Spatial and temporal variation in the susceptibility of Biomphalaria pfeifferi, the intermediate host of Schistosoma mansoni, Man, western Côte d'Ivoire Objective: This study aimed to characterize the susceptibility of the intermediate host snail Biomphalaria pfeifferi to Schistosoma mansoni infection in space and time and in relation to some environmental and climatic parameters. Methodology and results : Seven populations of B. pfeifferi were sampled at four dates : two in the dry season and two in the rainy season. From each sample of G0 snails collected in the field, 50 G1 offspring were obtained and individually exposed to a strain of S. mansoni. The susceptibility of snails was assessed based on the infection rate, in relation to the effects of population, habitat type, season and prevalence of human schistosomiasis. Population and season affected the infection rate with a higher value in the dry season. A positive correlation between infection rate and prevalence of schistosomiasis was observed. Conclusion and application of findings : There was a spatio-temporal variation in the susceptibility of B. pfeifferi to S. mansoni infection in the study area, which may result from the snail-schistosome coevolution. The temporal monitoring of the susceptibility of intermediate host populations may help interrupting the transmission of schistosomiaisis. For example, in a control programme, molluscicide treatments of habitats of intermediate hosts may be performed before, during and shortly after the peak susceptibility of snail populations to interrupt the life cycle of schistosomes.