Rift Valley fever in Rwanda, 2025: A descriptive case series of nine confirmed human cases

Background Rift Valley fever (RVF) is a deadly mosquito-borne viral disease. Rwanda reported its first major outbreak in 2018, followed by a larger one in 2022 with 173 human cases and 27 deaths. Given the limited clinical data available, we describe nine RVF cases highlighting symptoms, exposures, laboratory findings, and outcomes. Methods We conducted a retrospective, descriptive case series of nine laboratory-confirmed RVF patients from Kamonyi district, Rwanda, from November 2025 to December 2025.Demographic, clinical and laboratory data were extracted from Rwanda's routine Health Management Information System (HMIS), which runs on the District Health Information Software 2 (DHIS2) platform, and were summarised descriptively; no inferential testing was performed given the small sample. Proportions are reported with 95% confidence intervals (CI). Results Nine patients were included (median age 21 years, range 3-31; 5 males and 4 females). Cases were distributed across seven of the district's twelve sectors over an approximately four-week period; the highest single-day count was three cases on 25 November 2025. Reported (suspected) exposures were contact with sick or dead animals (5/9), handling of raw meat (2/9), and consumption of unpasteurised milk (1/9). Fever affected 8/9 (89%), headache 6/9 (67%), and abdominal pain and vomiting 5/9 (56%) each. Laboratory findings included hematological abnormalities and hepatocellular injury, with thrombocytopenia and elevated transaminases the most consistent findings; renal function was largely preserved. One death occurred during the acute phase (case-fatality rate 11.1%). Conclusion Human RVF transmission in Kamonyi District followed a diffuse, multi-source pattern consistent with widespread livestock circulation across the district. Strengthening integrated One Health surveillance linking animal, human, and vector monitoring is critical to early outbreak detection and response in Rwanda and the broader region.