Rift Valley fever: is it a threat to humans and animals?

Marc Souris, a researcher at the Research Institute for Development in France, discusses Rift Valley fever: what it is how it spreads and how to stop it

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Rift Valley fever (RVF) is a viral disease transmitted by mosquitoes that mainly affects livestock. It can also infect humans. While most human cases remain mild, it can cause death. The disease causes heavy economic and health losses for livestock farmers. As a researcher, I have contributed to several studies on this mosquito-borne virus. So, what exactly is Rift Valley fever, how is it treated, and how can it be controlled?

WHAT IS RIFT VALLEY FEVER?

Rift Valley fever is a zoonosis (a disease affecting animals that can be transmitted to humans). It is caused by the RVF virus, a phlebovirus from the Phenuiviridae family (order Bunyavirales). The disease primarily affects domestic animals, mainly cattle, sheep and goats, but also camelids and other small ruminants. It can occasionally infect humans.

In animals, the disease causes high morbidity (reduced milk production), high newborn mortality, mass abortions in pregnant females, and death in 10% to 20% of cases. This leads to serious economic losses for farmers.

Most people who get Rift Valley fever have no symptoms or just flu-like syndrome. But in a few people, it can become very serious, causing complications such as eye disorders, meningoencephalitis (inflammation of the brain), or haemorrhagic fever. The fatality rate among infected people is around 1%.

HOW IT IS TRANSMITTED

In animals, the disease is mainly spread through bites from infected mosquitoes.

At least 50 mosquito species can transmit the Rift Valley fever virus, including the Aedes, Culex, Anopheles and Mansonia species. Mosquitoes become infected when they feed on animals carrying the virus in their blood, then transmit it to other animals through their bites.

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