OUTBREAK: Rift Valley Fever
Rift Valley fever in Senegal - 2025
Background
Rift Valley Fever (RVF) is a mosquito-borne, zoonotic disease caused by the Rift Valley fever virus (RVFV), belonging to the Phenuiviridae viral family which is part of the Bunyaviricetes. It was first discovered during an outbreak among sheep in Kenya in 1930 led to the death of several lambs. In 1944, the virus was isolated from mosquitoes, confirming that mosquitoes act as a vector for transmitting the virus from livestock to humans. Since its discovery, outbreaks have been reported across Africa and the Arabian Peninsula. Senegal experienced its first RVF outbreak in 1987 at its border with Mauritania which led to over 200 human deaths. After 1987, Senegal continued to experience RVF outbreaks but no human deaths were reported. The last RVF outbreak in Senegal, prior to the 2025 outbreak, occurred in 2020.
RVF is primarily transmitted to humans by mosquitoes or through direct contact with infected animals. Transmission is amplified during periods of heavy rainfall which increases the number of infected mosquitoes. There has been no evidence of human-to-human transmission so far. Most humans develop a mild, self-limiting disease but severe illness such as haemorrhagic disease, neurological disease, hepatitis, and occular disease can occur. Fatalities occur in approximately 0.5% to 2% of cases. Fatality among cases that develop a haemorrhagic disease is approximately 50%. There are no licensed vaccines or therapeutics against RVF for use in humans.
Current Outbreak
On 21 September 2025, the Senegal Ministry of Health declared a RVF outbreak in northern, livestock producing districts. Since then, and as of 11 October 2025, there have been 147 RVF cases and 19 deaths. This is the first RVF outbreak since 1987 that has led to human deaths in Senegal. The outbreak has occurred during a period of heavy rainfall and flooding which is believed to have amplified mosquito breeding grounds and contributed to the severity of the outbreak. Genomic analysis confirms the presence of lineage H which was introduced to Senegal in 2020. The analysis indicates that there has been adaptation over time, as opposed to a new lineage introduced, and emphasises the importance of genomic surveillance.
For more information about RVF in Senegal, our outbreak summary report will soon be available.
Key public health and research updates
October 2025:
- Bunyaviricetes CORC urgent Scientific Consultation meeting held. Research priorities are expected to be developed and will be posted here when available.
September 2025:
- On 21 September, Senegal declared a RVF outbreak in northern districts.
October 2024:
- CEPI announces that a Phase II clinical trial is expected to commence investigating ChAdOx1 vaccine candidate in Kenya. They state that this would be the furthest stage of vaccine testing for RVF in humans.
July 2024:
- WHO published ‘Pathogens prioritization: a scientific framework for epidemic and pandemic preparedness’ listing Rift Valley Fever as a high PHEIC (Public Health Emergency of International Concern) risk.
November 2019:
- WHO R&D published Guidance on clinical trial design for RVF vaccines and therapeutics.
May 2019:
- The WHO R&D Blueprint team published a Research and Development Roadmap on Rift Valley Fever.
October 2013:
- Senegal experiences an RVF outbreak. No deaths reported.
Outbreak-specific research priorities
The WHO R&D Blueprint team published a Roadmap outlining research priorities for RVF in 2019. A preliminary list of research priorities is expected to be published as an output from the CORC Scientific Consultation held on 14 October 2025.
Relevant Links
Pandemic PACT data
See below our data visualisations for RVF research grant funding.
Global annual funding for research on diseases with a pandemic potential
Total number of grants and US dollars committed for each disease
Please note: Grants may fall under more than one disease. Funding amounts are included only when they have been published by the funder and are included within the year of the grant award start date.
Global Distribution of Grants by Research Area
The chart shows the total amount of funding allocated for different research areas for all diseases. Use filters on the left for advanced filtering depending on your interests. Use the 'View sub-categories' buttons to explore the sub-categories.
Number of grants
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Please note: Grants may fall under more than one research category, and funding amounts are included only when they have been published by the funder.
Global Map of Geographical Distribution of Funding Organisations OR Research Locations
The information on the research location was collected where available from the grant application, and can be different to the location of research institution.
Countries
WHO Regions
Please note: Funding amounts are included only when they have been published by the funder. Some research projects are undertaken in multiple locations (countries) and some are funded by multiple funders. Where research location is not explicitly specified the default used is the location of the research institution receiving the funds.
Regional Distribution of Funding by Research Areas
Each research category is shown in a different colour
Please note: Grants may fall under more than one research category, and funding amounts are included only when they have been published by the funder.
Regional Flow of Research Grants
The chart illustrates the flow of research grants by region, tracing it from funder to research institution and ultimately to the location where the research is conducted.
If the full chart is not visible, please scroll horizontally to view.
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Please note: Funding amounts are included only when they have been published by the funder. Some research projects are undertaken in multiple locations (countries). Where research location is not explicitly specified the default used is the location of the research institution receiving the funds.
Annual Trends in New Global Grants for Research Areas
The chart shows the total amount of funding allocated to different research areas by calendar year of award start date.
Please note: Grants may fall under more than one research category. Funding amounts are included only when they have been published by the funder and are included within the year of the grant award start date.