The balance between Th1 cytokines (tumor necrosis factor [TNF]-alpha, interferon [IFN]-gamma) and Th2 cytokines (interleukin [IL]-10, -4) may be critical in the development of severe falciparum malaria. Therefore, plasma concentrations of these cytokines were determined in children with various manifestations of malaria. Plasma levels of IFN-gamma and IL-4 were undetectable in most children. However, TNF-alpha and IL-10 were significantly elevated in children with high-density parasitemia and malaria anemia compared with children in control groups. In children with mild malaria, IL-10, but not TNF-alpha, was significantly elevated. While the highest concentrations of TNF-alpha were found in children with malaria anemia, IL-10 levels were highest in children with high-density uncomplicated malaria. The mean ratio of IL-10 to TNF-alpha was significantly higher in children with mild and high-density parasitemia (4.64, P<.005) than in children with malaria anemia (1.77). Thus, higher levels of IL-10 over TNF-alpha may prevent development of malaria anemia by controlling the excessive inflammatory activities of TNF-alpha.

Malarial anemia (MA) is a multifactorial disease for which the complex etiological basis is only partially defined. The association of clinical, nutritional, demographic, and socioeconomic factors with parasitemia, anemia, and MA was determined for children presenting at a hospital in a holoendemic area of Plasmodium falciparum transmission in western Kenya. Parasitemia was not associated with malaria disease severity. In univariate logistic regression, fever was significantly associated with parasitemia, and wasting was associated with increased presentation of MA. Caretaker's level of education and occupation were significantly correlated with parasitemia, anemia, and MA. Housing structure was also significantly associated with parasitemia and anemia. Bed net use was protective against parasitemia but not anemia or MA. Multivariate logistic regression models demonstrated that fever, mother's occupation, and bed net use were associated with parasitemia. In the current study, none of the factors were associated with anemia or MA in the multivariate models.