Generality/Definition
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Vitamin A is essential to health and is generally acquired by humans in a healthy diet. Vitamin A deficiency (VAD) is a major contributor to childhood mortality and is also likely to be a contributing factor to maternal deaths.
Source: Vitamin A Deficiency (who.int)
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Childhood blindness refers to a group of diseases and conditions occurring in childhood or early adolescence, which, if left untreated, result in blindness or severe visual impairment that are likely to be untreatable later in life. The major causes of blindness in children vary widely from region to region, being largely determined by socioeconomic development, and the availability of primary health care and eye care services. In high-income countries, lesions of the optic nerve and higher visual pathways predominate as the cause of blindness, while corneal scarring from measles, vitamin A deficiency, the use of harmful traditional eye remedies, ophthalmia neonatorum, and rubella cataract are the major causes in low-income countries.
Source: WHO | VISION 2020 priority eye diseases (v2020.org)
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Epidemiology
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Every year, some 12 million children in developing countries die before they reach their fifth birthday, many during the first year of life. Seven out of ten of these deaths are due to acute respiratory disease infections (mostly pneumonia), diarrhoea, measles, malaria or malnutrition - or more commonly some combination of these conditions. These same children are often most at risk of vitamin A deficiency (VAD) a known contributing factor to these causes of death and disease.
Source: Vitamin A Deficiency (who.int)
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For Vitamin A deficiency, at a cost of only 5 US cents a dose, vitamin A supplements reduce child mortality by up to 34% in areas where Vitamin A deficiency is a public health problem. As Vitamin A deficiency manifests often during an outbreak of measles, properly planned and implemented national vaccination programmes against measles has reduced the prevalence of eye complications.
Source: WHO | VISION 2020 priority eye diseases (v2020.org)
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Prevention
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Vitamin A deficiency can be prevented by including foods rich in vitamin A or beta-carotene as a regular component of the diet; liver, meat, eggs, milk, and dairy products are examples. Foods rich in beta-carotene include red peppers, carrots, pumpkins, as well as those just mentioned. Margarine is rich in beta-carotene, because this chemical is used as a coloring agent in margarine production. In Africa, Indonesia, and the Philippines, vitamin A deficiency is prevented by public health programs that supply children with injections of the vitamin.
Source: Vitamin A deficiency (healthatoz.com)
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The provision of high does vitamin A supplementation every 4-6 months not only protects against blindness but also has a significant impact on the health of children 6-59 months of age, reducing the risk of dying from all causes by 23%. Vitamin A supplementation has been shown to have a significant impact on child mortality and morbidity.
Source: Vitamin A Deficiency (who.int)
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Symptoms
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The earliest symptom of vitamin A deficiency is night blindness. Prolonged deficiency results in drying of the conjunctiva (the mucous membrane that lines the inner surface of the eyelids and extends over the forepart of the eyeball). With continued vitamin A deficiency, the drying extends to the cornea (xerophthalamia). The cornea eventually shrivels up and becomes ulcerated (keratinomalacia). Superficial, foamy gray triangular spots may appear in the white of the eye (Bitot's spots). Finally, inflammation and infection occur in the interior of the eye, resulting in total and irreversible blindness.
Source: Vitamin A deficiency (healthatoz.com)
Diagnosis
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Vitamin A status is measured by tests for retinol. Blood-serum retinol concentrations of 30-60 mg/dl are considered in the normal range. Levels that fall below this range indicate vitamin A deficiency. Night blindness is measured by a technique called electroretinography. Xerophthalamia, keratinomalacia, and Bitot's spots are diagnosed visually by trained medical personnel.
Source: Vitamin A deficiency (healthatoz.com)
Illustrations
Information for specialists
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Key resource documents related to VAD and immunization:
- Integration of vitamin A supplementation with immunization: policy and programme implications. Report of a meeting, 12-13 January 1998. (version française)
- Distribution of vitamin A during national immunization days. A generic guide to the Field guide for supplementary activities aimed at achieving polio eradication. (version française)
- Using national immunization days to deliver vitamin A. EPI Update 33, November 1998. (version française)
Source: Vitamin A Deficiency (who.int)
Scientific articles:
All recent articles for "Vitamin A Deficiency"
Clinical trials for "Vitamin A Deficiency":
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