Schistosomiasis in natural waters of eastern Puerto Rico.

Using studies documenting areas of high prevalence of the parasitic disease Schistosomiasis in Eastern Puerto Rico, we searched 18 sites for the disease\u27s snail host Biomphalaria glabrata. No B. glabrata snails were found and populations of the competitive snails, Thiara granifera and Marisa cornaurietis, were documented. We believe that the population of B. glabrata is on the decline due, among other reasons, to these competitive snails, therefore decreasing the risk and human infection with Schistosoma mansoni. Further studies are recommended