Rift Valley Fever in Travellers

Rift Valley fever (RVF) is a mosquito-borne viral zoonosis affecting humans, livestock, and wildlife. The virus causes epizootics of abortions and deaths of young livestock, resulting in substantial economic losses. A “One Health” (OH) approach is critical for prevention and control strategies. The geographic range of RVF outbreaks has expanded to multiple African countries, with the first reports outside of the African continent in 2000 in Yemen and Saudi Arabia. The majority of human infections result from direct or indirect contact with blood or tissues from infected animals during handling, slaughter, assisting with animal births or through veterinary procedures rather than mosquito transmission. Occupational groups such as herders, farmers, slaughterhouse workers, and veterinarians are at higher risk of infection. To date, no human-to-human transmission of RVF has been documented. There is potential for the disease to expand to new, previously unaffected geographical locations through trade or transhumance and mosquitoes. RVF poses a very low risk to travellers outside of travel to areas affected by current epizootics and occupational risks. A detailed history of possible exposure to suspected or confirmed animals with RVF is key in performing a differential diagnosis in humans presenting with acute febrile illness. A low percentage of patients develop a much more severe form of the disease, but the overall mortality rate is <1%. Complications include ocular (retinal) disease (0.5–2% of patients), meningoencephalitis (<1%), hepatitis, or haemorrhagic fever (<1%). No specific treatment is available for RVF; management comprises general supportive therapy. Currently there is no approved RVF vaccine for humans.