Senegal has recorded seven cases of Rift Valley fever (RVF) and four deaths, according to Dr. Boly Diop, head of epidemiological surveillance at the Ministry of Health and Public Hygiene, in a statement dated September 25, 2025. This viral zoonosis, still little known to the general public, is of concern to health experts because of its health and economic impacts in Africa.

When livestock becomes a source of danger

First identified in Kenya in 1931, RVF is caused by a phlebovirus transmitted by mosquitoes (Aedes, Culex). It first strikes herds, causing mass abortions in sheep, goats, and cows, as well as high mortality among young animals. Humans become infected through the bite of contaminated mosquitoes or through contact with the blood, organs, or milk of infected animals, particularly exposing livestock farmers, veterinarians, butchers, and their families. Faced with this threat, a strategy combining animal vaccination, vector control, and public awareness is essential to reduce its impact. Ignoring this zoonosis is like allowing a silent health bomb to grow.

A deceptive and sometimes devastating illness

“In most infected people, the disease manifests itself with a sudden fever, headaches, muscle aches, and extreme fatigue, a symptom often confused with the flu or malaria,” explains Dr. Boly Diop. These mild forms mask a darker reality. “In a minority of cases, RVF progresses to severe and often fatal forms,” he adds. Severe manifestations include:

1. Hemorrhagic fever : liver damage, jaundice, bloody vomiting, internal or external bleeding, which can lead to death in less than 72 hours.
2. Meningoencephalitis : The virus invades the brain, causing convulsions, confusion, coma and lasting neurological sequelae.
3. Eye damage: inflammation of the retina which can lead to irreversible blindness.

According to the World Health Organization (WHO), these severe forms kill up to 50% of patients with hemorrhagic fever, with the fatality rate varying depending on the outbreak and the quality of care.

A recurring threat in West Africa

Over the past few decades, RVF has struck several African countries, including Mauritania, Niger, and Senegal. Each time, the scenario is the same: heavy rains cause mosquitoes to multiply, herds become infected, and then human cases appear.

In 2020, an outbreak in Mauritania caused nearly 80 human cases, more than a third of whom died. These figures, often underestimated due to a lack of surveillance, demonstrate the extent to which this disease remains a silent killer.

No specific treatment, crucial prevention

No antiviral treatment or vaccine approved for humans currently exists. Lamine Sène of the Pasteur Institute explains that the Vaccinopole is working to "develop vaccines against neglected diseases, such as Lassa fever and Rift Valley fever, and to strengthen research to respond rapidly to future pandemics, similar to the mobilization against Covid-19."

Treatment is symptomatic: rehydration, transfusions in case of hemorrhage, intensive care for severe cases. "In rural areas, these means are rarely available, which explains the high mortality rate," he notes. Vaccines exist for animals, but their use remains limited. Prevention relies on monitoring herds, mosquito control, and individual measures: avoiding contact with carcasses, consuming pasteurized milk and thoroughly cooked meat, and using mosquito nets and repellents.

RVF illustrates the importance of the "One Health" approach, linking human, animal, and environmental health. As long as herds remain vulnerable and mosquitoes swarm after each rainy season, the risk of new deadly outbreaks will remain high.