Abstract

Ability of the snail species to repopulate an aquatic environment is a risk factor to be considered by an epidemiologist in an area where schistosomiasis is endemic. A survey was conducted on the distribution of aquatic snail species in schistosome endemic areas, Kwara State, North-Central Nigeria. Physicochemical factors (water temperature, velocity, depth of water, atmospheric temperature, transparency, pH, electrical conductivity, and dissolved oxygen) were measured for twelve months with a field meter while other parameters were done in the laboratory. Aquatic flora influencing the abundance of the potential snail intermediate hosts in the selected water bodies was also observed. Spearman’s rank correlation coefficient was used to test the relationship between physicochemical parameters and snail species. Overall, 5,246 aquatic snails comprising five species of Planorbidae and a species each of Thiaridae, Lymnaeidae, Ampullariidae, Bithyniidae, and Bivalviae were identified in three sampled stations. In this study, Bulinus truncatus correlated positively with air temperature (r=0.401; p<0.05), water temperature (r=0.324; p<0.01), calcium (r=0.465; p<0.01), and magnesium (r=0.428; p<0.01); however, a negative significant relationship occurred between B. truncatus and water depth (r=-533; p<0.01), nitrate (r=-0.433; p<0.01). The occurrence of B. jousseaumei was strongly associated with dissolved oxygen (r=0.260; p<0.05). Since the presence of snail intermediate host of schistosome is confirmed in the study area and the effect of different physicochemical parameters on the survival of the snail species is demonstrated, environmental modification and the introduction of control measures should be done to eliminate schistosomiasis in the study area. 

Key words: Bionomics, bulinid species, Nigeria, physicochemical parameters, schistosomiasis.