Association of splenomegaly with cerebral malaria and decreased concentrations of reactive nitrogen intermediates in Thailand

The role of the spleen during Plasmodium falciparum malaria in humans is un clear. In Thailand, malaria transmission is low and splenomegaly is rarer t han in high transmission areas. We compared the prevalence of splenomegaly between 52 cerebral malaria patients and 191 patients without complications despite a high parasite biomass. We also measured concentrations of reacti ve nitrogen intermediates (RNIs) in a fraction of these cases recruited in 1998 (24 cerebral malaria and 56 controls). Splenomegaly was significantly associated with cerebral malaria (adjusted odds ratio = 2.07 [95% confidenc e interval = 1-4.2]; P = 0.048). There was a linear trend for this associat ion (P = 0.0003). After adjusting for potential confounders, concentrations of RNIs were significantly lower in the presence of splenomegaly (P = 0.01 ). These results suggest that in humans, as in animal models, the spleen ma y be involved in the pathogenesis of cerebral malaria. The relationship bet ween RNI concentrations and the spleen suggest that nitric oxide may have a regulating role in the complex physiology of the spleen during malaria.