Medical Implications of Coinfection With Malaria and Filariasis Parasites

Residents of malaria-endemic regions are frequently exposed to a variety of other parasites concurrently with malarial parasites. In Mali, lymphatic filariasis due to Wuchereria bancrofti co-exists in several regions highly endemic for malaria, and co-infection is common in the residents of these areas. Because of the chronicity of filarial infections and an associated bias towards the development of an adaptive immune response dominated by Th2 cytokines, a pre-existing filarial infection has the potential to alter the immune response towards incoming malarial parasites, clearance of which are considered to be dependent on a robust Th1 response. This could, in turn, affect the clinical manifestations and outcomes of malaria infection. Conversely, immune responses to filarial parasites may be modulated in the presence of malarial parasites. In addition to sharing a human host, Plasmodium falciparum and Wuchereria bancrofti are transmitted by the same mosquito vector, Anopheles gambiae, and interaction between the two species in the vector may have important implications for transmission of these two infections. The primary goals of this study are to determine the effect of concurrent infections with P. falciparum and W. bancrofti parasites on the prevalence and severity of malaria infection in children living in a Malian village co-endemic for two parasites and to assess the effects of co-infection on the immune responses to these two parasites over the course of the malaria transmission season. The epidemiology of co-infection at the human and vector level will also be examined.