The Mollusca inhabiting rice fields in northern Cameroon and their role as intermediate hosts for schistosomes

A systematic account is given of the freshwater gastropod and bivalve fauna of Ouro- Doukoudje, northern Cameroon, based on a survey conducted from July 2000 to June 2001 at 12 sites in rice fields spanning 800 ha. In total, 14 species were encountered, one of them (lIgBurnupial/Ig sp.) being a first record for the area. Thirteen of the species are widely distributed in the Sahelo-Sudanese or Afrotropical regions. Bulinus senegalensis, Bulinus forskalii, Bulinus globosus, Biomphalaria pfeifferil/Ig and Lymnaea natalensisl/Ig occurred throughout the study area and are potential intermediate hosts for schistosomes. Only Biomphalaria pfeifferil/Ig was found to be naturally infected with Schistosoma mansonil/Ig at nearly all sites in the rice fields. Infection rates were high and varied among sites (21.0-68.6%) and months (14.8-76.6%). Bulinus forskaliil/Ig was scarce in, and Bulinus truncatusl/Ig absent from, the study area. Our data are compared with published data for this area as well as for northern Cameroon.