El Niño raises fresh Rift Valley fever threat across East Africa

Kenya, August 10, 2026 - A potentially strong El Niño event expected to bring above-average rainfall to East Africa has triggered a warning over an increased risk of Rift Valley fever (RVF), with Kenya and other countries urged to strengthen disease surveillance and preparedness.

The Intergovernmental Authority on Development (IGAD) Centre for Pastoral Areas and Livestock Development, working with the Food and Agriculture Organization of the United Nations (FAO), said intensifying El Niño conditions could create favourable ecological conditions for the spread of the mosquito-borne disease.

According to the latest assessment, there is a 97 per cent probability that El Niño will persist into early 2027, with the phenomenon expected to strengthen towards a potentially strong to very strong event between October and December.

The weather pattern is expected to increase rainfall across much of Eastern Africa, raising the likelihood of widespread flooding, flash floods and riverine flooding, as well as landslides and damage to infrastructure.

Kenya is among countries identified as being at heightened risk, alongside Burundi, Ethiopia, Rwanda, Somalia, South Sudan, Uganda and Tanzania.

IGAD and FAO warned that heavy rainfall and flooding could create extensive breeding grounds for Aedes and Culex mosquitoes which are among the principal vectors responsible for transmitting RVF.

“Enhanced mosquito breeding, coupled with increased livestock exposure and movement, may elevate the risk of RVF outbreaks and complicate surveillance and response efforts,” the assessment says.

The warning is particularly significant for pastoral and agro-pastoral communities, whose livelihoods depend heavily on livestock and who frequently move animals in search of pasture and water.

Flooding can also disrupt veterinary services, damage water and pasture infrastructure and make it difficult for health workers to reach affected communities.

The agencies noted that stagnant water left behind by heavy rains provides ideal breeding conditions for mosquitoes. At the same time, livestock congregation around watering and grazing areas, seasonal transhumance and cross-border animal movements could accelerate the spread of the virus.

RVF is an acute viral disease that affects both animals and humans. It has been reported in sheep, goats, cattle, buffaloes and camels and is transmitted mainly through infected mosquitoes and contact with infected animals.

The disease can have devastating consequences for livestock keepers because outbreaks may result in widespread abortions and deaths among young animals, reducing herd numbers and threatening household incomes and food security.

The assessment warned that outbreaks can also disrupt livestock trade, reduce household earnings and limit families’ ability to access healthcare and educate children.

The regional warning comes as East African countries prepare for increased rainfall and possible flooding, raising the need for early action before outbreaks occur.

IGAD and FAO have called on governments to strengthen coordination between animal health, public health, wildlife and environmental authorities under a One Health approach.

Countries have also been urged to activate national and sub-national One Health coordination platforms and emergency operations centres where necessary, while reviewing contingency plans and conducting simulation exercises based on lessons from previous RVF outbreaks.

The agencies recommend increased surveillance in high-risk areas, including livestock markets, slaughterhouses, border crossings, quarantine stations and pastoral migration corridors.

Livestock keepers and communities have been encouraged to report unusual livestock deaths, abortions and illness promptly to veterinary authorities.

The assessment also calls for the integration of climate, weather and environmental information into disease surveillance systems to enable authorities to take anticipatory action when conditions indicate an increased risk.

Governments have further been advised to ensure laboratories have adequate testing capacity and that field teams are trained and equipped to investigate suspected cases and safely handle samples.

Preventive measures could include targeted vaccination where appropriate, safe livestock movement, quarantine measures, vector control, improved farm biosecurity and enhanced surveillance of mosquito populations.

Communities have also been urged to avoid unsafe handling of sick or dead animals and aborted materials, while promoting measures to reduce exposure to mosquito bites.

The agencies stressed the importance of cross-border cooperation, particularly along livestock trade routes and pastoral corridors linking countries in the region.

Joint risk assessments, coordinated surveillance and information sharing between neighbouring countries will be critical in detecting and containing potential outbreaks, the assessment says.

IGAD and FAO are using climate and vegetation data to identify areas where environmental conditions could support RVF transmission. The FAO RVF Early Warning panel of experts then reviews forecast risk areas with specialists on the ground before an alert is issued.

The agencies said early warning and anticipatory action could help countries minimise the health, livestock and economic consequences of a potential RVF outbreak as the region heads into the peak October-December rainfall season.