Rift Valley Fever: Deadly Virus Threatens Livestock and Humans

Rift Valley Fever (RVF) is a significant zoonotic disease, meaning it can spread from animals to humans, primarily impacting livestock like camels, sheep, and cows. The World Health Organization has designated it a priority pathogen due to its pandemic potential and the current lack of effective vaccines and treatments.

Outbreaks, historically occurring in Africa and the Middle East, are often associated with periods of heavy rainfall and flooding. These conditions lead to a surge in mosquito populations, the primary vectors for transmission. Human symptoms can vary widely, from asymptomatic cases to a severe, often fatal, hemorrhagic form.

Transmission to humans typically occurs through direct contact with the blood, bodily fluids, or tissues of infected animals, particularly during handling or slaughter. Consumption of unpasteurised milk from affected animals also poses a risk. Mosquito bites from infected species, especially Aedes and Culex, are another key transmission route, with human-to-human transmission being exceedingly rare.

As of June 23, 2026, there is no specific cure for RVF; management is supportive, focusing on symptom relief. Research into antiviral therapies and vaccines for humans is progressing, with the first phase II trial of an RVF vaccine recently initiated in Kenya in July 2025.

The virus was first identified in Kenya in 1931. Significant outbreaks have since been recorded across sub-Saharan Africa, with notable occurrences in Egypt in 1977, East Africa in 1997-1998 following extensive flooding, and its first recorded appearance outside Africa in Saudi Arabia and Yemen in 2000, attributed to the trade of infected livestock.