christmas disease. See Hemophilia Chronic fatigue immune deficiency syndrome. See Chronic fatigue syndrome Chronic fatigue syndrome, 1:196–202 causes and symptoms, 1:197, 198–200 cognitive behavioral therapy (CBT), 1:201 definition, 1:196 demographics, 1:197–198 description, 1:197 diagnosis, 1:197, 200 Epstein-Barr virus (EBV), 1:198, 3:615 the future, 1:201 low blood pressure, 1:197, 199 prevention, 1:201 prognosis, 1:201 treatment, 1:200–201 Chronic heartburn. See Gastroesophageal reflux disease Chronic lymphocytic thyroiditis. See Hashimoto disease Chronic obstructive pulmonary disease, 1:124, 202–203, 2:351 See also Bronchitis; Emphysema; Smoking The clap. See Gonorrhea Cleft lip and palate, 1:203–208 causes and symptoms, 1:203, 204–205 definition, 1:203 demographics, 1:203–204 description, 1:203 diagnosis, 1:205 the future, 1:207 prevention, 1:207 prognosis, 1:206–207 UXL Encyclopedia of Diseases and Disorders

Index

submucous cleft, 1:203 treatment, 1:204, 205–206 Clubfoot, 1:208–213 causes and symptoms, 1:208, 210–211 definition, 1:208 demographics, 1:209 description, 1:208–209 diagnosis, 1:209, 211 Edwards syndrome, 1:210 famous people with clubfoot, 1:210 flexible clubfoot, 1:208, 211 the future, 1:212 Ponseti method, 1:211, 212 prevention, 1:212 prognosis, 1:212 resistant clubfoot, 1:208, 211 treatment, 1:211–212 CO intoxication. See Carbon monoxide poisoning Coarctation of the aorta (COA), 2:241 Cochlear implant, 3:483 Cognitive-behavioral therapy (CBT), 1:49, 50, 133, 135, 201, 4:800 Cold exposure to the extremities. See Frostbite Cold-related injury. See Frostbite Cold sore, 2:215–219 causes and symptoms, 2:215, 217 definition, 2:215 demographics, 2:216–217 description, 2:215–216 diagnosis, 2:216, 217 the future, 2:219 herpes simplex virus (HSV-1, HSV-2), 2:215–217, 417, 418 prevention, 2:218–219 prodrome, 2:215, 219 prognosis, 2:218 treatment, 2:217–218 Colon cancer. See Colorectal cancer Colorectal cancer, 2:220–227 barium enema, 2:223 causes and symptoms, 2:220, 222–223 colonoscopy, 2:223–224, 225–226 definition, 2:220 demographics, 2:220–222 description, 2:220 UXL Encyclopedia of Diseases and Disorders

diagnosis, 2:221, 223–224 the future, 2:226 metastasis, 2:224, 226 polyps, 2:220, 221, 222, 223–224, 226 prevention, 2:225–226 prognosis, 2:225 sigmoidoscopy, 2:223 staging, 2:224–225, 226 treatment, 2:224–225 virtual colonoscopy, 2:221, 224 Common cold, 2:227–232 causes and symptoms, 2:227, 228–230 cold virus, 2:228, 228–229, 231 definition, 2:227 demographics, 2:228 description, 2:227–228 diagnosis, 2:230 the future, 2:231 home care, 2:229 prevention, 2:231 prognosis, 2:230 treatment, 2:229, 230 Concussion, 2:232–239 causes and symptoms, 2:233–235 definition, 2:232–233 demographics, 2:233 description, 2:233 diagnosis, 2:235 the future, 2:238 post-concussion syndrome (PCS), 2:237, 238 prevention, 2:237 prognosis, 2:237 in sports, 2:233, 234, 235, 236, 237 treatment, 2:236 Congenital heart defect (CHD). See Congenital heart disease Congenital heart disease, 2:239–245 aortic stenosis, 2:241, 243 atrial septal defect (ASD), 2:241, 243 cardiac catheterization, 2:243 causes and symptoms, 2:239, 242 chest x rays, 2:243 coarctation of the aorta (COA), 2:241 cyanosis and cyanotic heart defects, 2:239, 240–241, 245 lxxix

Index

definition, 2:239 demographics, 2:241–242 description, 2:239, 3:492 diagnosis, 2:240, 242–243 in Down syndrome, 2:242, 310, 314 echocardiograms, 2:243 in Edwards syndrome, 2:242, 347 electrocardiogram (ECG or EKG), 2:243 the future, 2:244 in Marfan syndrome, 2:242, 4:704–705, 705, 707, 708, 709 noncyanotic heart defects, 2:239, 241 in Patau syndrome, 2:242, 4:811, 812 persistent truncus arteriosus, 2:241 prevention, 2:244 prognosis, 2:244 pulse oximetry, 2:243 tetralogy of Fallot, 2:240, 244 transposition of the great vessels (TGA), 2:240 treatment, 2:243 tricuspid atresia, 2:241 in Turner syndrome, 2:242 ventricular septal defect (VSD), 2:240, 241 Congenital talipes equinovarus (CTEV). See Clubfoot Congestive heart failure (CHF). See Heart failure Conjoined twins, 2:246–251 Bijani, Laden and Laleh, 2:247 Bunker, Chang and Eng, 2:248, 248 causes and symptoms, 2:246, 248–249 craniopagus, 2:247 definition, 2:246 demographics, 2:247 description, 2:246–247 diagnosis, 2:249 the future, 2:250 ischiopagus, 2:246 omphalopagus, 2:246 parasitic twins, 2:247 prevention, 2:250 prognosis, 2:250 pygopagus, 2:246 thoracopagus, 2:246 treatment, 2:249–250 Conjunctivitis, 2:252–256 lxxx

allergic conjunctivitis, 2:252 causes and symptoms, 2:252–254 chemical splash (toxic conjunctivitis), 2:253–254 chronic conjunctivitis, 2:254 definition, 2:252 demographics, 2:252 description, 2:256 diagnosis, 2:253, 254 the future, 2:257 ophthalmia neonatorum, 2:252, 253, 255, 256 prevention, 2:254, 256 prognosis, 2:256 treatment, 2:256 viral conjunctivitis, 2:252–253 Consumption. See Tuberculosis Contact lenses astigmatism, 1:79, 80 hyperopia, 3:581 myopia, 4:752, 473, 474 Cooley’s anemia. See Thalassemia COPD. See Chronic obstructive pulmonary disease Core temperature drop. See Hypothermia Coronary artery disease, 2:257–263 ACE inhibitors, 2:261 angina (chest pain), 2:259 beta blockers, 2:261 calcium channel blockers, 2:261 causes and symptoms, 2:257, 259 chest x rays, 2:260 coronary angiography, 2:260 coronary angioplasty, 2:261, 3:489 coronary artery bypass surgery, 2:261, 3:489 definition, 2:257 demographics, 2:258–259 description, 2:257–258 diagnosis, 2:259–260 electrocardiogram (ECG or EKG), 2:260 the future, 2:262 nitroglycerin, 2:261 plaque, 2:257, 258, 259, 3:487 prevention, 2:262 prognosis, 2:261 smoking, 2:259, 260, 262 treatment, 2:260–261 Coronary heart disease. See Coronary artery disease UXL Encyclopedia of Diseases and Disorders

Index

Coryza. See Common cold Cot death. See Sudden infant death syndrome Coxsackievirus infection. See Hand-foot-and-mouth disease CP. See Cerebral palsy Crabs. See Lice infestation Cradle cap. See Dermatitis Creutzfeldt-Jakob disease, 2:263–270 causes and symptoms, 2:264, 265–267 definition, 2:263–264 demographics, 2:264–265 description, 2:264 diagnosis, 2:265, 267 the future, 2:269 prevention, 2:268 prions, 2:263, 265–266, 269, 5:1199 prognosis, 2:268 transmissible spongiform encephalopathies (TSEs), 2:264 treatment, 2:268 variant Creutzfeldt-Jakob disease (vCJD), 2:264–265 See also Prion diseases Crib death. See Sudden infant death syndrome Crohn disease, 2:270–276 anemia, 1:45, 2:273 appendicitis, 1:59, 60 causes and symptoms, 2:270, 273 colonoscopy, 2:273–274 colostomy, 2:274 comparison to ulcerative colitis, 5:1141, 1142, 1143, 1144 definition, 2:270 demographics, 2:271–272, 5:1142 description, 2:270–271 diagnosis, 2:271, 273 fistulas, 2:271, 273, 275 the future, 2:275 penetrating Crohn disease, 2:271 prevention, 2:275 prognosis, 2:274–275 sigmoidoscopy, 2:273–274 smoking, 2:273 stricturing disease, 2:271, 272, 274 treatment, 2:272, 274 UXL Encyclopedia of Diseases and Disorders

Crossed eyes. See Strabismus Curvature of the spine. See Scoliosis Cushing syndrome, 1:187, 191, 4:772, 774 Cystic fibrosis, 2:276–282 causes and symptoms, 2:276, 278–279 CFTR gene, 2:278, 279, 281 definition, 2:276 demographics, 2:277–278, 416 description, 2:276–277 diagnosis, 2:279 the future, 2:281 gene therapy, 2:281 genetic testing, 2:279, 281 mucus, 2:276–277, 277, 280 prenatal and newborn testing, 2:279 prevention, 2:281 prognosis, 2:281 treatment, 2:280 Cystitis. See Urinary tract infections

D1 trisomy. See Patau syndrome Dallaire, Roméo, 4:853, 853 Dandruff. See Dermatitis de Young, Margot, 3:558 Deafness. See Hearing loss Debridement, 1:140, 142, 2:401, 407, 4:766, 5:1084 Deep brain stimulation (DBS), 4:781–782, 808, 5:1109 Degenerative joint disease. See Osteoarthritis Dental caries. See Tooth decay Depression, 2:283–290 antidepressant medications, 2:287 causes and symptoms, 2:283, 285–286 definition, 2:283–284 demographics, 2:284–285 description, 2:284 diagnosis, 2:286 dysthymia (dysthymic disorder), 2:283, 284, 289 electroconvulsive therapy (ECT), 2:287 the future, 2:288 prevention, 2:288 lxxxi

Index

prognosis, 2:288 psychotherapy, 2:287 psychotic depression, 2:283 treatment, 2:287–288 Depressive disorder. See Depression Dermatitis, 2:290–297 atopic dermatitis (eczema), 2:290, 291, 292, 294, 295 causes and symptoms, 2:290, 292–293 cercarial dermatitis (swimmer’s itch), 2:290–291, 292, 293, 294, 295 contact dermatitis, 1:28, 31, 2:290, 291–292, 293–295 definition, 1:31, 2:290 demographics, 2:291–292 description, 2:290–291 diagnosis, 2:293 filaggrin, 2:292, 341, 343 the future, 2:296 prevention, 2:295 prognosis, 2:294–295 radiation dermatitis (photodermatitis, sunburn), 2:291, 292, 293, 294, 295 seborrheic dermatitis, 2:291, 292, 293, 294, 295 seborrheic dermatitis (cradle cap, dandruff), 2:291 treatment, 2:291, 294 Desert fever. See Gulf War syndrome Developmental disability, 2:297–303 causes and symptoms, 2:297, 299–300 definition, 2:297, 300 demographics, 2:299 description, 2:297–299 developmental milestones in children, 2:298 diagnosis, 2:300 the future, 2:302 prevention, 2:301 prognosis, 2:301 treatment, 2:300–301 Diabetes, 2:303–310 blood tests, 2:304, 306–307 causes and symptoms, 2:303, 306 definition, 2:303–304 demographics, 2:305–306 description, 2:304–305 lxxxii

diagnosis, 2:304, 306–307 the future, 2:308–309 gangrene, 2:405–406, 408, 409 gestational diabetes, 2:304 hypercholesterolemia, 3:574 hypoglycemia, 3:591–592, 592, 593–594 insulin injections, 2:303–304, 305, 307 insulin resistance, 2:304, 306 pre-diabetes, 2:304 prevention, 2:308 prognosis, 2:307–308 treatment, 2:305, 307 type 1 (insulin-dependent) diabetes, 2:303–304, 306, 307, 308 type 2 (adult-onset) diabetes, 2:304, 308 Diabetes mellitus (DM). See Diabetes Diabetic ulcers. See Ulcers Diana, Princess of Wales, 1:131, 131 Didion, Joan, 4:739 Diffuse toxic goiter. See Graves disease Diphtheria, 5:999, 1085, 1087, 1089 Disseminated sclerosis. See Multiple sclerosis Diuretics abuse in anorexia, 1:46, 50 abuse in bulimia, 1:131, 133, 135 heart failure, 3:497 hypertension, 3:587 Dope. See Marijuana use Down, John Langdon Haydon, 2:312 Down syndrome, 2:310–317 advocacy, 2:312, 316 Alzheimer disease, 2:314 causes and symptoms, 2:310, 311–313 Celiac disease, 1:162 congenital heart disease, 2:242, 310, 314 definition, 2:310 demographics, 2:311 description, 2:310–311 diagnosis, 2:311, 313–314 the future, 2:315–316 leukemia, 2:310, 314, 3:661 mosaic trisomy 21, 2:312, 314 nondisjunction, 2:312, 315 prevention, 2:315 prognosis, 2:314 UXL Encyclopedia of Diseases and Disorders

Index

translocation, 2:313, 315 treatment, 2:314 Drug and alcohol abuse in schizophrenia, 4:913–914, 917 Dwarfism. See Achondroplasia Dyslexia, 2:317–323 causes and symptoms, 2:317, 319–320 decoding, 2:317, 322 definition, 2:317 demographics, 2:318 description, 2:317–318 diagnosis, 2:320 the future, 2:322 prevention, 2:322 prognosis, 2:321 spoken language difficulties, 2:317–318, 320 treatment, 2:321 written language difficulties, 2:317–318, 318, 319–320 Dysphonia. See Laryngitis Dysthymia. See Depression

E. coli. See Food poisoning Ear infection, 2:325–332 causes and symptoms, 2:325, 327–328 definition, 2:325 demographics, 2:326–327 description, 2:325–326 diagnosis, 2:326, 328–329 Eustachian tubes, 2:325, 326, 327, 329–330, 331 the future, 2:331 mastoiditis, 2:330 otitis externa, 2:325–326, 328, 329 otitis media, 2:326, 327, 328, 329–330 otitis media with effusion (OME), 2:326, 328, 329 prevention, 2:330 prognosis, 2:330 treatment, 2:329–330 Eating disorders, 2:332 Ebola and Marburg hemorrhagic fevers, 2:333–338 UXL Encyclopedia of Diseases and Disorders

causes and symptoms, 2:333, 335, 5:1199 definition, 2:333 demographics, 2:334–335 description, 2:333–334 diagnosis, 2:335–336 Ebola virus, 2:333, 334, 336 filoviruses, 2:333–334, 335–337 the future, 2:337 Marburg virus, 2:333, 337 prevention, 2:336 prognosis, 2:336 treatment, 2:336 Ebola HF. See Ebola and Marburg hemorrhagic fevers Eczema, 2:338–344 causes and symptoms, 2:292, 338, 340–341 definition, 2:338 demographics, 1:28, 2:291, 339–340 description, 1:27, 2:290, 339 diagnosis, 2:339, 341 filaggrin, 2:292, 341, 343 the future, 2:343 prevention, 2:294, 343 prognosis, 2:294, 343 self-care, 2:340 treatment, 2:294, 340, 342–343 See also Dermatitis Edwards syndrome, 2:344–350 causes and symptoms, 2:344, 346–347 clubfoot or rocker-bottom feet, 1:210 congenital heart disease, 2:242, 347 definition, 2:344–345 demographics, 2:345–346 description, 2:345 diagnosis, 2:345, 347 the future, 2:348 mosaic trisomy 18, 2:346–347 nondisjunction, 2:346, 349 perinatal hospice, 2:346, 348–349 prevention, 2:348 prognosis, 2:348 translocation, 2:346, 349 treatment, 2:348 Eisenhower, Dwight D., 2:272, 272 Ekbom’s syndrome. See Restless legs syndrome lxxxiii

Index

El Greco, 1:79 Electrocardiogram (ECG or EKG), 2:243, 260, 3:488, 496 Electroencephalogram (EEG), 4:933, 936 Electroconvulsive therapy (ECT), 1:108, 109, 2:287 Emerging diseases, 2:350–351 Emerson, Ralph Waldo, 1:34 Emphysema, 2:351–358 antibiotic treatment, 2:356 bronchodilators, 2:356 causes and symptoms, 2:351, 354–355 changes in lung tissue, 2:351–352, 352 chest x rays, 2:355 definition, 2:351 demographics, 2:353–354 description, 2:351–353 diagnosis, 2:355 famous people affected, 2:353 the future, 2:357–358 oxygen therapy, 2:356 prevention, 2:357 prognosis, 2:357 pulmonary function tests (PFTs), 2:355 pulmonary rehabilitation, 2:356 smoking, 2:353–354, 357 steroid medications, 2:356 surgery, 2:356 treatment, 2:355–356 Encephalitis, 2:359–365 acyclovir, 2:362, 363 causes and symptoms, 2:359, 360–361 definition, 2:359 demographics, 2:359–360 description, 2:359, 4:730 diagnosis, 2:360, 361–362 eastern equine encephalitis, 2:360, 364 the future, 2:364 herpes simplex virus (HSV) encephalitis, 2:360, 360, 363 Japanese encephalitis, 2:360, 363 La Crosse encephalitis, 2:360 prevention, 2:363–364, 4:731 prognosis, 2:363 treatment, 2:361, 362 viral encephalitis types, 2:360 lxxxiv

West Nile virus, 2:360, 361, 363, 364, 366 Endocarditis, 5:1022–1023, 1024, 1025 Enterovirus infection. See Hand-foot-and-mouth disease; Meningitis Epilepsy. See Seizure disorder EpiPen, 1:40, 41, 43, 3:542 Epityphlitis. See Appendicitis Epstein-Barr infection chronic fatigue syndrome, 1:198, 3:615 Hodgkin disease, 3:546 infectious mononucleosis, 3:612, 613, 614, 615, 616 tonsillitis, 5:1094, 1095 Escalante’s syndrome. See Fragile X Excessive daytime sleepiness. See Narcolepsy Eyeglasses astigmatism, 1:80, 4:752 hyperopia, 3:581, 4:752 myopia, 4:752, 473, 474

Farsightedness. See Hyperopia Fasciitis necroticans. See Necrotizing fasciitis Fatal familial insomnia (FFI), 2:264, 269 Fatness. See Obesity Fetal alcohol syndrome, 2:367–372 causes and symptoms, 2:367, 368–369 definition, 2:367 demographics, 1:21, 2:367–368 description, 1:20–21, 2:367, 369 diagnosis, 2:368, 369–370 the future, 2:371–372 prevention, 2:371 prognosis, 2:371 treatment, 2:370–371 Fever blister. See Cold sore Fibrocystic disease of the pancreas. See Cystic fibrosis Fibromyalgia, 2:373–378 causes and symptoms, 2:373, 374–375 definition, 2:373 demographics, 2:373–374 description, 2:373 diagnosis, 2:374, 375 UXL Encyclopedia of Diseases and Disorders

Index

fibro fog, 2:374, 377 the future, 2:376 Lyrica, 2:375–376 pain perception, 2:375 pressure points, 2:373, 374, 375, 377 prevention, 2:376 prognosis, 2:376 treatment, 2:375–376 Fibromyositis. See Fibromyalgia Fibrositis. See Fibromyalgia Filoviruses, 2:333–334, 335–337 Flashbacks, 4:852, 853, 854, 857 Flesh-eating disease. See Necrotizing fasciitis Flu. See Influenza Følling, Ivar Asbjørn, 4:823 Følling’s disease. See Phenylketonuria Food poisoning, 2:378–384 bacterial infections, 2:379, 379 causes and symptoms, 2:378, 379, 381 chemicals, 2:379 definition, 2:378 demographics, 2:378–379 description, 2:378 diagnosis, 2:381 fugu (puffer fish), 2:380, 380 the future, 2:383 natural toxins, 2:380 parasites, 2:379 prevention, 2:382–383 prognosis, 2:382 staphylococcal food poisoning, 5:1023, 1025 treatment, 2:381–382 viruses, 2:379 Foodborne illness. See Food poisoning Four Corners disease. See Hantavirus infection Fractures, 2:384–390 causes and symptoms, 2:384, 387 closed fracture, 2:384 compression fracture, 2:385, 387 definition, 2:384–385 demographics, 2:386 description, 2:385 diagnosis, 2:385, 387 displaced fracture, 2:385 first aid, 2:386 UXL Encyclopedia of Diseases and Disorders

the future, 2:390 greenstick fracture, 2:385 multi-fragmentary (comminuted) fracture, 2:384 open (compound) fracture, 2:385, 388 prevention, 2:388–390 prognosis, 2:388 simple fracture, 2:384 stress (hairline) fracture, 2:385, 386, 387, 389 treatment, 2:386, 387–388 undisplaced fracture, 2:385 Fragile X, 2:391–396 causes and symptoms, 2:391, 392–393 definition, 2:391 demographics, 2:392 description, 2:391–392, 392 diagnosis, 2:393–394 FMR1 gene, 2:391, 392, 394 fragile X mental retardation 1 (FMR1) protein, 2:391, 395 the future, 2:395 premutation, 2:391–392, 395 prevention, 2:394 prognosis, 2:394 treatment, 2:394 Frostbite, 2:396–401 and burns, 1:137 causes and symptoms, 2:396 definition, 2:396 demographics, 2:396–397 description, 1:137, 2:396 diagnosis, 2:397, 398–399 the future, 2:400 and mountain climbing, 2:396, 397, 398 prevention, 2:400 prognosis, 2:400 technetium scintigraphy, 2:398–399 treatment, 2:399 Fugu (puffer fish), 2:380, 380

Gangrene, 2:403–409 bedsores, 2:403, 406, 409 causes and symptoms, 2:403, 406 lxxxv

Index

Clostridium perfringens (C. perfringens), 2:403, 404, 407 definition, 2:403 demographics, 2:405–406 description, 2:404–405 diabetes, 2:405–406, 408, 409 diagnosis, 2:404, 406–407 dry gangrene, 2:403, 404, 406, 407, 408 the future, 2:409 gas gangrene, 2:403, 404–405, 406, 407–408, 409 hyperbaric oxygen (HBO) chambers, 2:408, 409 prevention, 2:408 prognosis, 2:408 smoking, 2:403, 406 treatment, 2:407–408 wet gangrene, 2:403, 404, 407–408 Ganja. See Marijuana use Gastroesophageal reflux disease, 2:410–416 acid probe test, 2:413 antacids, 2:413 barium swallow, 2:412–413 bronchitis, 1:126 causes and symptoms, 2:410, 412 definition, 1:126, 2:410, 411, 3:649 demographics, 2:410–411 description, 2:410, 411 diagnosis, 2:412–413 endoscopy, 2:413 the future, 2:415 H2 blockers, 2:413 heartburn (acid indigestion), 2:410–411, 412 laryngitis, 3:649, 650 lower esophageal sphincter (LES), 2:410, 412, 415 prevention, 2:414 prognosis, 2:414 prokinetics, 2:414 proton pump inhibitors (PPIs), 2:414 treatment, 2:413–414 Gene therapy, 2:281 Genetic disorders, 2:416–417 See also specific types Genital herpes, 2:417–422 causes and symptoms, 2:417, 419 lxxxvi

definition, 2:417 demographics, 2:418 description, 2:417–418 diagnosis, 2:420 the future, 2:421 herpes simplex virus (HSV-1, HSV-2), 2:215, 217, 417–418, 418, 419 prevention, 2:420–421 prognosis, 2:420 treatment, 2:419, 420 Genital warts. See HPV infection GERD. See Gastroesophageal reflux disease German measles. See Rubella Gigantism, 2:422–427 acromegaly, 2:422, 423, 424–427 causes and symptoms, 2:422, 423–425 definition, 2:422 demographics, 2:423 description, 2:422–423, 423 diagnosis, 2:425 the future, 2:427 prevention, 2:426 prognosis, 2:426 treatment, 2:425–426 Gilles de la Tourette syndrome. See Tourette syndrome Gingivitis. See Periodontal disease Glandular fever. See Infectious mononucleosis Glaucoma, 2:428–434 causes and symptoms, 2:428, 430, 431 closed-angle glaucoma, 2:428, 430, 431, 432 congenital glaucoma, 2:428, 430, 432 definition, 2:428–429 demographics, 2:430–431 description, 2:429–430, 5:1161 diagnosis, 1:158, 2:429, 431–432 the future, 2:433–434 gonioscopy, 2:432 normal-pressure glaucoma, 2:429, 431 open-angle glaucoma, 2:428, 430, 431, 432, 433 peripheral vision and tunnel vision, 2:430, 432 pigmentary glaucoma, 2:429 prevention, 2:433 primary glaucoma, 2:428–429, 431 UXL Encyclopedia of Diseases and Disorders

Index

prognosis, 2:433 secondary glaucoma, 2:429, 433 tonometry, 1:158, 159, 2:432 treatment, 2:432–433 Gliomas. See Brain tumors Glucose disorder. See Hypoglycemia Gluten sensitivity. See Celiac disease Goiter Graves disease, 2:440, 441, 443, 445 Hashimoto disease, 3:461, 464, 465 hypothyroidism, 3:604, 606, 608, 609 Gonococcal infection. See Gonorrhea Gonorrhea, 2:435–440 causes and symptoms, 2:435, 436–437 definition, 2:435 demographics, 2:435 description, 2:435 diagnosis, 2:437 disseminated gonococcal infection (DGI), 2:437, 439 drug-resistant strains, 2:438 ectopic pregnancy, 2:437, 439 the future, 2:438–439 infants, 2:436, 436, 438 and mercury, 2:437 Neisseria gonorrhoeae (gonococcus), 2:435, 439 ophthalmia neonatorum, 2:252, 253, 255, 256 pelvic inflammatory disease (PID), 2:436–437, 439 prevention, 2:438 prognosis, 2:438 treatment, 2:437–438 Gougerot disease. See Sjögren syndrome Gougerot-Sjögren syndrome. See Sjögren syndrome Grass. See Marijuana use Grass fever. See Hay fever Graves disease, 2:440–445 causes and symptoms, 2:440, 441, 441–443 definition, 2:440 demographics, 2:440–441 description, 2:440 diagnosis, 2:441, 443–444 exophthalmos (bulging eyes), 2:440, 441, 443, 445 the future, 2:444 UXL Encyclopedia of Diseases and Disorders

goiter, 2:440, 441, 443, 445 prevention, 2:444 prognosis, 2:444 thyroid storm, 2:443, 445 treatment, 2:442, 444 Greco, El (Domenikos Theotokopoulos), 1:79, 79 Green monkey fever. See Ebola and Marburg hemorrhagic fevers Gregory, D.J., 1:168 Group A streptococcus necrotizing fasciitis, 4:765 rheumatic fever, 4:889, 892, 893 scarlet fever, 4:907, 908, 911, 912 strep throat, 5:1039, 1041, 1042, 1043 tonsillitis, 5: 1094, 1096, 1097 toxic shock syndrome, 5:1110, 1111, 1112, 1114, 1115 Gulf War syndrome, 2:445–450 causes and symptoms, 2:446, 447–448 controversial status, 2:445, 447, 448 definition, 2:445–446 demographics, 2:446 description, 2:446 diagnosis, 2:447, 448 epidemiology, 2:448, 449, 450 the future, 2:449 multiple chemical sensitivity (MCS), 2:447, 450 prevention, 2:449 prognosis, 2:449 psychological stress, 2:447–448 treatment, 2:449 Gum disease. See Periodontal disease

H5N1 infection. See Avian influenza Hand-foot-and-mouth disease, 3:451–455 causes and symptoms, 3:451, 453 coxsackievirus A16, 3:451, 453, 455 definition, 3:451 demographics, 3:452–453 description, 3:451–452 diagnosis, 3:452, 453 enteroviruses, 3:451–452, 453, 455 lxxxvii

Index

the future, 3:455 prevention, 3:454–455 prognosis, 3:454 treatment, 3:453–454 Hantavirus infection, 3:456–461 causes and symptoms, 3:456, 457, 458, 5:1199 definition, 3:456 demographics, 3:456–457 description, 3:456 diagnosis, 3:458 extracorporeal membrane oxygenation (ECMO), 3:459 the future, 3:459–460 hantaviruses, 3:457, 457, 458 prevention, 3:459 prognosis, 3:459 research, 3:458, 458 treatment, 3:459 Hantavirus pulmonary syndrome (HPS). See Hantavirus infection Hard of hearing. See Hearing loss Harelip. See Cleft lip and palate Harrison, William Henry, 4:834 Hash. See Marijuana use Hashimoto, Haraku, 3:463 Hashimoto disease, 3:461–466 causes and symptoms, 3:461–463 definition, 3:461 demographics, 3:461 description, 3:461 diagnosis, 3:461, 463–464 the future, 3:464–465 goiter, 3:461, 464, 465 hypothyroidism, 3:461, 462, 603, 604, 607 prevention, 3:464 prognosis, 3:464 thyroid-stimulating hormone (TSH), 3:463, 464 treatment, 3:464 Hashimoto thyroiditis. See Hashimoto disease Hay fever, 3:466–472 antihistamines, 3:469 causes and symptoms, 3:466, 467–468 decongestants, 3:469 definition, 3:466 demographics, 1:28, 3:466–467 lxxxviii

description, 3:466 desensitization (allergy shots), 3:469–470, 471 diagnosis, 3:468–469 the future, 3:470 histamine, 3:468, 471 nasal corticosteroids, 3:469 pollen from ragweed, trees, or grass, 3:466–469, 467 Pollinex Quattro vaccine, 3:470 prevention, 3:468, 470 prognosis, 3:469–470 treatment, 3:469 Hazelton, Robert, 5:1028 HbS disease. See Sickle cell anemia HBV infection. See Hepatitis B Head pain. See Headache Headache, 3:472–478 causes and symptoms, 3:472, 473, 474–475 cluster headaches, 3:473, 474, 476 definition, 3:472 demographics, 3:474 description, 3:472–474 diagnosis, 3:475 the future, 3:476–477 migraine headaches, 3:472–473, 474, 475, 477 ordinary headaches, 3:473, 476 post-traumatic headaches, 3:473 prevention, 3:476 primary headaches, 3:472–473, 475–476 prognosis, 3:476 reactive headaches, 3:474 rebound headaches, 3:474 secondary headaches, 3:472, 473–474, 475 sinus headaches, 3:473 tension headaches, 3:473, 475–476 treatment, 3:475–476 Hearing loss, 3:478–485 bone-implanted hearing aid (BAHA), 3:482 causes and symptoms, 3:478, 481 cochlear implant, 3:483 conductive hearing loss (CHL), 3:478–480, 481, 482, 483 decibel levels of sounds, 3:480 definition, 3:478 demographics, 2:299, 3:480 UXL Encyclopedia of Diseases and Disorders

Index

description, 3:478–479 diagnosis, 3:482 the future, 3:484 hearing aids, 3:482 mixed hearing loss, 3:478 noise-induced hearing loss (NIHL), 3:480, 481, 482 prevention, 3:482, 483 prognosis, 3:483 sensorineural hearing loss (SNHL), 3:478, 480, 481, 482–483 tinnitus, 3:480, 484 treatment, 3:482–483 tumors (brain or auditory nerve), 3:479, 480, 481, 482 Hearing aids, 3:482 Heart attack, 3:485–491 beta blockers, 3:489, 490 blood tests, 3:488 causes and symptoms, 3:485, 487–488 coronary angiography, 3:486, 488–489 coronary angioplasty, 2:261, 3:489 coronary artery bypass surgery, 2:261, 3:489 definition, 3:485 demographics, 3:486–487 description, 3:485–586 diagnosis, 3:486, 488–489 electrocardiogram (ECG or EKG), 3:488 the future, 3:490 ischemia, 3:487, 491 nitroglycerin, 3:487, 489 plaques and atherosclerosis, 3:487, 491 prevention, 3:490 prognosis, 3:489–490 silent heart attacks, 3:486 smoking, 3:490 treatment, 3:487, 489 Heart diseases, 3:492 Heart failure, 3:492–499 ACE inhibitors, 3:497 acute heart failure, 3:493, 497, 498 aldosterone antagonists, 3:497 beta blockers, 3:497 cardiac catheterization, 3:497 cardiac resynchronization therapy (CRT), 3:497 UXL Encyclopedia of Diseases and Disorders

causes and symptoms, 3:493, 495–496 chest x ray, 3:496 definition, 3:492–493 demographics, 3:494–495 description, 3:493–494 diagnosis, 3:494, 496–497 digoxin, 3:497 diuretics, 3:497 echocardiogram, 3:496 electrocardiogram (ECG or EKG), 3:496 the future, 3:498 heart pumps (left ventricular assist devices, LVADs), 3:497–498 implantable cardioverter defibrillators (ICDs), 3:497 left-sided heart failure, 3:493 prevention, 3:498 prognosis, 3:498 right-sided heart failure, 3:493 stress test, 3:496 treatment, 3:497–498 Heat cramps, 3:499–503 causes and symptoms, 3:500 definition, 3:499 demographics, 3:500 description, 3:500 diagnosis, 3:500 the future, 3:502 prevention, 3:501–502 prognosis, 3:501 treatment, 3:500–501 Heat exhaustion, 3:503–508 causes and symptoms, 3:504–505, 511 definition, 3:503 demographics, 3:504 description, 3:504 diagnosis, 3:505 the future, 3:507 prevention, 3:506–507, 511 prognosis, 3:506 treatment, 3:505–506 Heat illness. See Heat exhaustion Heat-related muscle cramps. See Heat cramps Heat stress. See Heat exhaustion Heat stroke, 3:508–515 lxxxix

Index

causes and symptoms, 3:509, 510–511 definition, 3:508–509 demographics, 3:509–510 description, 3:509 diagnosis, 3:511 exertional heat stroke (EHS), 3:509 first aid, 3:510 the future, 3:513–514 nonexertional heat stroke (NEHS), 3:509 prevention, 3:505, 512–513 prognosis, 3:512 treatment, 3:509, 510, 511–512 Hemoglobin H disease. See Thalassemia Hemoglobin SS disease. See Sickle cell anemia Hemophilia, 3:515–521 acquired hemophilia, 3:515 AIDS infections of hemophilia patients from blood, 3:517 causes and symptoms, 3:515, 518 coagulation cascade, 3:517, 520 coagulation factors, 3:516–517, 518, 519, 520 definition, 3:515 demographics, 3:517–518 in descendants of Queen Victoria, 3:516 description, 3:516, 516–517 desmopressin (DDAVP), 3:519 diagnosis, 3:518–519 the future, 3:520 genetic mutations, 3:515, 518, 519, 520 hemophilia A (classic hemophilia), 3:515, 517–518, 519 hemophilia B (Christmas disease), 3:515, 517–518, 519 prevention, 3:519–520 prognosis, 3:519 treatment, 3:517, 519 Henson, Jim, 4:834 Hepatitis A, 3:521–526 causes and symptoms, 3:521, 523–524 definition, 3:521 demographics, 3:522–523 description, 3:521–522 diagnosis, 3:524 the future, 3:526 Havrix vaccine, 3:525, 526 xc

hepatitis A (HAV) virus, 3:521–522, 522, 523, 525 prevention, 3:525 prognosis, 3:524 treatment, 3:524 Hepatitis B, 3:527–532 acute hepatitis B, 3:527, 529, 530 causes and symptoms, 3:527, 528–529 chronic hepatitis B, 3:527–528, 529, 530–531 definition, 3:527 demographics, 3:527–528 description, 3:527 diagnosis, 3:529–530 fulminant hepatitis, 3:529, 530 the future, 3:531 HBV vaccine (Engerix-B), 3:527, 530, 531 hepatitis B (HBV) virus, 3:527–528 hepatitis D (HDV) virus, 3:529 prevention, 3:527, 530, 531 prognosis, 3:530–531 treatment, 3:530 Hepatitis C, 3:533–539 causes and symptoms, 3:533, 534–535 definition, 3:533 demographics, 3:533–534 description, 3:533 diagnosis, 3:535–536 the future, 3:537–538 hepatitis C virus (HCV), 3:533–534, 534, 535, 536–537 outbreaks due to contaminated syringes, 3:535 prevention, 3:537 prognosis, 3:536–537 treatment, 3:536 Hepatitis D (HDV), 3:529 Hepatitis E (HEV), 3:523 Herpes. See Cold sore; Genital herpes Herrick, James, 5:951 Herzog, Maurice, 2:398 High blood cholesterol. See Hypercholesterolemia High blood pressure (HBP). See Hypertension High cholesterol. See Hypercholesterolemia High-functioning autism (HFA). See Asperger syndrome Highly active antiretroviral therapy (HAART), 1:16–17, 18 UXL Encyclopedia of Diseases and Disorders

Index

Hinton, Walter Augustus, 5:1070 HIV infection. See AIDS Hives, 3:539–544 angioedema, 3:539, 541, 542, 543 causes and symptoms, 3:539, 541 definition, 3:539 demographics, 1:28, 3:541 dermatographism, 3:540, 541, 543 diagnosis, 3:540, 542 the future, 3:543 prevention, 3:543 prognosis, 3:542–543 treatment, 3:541, 542 Hodgkin disease, 3:544–550 causes and symptoms, 3:544, 546–547 definition, 3:544 demographics, 3:546 description, 3:544–545, 690 diagnosis, 3:545, 547 the future, 3:550 nodular lymphocyte predominant Hodgkin disease (NLPHD), 3:545 prevention, 3:549 prognosis, 3:548 treatment, 3:547–548 Hodgkin lymphoma (HL). See Hodgkin disease HPV infection, 3:550–556 cancer (noncervical), 3:551, 552, 553 causes and symptoms, 3:550, 552–553 cervical cancer, 3:550, 551, 552, 554, 4:945 definition, 3:550 demographics, 3:551–552 description, 3:550–551 diagnosis, 3:551, 553 the future, 3:555 human papillomavirus, 3:550–551 prevention, 3:555 prognosis, 3:554 treatment, 3:553–554 vaccine (Gardasil), 3:555, 5:1173 warts, 3:550–551, 552–554, 555, 5:1169, 1170, 1173 Hughes, Howard, 4:778, 778 Human papillomavirus infection. See HPV infection Hunt, Linda, 5:1135 UXL Encyclopedia of Diseases and Disorders

Huntington disease, 3:556–562 causes and symptoms, 3:556, 558–559 definition, 3:556 demographics, 3:557 description, 3:556–557 diagnosis, 3:559 families near Lake Maracaibo, Venezuela, 3:557, 558 the future, 3:560 prevention, 3:560 prognosis, 3:560 treatment, 3:559–560 Huntington’s chorea. See Huntington disease Hutchinson-Gilford syndrome, 3:562–566 causes and symptoms, 3:562, 563, 563–564 definition, 3:562 demographics, 3:563 description, 3:562–563 diagnosis, 3:564 failure to thrive (FTT), 3:562, 565 the future, 3:565 LMNA gene, 3:563–564 prevention, 3:565 prognosis, 3:564–565 treatment, 3:564 Hydrocephalus, 3:566–572 achondroplasia, 1:4 acquired hydrocephalus, 3:567, 568 causes and symptoms, 3:566, 567, 568–569 cerebrospinal fluid (CSF), 3:566 communicating hydrocephalus, 3:567 congenital hydrocephalus, 3:567, 568 definition, 1:5, 3:566–567 demographics, 3:568 description, 3:567–568 diagnosis, 3:568, 569 the future, 3:570–571 noncommunicating (obstructive) hydrocephalus, 3:567, 570 normal pressure hydrocephalus (NPH), 3:567, 568, 569 prevention, 3:570 prognosis, 3:570 shunts, 3:568, 570–571 spina bifida, 5:1005, 1006, 1007 treatment, 3:568, 570 xci

Index

Hydrophobia. See Rabies Hydrops fetalis. See Thalassemia Hyperactive airway disease. See Asthma Hyperbaric oxygen (HBO) chambers carbon monoxide poisoning, 1:152, 153 gangrene, 2:408, 409 necrotizing fasciitis, 4:766 smoke inhalation, 5:988, 989 Hypercholesterolemia, 3:572–578 bile acid-binding resins, 3:576 causes and symptoms, 3:572, 574–575 cholesterol, general information, 3:572, 575 cholesterol absorption inhibitors, 3:576 definition, 3:572 demographics, 3:573–574 description, 3:572–573 diagnosis, 3:575 diet, 3:574, 575, 576–577 familial hypercholesterolemia, 3:574 fibrates, 2:261, 3:576 the future, 3:577 high-density lipoprotein (HDL), 3:573, 575 low-density lipoprotein (LDL), 3:573, 575 niacin (Niaspan), 2:261, 3:576 plaque deposit formation, 3:572–573, 573, 577 prevention, 3:576–577 prognosis, 3:576 smoking, 3:574, 576 statins, 2:261, 3:576 treatment, 3:575–576 triglycerides, 3:573, 575 very low-density lipoprotein (VLDL), 3:573 Hyperextension injury. See Whiplash Hyperopia, 3:578–583 and amblyopia, 3:581, 582 causes and symptoms, 1:78, 3:578, 580–581 contact lenses, 3:581 definition, 3:578 demographics, 3:578–580 description, 3:578, 579, 5:1161 diagnosis, 3:580, 581 eyeglasses, 3:581, 4:752 the future, 3:582 laser surgery, 3:581 lens implantation, 3:581 xcii

presbyopia, 3:580, 582 prevention, 3:580, 582 prognosis, 3:582 treatment, 3:581–582 Hypersensitivity reaction. See Allergies Hypertension, 3:583–590 ACE inhibitors, 3:587 alpha blockers, 3:588 beta blockers, 3:587 calcium channel blockers, 3:587 causes and symptoms, 3:584, 586 definition, 3:583–584 demographics, 3:585–586 description, 3:584–585 diagnosis, 3:584, 585, 586–587 diastolic blood pressure, 3:584, 586, 589 diuretics, 3:587 essential hypertension, 3:584, 589 the future, 3:588–589 prevention, 3:588 prognosis, 3:588 secondary hypertension, 3:584, 586 systolic blood pressure, 3:584, 586, 589 treatment, 3:587–588 vasodilators, 3:587 Hyperthermia. See Heat exhaustion; Heat stroke Hyperthyroidism. See Graves disease Hypoglycemia, 3:590–596 causes and symptoms, 3:590, 592–593 definition, 3:590 demographics, 3:592 description, 3:590–592 diabetes, 3:591–592, 592, 593–594 diagnosis, 3:593 fasting hypoglycemia, 3:592, 593, 594, 595 the future, 3:595 GlucaGen Hypokit, 3:591 prevention, 3:594–595 prognosis, 3:594 reactive hypoglycemia, 3:592, 593–594, 595 treatment, 3:591, 594 Whipple’s triad, 3:593, 595 Hypothermia, 3:596–602 body heat regulation, 3:597, 597–598 causes and symptoms, 3:596, 599 UXL Encyclopedia of Diseases and Disorders

Index

definition, 3:596–597 demographics, 3:598–599 description, 3:597–598 diagnosis, 3:599–600 the future, 3:601–602 iodine deficiency, 3:603, 605 Nazi experiments during World War II, 3:598 prevention, 3:601 primary hypothermia, 3:596 primary hypothyroidism, 3:603 prognosis, 3:600 secondary hypothermia, 3:596–597 treatment, 3:600 Hypothyroidism, 3:603–609 causes and symptoms, 3:603, 604–606 congenital hypothyroidism (cretinism), 3:603, 607, 609 definition, 3:465, 603 demographics, 3:603–604 description, 3:603 diagnosis, 3:604, 605, 606–607 the future, 3:608 goiter, 3:604, 606, 608, 609 Hashimoto disease, 3:461, 462, 603, 604, 607 prevention, 3:608 prognosis, 3:607–608 secondary hypothyroidism, 3:603, 605 thyroid-stimulating hormone (TSH), 3:463, 464, 605, 606–607 treatment, 3:607 Turner syndrome, 5:1136

Immunologic reaction. See Anaphylaxis Impetigo, 1:174 Infantile paralysis. See Polio Infection of the tonsils. See Tonsillitis Infectious diseases, 3:611–612 See also specific diseases Infectious hepatitis. See Hepatitis A Infectious mononucleosis, 3:612–617 causes and symptoms, 3:612, 613–614 definition, 3:612 UXL Encyclopedia of Diseases and Disorders

demographics, 3:613 description, 3:612 diagnosis, 3:613, 614–615, 5:1000 Epstein-Barr infection, 3:612, 613, 614, 615, 616 the future, 3:616 prevention, 3:616 prognosis, 3:615 treatment, 3:615 Inflammation of the brain. See Encephalitis Inflammatory bowel disease (IBD). See Crohn disease; Ulcerative colitis Influenza, 3:617–623 causes and symptoms, 3:617, 620–621 definition, 3:617 demographics, 3:618, 620 description, 3:617–618 diagnosis, 3:618, 621 flu vaccines, 3:620, 622 the future, 3:623 H1N1 subtype of influenza A virus, 1:97 H5N1 subtype of influenza A virus, 1:97, 98, 99, 100 influenza pandemics, 1:97, 100, 3:611, 617, 619, 619–620 prevention, 3:622 prognosis, 3:622 treatment, 3:621–622 virus growth in respiratory tract, 3:618, 620 Influenza virus A infection. See Avian influenza Inhalation injury. See Smoke inhalation Inherited myopathy. See Muscular dystrophy Iron-deficiency anemia, 3:624–630 causes and symptoms, 1:45, 3:624, 626–627 definition, 3:624 description, 3:624 diagnosis, 3:625, 627 ferritin, 3:627 the future, 3:629 iron supplements, 3:626, 627–628, 656 prevention, 3:628–629 prognosis, 3:628 treatment, 3:626, 627–628 Iron-poor blood. See Iron-deficiency anemia Irritable bowel syndrome, 3:630–635 causes and symptoms, 3:630, 632 comparison to ulcerative colitis, 5:1141 xciii

Index

definition, 3:630 demographics, 3:631–632 description, 3:630–631, 631 diagnosis, 3:633 the future, 3:634–635 prevention, 3:634 prognosis, 3:634 treatment, 3:633–634

Jackson, Stonewall, 4:834 Jenner, Edward, 5:978 Joyner-Kersee, Jackie, 1:72, 72 Jungle fever. See Malaria

Kempe, C. Henry, 1:180 Kennedy, John F., 4:792 Kepler, Johannes, 4:752, 752 Keratoconus, 1:78, 81 Kinetosis. See Motion sickness Kissing disease. See Infectious mononucleosis Klinefelter syndrome, 3:637–642 causes and symptoms, 3:637, 638–639 definition, 3:637 demographics, 3:637–638 description, 3:637, 639 diagnosis, 3:638, 639 the future, 3:640–641 nondisjunction, 3:638, 641 prevention, 3:640 prognosis, 3:640 treatment, 3:639–640 Koch, Robert, 5:1127 Kuru, 2:264, 269

Lachenal, Louis, 2:398 Lactase deficiency. See Lactose intolerance xciv

Lactose intolerance, 3:643–648 causes and symptoms, 3:643–644, 645 definition, 3:643 demographics, 3:644–645 description, 3:643–644 diagnosis, 3:645–646 eliminating lactose from diet, 3:644, 646 the future, 3:647 prevention, 3:647 prognosis, 3:647 treatment, 3:646 Lahr, Bert, 4:834 Laryngitis, 3:648–652 acute laryngitis, 3:648, 649, 650 causes and symptoms, 3:648, 649–650 chronic laryngitis, 3:648, 650 definition, 3:648 demographics, 3:649 description, 3:648 diagnosis, 3:650 the future, 3:651 gastroesophageal reflux disease (GERD), 3:649, 650 prevention, 3:651 prognosis, 3:650–651 smoking, 3:649, 651 treatment, 3:649, 650 Laveran, Charles Louis Alphonse, 4:699 Lead poisoning, 3:652–658 causes and symptoms, 3:652, 653, 653–655 chelation therapy, 3:656, 657 definition, 3:652 demographics, 3:653 description, 3:652–653 diagnosis, 3:655–656 the future, 3:657 prevention, 3:657 prognosis, 3:656 sources of lead poisoning, 3:653, 654 treatment, 3:656 Lead toxicity. See Lead poisoning Learning disorders, 3:658–659 Lens opacity. See Cataracts Leukemia, 3:659–665 acute lymphocytic leukemia (ALL), 3:660, 661, 663, 664 UXL Encyclopedia of Diseases and Disorders

Index

acute myeloid leukemia (AML), 3:660, 661, 663, 664 causes and symptoms, 3:659, 661–662 chronic lymphocytic leukemia (CLL), 3:659–660, 661, 662–663, 664 chronic myeloid leukemia (CML), 3:660, 661, 663, 664 definition, 3:659–660 demographics, 3:660–661 description, 3:659–660 diagnosis, 3:660, 662 in Down syndrome, 2:310, 314, 3:661 the future, 3:664 Philadelphia chromosome, 3:660, 661, 665 prevention, 3:664 prognosis, 3:663–664 treatment, 3:662–663 Leukoderma. See Vitiligo Lewis, Carl, 3:605, 605 Lice infestation, 3:665–670 body or clothing lice, 3:666, 667, 669 causes and symptoms, 3:666, 667 definition, 3:665–666 demographics, 3:666–667 description, 3:666 diagnosis, 3:668 the future, 3:670 head lice, 3:666, 667, 667, 668, 669 nits, 3:666, 667, 668, 669 prevention, 3:669 prognosis, 3:669 pubic lice, 3:666–667, 669 "To a Louse" (poem by Robert Burns), 3:668 treatment, 3:668–669 Lincoln, Abraham, 4:706, 706, 5:1035 Little People of America (LPA), 1:3, 4 Liszt, Franz, 4:834 Lockjaw. See Tetanus Losing one’s voice. See Laryngitis Low blood sugar. See Hypoglycemia Lues. See Syphilis Lung cancer, 3:670–677 asbestos, 3:672, 673 causes and symptoms, 3:671, 673 definition, 3:670–671 UXL Encyclopedia of Diseases and Disorders

demographics, 3:671–672 description, 3:671 diagnosis, 3:672, 673–675 the future, 3:676 non-small cell lung cancer (NSCLC), 3:670–671, 674, 675 prevention, 3:672, 675–676 primary lung cancer, 3:671, 673 prognosis, 3:671–672, 675 radon, 3:672, 673, 676 secondary lung cancer, 3:671 small cell lung cancer (SCLC), 3:670–671, 674, 675 smoking, 3:671, 672, 673, 675, 676, 5:991–992 staging, 3:674–675 treatment, 3:675 Lupus, 3:677–683 causes and symptoms, 3:677, 679–680 definition, 3:677–678 demographics, 3:678–679 description, 3:678 diagnosis, 3:678, 680 discoid lupus, 3:677 drug-induced lupus, 3:677 the future, 3:682 men and lupus, 3:679 neonatal lupus, 3:678 prevention, 3:682 prognosis, 3:681 systemic lupus erythematosus (SLE), 3:677, 681 treatment, 3:681 Lyme disease, 3:683–690 Borrelia burgdorferi, 3:683, 685, 686, 687, 688 causes and symptoms, 3:683, 685, 5:1199 definition, 3:683 demographics, 3:684, 686 description, 3:694 diagnosis, 3:686–687, 694 encephalitis, 2:360 erythema chronicum migrans (EM), 3:684, 684, 685, 687, 689 the future, 3:688–689 history, 3:685 prevention, 3:687–688 prognosis, 3:687 spirochete, 3:683, 686, 689 xcv

Index

ticks, 3:683, 684–686, 685, 687, 688 treatment, 3:687 Lymphocytic lymphoma. See Lymphoma Lymphoma, 3:690–696 B-cell lymphomas, 3:691, 692, 694 causes and symptoms, 3:690, 692 definition, 3:660, 665, 690 demographics, 3:691–692 description, 3:690–691 diagnosis, 3:691, 692–693 the future, 3:695 indolent non-Hodgkin lymphomas, 3:691, 694 intermediate- or high-grade lymphomas, 3:691, 694 prevention, 3:695 prognosis, 3:694–695 staging, 3:693–694 T-cell lymphomas, 3:690, 691, 692, 694 treatment, 3:693–694

Mad cow disease, 2:264, 269 See also Creutzfeldt-Jakob disease Malaria, 4:697–703 causes and symptoms, 4:698, 700, 730 DDT (dichloro-diphenyltrichloroethane) for mosquito control, 4:699 definition, 4:697 demographics, 4:698, 700 description, 4:697–698 diagnosis, 4:700–701 the future, 4:702 Plasmodium (including P. falciparum), 4:697–698, 700–701, 702 prevention, 4:701–702, 730–731 prognosis, 4:701 red blood cell destruction, 4:697–698, 698 and sickle cell trait, 5:952–953 treatment, 4:701 Manic-depressive disorder. See Bipolar disorder Marburg HF. See Ebola and Marburg hemorrhagic fevers Marfan syndrome, 4:704–710 beta blockers, 4:708, 709 xcvi

causes and symptoms, 4:704, 705–707 congenital heart disease, 2:242, 4:704–705, 705, 707, 708, 709 definition, 4:704 demographics, 4:705 description, 4:704–705 diagnosis, 4:707–708 FBN1 gene mutation, 4:704, 705–706, 707, 709–710 fibrillin-1 protein, 4:705–706 the future, 4:710 prevention, 4:709 prognosis, 4:709 scoliosis, 4:704, 707, 708, 709 treatment, 4:708–709 visual disorders, 4:704, 706 Marijuana use, 4:711–717 addiction, 4:714, 715, 716 Cannabis sativa (hemp, marijuana), 4:711, 712 causes and symptoms, 4:711, 712–714 definition, 4:711 demographics, 4:711–712 description, 4:711 diagnosis, 4:714–715 dronabinol, 4:713, 716 the future, 4:716 hashish, 4:711, 716 medical marijuana use, 4:713, 713 prevention, 4:716 prognosis, 4:715–716 THC (delta-9-tetrahydrocannabinol), 4:711, 712, 713, 714 treatment, 4:715 Marker X syndrome. See Fragile X Martin-Bell syndrome. See Fragile X Mary Jane (MJ). See Marijuana use Mast cells, 1:31, 39, 41, 44 McKinley, William, 2:405, 405 Measles, 4:717–723 causes and symptoms, 4:717, 719–720 definition, 4:717 demographics, 4:718–719 description, 4:717–718 diagnosis, 4:720 epidemics among Native Americans, 4:719 UXL Encyclopedia of Diseases and Disorders

Index

the future, 4:722 MMR vaccine, 4:721–722 prevention, 4:721–722 prognosis, 4:721 treatment, 4:720–721 Mediterranean anemia. See Thalassemia Melanoma. See Skin cancer Meningiomas. See Brain tumors Meningitis, 4:723–730 acute meningitis, 4:724, 726, 727 acyclovir, 4:727 bacterial meningitis, 4:723–725, 726–727 causes and symptoms, 4:724, 726 chronic meningitis, 4:724 definition, 4:723–724 demographics, 4:725 description, 4:724–725 diagnosis, 4:726–727 enteroviruses, 4:724 fungal meningitis, 4:725 the future, 4:729 prevention, 4:728 prognosis, 4:727–728 subacute meningitis, 4:724, 726 treatment, 4:727 vaccines, 4:725, 728–729 viral (aseptic) meningitis, 4:723, 724, 726–728 Mental retardation. See Developmental disability Methamphetamine, 1:18, 5:1101 Migraine headaches, 3:472–473, 474, 475, 477 Mild traumatic brain injury (MTBI). See Concussion Minor head trauma. See Concussion MMR vaccine and autism, 1:92 for measles, 4:721–722 for rubella, 4:901, 904 Monet, Claude, 1:157 Mono. See Infectious mononucleosis Monosomy X. See Turner syndrome Morris, Craig, 1:65 Mosaicism definition, 2:315, 349, 4:814, 5:1125, 1138 Down syndrome, 2:312, 314 Edwards syndrome, 2:346–347 UXL Encyclopedia of Diseases and Disorders

Patau syndrome, 4:811 triple X syndrome, 5:1122, 1123 Turner syndrome, 5:1135, 1137 Mosquito-borne diseases, 4:730–731 See also specific diseases Motion sickness, 4:731–736 area postrema, 4:733, 736 causes and symptoms, 4:731, 732, 732–733 central nervous system, effect on balance, 4:733 definition, 4:731 demographics, 4:731–732 description, 4:731 diagnosis, 4:734 eyes, effect on balance, 4:733 the future, 4:735–736 pressure receptors, effect on balance, 4:733 prevention, 4:735 prognosis, 4:735 sensory receptors, effect on balance, 4:733 treatment, 4:734–735 vestibular system, effect on balance, 4:732–733, 736 Mouth ulcers. See Canker sores Mozart, Amadeus, 4:891, 891 MRSA infection. See Staph infection MS. See Multiple sclerosis Mucous colitis. See Irritable bowel syndrome Mucoviscidosis. See Cystic fibrosis Müller, Paul Hermann, 4:699 Multiple chemical sensitivity (MCS), 2:447, 450 Multiple endocrine neoplasia type 2B (MEN 2B), 4:706 Multiple sclerosis, 4:737–743 causes and symptoms, 4:737, 739–740 clinically isolated syndrome (CIS), 4:738, 742 definition, 4:737 demographics, 4:738 description, 4:737–738, 739 diagnosis, 4:738, 740–741 the future, 4:742 prevention, 4:742 primary progressive (PP) multiple sclerosis, 4:737, 738 prognosis, 4:742 progressive relapsing (PR) multiple sclerosis, 4:738 xcvii

Index

relapsing-remitting (RR) multiple sclerosis, 4:737, 739, 742 treatment, 4:741 Muscular dystrophy, 4:743–750 Becker muscular dystrophy, 4:744, 746 causes and symptoms, 1:78, 4:744, 746–747 congenital muscular dystrophy, 4:745, 748 definition, 4:743–744 demographics, 4:746 description, 4:744, 744–745 diagnosis, 4:747–748 distal muscular dystrophy, 4:745, 746 Duchenne muscular dystrophy, 4:744, 746, 748–749 Emery-Dreifuss muscular dystrophy, 4:745, 746 facioscapulohumeral muscular dystrophy, 4:745 the future, 4:749 limb-girdle muscular dystrophy, 4:745, 746 myotonic muscular dystrophy, 4:745 oculopharyngeal muscular dystrophy, 4:745, 746 prevention, 4:748 prognosis, 4:748 scoliosis, 4:747, 748, 749 treatment, 4:748, 749 Myocardial infarction (MI). See Heart attack Myopia, 4:750–756 causes and symptoms, 4:750, 752–753 contact lenses, 4:752, 753, 754 definition, 4:750 demographics, 4:751 description, 4:750–751, 751, 5:1161 diagnosis, 4:753 eyeglasses, 4:752, 753, 754 the future, 4:755 laser surgery, 4:754 lens implantation, 4:754 orthokeratology (Ortho-K), 4:753–754 prevention, 4:754–755 prognosis, 4:754 school myopia, 4:752–753 treatment, 4:753–754 Myxedema. See Hypothyroidism

xcviii

Narcolepsy, 4:757–763 cataplexy, 4:758, 759, 761, 762 causes and symptoms, 4:757, 759–760 definition, 4:757 demographics, 4:758–759 description, 4:757–758, 758 diagnosis, 4:760–761 excessive daytime sleepiness (EDS), 4:759 the future, 4:762 hypnagogic hallucinations, 4:757, 759–760 multiple sleep latency test (MSLT), 4:760 non-rapid eye movement (NREM) sleep, 4:757–758 prevention, 4:761 prognosis, 4:761 rapid eye movement (REM) sleep, 4:757–758 sleep paralysis, 4:758, 760 treatment, 4:761 Nash, John, 4:913 Ndereba, Catherine, 3:501 Nearsightedness. See Myopia Necrotizing fasciitis, 4:763–768 causes and symptoms, 4:765–766 definition, 4:763 demographics, 4:764 description, 4:763, 765 diagnosis, 4:766 fascia infection and destruction, 4:763, 765 the future, 4:767 Group A streptococcus, 4:765 hyperbaric oxygen (HBO) chambers, 4:766 prevention, 4:767 prognosis, 4:766–767 treatment, 4:766 Nervous indigestion. See Irritable bowel syndrome Nettle rash. See Hives Neural tube defect (NTD). See Spina bifida Newton, Chelsea, 2:234 Nicotine dependence. See Smoking


Index

Nobel Prize winners Banting, Frederick, 2:305 Følling, Ivar Asbjørn, 4:823 Koch, Robert, 5:1127 Laveran, Charles Louis Alphonse, 4:699 Müller, Paul Hermann, 4:699 Nash, John, 4:913 Ross, Ronald, 4:699, 699 Wagner-Jauregg, Julius, 4:699 Non-A, non-B hepatitis. See Hepatitis C Non-Hodgkin lymphoma (NHL). See Lymphoma Nontropical sprue. See Celiac disease Nowinski, Christopher, 2:235

Obesity, 4:769–775 body mass index (BMI), 1:185, 191, 4:769, 772, 773, 774 causes and symptoms, 4:769, 771–772 definition, 4:769 demographics, 4:771 description, 4:769–770 diagnosis, 4:772 the future, 4:774–775 genetic factors, 4:770, 771 health effects, 4:770, 773 leptin, 4:774 morbid obesity, definition, 4:769 overweight, definition, 4:769 prevention, 4:774 prognosis, 4:773 treatment, 4:772–773 weight-loss (bariatric) surgery, 4:773 Obesity, childhood. See Childhood obesity Obsessive-compulsive disorder, 4:776–783 causes and symptoms, 4:776, 777, 778–780 compulsions, 4:776, 778, 780, 782 deep brain stimulation (DBS), 4:781–782 definition, 4:776 demographics, 4:777–778 description, 4:776–777 diagnosis, 4:777, 780 UXL Encyclopedia of Diseases and Disorders

exposure and ritual (or response) prevention (ERP), 4:780–781 the future, 4:781–782 obsessions, 4:776, 777, 778, 779, 782 prevention, 4:781 prognosis, 4:781 serotonin reuptake inhibitors (SSRIs), 4:781 treatment, 4:780–781 Yale-Brown Obsessive Compulsive Scale (Y-BOCS), 4:780 OCD. See Obsessive-compulsive disorder Oral herpes. See Cold sore Orofacial cleft. See Cleft lip and palate Orthokeratology (Ortho-K), 1:80, 81, 4:753–754 Osteoarthritis, 4:783–790 arthroscopy, 4:788 causes and symptoms, 1:63, 4:783, 784, 785–786 coping strategies, 4:785 cortisone, 4:787 definition, 4:783 demographics, 4:784–785 description, 1:63–64, 4:783–784, 784 diagnosis, 4:786–787 the future, 4:788–789 glucosamine and chondroitin sulfate, 4:788 nonsteroidal anti-inflammatory drugs (NSAIDs), 4:784, 787 prevention, 4:788 prognosis, 4:788 surgical treatments, 4:788 treatment, 4:785, 787–788 Tylenol (acetaminophen), 4:787 viscosupplements, 4:788 Osteoarthrosis. See Osteoarthritis Osteoporosis, 4:790–796 calcium supplements, 4:792, 794–795 causes and symptoms, 4:790, 793 definition, 4:790 demographics, 4:791–792 description, 4:790–791, 791 diagnosis, 4:793–794 the future, 4:795 in men, 4:792 prevention, 4:794–795 xcix

Index

prognosis, 4:794 T-score, 4:793–794, 795 treatment, 4:794 Type 1 osteoporosis, 4:790, 791 Type 2 osteoporosis, 4:790, 791, 795 Type 3 osteoporosis, 4:790–791 vitamin D, 4:792, 793, 794–795 Otitis externa. See Ear infection Otitis media. See Ear infection Overweight. See Obesity

Pain perception, 2:375 PANDAS disorders (Pediatric Autoimmune Neuropsychiatric Disorders Associated with Streptococcal infections), 4:908, 911, 5:1041, 1043 Panic disorder, 4:797–802 agoraphobia, 4:798, 800, 801 causes and symptoms, 4:797, 799 cognitive behavioral therapy (CBT), 4:800 coping strategies, 4:798 definition, 4:797 demographics, 4:798–799 description, 4:797–798 diagnosis, 4:799–800 exposure therapy, 4:800 the future, 4:801–802 panic attack characteristics, 4:797–798, 801 prevention, 4:801 prognosis, 4:801 treatment, 4:798, 800–801 Paralysis agitans. See Parkinson disease Parasitic diseases, 4:802–803 See also specific diseases Parkinson disease, 4:803–809 causes and symptoms, 4:803, 805–806 deep brain stimulation (DBS), 4:781–782, 808 definition, 4:803 demographics, 4:804–805 description, 4:803–804, 804 diagnosis, 4:806–807 dopamine, 4:805, 807, 808, 809 c

the future, 4:808 levodopa, 4:807 prevention, 4:808 prognosis, 4:808 substantia nigra, 4:805, 807 treatment, 4:807–808 Pasteur, Louis, 1:52, 53, 4:873, 875, 875 Patau syndrome, 4:810–815 causes and symptoms, 4:810–812 congenital heart disease, 2:242, 4:811, 812 definition, 4:810 demographics, 4:810 description, 4:810 diagnosis, 4:812–813 the future, 4:813–814 holoprosencephaly, 4:812 mosaic Patau syndrome, 4:811 nondisjunction, 4:810, 814 polydactyly, 4:812 prevention, 4:813 prognosis, 4:813 rocker-bottom feet, 4:812 spina bifida, 4:812 translocation, 4:811, 814 treatment, 4:813 Pavarotti, Luciano, 4:834 Pediatric traumatic brain injury. See Shaken baby syndrome Pediculosis. See Lice infestation Pelvic inflammatory disease (PID), 1:195, 2:436–437, 439 Peptic ulcer disease (PUD). See Ulcers Peptic ulcers. See Ulcers Periodontal disease, 4:815–820 causes and symptoms, 4:815, 817 definition, 4:815 demographics, 4:816–817 description, 4:815–816 diagnosis, 4:818 the future, 4:820 gingivitis, 4:815–816, 818, 819 periodontitis, 4:815, 816, 819 plaque, 4:815–816, 817, 818, 819 prevention, 4:819 prognosis, 4:818–819 UXL Encyclopedia of Diseases and Disorders

Index

smoking, 4:816–817, 819 tartar, 4:818, 819 treatment, 4:818 Persian Gulf syndrome. See Gulf War syndrome Persistent truncus arteriosus, 2:241 Pertussis. See Whooping cough Pervasive developmental disorder (PDD) definition, 1:64, 69 pervasive developmental disorder not otherwise specified (PDD-NOS), 1:96 See also Asperger syndrome; Autism; Autism spectrum disorders Pharyngitis. See Sore throat Phenylketonuria, 4:821–826 causes and symptoms, 4:821, 822 definition, 4:821 demographics, 4:821–822 description, 4:821 diagnosis, 4:822, 823 the future, 4:825 Kuvan, 4:824, 825 PAH gene, 4:821, 822 PKU diet, 4:821, 823–824 prevention, 4:824 prognosis, 4:824 treatment, 4:823–824 Photodermatitis. See Sunburn Pimples. See Acne Pink eye. See Conjunctivitis Pituitary gigantism. See Gigantism PKU. See Phenylketonuria Plague, 4:826–832 bioterrorism threat, 4:830–831 Black Death pandemic in fourteenth century, 3:611, 4:828, 828 bubonic plague, 4:826, 828, 829, 830 causes and symptoms, 4:826, 827–829 definition, 4:826 demographics, 4:827 description, 4:826 diagnosis, 4:827, 829 the future, 4:830–831 pneumonic plague, 4:826, 829, 830 prevention, 4:830 prognosis, 4:830 UXL Encyclopedia of Diseases and Disorders

rats and fleas as disease vectors, 4:802–803, 827–828, 5:1199 septicemic plague, 4:826, 829 treatment, 4:829–830 Yersinia pestis, 4:826, 827 Plasmodium infection. See Malaria Plumbism. See Lead poisoning Pneumonia, 4:832–839 aspiration pneumonia, 4:833 avian influenza, 1:97, 4:834 bacterial pneumonia, 4:835, 837, 838 causes and symptoms, 4:832, 836 chemical pneumonia, 4:833 community-acquired pneumonia (CAP), 4:833, 839 definition, 4:832–834 demographics, 4:835–836 description, 4:834–835 diagnosis, 4:833, 836–837 famous people killed by pneumonia, 4:834 the future, 4:838 mycoplasmal pneumonia, 4:833, 835, 837, 839 nosocomial pneumonia, 4:833, 839 opportunistic pneumonia, 4:833 Pneumocystis carinii pneumonia, 1:15, 4:833 pneumonia severity index (PSI), 4:837 prevention, 4:838 prognosis, 4:837 severe acute respiratory syndrome, 4:834, 939 staphylococcal pneumonia, 5:1023, 1024, 1025 treatment, 4:837 vaccines, 4:838 ventilator-associated pneumonia, 4:833, 837 viral pneumonia, 4:835, 837 walking pneumonia, 4:833 Pneumonic plague. See Plague Polio, 4:839–846 abortive poliomyelitis, 4:840, 842–843 bulbar polio, 4:843 bulbospinal polio, 4:843 categories of polio, 4:840 causes and symptoms, 4:839, 840, 841–843 definition, 4:839 demographics, 4:841, 841, 845 description, 4:840, 841 ci

Index

diagnosis, 4:843 the future, 4:844–845 nonparalytic meningitis, 4:840, 843 paralytic polio, 4:840, 841, 842, 843–844 post-polio syndrome (PPS), 4:844 prevention, 4:844 prognosis, 4:844 Roosevelt, Franklin Delano, 4:842, 842 Sabin vaccine, 4:840, 844 Salk vaccine, 4:840, 842, 844 spinal polio, 4:843, 844 treatment, 4:843 Poliomyelitis. See Polio Post-viral fatigue syndrome. See Chronic fatigue syndrome Postnatal depression. See Postpartum depression Postpartum depression, 4:846–851 baby blues, 4:846, 847, 851 causes and symptoms, 4:846, 848–849 cognitive behavioral therapy (CBT), 4:849 definition, 2:283, 289, 4:846 demographics, 4:847–848 description, 4:846–847 diagnosis, 4:849 Edinburgh Postnatal Depression Scale, 4:849 the future, 4:850 postpartum psychosis, 4:846–847, 850, 851 prevention, 4:850 prognosis, 4:850 treatment, 4:849–850 Yates, Andrea, 4:847 Posttraumatic stress disorder, 4:851–858 causes and symptoms, 4:852, 854–855 definition, 4:851–852 demographics, 4:852, 854 description, 4:852, 853 diagnosis, 4:855 flashbacks, 4:852, 853, 854, 857 following terrorist attacks of September 11, 2001, 4:852, 854 the future, 4:856 prevention, 4:856 prognosis, 4:856 treatment, 4:855–856 Pot. See Marijuana use cii

Prader-Willi syndrome, 1:187, 191 Premature birth. See Prematurity Prematurity, 4:858–864 causes and symptoms, 4:858, 860–861 definition, 4:858 demographics, 4:859–860 description, 4:858–859, 859 diagnosis, 4:861 extremely low birth weight (ELBW) babies, 4:859, 863 the future, 4:864 incubators, 4:862 low birth weight (LBW) babies, 4:858 monitoring of breathing, 4:862 nutrition and fluids, 4:862 prevention, 4:861, 863–864 progesterone, 4:859, 861, 864 prognosis, 4:863 surfactant, 4:862 treatment, 4:859, 861–863 very low birth weight (VLBW) babies, 4:859, 862 Preterm birth. See Prematurity Prion diseases fatal familial insomnia (FFI), 2:264, 269 kuru, 2:264, 269 mad cow disease, 2:264, 269 prion, definition, 2:263, 265–266, 269, 5:1199 scrapie, 2:264, 269 See also Creutzfeldt-Jakob disease Problem drinking. See Alcoholism Progeria. See Hutchinson-Gilford syndrome Prostate cancer, 4:865–871 benign prostatic hypertrophy (BPH), 4:865, 867, 870 biopsies, 4:867–868 causes and symptoms, 4:865, 867 chemotherapy, 4:869 cryotherapy, 4:869, 870 definition, 4:865 demographics, 4:866–867 description, 4:865–866 diagnosis, 4:866, 867 digital rectal examination (DRE), 4:867, 868 the future, 4:870 UXL Encyclopedia of Diseases and Disorders

Index

hormone therapy, 4:869 metastasis, 4:865, 870 prevention, 4:869–870 prognosis, 4:869 prostate-specific antigen test (PSA), 4:867, 868 prostatectomy, 4:869, 870 radiation therapy, 4:868–869 staging, 4:868 surgery, 4:869 transurethral resection of the prostate (TURP), 4:869 treatment, 4:868–869 watchful waiting, 4:868 Psychological stress. See Stress Psychotherapy, 2:287, 5:1047 PTSD. See Posttraumatic stress disorder Pulled muscles. See Sprains and strains

Rabies, 4:873–879 animal species as source, 4:873–874 causes and symptoms, 4:873, 875–876, 5:1199 definition, 4:873 demographics, 4:874–875 description, 4:873–874 diagnosis, 4:874, 876 the future, 4:878 immune globulin, 4:876, 877 post-exposure prophylaxis (PEP), 4:877–878 prevention, 4:877–878 prognosis, 4:877 rabies virus, 4:874, 875 treatment, 4:876–877 vaccine, 4:873, 874–875, 877, 878 Ragpicker’s disease. See Anthrax Reading disorder. See Dyslexia Red eye. See Conjunctivitis Regional enteritis. See Crohn disease Restless legs syndrome, 4:880–884 causes and symptoms, 4:880, 881–882 definition, 4:880 demographics, 4:880–881 description, 4:880 UXL Encyclopedia of Diseases and Disorders

diagnosis, 4:881, 882 the future, 4:883 prevention, 4:883 prognosis, 4:883 treatment, 4:882–883 yoga therapy, 4:882 Reye, Ralph Douglas, 4:886 Reye-Johnson syndrome. See Reye syndrome Reye syndrome, 4:884–888 aspirin risk, 1:176, 3:621, 4:720, 885–886, 888 causes and symptoms, 4:884, 885–886 definition, 1:176, 3:623, 4:884 demographics, 4:884–885 description, 4:884 diagnosis, 4:885, 886–887 the future, 4:888 prevention, 4:888 prognosis, 4:887–888 treatment, 4:887 Rheumatic fever, 4:889–894 carditis, 4:890, 890, 892, 893 causes and symptoms, 4:889, 892 chorea, 4:890, 891, 892, 893 definition, 4:889 demographics, 4:890–891 description, 3:492, 4:889–890, 891 diagnosis, 4:892 the future, 4:894 Group A streptococcus, 4:889, 892, 893 nodules beneath the skin, 4:890, 892 prevention, 4:893 prognosis, 4:893 rheumatic heart disease, 4:889, 890, 890, 891, 894 treatment, 4:893 Rheumatoid arthritis, 4:894–900 anti-CCP test, 4:897 anti-inflammatory drugs, 4:898 biologic response modifiers (biologics), 4:898, 900 causes and symptoms, 4:895, 896–897 definition, 4:894–895 demographics, 4:895–896 description, 1:64, 4:895, 896 diagnosis, 4:897 ciii

Index

disease-modifying anti-rheumatic drugs (DMARDs), 4:898, 900 flares, 4:895, 899 the future, 4:899–900 nodules beneath the skin, 4:895, 897 prevention, 4:899 prognosis, 4:899 remissions, 4:895, 899 rheumatoid factor (RF), 4:897 Sjögren syndrome, 4:897, 5:958 treatment, 1:64, 4:897–899 Rodríguez Vargas, Fernando, 5:1100 Roebling, John Augustus, 5:1083, 1083 Roosevelt, Franklin Delano, 4:842, 842 Rose fever. See Hay fever Rosenthal, Norman, 4:928 Ross, Ronald, 4:699, 699 Roussimoff, André (André the Giant), 2:424, 424 Royal disease. See Hemophilia Rubella, 4:901–905 causes and symptoms, 4:901, 902–903 congenital rubella syndrome (CRS), 4:901–902, 903, 904 definition, 4:901 demographics, 4:901–902 description, 4:901 diagnosis, 4:903 the future, 4:904 measles-mumps-rubella (MMR) vaccine, 1:92, 4:721–722, 901, 904 prevention, 4:903–904 prognosis, 4:903 rash, 4:901, 902, 902–903 treatment, 4:903 Rubeola. See Measles Rudolph, Wilma, 4:909, 909 Ryan White CARE Act, 1:14

S. aureus infection. See Staph infection; Toxic shock syndrome SAD. See Seasonal affective disorder civ

Salk, Jonas, 4:842 SARS. See Severe acute respiratory syndrome Saudi flu. See Gulf War syndrome Scalds. See Burns and scalds Scarlatina. See Scarlet fever Scarlet fever, 4:907–912 causes and symptoms, 4:907, 908–910 definition, 4:907 demographics, 4:908 description, 4:907–908 diagnosis, 4:908, 910 Forchheimer spots, 4:909, 911 the future, 4:912 Group A streptococcus, 4:907, 908, 911, 912 PANDAS disorders, 4:908, 911, 5:1041, 1043 prevention, 4:911–912 prognosis, 4:911 treatment, 4:910 Schizophrenia, 4:912–920 causes and symptoms, 4:913, 915–916 definition, 4:912–913 delusions, 4:913, 915, 916, 918 demographics, 4:914–915 description, 4:913–914 diagnosis, 4:914, 916 drug and alcohol abuse, 4:913–914, 917 the future, 4:919 hallucinations, 4:913, 915, 916, 918 prevention, 4:918 prognosis, 4:918 treatment, 4:917–918 Schultz, Charles, 2:222, 222 Scoliosis, 4:920–926 braces, 4:921, 924 causes and symptoms, 4:920, 922–923 cerebral palsy, 1:167, 172, 4:924 congenital scoliosis, 4:921, 922 definition, 4:920 demographics, 4:921–922 description, 4:920–921, 921 diagnosis, 4:923 the future, 4:925 idiopathic scoliosis, 4:920, 923–924 Marfan syndrome, 4:704, 707, 708, 709 muscular dystrophy, 4:747, 748, 749, 924 UXL Encyclopedia of Diseases and Disorders

Index

nonstructural (functional) scoliosis, 4:920 prevention, 4:925 prognosis, 4:924 spina bifida, 5:1005, 1006 structural scoliosis, 4:920 surgery, 4:924 treatment, 4:923–924 Scopolamine patch, 1:104, 4:734 Scrapie, 2:264, 269 Seasickness. See Motion sickness Seasonal affective disorder, 4:926–931 causes and symptoms, 4:926, 928–929 circadian rhythm disruptions, 4:928 definition, 2:283–284, 4:926 demographics, 4:927–928 description, 4:926–927 diagnosis, 4:929 the future, 4:930 light therapy, 4:927, 928, 929–930 melatonin, 4:928, 930, 931 prevention, 4:930 prognosis, 4:930 serotonin, 4:928, 931 summer SAD (reverse seasonal affective disorder, RSAD), 4:926, 927, 928, 929, 930 treatment, 4:927, 929–930 Seizure disorder, 4:932–938 causes and symptoms, 4:932, 934–935 complex focal seizures, 4:935 definition, 4:932 demographics, 4:934 description, 4:932–933 diagnosis, 4:933, 935–936 electroencephalogram (EEG), 4:933, 936 first aid, 4:934 focal seizures, 4:932–933, 935 the future, 4:937 generalized absence (petit mal) seizures, 4:935 generalized atonic seizures, 4:935 generalized (grand mal) seizures, 4:932, 934 generalized myoclonic seizures, 4:935 generalized tonic-clonic seizures, 4:935 intractable epilepsy, 4:937 nonepileptic seizures, 4:933 prevention, 4:937 UXL Encyclopedia of Diseases and Disorders

prognosis, 4:937 simple focal seizures, 4:935 status epilepticus, 4:933, 937 treatment, 4:934, 936 triggers, 4:933 vagus nerve stimulator, 4:936 Selye, Hans, 5:1043 Septicemic plague. See Plague Severe acute respiratory syndrome, 4:938–944 causes and symptoms, 4:939, 940 definition, 4:938–939 demographics, 4:939–940 description, 4:939 diagnosis, 4:940–942 the future, 4:943 pneumonia, 4:834, 939 prevention, 4:942–943 prognosis, 4:942 SARS virus (SARS-associated coronavirus, SARS-CoV), 4:939, 940, 940 treatment, 4:942 Sexually transmitted diseases, 4:944–945 See also specific diseases Shaken baby syndrome, 5:947–951 advice for caregivers, 5:948 causes and symptoms, 5:947, 948–949 definition, 5:947 demographics, 5:947–948 description, 5:947 diagnosis, 5:949 the future, 5:950 prevention, 5:948, 950 prognosis, 5:949 treatment, 5:949 Shaken infant syndrome. See Shaken baby syndrome Shaking palsy. See Parkinson disease Short-limb dwarfism. See Achondroplasia Shortsightedness. See Myopia Siamese twins. See Conjoined twins Sickle cell anemia, 5:951–957 bone marrow transplant (BMT), 5:955, 956 causes and symptoms, 1:45, 5:952, 953–954 definition, 5:951–952 demographics, 5:952–953 description, 1:45, 5:952 cv

Index

diagnosis, 5:954–955 effect on red blood cells, 5:952, 953 eye disorders, 5:952, 954 the future, 5:956–957 hand/foot syndrome, 5:954 hemoglobin S, 5:952, 955, 956 hydroxyurea, 5:955 prevention, 5:956 prognosis, 5:956 resistance to malaria, 5:952–953 sickle cell crisis, 5:952, 954, 955, 957 sickle cell trait, 5:952–953, 955, 956 strokes, 5:952, 954 treatment, 5:955–956 Sickle cell disease. See Sickle cell anemia Sideropenic anemia. See Iron-deficiency anemia SIDS. See Sudden infant death syndrome Sin Nombre virus (SNV). See Hantavirus infection Sjögren syndrome, 5:958–963 causes and symptoms, 5:958, 959–960 definition, 4:897, 5:958 demographics, 5:958–959 description, 5:958 diagnosis, 5:959, 960–961 the future, 5:962 neonatal lupus, 3:678 prevention, 5:962 prognosis, 5:962 with rheumatoid arthritis, 4:897, 5:958 tooth decay, 5:959, 961, 962, 1101 treatment, 5:961 xerostomia, 5:959, 962 Skin cancer, 5:963–970 basal cell carcinoma (BCC), 5:963–964, 965, 966, 967 causes and symptoms, 5:963, 965–966, 1065 definition, 5:963 demographics, 5:964–965 description, 5:963–964 diagnosis, 5:966 the future, 5:968–969 melanoma, 5:964–966, 967, 969, 1066 prevention, 5:967–968 prognosis, 5:967 self-examination of skin, 5:968 cvi

solar keratoses, 5:964, 965, 966, 969 squamous cell carcinoma (SCC), 5:964, 965, 966, 967 and sunburn, 5:1064, 1065, 1066, 1067 tanning and ultraviolet exposure, 5:964, 965, 967–968 treatment, 5:966–967 Skin rash. See Dermatitis Sleep apnea, 5:970–976 causes and symptoms, 5:970, 973 central sleep apnea (CSA), 5:970, 971, 975 complex (or mixed) sleep apnea, 5:970 continuous positive airway pressure device (CPAP) devices, 5:971, 975, 976 definition, 5:970 demographics, 5:972–973 description, 5:970–972 diagnosis, 5:973 the future, 5:975–976 obstructive sleep apnea (OSA), 5:970–972, 974 polysomnography, 5:973 prevention, 5:975 prognosis, 5:975 treatment, 5:974–975 Sleep disorders, 5:977 See also specific disorders Smallpox, 5:977–984 causes and symptoms, 5:978, 980 cowpox, 5:978 definition, 5:977–978 demographics, 5:979 description, 5:978–979, 979 diagnosis, 5:980–981 differences from chickenpox, 5:980–981 epidemics in eighteenth century, 3:611 eradication of disease, 5:978 the future, 5:982–983 hemorrhagic smallpox, 5:982 malignant smallpox, 5:982 prevention, 5:978, 982 prognosis, 5:982 treatment, 5:981–982 vaccination, 5:978, 981–982 variola major, 5:978, 982 UXL Encyclopedia of Diseases and Disorders

Index

variola minor, 5:978, 982 variola virus, 5:977–978, 980 Smoke inhalation, 5:984–990 and burns, 1:137 causes and symptoms, 5:984, 986–987 definition, 5:984 demographics, 5:985–986 description, 1:137, 5:984–985, 985 diagnosis, 5:987 the future, 5:989 hyperbaric oxygen (HBO) chambers, 5:988, 989 personal safety, 5:986 prevention, 5:988–989 prognosis, 5:988 treatment, 5:987–988 Smoke-related injury. See Smoke inhalation Smoking, 5:990–997 American Cancer Society (ACS), 5:992 bronchitis, 1:125, 128 cataracts, 1:156, 159 causes and symptoms, 5:990, 993 chronic obstructive pulmonary disease, 1:202–203 coronary artery disease, 2:259, 260, 262 Crohn disease, 2:273 definition, 5:990 demographics, 5:992–993 description, 5:990–992, 991 diagnosis, 5:993–994 emphysema, 2:353–354, 357 the future, 5:996 gangrene, 2:403, 406 heart attack, 3:490 hypercholesterolemia, 3:574, 576 laryngitis, 3:649, 651 lung cancer, 3:671, 672, 673, 675, 676, 5:991–992 lung tissue damage, 5:991 nicotine, 5:990–991, 993, 995 nicotine vaccines, 5:996 nicotine withdrawal, 5:993–994, 993–995 periodontal disease, 4:816–817, 819 prevention, 5:995 prognosis, 5:995 UXL Encyclopedia of Diseases and Disorders

smoking cessation, 5:994–995 treatment, 5:994 Snellen chart, 1:78, 157, 159, 4:753, 755 Soft tissue gangrene. See Necrotizing fasciitis Sore throat, 5:997–1002 causes and symptoms, 5:997, 998–999 definition, 5:997 demographics, 5:998 description, 5:997–998 diagnosis, 5:998, 999–1000 the future, 5:997, 999, 1001 prevention, 5:1001 prognosis, 5:1000–1001 treatment, 5:1000 Spanish fever. See Influenza Spastic colon. See Irritable bowel syndrome Spastic paralysis. See Cerebral palsy Spina bifida, 5:1002–1008 causes and symptoms, 5:1002, 1004–1005 definition, 5:1002 demographics, 5:1004 description, 5:1002–1003, 1003 diagnosis, 5:1003, 1006 and euthanasia, 5:1004 folic acid, 5:1004–1005 the future, 5:1007 hydrocephalus, 5:1005, 1006, 1007 meningocele, 5:1003, 1005, 1006 myelomeningocele (open spina bifida), 5:1003, 1004, 1005, 1006 prevention, 5:1004–1005, 1007 prognosis, 5:1006–1007 scoliosis, 5:1005, 1006 spina bifida occulta, 5:1003, 1005, 1006 tethering of the spinal cord, 5:1005 treatment, 5:1006 Spinal cord injury, 5:1008–1014 causes and symptoms, 5:1008, 1010–1011 definition, 5:1008–1009 demographics, 5:1009–1010 description, 5:1009 diagnosis, 5:1009, 1011 first aid, 5:1009, 1010, 1013 the future, 5:1013 Medrol, 5:1012, 1013 cvii

Index

patterns of disability by vertebrae, 5:1010–1011 prevention, 5:1013 prognosis, 5:1012 treatment, 5:1010, 1011–1012 Spinal cord trauma. See Spinal cord injury Spinal meningitis. See Meningitis Sprains and strains, 5:1014–1020 causes and symptoms, 5:1014, 1016, 1017 classification, 5:1015, 1016 definition, 5:1014–1015 demographics, 5:1016–1017 description, 5:1015, 1016 diagnosis, 5:1015, 1017 eversion injury, 5:1015 the future, 5:1019 inversion injury, 5:1014–1015 prevention, 5:1018–1019 prognosis, 5:1018 treatment, 5:1018 Squint eye. See Strabismus St. Vitus’ dance. See Huntington disease Staging of cancer. See Cancer staging Stanwyck, Barbara, 2:353 Staph infection, 5:1020–1027 causes and symptoms, 5:1020, 1022–1023 definition, 5:1020 demographics, 5:1020 description, 5:1020–1021 diagnosis, 5:1023–1024 endocarditis, 5:1022–1023, 1024, 1025 eye infections, 5:1023, 1024–1025 food poisoning, 5:1023, 1025 the future, 5:1026 joint infections, 5:1023, 1024 methicillin-resistant Staphylococcus aureus (MRSA), 5:1021, 1021, 1022 pneumonia, 5:1023, 1024, 1025 prevention, 5:1025–1026 prognosis, 5:1025 skin and soft tissue infections, 5:1022, 1024 staph carriers, 5:1021 Staphylococcus aureus, 5:1020–1021, 1022, 1023, 1025 Staphylococcus epidermidis, 5:1021, 1022, 1023 treatment, 5:1024–1025 cviii

Staphylococcal infection. See Staph infection STDs. See Sexually transmitted diseases Steroid use, 5:1027–1033 causes and symptoms, 5:1027, 1029–1030 corticosteroids (glucocorticoids), 5:1027 cycling, 5:1029, 1032 definition, 5:1027 demographics, 5:1029 description, 5:1027–1029, 1028 diagnosis, 5:1030–1031 the future, 5:1032 prevention, 5:1031–1032 prognosis, 5:1031 stacking, 5:1029, 1032 treatment, 5:1031 Still, George, 1:83 Strabismus, 5:1033–1038 and amblyopia, 3:581, 582, 5:1034, 1036, 1038 causes and symptoms, 1:78, 5:1033, 1035–1036 definition, 5:1033, 1161 demographics, 5:1035 description, 5:1033–1034, 1034 diagnosis, 5:1035, 1036–1037 the future, 5:1038 prevention, 5:1037–1038 prognosis, 5:1037 pseudostrabismus (false strabismus), 5:1034 treatment, 5:1037 Strep throat, 5:1039–1043 causes and symptoms, 5:1039–1040 definition, 5:1039 demographics, 5:1039 description, 5:1039 diagnosis, 5:1000, 1040, 1040, 1042, 1095 the future, 5:1042 Group A streptococcus, 5:1039, 1041, 1042, 1043 PANDAS disorders, 4:908, 911, 5:1041, 1043 prevention, 5:1042 prognosis, 5:1000–1001, 1041 treatment, 5:1000, 1040–1041 Streptococcal infection, Group A. See Group A streptococcus Streptococcal pharyngitis. See Strep throat Streptococcal sore throat. See Strep throat Stress, 5:1043–1050 UXL Encyclopedia of Diseases and Disorders

Index

causes and symptoms, 5:1044, 1046–1047 definition, 5:1043–1044 demographics, 5:1045–1046 description, 5:1044–1045 diagnosis, 5:1047 eustress, 5:1044, 1049 the future, 5:1049 hypothalamic-pituitary-adrenal (HPA) system, 5:1044 lifestyle changes, 5:1047 prevention, 5:1048–1049 prognosis, 5:1048 psychotherapy, 5:1047 relaxation response, 5:1045 stress hormones, 5:1044–1046, 1046 stress management, 5:1048, 1049 stressors, 5:1043–1044, 1045, 1049 treatment, 5:1047–1048 Stroke, 5:1050–1057 aneurysm, 3:585, 5:1053, 1054, 1056 causes and symptoms, 5:1050, 1051, 1053 definition, 5:1050 demographics, 5:1051–1052 description, 5:1050–1051 diagnosis, 5:1053–1054 first aid, 5:1052 the future, 5:1055–1056 hemorrhagic stroke, 5:1050, 1053, 1054, 1055 ischemic stroke, 5:1050, 1053, 1054, 1055, 1056 plasminogen activator (tPA), 5:1052, 1056 prevention, 5:1055 prognosis, 5:1055 rehabilitation, 5:1051, 1054 transient ischemic attacks (TIAs), 5:1050–1051, 1055 treatment, 5:1051, 1052, 1054 Strzelczyk, Justin, 2:235 Sudden infant death syndrome, 5:1057–1062 “Back to Sleep” campaign, 5:1058 causes and symptoms, 5:1057, 1059–1060 definition, 5:1057 demographics, 5:1057–1059 description, 5:1057 UXL Encyclopedia of Diseases and Disorders

diagnosis, 5:1060 distinguishing SIDS from child abuse, 5:1060–1061 the future, 5:1061–1062 prevention, 5:1058, 1061 treatment, 5:1060–1061 Sudden unexpected death in infancy. See Sudden infant death syndrome Sunburn, 5:1063–1068 actinic keratosis, 5:1064, 1067 cataracts, 5:1066, 1067 causes and symptoms, 5:1063, 1064–1065 definition, 5:1063 demographics, 5:1063 description, 5:1063, 1064 diagnosis, 5:1065 first aid, 5:1065 the future, 5:1067 prevention, 5:1066 prognosis, 5:1066 skin cancer, 5:1064, 1065, 1066, 1067 treatment, 5:1065–1066 See also Dermatitis Swimmer’s ear. See Ear infection Swimmer’s itch. See Dermatitis Syphilis, 5:1068–1074 causes and symptoms, 5:1068, 1071 chancres, 5:1069, 1071, 1072, 1073 definition, 5:1068 demographics, 5:1070–1071 description, 5:1068–1070, 1069 diagnosis, 5:1072 the future, 5:1073 gummas, 5:1070, 1073 latent (dormant) syphilis, 5:1069–1070, 1071 prevention, 5:1073 primary syphilis, 5:1069, 1070, 1071, 1072, 1073 prognosis, 5:1073 rapid plasma reagin test (RPR), 5:1072 secondary syphilis, 5:1069, 1069, 1070, 1071, 1072, 1073 spirochete, 5:1068–1069, 1072, 1073 tertiary syphilis, 5:1070, 1071, 1072–1073 treatment, 5:1070, 1072–1073 cix

Index

Treponema pallidum, 5:1068, 1071, 1072, 1073 Venereal Disease Research Laboratory Test (VDRL), 5:1072 Systemic lupus erythematosus (SLE). See Lupus

Tattooing, 5:1165 Tay-Sachs disease (TSD), 2:278 TB. See Tuberculosis Tendinitis, 5:1075–1080 Achilles tendinitis, 5:1076, 1077, 1080 causes and symptoms, 5:1075, 1077 definition, 5:1075 demographics, 5:1076–1077 description, 5:1075–1076, 1076 diagnosis, 5:1078 extracorporeal shockwave therapy (ESWT), 5:1078–1079 the future, 5:1079–1080 golfer’s elbow, 5:1075, 1076, 1077, 1078 jumper’s knee, 5:1075 knee tendinitis, 5:1077 nonsteroidal anti-inflammatory drugs (NSAIDs), 5:1077, 1078, 1079–1080 pitcher’s shoulder, 5:1075, 1076 prevention, 5:1079 prognosis, 5:1079 rotator cuff tendinitis, 5:1075, 1077, 1078 tennis elbow, 5:1075, 1076, 1077, 1079 treatment, 5:1077, 1078–1079 Tendinopathy. See Tendinitis Tension. See Stress Tetanus, 5:1081–1086 causes and symptoms, 5:1081, 1082–1084 cephalic tetanus, 5:1081, 1085 Clostridium tetani, 5:1081 definition, 5:1081 demographics, 5:1081–1082 description, 5:1081, 1082 diagnosis, 5:1084 the future, 5:1085 generalized tetanus, 5:1081, 1085 cx

local tetanus, 5:1081, 1085 neonatal tetanus, 5:1081, 1082, 1082, 1085 prevention, 5:1085 prognosis, 5:1085 tetanus immune globulin (TIG), 5:1084 treatment, 5:1084 vaccine, 5:1081, 1085, 1089–1190 Tetralogy of Fallot, 2:240, 244 Thalassemia, 5:1086–1092 alpha thalassemia, 5:1087–1089, 1090, 1091 beta thalassemia, 5:1087, 1088, 1089, 1090, 1091 blood transfusions, 5:1089–1090 causes and symptoms, 5:1086, 1087, 1088–1089 chelation therapy, 5:1089–1090, 1091 Cooley’s anemia (thalassemia major), 5:1087, 1089, 1090, 1091 definition, 5:1086 demographics, 5:1087–1088 description, 1:45, 5:1086–1087 Desferal, 5:1090 diagnosis, 5:1089 the future, 5:1091 hemoglobin H disease, 5:1088, 1089, 1090 hydrops fetalis (alpha thalassemia major), 5:1087, 1089, 1090, 1091 prevention, 5:1091 prognosis, 5:1090 thalassemia intermedia, 5:1089 thalassemia minor, 5:1089 thalassemia trait, 5:1087, 1088, 1091 treatment, 5:1089–1090 Theotokopoulos, Domenikos (El Greco), 1:79, 79 Thermal injuries. See Burns and scalds Thin bones. See Osteoporosis Thomas, Lee, 5:1164 Three-day measles. See Rubella Thyroid-stimulating hormone (TSH), 3:463, 464, 605, 606–607 Tick-borne diseases, 5:1092 See also specific diseases Tierney, Gene, 4:904 Tolstoy, Leo, 4:834 UXL Encyclopedia of Diseases and Disorders

Index

Tonsillar sore throat. See Tonsillitis Tonsillitis, 5:1093–1098 antibiotic overuse, 5:1097 causes and symptoms, 5:1093, 1094–1095 definition, 5:1093 demographics, 5:1093–1094 description, 5:1093, 1094 diagnosis, 5:1094, 1095 Epstein-Barr virus (EBV), 5:1094, 1095 the future, 5:1097 Group A streptococcus, 5:1094, 1096, 1097 prevention, 5:1096–1097 prognosis, 5:1096 recurrent tonsillitis, 5:1093, 1096 tonsillectomy, 5:1095, 1096, 1097 treatment, 5:1095–1096 Tooth cavities. See Tooth decay Tooth decay, 5:1098–1104 abscesses, 5:1099, 1101, 1102, 1103 brushing, 5:1098, 1103 causes and symptoms, 5:1098, 1101 definition, 5:1098 demographics, 5:1099–1101 dentin, 5:1099, 1101, 1103 description, 5:1098–1099, 1099 diagnosis, 5:1101–1102 enamel, 5:1098–1099, 1101, 1103 extraction, 5:1102 fillings (dental restorations), 5:1102 flossing, 5:1098, 1103 fluoride, 5:1100, 1102, 1103 the future, 5:1103 plaque, 5:1098, 1101, 1103 prevention, 5:1102–1103 prognosis, 5:1102 pulp, 5:1099, 1101, 1102, 1103 root canal, 5:1102 Sjögren syndrome, 5:959, 961, 962, 1101 tartar, 5:1098, 1103 toothache, 5:1098, 1099, 1101 treatment, 5:1102 Tourette syndrome, 5:1104–1110 causes and symptoms, 5:1105, 1107 coprolalia, 5:1105, 1109 deep brain stimulation (DBS), 4:781–782, 5:1109 UXL Encyclopedia of Diseases and Disorders

definition, 1:69, 5:1104–1105 demographics, 5:1105–1106 description, 5:1105, 1106 diagnosis, 5:1107–1108 the future, 5:1109 prevention, 5:1109 prognosis, 5:1108–1109 tics, 5:1104–1105, 1107–1108, 1109 treatment, 5:1108 Toxic shock syndrome, 5:1110–1116 causes and symptoms, 5:1110, 1112–1113 definition, 5:1110 demographics, 5:1111–1112 description, 5:1110–1111, 1111 diagnosis, 5:1113 the future, 5:1115 and menstruation, 5:1110–1111 prevention, 5:1114 prognosis, 5:1114 Staphylococcus aureus, 5:1110, 1111, 1112, 1114, 1115 Streptococcus pyogenes (Group A streptococcus), 5:1110, 1111, 1112, 1114, 1115 tampons, 5:1110–1111, 1112, 1114 toxic shock-like syndrome (TSLS), 5:1110, 1111, 1113–1114, 1115 treatment, 5:1113–1114 Toxoplasma infection. See Toxoplasmosis Toxoplasmosis, 5:1116–1121 and AIDS, 1:15, 5:1117, 1118, 1120 cats as disease vectors, 4:803, 5:1116, 1117–1118 causes and symptoms, 5:1116, 1117–1119 definition, 5:1116 demographics, 5:1116–1117 description, 5:1116 diagnosis, 5:1117, 1119–1120 encephalitis, 2:360 the future, 5:1121 and pregnancy, 5:1116, 1118, 1119–1120 prevention, 5:1120 prognosis, 5:1120 Toxoplasma gondii, 5:1116 treatment, 5:1120 Trachoma, 1:192, 193, 195 cxi

Index

Transmissible spongiform encephalopathy (TSE). See Creutzfeldt-Jakob disease Transposition of the great vessels (TGA), 2:240 Treponema pallidum infection. See Syphilis Tricuspid atresia, 2:241 Triple X syndrome, 5:1122–1126 causes and symptoms, 5:1122–1124 definition, 5:1122 demographics, 5:1122 description, 5:1122, 1123 diagnosis, 5:1124 the future, 5:1125 mosaic trisomy X, 5:1122, 1123 nondisjunction, 5:1122–1123, 1125 prevention, 5:1125 prognosis, 5:1124–1125 treatment, 5:1124 Trisomy 13. See Patau syndrome Trisomy 18. See Edwards syndrome Trisomy 21. See Down syndrome Trisomy XXX. See Triple X syndrome Tuberculosis, 5:1126–1133 active TB, definition, 5:1127 causes and symptoms, 5:1127, 1129–1130 definition, 5:1126–1127 demographics, 5:1128–1129 description, 5:1127–1128 diagnosis, 5:1128, 1130 directly observed therapy (DOT), 5:1131 extremely drug-resistant TB (XDR-TB), 5:1129, 1132 the future, 5:1132 isoniazid (INH), 5:1129, 1130–1131 latent TB, 5:1127, 1128, 1130, 1131, 1132 Mantoux test (PPD test), 5:1130, 1132 multiple drug-resistant tuberculosis (MDR-TB), 5:1129, 1130, 1131, 1132 Mycobacterium tuberculosis, 5:1126, 1127, 1128, 1129 prevention, 5:1131–1132 prognosis, 5:1131 QuantiFERON-TB Gold (QFT) test, 5:1132 reactivation TB, 5:1127, 1128 rifampin, 5:1129 cxii

treatment, 5:1130–1131 vaccine, 5:1132 Tubman, Harriet, 4:834, 834 Turner syndrome, 5:1133–1139 causes and symptoms, 5:1133, 1135–1136 childhood obesity, 1:187 congenital heart disease, 2:242 definition, 5:1133 demographics, 5:1134–1135 description, 5:1133–1134 diagnosis, 5:1134, 1136 estrogen replacement therapy, 5:1136–1137, 1138 the future, 5:1138 growth hormone therapy, 5:1136–1137, 1138 hypothyroidism, 5:1136 mosaic Turner syndrome, 5:1135, 1137 nondisjunction, 5:1135, 1138 prevention, 5:1137–1138 prognosis, 5:1137 treatment, 5:1136–1137 Twisted ankle. See Sprains and strains

Ulcerative colitis, 5:1141–1147 causes and symptoms, 5:1141, 1143 colonoscopy, 5:1144 comparison to Crohn disease, 5:1141, 1142, 1143, 1144 comparison to irritable bowel syndrome, 5:1141 definition, 5:1141 demographics, 5:1142–1143 description, 5:1141–1142 diagnosis, 5:1142, 1144 fulminant colitis, 5:1142, 1145 the future, 5:1146 pancolitis, 5:1141, 1146 prevention, 5:1145 proctitis, 5:1141, 1145, 1146 prognosis, 5:1145 sigmoidoscopy, 5:1144 treatment, 5:1144–1145 UXL Encyclopedia of Diseases and Disorders

Index

Ulcers, 5:1147–1153 causes and symptoms, 5:1147, 1148–1149 definition, 5:1147 demographics, 5:1147–1148 description, 5:1147, 1148 diagnosis, 5:1150 endoscopy, 5:1148, 1150 the future, 5:1152 Helicobacter pylori (H. pylori), 1:145, 5:1148–1149, 1150–1152 nonsteroidal antiinflammatory drugs (NSAIDs), 5:1148, 1149, 1150, 1151, 1152 perforated ulcers, 5:1148 prevention, 5:1151–1152 prognosis, 5:1151 treatment, 5:1150–1151 upper GI (gastrointestinal) series, 5:1150 Ullrich-Turner syndrome. See Turner syndrome Unsoeld, Willi, 2:398 Urbani, Carlo, 4:941, 941 Urinary tract infections, 5:1153–1159 causes and symptoms, 5:1153, 1156 in children, 5:1155 cystitis, 5:1153, 1154, 1157, 1159 definition, 5:1153 demographics, 5:1155–1156 description, 5:1153–1155, 1154 diagnosis, 5:1156–1157 the future, 5:1158 prevention, 5:1158 prognosis, 5:1157 pyelonephritis, 5:1153, 1154–1155, 1157, 1159 treatment, 5:1157 Urticaria. See Hives

Varicella. See Chickenpox Variola major. See Smallpox Variola minor. See Smallpox Ventricular septal defect (VSD), 2:240, 241 Verrucae. See Warts Viral hemorrhagic fever. See Ebola and Marburg hemorrhagic fevers UXL Encyclopedia of Diseases and Disorders

Viral hepatitis. See Hepatitis A Vision disorders, 5:1161 See also specific disorders Vitiligo, 5:1162–1167 autologous melanocyte transplantation, 5:1165–1166 causes and symptoms, 5:1162, 1163–1164 corticosteroid therapy, 5:1165 definition, 5:1162 demographics, 5:1162–1163 description, 5:1162, 1163, 1164 diagnosis, 5:1164 focal vitiligo, 5:1162 the future, 5:1166 generalized vitiligo, 5:1162 micropigmentation (tattooing), 5:1165 prevention, 5:1166 prognosis, 5:1166 PUVA (psoralen/ultraviolet A) therapy, 5:1165 segmental vitiligo, 5:1162 skin grafts, 5:1165 treatment, 5:1164–1166

Wadlow, Robert, 2:422 Wagner-Jauregg, Julius, 4:699 Walleye. See Strabismus Warts, 5:1169–1174 causes and symptoms, 5:1169, 1170–1171 common warts, 5:1169, 1170, 1173 definition, 5:1169 demographics, 5:1170 description, 5:1169–1170, 1170 diagnosis, 5:1170, 1171 flat warts, 5:1169, 1170, 1171 the future, 5:1173 genital warts, 5:1169, 1170, 1172, 1173 human papillomavirus (HPV), 3:550–551, 552–554, 555, 5:1169, 1170, 1173 mosaic warts, 5:1169 plantar warts, 5:1169, 1170, 1171, 1172, 1173 prevention, 5:1172–1173 cxiii

Index

prognosis, 5:1100 treatment, 5:1171–1172 Water on the brain. See Hydrocephalus Waters, Andre, 2:235 Weathers, Seaborn Beck, 2:397 Weaver, Zach, 2:392 Weed. See Marijuana use West Nile fever. See West Nile virus infection West Nile virus infection, 5:1174–1180 causes and symptoms, 5:1174, 1175, 1177 demographics, 5:1175 description, 4:730, 5:1174 diagnosis, 2:361, 5:1177 encephalitis, 2:360, 366 the future, 5:1178–1179 prevention, 2:363, 5:1178 prognosis, 2:363, 5:1178 treatment, 5:1177–1178 vaccines, 2:363, 364, 5:1178–1179 West Nile encephalitis, 5:1174, 1176, 1177, 1178 West Nile meningitis, 5:1177, 1178 West Nile virus, 5:1175, 1175 Whiplash, 5:1180–1185 causes and symptoms, 5:1180, 1181–1182 definition, 5:1180 demographics, 5:1180–1181 description, 5:1180, 1181 diagnosis, 5:1182–1183 the future, 5:1184 prevention, 5:1183–1184 prognosis, 5:1183 treatment, 5:1182, 1183 White, Ryan, 1:14, 14 Whooping cough, 5:1185–1190 Bordetella pertussis, 5:1186, 1187 causes and symptoms, 5:1185, 1187–1188 definition, 5:1185 demographics, 5:1185–1187 description, 5:1185 diagnosis, 5:1188 the future, 5:1189–1190 prevention, 5:1189 prognosis, 5:1188–1189

cxiv

treatment, 5:1188 vaccination, 5:1081, 1085, 1086, 1087, 1089–1190 Winkler, Henry (the Fonz), 2:319, 319 Winter blues. See Seasonal affective disorder Winter depression. See Seasonal affective disorder Wolfe, Frederick, 2:373 Woolsorter’s disease. See Anthrax

Xeroderma pigmentosum, 5:1191–1197 Camp Sundown, 5:1193 causes and symptoms, 5:1191, 1194 definition, 5:1191 demographics, 5:1193–1194 description, 5:1191–1193, 1192 diagnosis, 5:1194–1195 the future, 5:1196 nucleotide excision repair (NER), 5:1191, 1197 prevention, 5:1196 prognosis, 5:1196 skin cancers, 5:1191, 1193, 1195, 1196 solar keratoses, 5:1193, 1195, 1197 stages, 5:1192–1193 treatment, 5:1195 XXX syndrome. See Triple X syndrome XXY syndrome. See Klinefelter syndrome

Yates, Andrea, 4:847 Yaws, 5:1072, 1073 Yoga therapy, 4:882

Zits. See Acne Zollinger-Ellison syndrome, 5:1149 Zoonoses, 5:1199–1200 See also specific diseases


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