Rift Valley fever (RVF) is an acute, fever-causing disease caused by RVF virus, a bunyavirus that is transmitted by a mosquitoes to domestic livestock.

Human infections can result from mosquito bites as well as direct or indirect contact with the blood or organs of infected animals (care or slaughter of infected animals and possibly from ingestion of raw milk).

Those primarily affected are domestic livestock and humans in endemic areas of Africa.

TRANSMISSION: Rift Valley fever virus is carried by mosquitoes and can spread to people and animals, including cows, buffalo, sheep, goats, and camels. RVF most often affects domestic animals including livestock and causes severe illness, pregnancy loss and death in the animals. 

People usually get RVF through contact with blood, body fluids, or tissues of infected animals in areas where the virus is found, following activities without taking steps to prevent infection:

• Slaughtering or butchering
• Caring for sick animals
• Providing veterinary procedures like helping an animal give birth
• Eating or drinking raw or undercooked animal products

SYMPTOMS: Once a human host is infected the incubation period to the onset of illness is about 2-6 days. Humans experience flu-like symptoms, which may include fever, weakness, weight loss, dizziness, headache, nausea, vomiting, and muscle and joint pain.

About 1% of those infected experience more severe symptoms. These symptoms include: retinal inflammation, brain inflammation, or hemorrhagic fever. Onset of hemorrhagic fever results in 50% mortality in about 3-6 days after infection of the host.

SYMPTOMS IN DOMESTIC ANIMALS: The virus is typically recognized in domestic animal populations through symptoms consisting of elevated temperatures, increased rates of abortions, and high mortality rates among young animals.

TREATMENT: Treatment typically includes supportive care and the use of experimental antiviral drugs. At this time the U.S. does not have a licensed human or animal vaccine.

FOR MORE INFO, visit Rift Valley Fever - Florida Department of Health.