Identification of Bulinus forskalii as a potential intermediate host of Schistosoma h AE matobium in Senegal

Author summarySchistosomiasis is one of the most important neglected tropical diseases in the world. It is caused by blood flukes of the genus Schistosoma. In Senegal, the species Schistosoma h AE matobium is the most widespread and responsible for urinary Schistosomiasis in humans. Freshwater snails of the genus Bulinus including Bulinus truncatus, Bulinus globosus, Bulinus senegalensis and Bulinus umbilicatus are its main intermediate hosts. However, Bulinus forskalii, morphologically similar to Bulinus senegalensis is also frequently found but no study has ever mentioned its sensibility to S. h AE matobium in Senegal. The aim of our research is to reveal the relevance of Bulinus forskalii as a potential intermediate host of S. h AE matobium but also to provide an accurate identification of this snail. This study demonstrated the susceptibility of Bulinus forskalii to the S. h AE matobium parasite in Senegal by using innovative and refined identification methods to discriminate this snail and to characterize its infection. This result significantly contributes to the improvement of our knowledge on host-parasite interactions and should be taken into account in future epidemiological studies and schistosomiasis control programs. Understanding the transmission of Schistosoma h AE matobium in the Senegal River Delta requires knowledge of the snails serving as intermediate hosts. Accurate identification of both the snails and the infecting Schistosoma species is therefore essential. Cercarial emission tests and multi-locus (COX1 and ITS) genetic analysis were performed on Bulinus forskalii snails to confirm their susceptibility to S. h AE matobium infection. A total of 55 Bulinus forskalii, adequately identified by MALDI-TOF mass spectrometry, were assessed. Cercarial shedding and RT-PCR assays detected 13 (23.6%) and 17 (31.0%), respectively, Bulinus forskalii snails parasitized by S. h AE matobium complex fluke. Nucleotide sequence analysis identified S. h AE matobium in 6 (11.0%) using COX1 and 3 (5.5%) using ITS2, and S. bovis in 3 (5.5%) using COX1 and 3 (5.5%) using ITS2. This result is the first report of infection of Bulinus forskalii by S. h AE matobium complex parasites in Senegal using innovative and more accurate identification methods to discriminate this snail and characterize its infection by S. h AE matobium.