Comparative analysis of population genetics between Schistosoma japonicum-infected and uninfected Oncomelania hupensis snails using microsatellites.

Schistosomiasis is now at a low prevalence in China, but schistosome infections in intermediate host Oncomelania hupensis have been constantly reported. Previous studies have revealed a behavioral modification of snails associated with infection. However, there is a lack of comparative population genetics between schistosome-infected and uninfected snails. This study aimed to investigate any differences in genetic diversity and/or structure in O. hupensis associated with Schistosoma japonicum infection, with the purpose of providing information on snail control. Snail survey was performed in Ding town in Shitai county in Anhui, China. Infected snails were identified and sampled. Then an equal number of uninfected snails from the same place where infected snails were sampled, were randomly sampled. Population genetic analyses were conducted for infected snails and uninfected snails based on nine microsatellites. The mean snail density was 0.71 snails/0.11 m2, and the mean infected snail density was 0.00275/0.11 m2. 31 infected and 30 uninfected snails were successfully genotyped. Both exhibited high genetic diversity, but no significant differences were observed between both in all diversity measures, with exception of Allele richness (Ar). No genetic differentiation or structure was observed between two groups. While snail density has significantly decreased, the density of infected snails has not decreased. Higher Ar in infected snails indicates the stronger long-term evolutionary potential in this part of snails. This, together with high diversity in both infected and uninfected snails, may complex the epidemiology and control of schistosomiasis, given wild rodents (and other possible infected mammals) as local reservoirs for S. japonicum.