Variables influencing the distribution of freshwater mollusk intermediate hosts of Schistosoma mansoni in the Oicha Health Zone, North Kivu Province, Democratic Republic of the Congo

Introduction Schistosomiasis caused by Schistosoma mansoni remains a major neglected tropical disease in sub-Saharan Africa, where transmission depends on freshwater snail intermediate hosts. Purpose This study investigated environmental variables influencing the distribution and diversity of freshwater mollusk hosts in the Oicha Health Zone, Democratic Republic of the Congo. Methods A cross-sectional malacological survey was conducted across freshwater habitats. Mollusks were collected from 30 sites, with 21 sites included in statistical analyses due to species presence. Environmental variables were measured in situ. Community patterns were analyzed using non-metric multidimensional scaling (NMDS) with Bray–Curtis dissimilarity, and environmental associations were tested using permutation-based vector fitting (envfit). Multiple linear regression models were applied to assess predictors of species richness and Shannon diversity. Results Results showed five mollusk taxa belonging to two families (Lymnaeidae, Planorbidae). NMDS revealed clear structuring of communities along environmental gradients, particularly water velocity and vegetation cover. Regression analysis indicated that species richness decreased with increasing water velocity and altitude, while vegetation cover had a positive effect. Water chemistry variables influenced Shannon diversity, particularly conductivity and salinity. Conclusion These findings highlight hydrological conditions as the primary drivers of freshwater snail distribution and provide ecological insights for schistosomiasis control strategies in the region.