Global prevalance of vitamin A deficiency in populations at risk 1995-2005: WHO Global Database on Vitamin A Deficiency

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Global prevalence of vitamin a deficiency in populations at risk 1995–2005  WHO GLobal Database on vitamin a deficiency

WHO Global Database on Vitamin A Deficiency www.who.int/vmnis

ISBN 978 92 4 159801 9

Global prevalence of vitamin A deficiency in populations at risk 1995–2005 WHO Global Database on Vitamin A Deficiency

WHO

Global prevalence of vitamin A deficiency in populations at risk 1995–2005 WHO Global Database on Vitamin A Deficiency

WHO Library Cataloguing-in-Publication Data Global prevalence of vitamin A deficiency in populations at risk 1995–2005: WHO global database on vitamin A deficiency. 1.Vitamin A deficiency – epidemiology. 2.Vitamin A deficiency – etiology. 3.Vitamin A deficiency – complications. 4.Child. 5.Eye manifestations. 6.Databases as topic. I.World Health Organization. ISBN 978 92 4 159801 9

(NLM classification: WD 110)

Suggested citation: WHO. Global prevalence of vitamin A deficiency in populations at risk 1995–2005. WHO Global Database on Vitamin A Deficiency. Geneva, World Health Organization, 2009.

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Contents

Preface Acknowledgements Abbreviations

vii ix x

1. Introduction 1.1 Vitamin A deficiency: a public health problem 1.1.1 Etiology 1.1.2 Health consequences 1.1.3 Assessing vitamin A status and deficiency 1.2 Control of vitamin A deficiency

1 1 1 1 2 2

2. Methods 2.1 Data sources – The WHO Global Database on Vitamin A Deficiency 2.2 Selection of survey data 2.2.1 Administrative level 2.2.2 Population groups 2.3 Defining vitamin A deficiency 2.3.1 Serum or plasma retinol threshold 2.3.2 Estimated prevalence of night blindness and biochemical vitamin A deficiency for countries with no survey data 2.3.3 Uncertainty of estimates 2.3.4 Combining national estimates 2.3.5 Global prevalence of vitamin A deficiency in populations at risk 2.3.6 Classification of vitamin A deficiency as a problem of public health significance 2.4 Population covered by survey data, proportion of population, and the number of individuals with vitamin A deficiency in populations at risk 2.4.1 Population covered 2.4.2 Proportion of population and the number of individuals affected in countries at risk for vitamin A deficiency

4 4 4 4 5 5 5

3. Results and Discussion 3.1 Results 3.1.1 Population covered 3.1.2 Proportion of population and number of individuals with vitamin A deficiency in populations at risk 3.1.3 Public health significance of vitamin A deficiency 3.2 Discussion 3.2.1 Population covered 3.2.2 Strengths of estimates 3.2.3 Proportion of population and the number of individuals with vitamin A deficiency in populations at risk 3.2.4 Classification of countries by degree of public health significance of vitamin A deficiency 3.2.5 Comparison to previous estimates 3.2.6 Limitations of estimates 3.3 Conclusions

Contents

6 6 7 7 7 8 8 8 9 9 9 10 11 16 16 16 16 16 16 17 18

iii

References

19

Annexes Annex 1 WHO Member States grouped by WHO region and UN region as of 2007 Table A1.1 WHO Member States grouped by WHO region Table A1.2 WHO Member States grouped by UN region and subregion Annex 2 Results by UN region Table A2.1 Percentage of population at risk of vitamin A deficiency covered by night blindness and serum retinol prevalence surveys (national or subnational) conducted between 1995 and 2005, by UN region Table A2.2 Prevalence of night blindness and numbers of affected preschool-age children and pregnant women in countries at risk of vitamin A deficiency in each UN region Table A2.3 Prevalence of serum retinol