| swamp rice development, schistosomiasis, and onchocerciasis in southeast sierra leone. | seventy-four villages in eastern sierra leone, west africa, many having a recently developed rice swamp, were surveyed for the presence of schistosomiasis and onchocerciasis, and their vectors. prevalence rates for schistosoma haematobium and s. mansoni were low, although the infections were widespread. there is some evidence that s. mansoni is extending its range in sierra leone although this is problematical because of the apparent absence of biomphalaria pfeifferi, the recognized snail vector ... | 1982 | 7081542 |