Saulea vitrea and low prevalence of schistosomiasis.

Thirty-six sties, including pools, small streams, large rivers, and rice fields swamps were examined for the intermediate snail hosts of schistosomiasis and other mollusca in 19 villages spanning 4 chiefdoms in Sierra Leone. Half of the Saulea vitrea collected were examined for possible infection and none was found to be infected. In addition, we examined 785 stool and 913 urine samples from children living in the villages and found low prevalence and intensity of S. haemotobium (1.8%; 1.9XG) and S. mansoni (1.9%; 2.1XG) respectively. The low prevalence and intensity of infection with schistosomiasis where S. vitrea is in abundance suggest some effect of S. vitrea on schistosome snail intermediate host, but the mechanism remains unknown.