Schistosoma mansoni infection suppresses the growth of Plasmodium yoelii parasites in the liver and reduces gametocyte infectivity to mosquitoes

摘要

Author summary Malaria and schistosomiasis are parasitic infectious diseases that cause severe morbidity and mortality in the tropics. Chronic schistosomiasis causes malnutrition and impaired intellectual development to children while malaria can cause fatal acute infections. Since coinfection of these two parasites is common in the tropics, many studies of both epidemiology and coinfection in animal models have been performed in order to reveal interactions between them. Previous animal studies on the interactions between Plasmodium and Schistosoma parasites have focused on the blood stage pathology of the malaria infection, and have consistently shown that parasitaemia can be enhanced in the presence of the helminth. In contrast, we focused on liver immunopathology in mice during coinfection between with Schistosoma and Plasmodium. We show that S. mansoni infection inhibits Plasmodium parasite growth in the liver resulting in a large reduction in the percentage of mice that go on to develop blood stage malaria following inoculation of low numbers of sporozoites. We also demonstrate that gametocyte infectivity is much reduced in mice with S. mansoni infections. Our results imply that S. mansoni infection can reduce malaria transmission both from mosquitoes to mice, and from mice to mosquitoes.