Local Knowledge of Land Use Effects on Human-Rodent Interfaces in Lassa-Endemic Nigeria.

Lassa fever (LF) is endemic to West Africa with a disproportionate impact on rural communities. LF is caused by Mammarenavirus lassaense (LASV), an arenavirus hosted by Mastomys spp. rodents (multimammate rats). This study leverages local knowledge to examine how human settlement patterns and agricultural land use influence perceptions of Mastomys spp. population dynamics and affect human-rodent interactions across diverse social and ecological settings in Lassa-endemic areas of Nigeria. We used participatory rural appraisal (PRA) at three sites with varying settlement patterns and landscape structure to (1) summarize landcover and agricultural practices, (2) characterize human land use within different landcover types, and (3) identify types and frequency of human interactions with suspected Mastomys spp. PRA revealed consistent patterns of (1) perceived Mastomys spp. population ecology and behavior and (2) reported human-Mastomys spp. contact across villages and landcover types. All villages reported perceived increases in Mastomys spp. activity in response to seasonal land clearing and rice harvest. Perceptions of rodent movement varied between settlement types, with increased movement of Mastomys spp. between agricultural fields and residential compounds reported in villages where homes were interspersed with farmland. Regular contact with Mastomys spp. was widely reported in both households and fields, although contact type and frequency differed based on gendered agricultural duties and daily activity, revealing potentially underemphasized pathways for LASV transmission in agricultural settings. PRA data suggests human settlement patterns and agricultural land use mediate LASV reservoir movement and human-reservoir interfaces, potentially creating variation in LF exposure risk both within villages and across the endemic area.