Rift Valley Fever Outbreaks Continue in Mauritania and Senegal

The U.S. Centers for Disease Control and Prevention (CDC) today reported there are outbreaks of Rift Valley fever (RVF) in Mauritania and Senegal.

In a Level 1 Travel Health Notice published on December 11, 2025, the CDC says RVF is an acute viral hemorrhagic fever that causes illness in livestock and people.

However, there is currently no evidence of person-to-person transmission of RVF, which was first identified in 1931 in Kenya.

According to previous WHO data, in Mauritania, between September 27 and October 30, 2025, a total of 46 confirmed human cases of RVF, including 14 associated deaths (case fatality ratio: 30%), were reported in eleven districts from thirteen regions.

In Senegal, between September 20 and October 30, 2025, the Republic of Senegal reported a total of 358 confirmed human cases of RVF, including 28 deaths (case fatality rate: 7.8%).

The CDC says less than 2% of people infected with RVF will develop severe symptoms, which can include eye disease, hemorrhage, and encephalitis. Most people recover within one week, with treatment limited to supportive care.

While mortality is higher in severe cases, only about 1% of people who get RVF die, says the CDC.

An inactivated vaccine has been developed for human use, but it is not licensed or commercially available. It has been used experimentally to protect veterinary and laboratory personnel at high risk of RVF exposure.

In 2024 and early 2025, RVF vaccine candidates recieved funding rounds.