Spatial Distribution and Socioecological Drivers of Lassa Fever Cases in Edo and Ondo States: A Five-Year Retrospective Analysis

Lassa fever, caused by Lassa mammarenavirus, is endemic in West Africa with Nigeria consistently reporting the highest confirmed case burden. South South and South West Nigeria, particularly Edo and Ondo States, are recognized high-transmission zones, yet detailed spatial and socioecological analyses explaining transmission heterogeneity within these states remain limited. This retrospective epidemiological study analyzed 1,247 confirmed Lassa fever cases reported across Edo and Ondo States between 2019 and 2023 using Nigeria Centre for Disease Control (NCDC) surveillance records. Geographic information system (GIS) tools were used to map case clustering and generate spatial autocorrelation indices (Moran's I). Multiscale geographically weighted regression (MGWR) was applied to model associations between case rates and socioecological covariates including land use type, proximity to rodent habitat, housing structure type, food storage practices, and healthcare access. Results identified significant spatial clustering of cases in 8 local government areas, predominantly in forest-fringe agricultural communities. MGWR analysis identified proximity to forest edges (coefficient: 0.38), inadequate food storage (coefficient: 0.31), and low healthcare access scores (coefficient: -0.27) as the strongest local predictors of case burden. Seasonal peaks in January and February aligned with post-harvest rodent population surges. These findings provide spatially resolved epidemiological evidence to target Lassa fever prevention, rodent control, and community health resources in high-burden LGAs. Keywords: Lassa fever, spatial epidemiology, GIS, Mastomys natalensis, rodent control.