Vitamin A deficiency.

1. Brief description of the condition/disease Vitamin A deficiency is defined by tissue concentrations of vitamin A low enough to have adverse health consequences even if there is no evidence of clinical deficiency (xerophthalmia). Subclinical deficiency is defined by serum retinol levels [is less than] 0.70 [micro]mol/l, which are considered of moderate and severe public health significance when the prevalence in a population is [is greater than] 10% and [is greater than] 20%, respectively. The consequences of subclinical deficiency are increased risk of mortality from common childhood infections, such as diarrhoea and measles, and recent studies suggest increased risk of maternal mortality. Xerophthalmia occurs when ocular signs are present, including night blindness, Bitot's spots with conjunctival xerosis, and corneal xerosis (which are potentially reversible signs), and keratomalacia, which can result in partial or total irreversible blindness. 2. Current global burden and rating within the overall burden of disease Approximately 3 million children develop xerophthalmia annually, 250 000 to 500 000 of whom become blind, and at least 60% die within one year. Estimates of subclinical deficiency among preschoolaged children range from 75 million to 250 million. Recently reported studies from Nepal suggest that in South Asia alone, 1-2 million pregnant women may be at risk from subclinical vitamin A deficiency. 3. Feasibility (biological) of elimination/eradication Eliminating vitamin A deficiency and all its consequences, including blindness, as a public health problem is feasible if dietary intake is increased to the recommended levels through natural foods, fortified foods, and/or supplements, and if the burden of other infectious diseases, which exacerbate vitamin A deficiency and lower serum retinol levels, is reduced. It is unlikely that vitamin A deficiency will be eradicated because it is caused by an inadequate dietary intake for economic, social, or cultural reasons, some of which are based on individual human behaviour and choice. However, elimination can be monitored by the prevalence of low serum levels. 4. Estimated costs and benefits of elimination/eradication The cost of elimination depends on the mix of intervention strategies selected for implementation. After the initial capital investment costs, fortification of a staple food is a long-term low-cost intervention. Vitamin A supplements are inexpensive -- less than US$ 0.03 per capsule -- but costs for delivery may be high depending on the infrastructures used. Semiannual campaigns have proven cost-effective and achieved broad coverage. Similarly, linking the distribution of capsules to vaccination delivery systems has reduced delivery costs. Dietary modification to increase the quantity and quality of menus depends on physical and economic access to food sources and educational/social marketing to guide food choice behaviours. Expected societal benefits include reduced costs for use of medical resources by reduced disease severity and individual benefits of reduced risk of death. 5. Key strategies to accomplish the objectives A combination of strategies addressing short- and long-term needs is usually required for sustainable control and elimination. These strategies include direct measures to increase intake of vitamin A through food, such as dietary modification in terms of quantity and quality, fortification, and supplementation; and indirect measures through public health strategies to control disease; income-generating activities to increase buying power; and the empowerment of women through the use of strategies such as literacy and education programmes. …