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Reporting Rift Valley fever in Senegal: from training to action
After intense rainfall in September 2025, Rift Valley fever emerged across Senegal, Mauritania and Gambia, severely affecting both animals and humans. Although the disease is not new to these countries, its impact fluctuates significantly over time, underscoring the importance of preparedness and surveillance. During the peak of the epidemic, Senegal demonstrated how timely data collection and reporting through the World Animal Health Information System (WAHIS) can make the difference.
Between 16 and 18 September 2025, Mathioro Fall was in Abidjan, Côte d’Ivoire, attending a training session by the World Organisation for Animal Health (WOAH) on reporting animal diseases through WAHIS. As head of the animal health protection division at the ministry of agriculture, food sovereignty and livestock of Senegal, Dr. Fall is responsible for submitting animal disease outbreak updates to WAHIS — the reason for his trip to Côte d’Ivoire.
At that time, Rift Valley fever had already been present in Senegal, being reported since at least September 2020 in the Rao region. Shortly after completing the training, Dr. Fall logged in to WAHIS to close the previous event and opened a new one, due to an increase in Rift Valley fever outbreaks in both animals and humans. In fact, by the end of September, Senegalese health authorities confirmed human infections, including several fatalities, marking the beginning of a major event spanning Senegal, Mauritania and Gambia. This epidemic event was later recognised as high risk for human and animal health at national level by the joint assessment of the Food and Agriculture Organization of the United Nations (FAO), the World Health Organization (WHO) and WOAH.
In early December, Mathioro Fall was back in Saint-Louis — a four-hour drive from Dakar, the capital of Senegal — for a follow-up mission on the Rift Valley fever outbreaks. According to the data he has been collecting and sharing weekly with the international community, the epidemic appears to have reached its peak and case numbers are now expected to decline over time.
“The containment measures are proving effective,” explains Dr. Fall during a break from his field mission. “But we are now reviewing the actions taken to develop an improvement plan for future epidemics. Rift Valley fever is a priority disease in Senegal: we know the hotspots where it is likely to reoccur, and we know it has a cyclical pattern. It typically returns every two to three years, so this is the time to learn from what we have done and to strengthen surveillance and prevention across animal populations.”
Monitoring animal infections, to protect everyone’s health
Rift Valley fever is a vector-borne disease that can affect different animal species. The virus is carried and spread by mosquitoes and, in some cases, it can even survive for years in their eggs, including under dry conditions. When heavy rain causes the eggs to hatch, the virus can re-emerge and begin spreading again among animals. Humans can also become infected, most commonly through contact with the blood or bodily fluids of infected animals, but also through bites from mosquitoes.
The disease is particularly harmful to young lambs and goats, with mortality rates ranging from 70% to 100%. In sheep and calves, mortality drops to 20% to 70%, and it varies widely across other species. Pregnant sheep and cattle almost always abort: an outcome that is both devastating for farmers and a crucial sign for epidemiologists. As Dr. Fall explains: “Alongside targeted vaccinations, active surveillance of sentinel species and the use of insecticides on farms, we must work on raising farmers’ awareness on the disease symptoms so they can efficiently report abortions in their animals. This helps us recognise an outbreak in progress and ultimately allows our colleagues in human health to be alerted to any potential emerging threats.”
Training people on WAHIS best use
As soon as an outbreak of a new or previously eradicated listed animal disease occurs within their territory, WOAH Members are required to report it through WAHIS.
While the information system serves as a key data source for Veterinary Services, international organisations, and researchers interested in collecting and reusing animal health information, WAHIS’s effectiveness depends on the dedication and cooperation of the people reporting in it. As a recent study in the Asia-Pacific region highlighted, capability is crucial to ensuring timely disease notification. This is why trainings are regularly organised worldwide.
“I have been reporting through WAHIS for many years,” acknowledges Mathioro Fall, “but I must admit that the last training I attended provided me with useful tips to use the platform more efficiently and quickly.”
Diseases across borders
The map shows the outbreaks of Rift Valley fever reported by Senegal, Mauritania and Gambia through WAHIS between 30 September and 10 December 2025.
Like all diseases, Rift Valley fever knows no borders, and its vector-borne nature makes it particularly difficult to contain within a specific area. Senegal is not the only country affected by outbreaks in late 2025. Mauritania and Gambia reported cases during the same period, and South Africa also experienced a recurrence of the disease in an unrelated event. From the WAHIS disease-situation dashboard, it is possible to see that since 2023 the virus has been reported as present also in Burkina Faso, Burundi, Rwanda, Madagascar, Uganda, Ghana, Mozambique and Kenya. Reporting transparently the disease situation is the first step toward tackling the disease, as Dr Fall explains:
One country alone can’t definitively control a transboundary disease. This year’s event was exceptional, but we would have notified the presence of the disease regardless, because it is our duty as a WOAH Member. Sharing data on current outbreaks is vital to help other countries understand the situation.
Head of the animal health protection division at the Ministry of Agriculture, Food Sovereignty and Livestock, Senegal.
“In the past, for example, we used WAHIS data to assess the animal disease situation in our trade partners. By notifying, we empower our colleagues in other countries to understand what is happening, assess the risks, prepare accordingly and, if needed, advocate for resources with solid evidence in hand.”, shares Dr Fall.
Different ways to report through WAHIS
By collecting and making vast amounts of data available to anyone, WAHIS serves as a source of highly diverse information that can be consulted by a wide range of audiences. Countries and territories are expected to report data in two ways: through the early warning system and the monitoring system.
In the first case, when a previously absent or eradicated disease occurs in animals, the country notifies WOAH immediately via WAHIS. An alert is then sent, and the notifying country must provide weekly updates.
The monitoring system is designed to provide an overview of the presence or absence of a disease in a given area. WOAH Members are expected to submit a report every six months, providing epidemiological data on all diseases present in their territory. These data are displayed on WAHIS, but they can also be downloaded and reused by anyone interested.
Rift Valley fever has made headlines in West Africa in recent months, and, like many vector-borne diseases, it is unlikely to disappear anytime soon. Its ability to infect both domestic and wild animals, combined with the effects of climate change and extreme weather events, means that people will likely need to become more familiar with this disease. In the meantime, animal health officials are already collecting and sharing data to ensure they are ready to make the best decisions when needed.