[Micronutrients and tropical viral infections: one aspect of pathogenic complexity in tropical medicine]

In tropical zones, uncertain living conditions, inadequate food intake, and poor medical facilities enhance unnecessary morbidity and mortality especially involving infants and young children. In addition to protein-caloric malnutrition, deficiencies in essential micronutrients have a specific health impact. Such deficiencies can be the direct cause of disease such as vitamin A deficiency and blindness or have a promoting effect by compromising immune status and increasing susceptibility to and severity of infectious diseases especially of viral origin. The promoting effect of micronutrient deficiency plays a significant role in measles, rotavirus-related diarrhea, and, to a certain extent, progression of HIV infection. Several examples are described to illustrate the relationship between tropical viral infection and micronutrients including vitamin A, selenium, and various other antioxidants. These examples highlight the effect of infectious disease on micronutritional status (vitamin A and measles) and the need to develop reliable, practical tools to evaluate the relevance and effectiveness of dietary supplementation. In any case, improving living conditions and health programs such as the Expanded Vaccination Program are required and illustrate a transverse approach for prevention of infectious and non-infectious tropical disease. The relationship between micronutrients and infection is only one aspect of the multifactorial reality that must be dealt with in tropical medicine.