Spatial determinants of diarrheal disease in the Rokel-Seli river watershed, Sierra Leone

This study used spatial and non-spatial analyses to examine the drivers of diarrheal disease in the Rokel-Seli River watershed, Sierra Leone. Data sources included fecal coliform sampling (E. coli), land use and climate metrics, household surveys (n = 280), and medical records (n = 26,909 episodes from 139 health facilities). A dual modeling strategy: Poisson generalized linear models (GLM) and geographically weighted Poisson regression (GWPR) captured both household-level and subbasin-level predictors. Diarrhea was significantly associated with low educational attainment, inadequate toilet facilities and contaminated water sources (p < 0.05). Slope and housing density emerged as localized environmental risk factors, while rainfall and temperature showed weaker associations. Diarrhea clustered in both high- and low-density districts, with Magburaka reporting the highest burden. Findings underscore the need for targeted investments in education, sanitation and water infrastructure. This integrated spatial framework offers a scalable model for waterborne disease mitigation in watershed communities.