At least 42 people have died in Senegal and Mauritania following a deadly outbreak of Rift Valley Fever (RVF), one of the world’s most dangerous viral diseases, health officials said.
The World Health Organization (WHO) described the situation as an “unusually severe outbreak”, with 404 confirmed cases recorded as of October 30. The virus, which primarily affects livestock but can infect humans, began spreading in late September in northern Senegal’s livestock-producing regions before reaching parts of Mauritania.
WHO said it was first alerted to the outbreak on September 20, after human cases were confirmed in Senegal. Health experts and emergency response teams have since been dispatched to the affected areas to strengthen surveillance, treatment, and infection control.
“The risk of further spread remains high, especially with warm, humid weather and heavy rainfall that favor mosquito breeding,” WHO warned.
RVF is transmitted to humans through mosquito bites or direct contact with infected animal blood or organs, placing herders, farmers, butchers, and veterinarians at greatest risk. There is no evidence of human-to-human transmission.
While most infected people experience only mild flu-like symptoms, severe cases can lead to hemorrhagic fever, brain inflammation, or blindness — all potentially fatal. Officials said over 10% of cases in Senegal developed hemorrhagic symptoms, resulting in 20 deaths, while three in ten patients in Mauritania have died.
The WHO has now classified the public health risk as “high” at the national level but “low” globally, as authorities work to prevent the disease from spreading across borders through livestock trade and migration toward Mali and Gambia.
RVF outbreaks have previously caused major loss of life across Africa. In 1998, epidemics in Kenya and Somalia killed more than 470 people, and in 2000, the virus reached Saudi Arabia and Yemen, marking its first appearance outside Africa.
Senegal last suffered a major RVF outbreak in the late 1980s, when over 200 people died in Senegal and Mauritania.
There are no vaccines or specific treatments for RVF in humans, and WHO continues to list it among nine “priority diseases” with pandemic potential.
No RVF cases have ever been reported in the United Kingdom or most regions outside Africa and the Middle East.
