Stunting May Determine the Severity of Malaria-Associated Anemia in African Children

Abstract

Evidence from previous studies that malnourished children are protected against malaria is controversial. In individuals repeatedly exposed to malaria, immunity may develop first against severe disease, then against pyrogens, and last, against parasites. If this is true, this would suggest that reduced immune function that may exist in stunted children exacerbates the severity of malarial signs and symptoms, rather than the occurrence of parasitemia. On the other hand, several studies have suggested that malnourished children are protected to some degree against malaria. Our aim was to evaluate whether observational data support the hypothesis that nutritional inadequacies that cause stunting modify the associations between malaria and hematologic indicators such as hemoglobin concentration and serum concentrations of C-reactive protein and soluble transferrin receptor (sTfR). We showed earlier that increased serum concentrations of these receptors in asymptomatic malaria may be explained, at least in part, by increased erythropoiesis to compensate for malaria-induced hemolysis. Community-based cluster survey among Kenyan children aged 2 to 36 months asymptomatic for malaria or anemia (n = 318). When adjusted for age and wasting, the malaria-associated decrease in mean hemoglobin concentration was 8.5 g/L and 15.8 g/L in nonstunted and stunted children, respectively. The malaria-associated increase in geometric mean serum concentrations of sTfR was 1.1-fold and 1.8-fold in nonstunted and stunted children, respectively. The malaria-associated increase in geometric mean serum concentrations of C-reactive protein was 1.4-fold and 2.3-fold in nonstunted and stunted children, respectively. Thus, children with malaria and those who were stunted suffered from more severe anemia and had higher serum concentrations of C-reactive protein and sTfR than would be expected from the combined effect of the 2 working independently. Our results are consistent with the notion that the nutritional inadequacies causing stunting also impair host immunity, thus increasing the degree to which malaria is associated with decreased concentrations of hemoglobin, with increased inflammation, and with increased iron demand in developing erythroblasts. Increased intake of micronutrients may not only reduce stunting and nutritional anemia, but also reduce malaria-associated anemia.