Global prevalence of vitamin A deficiency in population at risk: 1995-2005
Summary of the global prevalence of vitamin A deficiency in populations at risk
In 1987, WHO estimated that vitamin A deficiency was endemic in 39 countries based on the ocular manifestations of xerophthalmia or deficient serum (plasma) retinol concentrations (<0.35 µmol/l). In 1995, WHO updated these estimates and reported that vitamin A deficiency was of public health significance in 60 countries, and was likely to be a problem in an additional 13 countries. The current estimates reflect the time period between 1995 and 2005, and indicate that 45 and 122 countries have vitamin A deficiency of public health significance based on the prevalence of night blindness and biochemical vitamin A deficiency (serum retinol concentration <0.70 µmol/l), respectively, in preschool-age children.
In this present edition, estimates of vitamin A deficiency are provided for preschool-age children as in the previous edition, and also for pregnant women. They are based on an increasingly assessed history of night blindness and a now more widely adopted serum (plasma) retinol concentration, using a cut-off of <0.70 µmol/l (<20 µg/dl) to define deficiency.
Globally, night blindness is estimated to affect 5.2 million preschool-age children (95% CI: 2.0-8.4 million) and 9.8 million pregnant women (95% CI: 8.7-10.8 million), which corresponds to 0.9% and 7.8% of the population at risk of VAD, respectively. Low serum retinol concentration (<0.70 µmol/l) affects an estimated 190 million preschool-age children (95% CI: 178-202 million) and 19.1 million pregnant women (95% CI: 9.30-29.0 million) globally. This corresponds to 33.3% of the preschool-age population and 15.3% of pregnant women in populations at risk of VAD, globally. The WHO Regions of Africa and South-East Asia were found to be the most affected by vitamin A deficiency for both population groups.
Despite a marked increase in submitted data, there are still numerous countries lacking national prevalence data. There is a need to inform and motivate governments and agencies to collect, and report to WHO, national data on the prevalence of deficiency and, whenever possible, vitamin A programme coverage conditions prevailing at the time that population assessment data were collected.
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