[Study of the distribution of schistosomiasis mollusks intermediate hosts in west africa. First results (author's transl)].

During 18 surveys carried out in 29 regions of 6 West african countries (Benin, Ivory Coast, Upper Volta, Mali, Niger and Togo), one species of Biomphalaria (Biomphalaria pfeifferi) and six species of Bulinus (Bulinus truncatus rohlfsi, B. globosus, B. jousseaumei, B. umbilicatus, B. senegalensis and B. forskalii) were collected. First indications of the distribution of these species demonstrated: the presence of 3 principal species (B. pfeifferi, B. globosus and B. truncatus rohlfsi); the absence of B. pfeifferi, above latitude 14 degrees north; the presence of a zone of B. truncatus rohlfsi in the north, a zone of B. globosus in the south and an intermediate zone where these two species are sympatrie; the possible presence of two strains of Schistosoma haematobium, each being transmitted by only one of the two preceding intermediate hosts. The authors point out that the parasitic diseases and their intermediate hosts are extending, as a result of the various hydraulic works and insist that the authorities should be duly made aware of the health problems generated by any development project.