Bilharzia or schistosomiasis is a parasitic disease present in the Marahoué region and constitutes a major public health problem. The spread of this disease is closely linked to the ecology of intermediate hosts, conditioned by environmental, climatic, socio-demographic and health factors. If morbidity is to be reduced, we need to have a better understanding of the spatial distribution of distribution factors, and to identify and locate outbreaks as well as areas at risk of contamination. The aim of this study is to map, using remote sensing and GIS, the areas at risk of bilharzian contamination in the Marahoué region. By classifying the parameters according to factors of risk and vulnerability to infection using Saaty’s multi-criteria analytical hierarchical process of complete aggregation by weighting, we were able to assign weights to each parameter. This methodology was used not only to draw up sensitivity and vulnerability maps for 2003 and 2013, but also to assess the risk of bilharzia infection. We noted four potential areas of risk of bilharzia contamination located around the region’s major towns. Of the 32 localities surveyed, 13 (40.62%) were located in high or medium risk areas. The year 2003 was marked by a predominance of présuméd intestinal bilharziasis, estimated at 62.50%. However, in 2013 we observed an acute presence of urinary bilharziasis estimated at 81.25%, compared with 18.75% for intestinal bilharziasis.