Evidence of inter-epidemic transmission of Rift Valley Fever virus circulation in Nigeria: a scoping review

Rift Valley fever virus (RVFV) is a zoonotic arbovirus of major public health and veterinary importance in Africa, yet its inter-epidemic transmission dynamics and baseline endemicity in Nigeria remain insufficiently synthesized relative to classic outbreak-prone regions. This scoping review systematically synthesizes over six decades of evidence (1959–2024) on the epidemiology, prevalence, transmission dynamics, diagnostics, and control of RVFV in Nigeria. Following PRISMA-ScR guidance, 24 peer-reviewed primary articles were included (following comprehensive systematic screening across electronic databases and grey literature sources) across human, livestock, wildlife, and vector populations. The evidence indicates that RVFV in Nigeria represents a long-established endemic zoonosis sustained through silent, low-amplitude transmission rather than explosive epidemics. Serosurveys in domestic livestock demonstrated an overall seroprevalence ranging from 3.3% to 33.3% across regions and species (most study estimates clustering between 5 and 30%), with higher values in northern pastoral regions characterized by transhumance, wetlands, and cross-border animal movement. Human seroprevalence is consistently lower (< 20%) and largely confined to occupationally exposed groups, suggesting under-recognition of infection due to non-specific clinical presentation and limited routine diagnostics. Entomological data implicate key mosquito vectors (predominantly Culex species) alongside biting midges (Culicoides spp.) and evidence of wildlife exposure, supporting a complex, ecologically resilient transmission system that enables year-round circulation independent of extreme climatic events. Diagnostic invisibility, fragmented surveillance, and weak One Health integration remain major constraints, while documented control interventions are scarce. Recent advances in molecular diagnostics, participatory epidemiology, and integrated One Health responses in other African countries highlight actionable opportunities for strengthening RVFV surveillance and control in Nigeria. This review underscores the urgent need for integrated, multi-sectoral surveillance and proactive control strategies to address the under-estimated burden of RVFV in Nigeria.