Investigating the Potential Role of Invasive Golden Apple Snail Pomacea canaliculata in the Transmission of Schistosomiasis in Mwea, Kirinyaga County, Kenya

Abstract

Schistosomiasis is a major public health challenge in irrigation-based communities. The recent establishment of the invasive snail, Pomacea canaliculata, within the Mwea Irrigation Scheme has raised concerns regarding its interaction with native vector snails and its potential influence on schistosomiasis transmission. However, its ecological relationship with native vector snails and the temporal patterns of reported human schistosomiasis following its establishment remain unclear. This study aimed to evaluate ecological and epidemiological evidence for the potential indirect role of P. canaliculata in schistosomiasis transmission by assessing its spatiotemporal distribution and abundance relative to native vector snails and examining temporal trends in reported human schistosomiasis following its establishment. A cross-sectional survey was conducted at 32 sites in irrigation canals and rice paddies during the rainy and dry seasons to assess snail distribution and abundance, while hospital surveillance records for 2019–2025 were analysed for temporal trends. Seasonal and habitat-related differences in snail abundance were assessed using non-parametric tests, while temporal trends in reported human schistosomiasis were evaluated using linear regression and Kendall’s tau correlation. P. canaliculata occurred at all 32 sites, with significantly higher abundance during the rainy season and in irrigation canals (p ≤ 0.05). Native vector snails were absent from 18 (56.2%) sites occupied by P. canaliculata and co-occurred at 14 (43.8%) sites. Reported human schistosomiasis cases declined by 86.7% between 2019 and 2025, with a significant overall temporal decline. The widespread establishment of P. canaliculata, its occurrence where native vector snails were absent, and the concurrent decline in reported human schistosomiasis following its establishment suggest a potential indirect role in transmission through ecological effects on native vector snail populations. However, temporal ecological changes cannot be established from a cross-sectional study. Longitudinal studies are therefore required to determine whether the continued establishment of P. canaliculata results in measurable changes in native vector snail populations and schistosomiasis transmission over time.