Transmission dynamics of hybrid schistosome species in Northern Senegal and their impact on human disease

Hybridization events between Schistosoma species are reported with increased frequency. Although many people are at risk of being infected with hybrids little is known about the control and disease dynamics of hybrid schistosomes in natural conditions. Interspecific hybridization strongly impacts the genetic constitution of schistosomes and increases their genetic diversity. Experimental studies have shown that hybrid offspring can have a higher fecundity, higher virulence, an increased transmission potential and different drug sensitivity. We studied the transmission dynamics of an emerging hybrid species, originating from a cross between the animal S. bovis and the human S. haematobium. We collected parasite genetic data and epidemiological data in rural villages in Northern Senegal. Schistosoma larvae (>1000) were genotyped with 17 microsatellite markers and a mitochondrial marker (partial cox1). Parasite genetic variation was linked with environmental data and with host variables (age, gender, infection intensity, pathology). The association of these different datasets rendered unique insights in the role of parasite genetic variation in infection intensity and pathology in human, and it sheds a first light on the disease caused by hybrid schistosomes. In the Senegal River basin this hybrid is widespread, our data shows that hybridization patterns differ between regions. The transmission of the hybrid on regional and local scales will be discussed, together with the problematic identification of hybrids using traditional molecular markers.status: publishe