Iron and infection in the tropics: paediatric clinical correlates.

Iron deficiency is prevalent in children worldwide. Programmes of presumptive therapy, mass supplementation and food fortification have been introduced in many countries. The continuing unresolved debate over the interaction of iron and infection in the clinical setting indicates the need for firm guidelines for these practices. Iron overload is associated with increased susceptibility to certain infections, although the exact mechanisms may vary with the main pathology. Iron treatment has been associated with acute exacerbations of infection, in particular malaria. In Papua New Guinea parenteral iron was associated with increased rates of malaria and increased morbidity due to respiratory disease in infants but not in school children. Several subsequent studies in Africa using oral iron showed deleterious effects. In most instances cited, immunity was compromised, and therapeutic doses of oral iron were used. Knowledge of malarial endemicity, immunity with respect to age and the prevalence of haemoglobinopathies is important in planning interventions. A fine balance needs to be struck in the timing and dose of oral iron if informed recommendations are to be made. In parallel with supplementation studies, the effects of iron chelation on infection are being reported increasingly. Such therapy is clearly protective against malaria and some other infections but may predispose to fungal and Yersinia infections.