RVFV

Rift Valley fever virus (RVFV) is a negative-sense, single-stranded RNA virus in the family Phenuiviridae, genus Phlebovirus. It causes Rift Valley fever, a zoonotic disease affecting humans and ruminant animals. The virus was first identified in Kenya in 1931.

The genome comprises three segments (L, M, S) that encode the RNA polymerase, structural envelope glycoproteins Gn and Gc with the nonstructural protein NSm, and the nucleocapsid N with NSs, a major virulence factor that suppresses host interferon responses.

In animals, infection predominates in sheep, cattle and goats, often causing abortion storms; in humans, infection occurs through bites from infected mosquitoes or contact with blood, body fluids, or tissues of infected animals. Primary vectors include Aedes and Culex species; transovarial transmission in Aedes can seed outbreaks after heavy rainfall.

The virus is endemic to sub-Saharan Africa and the Arabian Peninsula, with outbreaks typically linked to periods of heavy rainfall and flooding that amplify mosquito vectors. In livestock, abortion and high neonatal mortality are common; in humans, infection ranges from mild fever to hemorrhagic, encephalitic, or ocular disease.

Diagnosis relies on RT-PCR during the acute phase and serology (IgM and IgG) later; virus isolation occurs in BSL-3 laboratories. There is no widely approved antiviral therapy; treatment is supportive. Vaccination of livestock is a key control measure; veterinary vaccines such as MP-12 and Clone 13 are used in some settings.

Research continues on improved vaccines and diagnostics; RVFV is considered a potential emerging pathogen and biosafety risk due to its epidemiology and vector-borne transmission. Global surveillance and vector control, along with safe animal handling, are central to preventing outbreaks.