Scoping review finds evidence of endemic Rift Valley fever transmission in Nigeria

A scoping review of research published from 1959 through 2024 found that Rift Valley fever virus appears to circulate in Nigeria through persistent, low-level transmission between major epidemics, according to the review’s abstract. The synthesis characterizes the disease as a long-established endemic zoonosis rather than a problem limited to occasional explosive outbreaks, while noting that diagnostic and surveillance constraints make the extent of transmission difficult to determine.

The authors followed PRISMA-ScR guidance and screened electronic databases and grey literature. They included 24 peer-reviewed primary articles examining human, livestock, wildlife and vector populations. Serosurveys in domestic livestock reported overall seroprevalence ranging from 3.3% to 33.3% across regions and species, with most study estimates clustering between 5% and 30%. Higher values were reported in northern pastoral regions characterized by transhumance, wetlands and cross-border animal movement.

Human seroprevalence was consistently lower than 20% and was largely confined to occupationally exposed groups. The review’s authors interpret this pattern as suggesting that human infections may be under-recognized because of non-specific clinical presentation and limited routine diagnostics. Entomological evidence implicated mosquitoes, predominantly Culex species, as well as biting midges in the genus Culicoides. The review also identified evidence of wildlife exposure and concluded that these findings support a complex, ecologically resilient transmission system capable of sustaining year-round circulation independently of extreme climatic events.

The abstract identifies diagnostic invisibility, fragmented surveillance and weak integration across human, animal and environmental health as major constraints on characterizing Rift Valley fever in Nigeria. Documented control interventions were also described as scarce. The review notes advances in molecular diagnostics, participatory epidemiology and integrated One Health responses in other African countries, but the abstract does not report the effectiveness of such measures in Nigeria. Because this is a synthesis of varied primary studies rather than a single longitudinal analysis, the reported evidence supports an interpretation of sustained inter-epidemic circulation without providing a quantitative estimate of national incidence. The review concludes that the burden of Rift Valley fever is underestimated and calls for integrated, multisectoral surveillance and proactive control strategies.

Subject of Research: Scoping review of Rift Valley fever epidemiology and inter-epidemic transmission in Nigeria

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

Article References: Oyekan, O. A., Igah, O. E., Bakam, J. D., Ogunmolawa, O. R., Wungak, Y. S., Oyekan, O. D., Ehizibolo, D. O., Adedeji, A. J., Ularamu, H. G., & Meseko, C. A. (2026). Evidence of inter-epidemic transmission of Rift Valley Fever virus circulation in Nigeria: a scoping review. BMC Public Health. https://doi.org/10.1186/s12889-026-29876-8

Image Credits: AI Generated

DOI: 10.1186/s12889-026-29876-8

Keywords: Rift Valley fever, Nigeria, scoping review, inter-epidemic transmission, zoonosis, seroprevalence, livestock, mosquito vectors, One Health, surveillance, Evidence, inter-epidemic