Survey of Freshwater Molluscs and Their Role as Intermediate Hosts in Lokoja, Kogi State, North Central Nigeria

This study surveys the diversity of freshwater molluscs and assesses their potential role as intermediate hosts of parasitic trematodes in water bodies in and around Lokoja, Kogi State, located in Nigeria's North Central geopolitical zone. Freshwater snails are the obligate intermediate hosts for schistosomes and liver flukes, and their distribution directly determines the transmission risk of these diseases in human and livestock populations. Molluscs were collected by hand picking, kick sampling, and drag nets from 12 freshwater sites monthly over four months. Species were identified morphologically. Snails were examined for cercariae emergence by exposure to light stimulation in shallow water trays. Habitat type, water velocity, vegetation, and physicochemical parameters were recorded. A total of eight freshwater mollusc species were identified, dominated by Biomphalaria pfeifferi and Bulinus truncatus. Cercariae were recovered from 14.2 percent of Biomphalaria and 18.7 percent of Bulinus specimens, indicating active trematode transmission. Cercariae morphology was consistent with Schistosoma mansoni and bovine schistosomes. Snail densities were highest in slow-flowing, vegetated irrigation channels and rice paddy drains. The study identifies specific sites of high schistosomiasis transmission risk in the Lokoja area and recommends targeted mollusciciding of high-density Bulinus and Biomphalaria habitats, combined with health education for communities using these water bodies. Keywords: freshwater molluscs, intermediate hosts, schistosomiasis, Lokoja, Kogi State.