The Food and Agriculture Organization of the United Nations (FAO) and the Intergovernmental Authority on Development (IGAD) are urging countries across Eastern Africa to strengthen preparedness and surveillance measures as heavy rainfall and flooding associated with El Niño increase the risk of Rift Valley fever (RVF) outbreaks.
RVF is an acute viral disease that affects livestock, including sheep, goats, cattle, buffaloes and camels, and can also infect humans. The virus is transmitted mainly by mosquitoes, while the movement of infected animals can contribute to its geographical spread. Humans can also become infected through direct contact with infected animals or animal products.
Heavy rainfall and flooding linked to El Niño, which is approaching record strength, encourage the spread of RVF by expanding mosquito breeding sites and potentially disrupting veterinary services. Current El Niño conditions are comparable to those observed in 1997-98, when one of the largest recorded RVF epidemics and epizootics affected Eastern Africa.
The countries currently assessed as facing the highest risk are Ethiopia, Kenya, Somalia, South Sudan, Tanzania and Uganda. Risk is also increasing in Burundi and Rwanda, while lower but growing risks exist in the Comoros, northern Madagascar, the Department of Mayotte, south-western Saudi Arabia and western Yemen.
In their latest alert, FAO and IGAD are calling on affected countries to strengthen risk-based surveillance, pre-position vaccines and essential supplies, and enhance coordination across sectors and borders through a One Health approach.
The alert is delivered through the world’s largest Global early warning and prevention system for animal health (FAO-EMPRES). For more than 30 years, through continuous disease monitoring, risk assessment, forecasting and timely risk communication, EMPRES has helped Members anticipate animal disease threats and take appropriate prevention and preparedness measures.
Climate outlook and projected RVF risk
Above-average rainfall and flooding are expected across most of Eastern Africa. The heaviest rainfall is forecast for southern Ethiopia, Kenya, and central and southern Somalia, where there is a greater than 90 percent probability of receiving more than 400 mm of rainfall.
Burundi, Rwanda, South Sudan, Uganda and Tanzania are also expected to experience wetter-than-normal conditions. The western Indian Ocean islands and parts of the Arabian Peninsula, particularly western Saudi Arabia, face increased flood risk. Drier-than-normal conditions are expected in southern Sudan and across Southern Africa. Warmer than average temperatures are forecast for much of the Greater Horn of Africa.
Based on the October 2026 forecast of the FAO RVF Early Warning Decision Support Tool (RVF DST), conditions suitable for RVF transmission are expected to increase across much of Eastern Africa between October 2026 and January 2027.
Following a long period of rainfall deficits, rainfall has picked up in recent weeks in parts of southern Sudan, western South Sudan, eastern Ethiopia, southern Somalia and coastal Kenya, with heavy rains and a rising flood risk in Ethiopia and Somalia.
According to the RVF DST, Tanzania currently has the largest area classified as suitable for RVF transmission, followed by Ethiopia, Kenya, South Sudan and southern Sudan. New suitable areas have also emerged in southern Somalia, Rwanda and Burundi. With heavy rains forecast for the rest of the season, suitable areas are expected to expand further, including in Uganda.
These conditions are likely to create ideal mosquito breeding habitats. Combined with livestock movements, they could increase the risk of outbreaks and make surveillance and response more challenging.
FAO’s Rift Valley Fever Early Warning Decision Support Tool (RVF DST)
FAO’s Rift Valley Fever Early Warning Decision Support Tool is an innovative online platform developed to strengthen early warning, preparedness, and response to RVF – one of Africa’s most persistent and climate-sensitive zoonotic diseases. As part of FAO’s animal health intelligence capabilities, the tool integrates satellite data, climate forecasts, disease surveillance information and expert analysis to identify areas at elevated outbreak risk up to three months in advance.
Applying One Health principles, the RVF DST enhances real-time monitoring, data sharing, and multi-sectoral collaboration between animal health, human health, and environmental sectors. By providing advance plan targeted surveillance and preparedness measures to protect livestock, livelihoods, and lives before disease spreads.
