Intermediate host mollusks distribution associated to the risk of schistosomiasis transmission in bamako district

Introduction: Schistosomiasis is an endemic parasitic disease in Mali. Despite control efforts carried out by the Ministry of Health and Social Development, transmission still occur in Bamako district. This situation is most likely due to irregular mass treatment and, above all, to the lack of running water replaced by water body from rain or rivers, that favor the development of mollusks. Object: The current study aimed to investigate the distribution of intermediate host mollusks and the risk of schistosomiasis transmission in Bamako. Methode: This was a cross-sectional, one-time study conducted from April to June 2025. It covered all six communes. Gastropod collection was carried out between 8:00 a.m. and 11:00 a.m. Sample Specimens were collected using forceps on aquatic vegetation and on submerged or partially submerged supports. Results: Species identification and cercaria emission tests were performed in the Laboratory. From the total of 307 samples 66.4% (n = 204) belonged to Bulinus truncatus, 32.6% (n = 100) to Bulinus globosus, and 0.97% (n = 3) to Biomphalaria pfeifferi. Communes I (CI) and V (CV) provided the largest number of samples, with 35.8% (110/307) of the mollusks captured, whereas no samples were observed in communes II and III. Relative densities varied from 27.5 gastropods/person/15 minutes at Dialakorodji 1 to 0 at Bankoni, Bougouba (CII) and Farako (CIII). Natural infestation rates were higher in CI (7.95%), low in CIV (2.77%), and zero in CII, CIII, and V. Conclusion: Only one species, Bulinus truncatus, was found to be infested. The observation of mollusks infected with cercariae shows the existence of active transmission foci of schistosomiasis in the Bamako district. Control of mollusks through watercourse sanitation seem to be a useful complementary strategy to strengthen chemotherapy outcomes.