Spatio-temporal Ecology of Fasciola Vectors and Co-occurring Trematode Hosts in Kingwal Wetland, Kenya

Abstract

This study examined the spatial and temporal distribution of freshwater snails in Kingwal Wetland, Kenya, to assess their role in fascioliasis transmission. A total of 8,754 snails representing eight species were collected across seven sites over a 12-month period. The dominant species were Lymnaea auricularia (n = 1,192; 13.6%), Radix natalensis (n = 525; 6.0%), and Biomphalaria sudanica (n = 1,838; 21.0%), with L. auricularia and R. natalensis serving as key intermediate hosts of Fasciola gigantica. Spatial analysis revealed significant variation in species composition between sites (χ2 = 2,435.1, df = 42, p < 0.001), with Sites 1 and 2 exhibiting the highest species richness and abundance. Temporal trends showed snail abundance peaking during the rainy season (May–August), with the highest monthly count being recorded in May (n = 1,383). Dry-season months such as January and December had the lowest counts, with only 230 and 316 individuals, respectively. R. natalensis exhibited the highest Fasciola infection prevalence, peaking at 29.3% in June, compared to L. auricularia, which peaked at 19.8% in September. A chi-square test for monthly snail distribution confirmed significant seasonal variation (χ2 = 839.27, df = 77, p < 0.001), while a Cochran–Mantel–Haenszel test showed strong interaction between spatial and temporal factors (CMH = 1,192.37, df = 11, p < 0.001). These findings suggest that fascioliasis transmission risk is highest during wet months and is strongly influenced by habitat stability, vegetation, and anthropogenic activity. The results underscore the need for spatially targeted and seasonally timed control interventions, including habitat management and precision molluscicide application. This study contributes to a growing understanding of wetland ecosystems as dynamic transmission zones for snail-borne diseases and provides a foundation for data-driven fascioliasis control strategies in livestock-dependent communities living in wetland ecosystems.