Following confirmation of a Rift Valley fever (RVF) outbreak in sheep on a farm in Jacobsdal area, Free State in May 2018, human and vector surveillance was conducted on the affected farm by Provincial Department of Health and National Institute for Communicable Diseases (NICD). Mosquitoes collected on the affected farm tested negative for RVF virus, suggesting that active transmission had diminished due to decreased mosquito populations.
Farmworkers and residents, who had been involved in the handling of potentially contaminated animal tissues during the sheep outbreak, were interviewed and sampled for RVF testing at NICD.
Of 10 persons sampled, four individuals were retrospectively confirmed to have been infected with RVF virus; four individuals were shown to have probably been infected with RVFV, pending further tests on follow-up blood samples for confirmation; two individuals were not infected with RVFV despite handling potentially contaminated tissues.
Six of the eight cases reported having experienced mild symptoms (fever, muscle pain, headache) in the preceding month, while none developed a severe disease that necessitated hospitalization.
Rift Valley Fever is mosquito-borne virus that is endemic in parts of Africa. It primarily infects animals like sheep, cattle and goats and it can have an economic impact on a community due to the loss of livestock.
Humans get infected through contact with infected animal blood or organs. Butchering and slaughtering of animals is a primary cause of transmission to humans. Certain occupations are at a higher risk of getting Rift Valley Fever like farmers, herders and veterinarians.
It can also be transmitted to humans through mosquito bites and the bites of blood-sucking flies.
Most cases of Rift Valley Fever are mild and symptoms include fever, headaches and muscle pain. However, a small percentage of people can get serious disease which includes retinitis, encephalitis and a hemorrhagic fever. Fatalities happen in less than 1 percent of those infected.
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