MEASLES remains a devastating disease, for which specific therapy is lacking. Hopes for its control and eventual eradication rest on immunization, but measles kills about 2 million children each year1 and cripples an untold number through blindness2 and lung disease.3 , 4 The idea that vitamin A may have a protective effect in measles was first suggested more than 50 years ago5 but was ignored until Barclay et al.,6 in a randomized clinical trial, found twice as many deaths in the control group (12 of 92) as among children given high doses of vitamin A (6 of 88).6 Although the overall results did not reach statistical significance, vitamin A was significantly protective in the group under two years of age.6
That vitamin A should be of benefit in measles is biologically plausible.7 Measles depresses serum levels of vitamin A,8 9 10 11 and hyporetinemia (a serum retinol level below 0.7 μmol per liter [20 μg per deciliter]) is associated with increased mortality from the disease, particularly in children under two years of age.11 In almost every known infectious disease, vitamin A deficiency is known to result in greater frequency, severity, or mortality.12 Increased susceptibility to infection was one of the first features of nutritional vitamin A deficiency to be recognized,13 and even mild deficiency appears to be associated with an increased risk of pneumonia, diarrhea, and death in childhood.14 15 16 17 According to Scrimshaw et al., "no nutritional deficiency in the animal kingdom is more consistently synergistic with infection than that of vitamin A."12 They list nearly 50 studies (including 8 in humans) of diseases of bacterial, viral, or protozoan origin in which vitamin A deficiency resulted in increased frequency, severity, or mortality.12 In fact, vitamin A is sometimes referred to as the "anti-infective" vitamin.