Rift Valley fever virus

Rift Valley fever virus (RVFV) is a vector-borne disease of sheep, cattle and goats which humans are susceptible to. RVFV belongs to the Bunyaviridae family within the genus Phlebovirus. It is an enveloped virus containing a capsid and single-stranded RNA genome.

  • Rift Valley fever is a notifiable disease and should be reported.
    Please see the Defra website for advice on how to spot and report the disease.

Associated diseases:

RVFV causes rift valley fever which spreads over large areas of a country after heavy rains and sustained flooding as this provides ideal conditions for the vectors. Young animals are significantly more susceptible and a lot more likely to die. Severity of the disease varies by species, with lambs being “extremely susceptible”, calves “highly susceptible” and humans “moderately susceptible”.

Clinical signs of RVF tend to be nonspecific, which make individual cases difficult to diagnose, but high levels of mortality in young animals, high abortion rates and flu-like symptoms in humans are indicative.

Clinical signs:

  • Fever
  • Lethargy and listlessness
  • Abdominal pain
  • Nasal discharge
  • Anorexia
  • Bloody/fetid diarrhoea
  • Abortion
  • Mortality

In people, RVF is usually inapparent or a flu-like illness may present. About 1%–2% may develop severe disease including haemorrhages, lesions and encephalitis (inflammation of the brain). In these severe cases, the fatality rate may be 10%–20%.

Disease transmission:

RVFV is transmitted from animal to animal by mosquitoes; the main species that spreads the disease varies between regions. RVF can also be spread to humans through direct contact with infected animals and meat.

Disease prevalence:

RVF is endemic in tropical regions of eastern and southern Africa, with severe outbreaks occurring in Egypt, Mauritania, Kenya and Somalia. More recently, Madagascar, Swaziland and South Africa have also reported outbreaks.

Impact for Society – what are we doing?

Major outbreaks in Egypt in the 1970s and more recently in Kenya in 1998 have claimed the lives of hundreds of people. The disease also results in significant economic losses due to death and abortion among RVF-infected livestock.

The Institute is investigating the ability of European mosquitoes to transmit RVFV and measure the susceptibility of European livestock breeds to the disease. In doing this the Institute will be able to gain information about whether RVF is a threat in Europe and will be able to advise on how an outbreak may spread if one were to occur.


* Image by F. A. Murphy; J. Dalrymple courtesy of Public Health Image Library (PHIL)

Research papers

Jenkin D, Wright D, Folegatti PM, Platt A, Poulton I, Lawrie A, Tran N, Boyd A, Turner C, Gitonga JN, Karanja HK, Mugo D, Ewer KJ, Bowden TA, Gilbert SC, Charleston B, Kaleebu P, Hill AVS, Warimwe GM (2023)

The Lancet Infectious Diseases
Laureti M, Lee RX, Bennett A, Wilson LA, Sy VE, Kohl A, Dietrich I (2023)

Pathogens 12 (4) , 563
Ahmed A, Ali Y, Elduma A, Eldigail M H, Mhmoud R A, Mohamed N S, Ksiazek T G, Dietrich I, Weaver S C (2020)

Emerging Infectious Diseases 26 (12) , 3030-3033
Stedman A, Wright D, Wichgers Schreur P J, Clark M H A, Hill A V S, Gilbert S C, Francis M J, van Keulen L, Kortekaas J, Charleston B, Warimwe G M (2019)

npj Vaccines 4 (1) , 44
Clark M H A, Warimwe G M, Di Nardo A, Lyons N A, Gubbins S (2018)

PLoS Neglected Tropical Diseases 12 (7) , e0006627


Trim content

® The Pirbright Institute 2024 | A company limited by guarantee, registered in England no. 559784. The Institute is also a registered charity.