Rift Valley fever

Notifiable condition. Human-to-human transmission has not been demonstrated; however, standard precautions should still be implemented.

Majority of patients are asymptomatic; however, patients may have a mild, self-limited illness with fever and liver abnormalities. Approximately 8% to 10% of patients may have severe symptoms including ocular disease, encephalitis, or haemorrhagic fever.

Supportive therapy is the standard of care as there are no specific antiviral treatments.

A mild, usually self-limited infection caused by the Rift Valley fever virus (also known as RVFV). The virus belongs to the Bunyaviridae family (genus Phlebovirus). It is named after the Great Rift Valley in Kenya where it was first discovered in livestock in the early 1910s.[1]Murithi RM, Munyua P, Ithondeka PM, et al. Rift Valley fever in Kenya: history of epizootics and identification of vulnerable districts. Epidemiol Infect. 2011 Mar;139(3):372-80. http://www.ncbi.nlm.nih.gov/pubmed/20478084?tool=bestpractice.com [2]Daubney R, Hudson JR, Garnham PC. Enzootic hepatitis or Rift Valley fever. An undescribed virus disease of sheep, cattle and man from east Africa.1931;34(4):545-579. http://onlinelibrary.wiley.com/doi/10.1002/path.1700340418/abstract It is transmitted to humans by contact with the blood, other bodily fluids (e.g., amniotic fluid), organs, or drinking raw milk from infected livestock or wild animals (most commonly cows, sheep, goats, or camels).[3]Pepin M, Bouloy M, Bird BH, et al. Rift Valley fever virus (Bunyaviridae: Phlebovirus): an update on pathogenesis, molecular epidemiology, vectors, diagnostics and prevention. Vet Res. 2010;41:61. https://www.ncbi.nlm.nih.gov/pmc/articles/PMC2896810 http://www.ncbi.nlm.nih.gov/pubmed/21188836?tool=bestpractice.com Transmission also occurs via mosquito vectors including the Aedes and Culex species.[4]Tantely ML, Rakotoniaina JC, Tata E, et al. Biology of mosquitoes that are potential vectors of Rift Valley fever virus in different biotopes of the central highlands of Madagascar. J Med Entomol. 2013;50:603-610. http://www.ncbi.nlm.nih.gov/pubmed/23802456?tool=bestpractice.com [5]LaBeaud AD, Ochiai Y, Peters CJ, et al. Spectrum of Rift Valley fever virus transmission in Kenya: insights from three distinct regions. Am J Trop Med Hyg. 2007 May;76(5):795-800. http://www.ajtmh.org/docserver/fulltext/14761645/76/5/0760795.pdf?expires=1510772935&id=id&accname=guest&checksum=BF69482272A0CDDD3AB191EC9641AF60 http://www.ncbi.nlm.nih.gov/pubmed/17488893?tool=bestpractice.com [6]Golnar AJ, Turell MJ, LaBeaud AD, et al. Predicting the mosquito species and vertebrate species involved in the theoretical transmission of Rift Valley fever virus in the United States. PLoS Negl Trop Dis. 2014 Sep 11;8(9):e3163. http://journals.plos.org/plosntds/article?id=10.1371/journal.pntd.0003163 http://www.ncbi.nlm.nih.gov/pubmed/25211133?tool=bestpractice.com The virus causes outbreaks of abortion and death of young livestock (most commonly sheep, goats, and cattle). Outbreaks in humans are often linked to those in animals (epizootic outbreaks).[6]Golnar AJ, Turell MJ, LaBeaud AD, et al. Predicting the mosquito species and vertebrate species involved in the theoretical transmission of Rift Valley fever virus in the United States. PLoS Negl Trop Dis. 2014 Sep 11;8(9):e3163. http://journals.plos.org/plosntds/article?id=10.1371/journal.pntd.0003163 http://www.ncbi.nlm.nih.gov/pubmed/25211133?tool=bestpractice.com

BMJ talk medicine podcast: Rift valley fever - recognise, refer, and report, with Professor Clayton Wiley