Rift Valley fever (RVF) is a viral zoonosis that primarily affects animals but also has the capacity to infect humans. Wageningen Bioveterinary Research conducts research on this disease.
Infection with Rift Valley fever virus
Most human RVFV infections manifest as a transient, flu-like illness. However, a small percentage of humans develop encephalitis or hemorrhagic fever, which may be fatal. In animals the virus causes severe disease in ruminants like sheep, cattle, goats and camels. Sheep are the most susceptible target species. Age has also been shown to be a significant factor in the animal's susceptibility to the severe form of the disease: over 90 percent of lambs younger than three weeks of age may succumb to the infection.
The rate of abortion among pregnant infected ewes is almost 100 percent. The incubation period is approximately 2 days and is followed by an abrupt onset of fever and general malaise.
Wageningen Bioveterinary Research is developing a vaccine to prevent and control future outbreaks.
RVFV is a member of the family Phenuiviridae (genus Phlebovirus, order Bunyavirales). The virus was shown to be transmitted by 48 different mosquito species under laboratory conditions. Importantly, the mosquito species most prevalent in the Netherlands, Culex pipiens (the Northern house mosquito), was shown to be capable of transmitting the virus after feeding on infected sheep.
The disease was for the first time described after a large outbreak that occurred on a sheep farm in the Rift Valley in Kenya in 1930. Since that time, large outbreaks have occurred across Africa and the Arabian Peninsula. The most recent outbreaks occurred in 2018 in South Africa, Uganda, Rwanda and Kenya resulting in both animal and human fatalities.
Animation: the spread of RVF (1930-2018)
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Co-housing of Rift Valley fever virus infected lambs with immunocompetent or immunosuppressed lambs does not result in virus transmissionFrontiers in Microbiology 7 (2016). - ISSN 1664-302X
Rift Valley Fever Vaccine Virus Clone 13 Is Able to Cross the Ovine Placental Barrier Associated with Foetal Infections, Malformations, and StillbirthsPLoS Neglected Tropical Diseases 10 (2016)3. - ISSN 1935-2727
Four-segmented Rift Valley fever virus induces sterile immunity in sheep after a single vaccinationVaccine 33 (2015)12. - ISSN 0264-410X - p. 1459 - 1464.
Preliminary Evaluation of a Bunyavirus Vector for Cancer ImmunotherapyJournal of Virology 89 (2015)17. - ISSN 0022-538X - p. 9124 - 9127.
Nonspreading Rift Valley Fever Virus Infection of Human Dendritic Cells Results in Downregulation of CD83 and Full Maturation of Bystander CellsPLoS ONE 10 (2015)11. - ISSN 1932-6203 - 22 p.
Paramyxovirus-based producton of Rift Valley fever virus replicon particlesJournal of General Virology 95 (2014)12. - ISSN 0022-1317 - p. 2638 - 2648.
Creation of Rift Valley Fever Viruses with four-segmented Genomes reveals flexibility in Bunyavirus Genome Packaging.Journal of Virology 88 (2014)18. - ISSN 0022-538X - p. 10883 - 10893.
Evaluation of nonspreading Rift Valley fever virus as a vaccine vector using influenza virus hemagglutinin as a model antigenVaccine 32 (2014)41. - ISSN 0264-410X - p. 5323 - 5329.
Comparative efficacy of two next-generation Rift Valley fever vaccinesVaccine 32 (2014). - ISSN 0264-410X - p. 4901 - 4908.
One health approach to Rift Valley fever vaccine developmentAntiviral Research 106 (2014)24. - ISSN 0166-3542 - p. 24 - 32.