Epidemiological Interactions between Urogenital and Intestinal Human Schistosomiasis in the Context of Praziquantel Treatment across Three West African Countries

Background: in many parts of sub-saharan africa,urogenital and intestinal schistosomiasis co-occur,and mixed species infections containing both schistosoma haematobium and s. mansoni can be common. during co-infection,interactions between these two species are possible,yet the extent to which such interactions influence disease dynamics or the outcome of control efforts remains poorly understood. methodology/principal findings: here we analyse epidemiological data from three west african countries co-endemic for urogenital and intestinal schistosomiasis (senegal,niger and mali) to test whether the impact of praziquantel (pzq) treatment,subsequent levels of re-infection or long-term infection dynamics are altered by co-infection. in all countries,positive associations between the two species prevailed at baseline: infection by one species tended to predict infection intensity for the other,with the strength of association varying across sites. encouragingly,we found little evidence that co-infection influenced pzq efficacy: species-specific egg reduction rates (err) and cure rates (cr) did not differ significantly with co-infection,and variation in treatment success was largely geographical. in senegal,despite positive associations at baseline,children with s. mansoni co-infection at the time of treatment were less intensely re-infected by s. haematobium than those with single infections,suggesting competition between the species may occur post-treatment. furthermore,the proportion of schistosome infections attributable to s. mansoni increased over time in all three countries examined. conclusions/significance: these findings suggest that while co-infection between urinary and intestinal schistosomes may not directly affect pzq treatment efficacy,competitive interspecific interactions may influence epidemiological patterns of re-infection post-treatment. while re-infection patterns differed most strongly according to geographic location,interspecific interactions also seem to play a role,and could cause the community composition in mixed species settings to shift as disease control efforts intensify,a situation with implications for future disease management in this multi-species system. © 2015 knowles et al.