Distribution and molecular identification of freshwater snails in Ibadan North Local Government Area, Oyo State, Nigeria

Abstract

Schistosomiasis is a major public health concern in Nigeria, with transmission linked to freshwater snail as intermediate hosts. This study investigated the distribution, speciation, cercarial shedding patterns, and molecular identification of freshwater snails from selected water bodies in Ibadan, Nigeria. A cross-sectional descriptive study was conducted in Bodija area of Ibadan, with snail sampling carried out at Kongi, Ikolaba, and Adeyi. Freshwater snails were collected using standard scooping and hand-picking methods and identified morphologically using established taxonomic keys. Physico-chemical properties of the water bodies, including temperature, pH, electrical conductivity, total dissolved solids, and water transparency, were measured in situ and in the laboratory. Snails were examined for cercarial shedding and cercariae were identified morphologically to genus level. Molecular identification of two selected snail specimens was performed using PCR amplification and DNA sequencing, along with BLAST searches on NCBI databases. A total of 388 freshwater snails were collected, Physella acuta (102) and Melanoides tuberculata (286). Physico-chemical parameters were relatively stable and within ranges favorable for freshwater snail survival. Cercarial shedding was observed in 10 snails (2.6%), all of which were non-schistosome cercariae. Molecular analyses confirmed the species identity of the collected snails to be Physella acuta and Melanoides tuberculata. The absence of schistosome cercariae suggests a low level of active schistosomiasis transmission at the time of sampling. Continued surveillance with known vector snails, extended sampling periods, and parasite-specific molecular detection is recommended to better understand transmission dynamics and support schistosomiasis control strategies.