Investigation and response to rift valley fever outbreak in ruminant livestock from Ngoma District, eastern province of Rwanda, 2024

Background: Rift Valley fever (RVF) is a zoonotic mosquito-borne disease, causing high livestock morbidity and mortality, with potential human spillover. Rwanda has experienced repeated outbreaks, including significant ones in 2018 and 2022. In August 2024, a smaller localized outbreak was reported in Ngoma District, Eastern Province, providing insights into rapid detection, response, and recovery. Methods: Following confirmation of the index case by RT-PCR, 4062 blood samples were collected through active community and slaughterhouse surveillance. Epidemiological and demographic data were analyzed, and supportive treatment was provided to confirmed cases. A One Health response was implemented, including livestock vaccination, vector control, and coordinated surveillance. Results: Among sampled animals, 28 (0.69%) tested positive: 14 cattle, 9 goats, and 5 sheep. Sheep showed the highest infection rate (5.4%). Three animals died, yielding a case fatality rate of 10.7%, while 25 recovered after treatment. Positive cases clustered in six sectors near marshlands and the Akagera River. A total of 112,110 animals were vaccinated. No human cases were reported, and the outbreak was contained within 51 days. Conclusions: Rapid detection, targeted treatment, and mass vaccination, implemented through a multisectoral One Health response, successfully contained the outbreak and prevented human spillover. Sustained surveillance and cross-border coordination remain essential to mitigate future RVF threats.