This disease is named for the Rift Valley in Kenya where it was discovered

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Rift Valley fever

Transmission

• A severe mosquito-borne disease that primarily affects animals but can also infect humans
• The virus is most commonly found in animals such as camels, goats, cattle, sheep, and buffalo
• Humans get infected in three ways:
  • Bites from infected mosquitoes
  • Exposure to the body fluids, blood, or tissues of infected animals. This is common when people are involved in caring for animals (veterinary services) or animal slaughter
  • Ingesting unpasteurized or uncooked milk from infected animals
• Person-to-person transmission has never been recorded

Geography
Sub-Saharan Africa, Yemen, and Saudi Arabia

Incubation Period
2 – 6 days after infection

Signs and Symptoms

Most people infected do not have any symptoms, or have mild symptoms lasting 2 – 7 days including:

• Fever
• Headache
• Neck stiffness
• Joint pain
• Muscle pain
• Vomiting
• Loss of appetite
• Sensitivity to light

8 – 10% of those infected develop more severe syndromes:

• Ocular: Eye diseases with symptoms such as eye lesions and blurred/decreased vision
  • About 50% of patients with these symptoms will have permanent vision loss, but death is rare with this form of the disease
• Encephalitis: Brain inflammation which can lead to headaches, coma, seizures, loss of memory, hallucinations, confusion, disorientation, vertigo, convulsions, lethargy, and in rare cases persistent neurological deficits
  • Death with this form of the disease is also rare
• Hemorrhagic fever: Symptoms include vomiting blood, passing blood in the feces, rash/bleeding in the skin, bleeding from the nose or gums
  • Occurs in less than 1% of patients but has a 50% fatality rate

Diagnosis
Laboratory testing of blood samples

Treatment

• There is no vaccine or specific treatment
• Most patients receive supportive therapy for their symptoms

Prognosis

• Typically, patients recover within two days to one week after onset of illness
• 1 – 10% of patients may have permanent blindness

Prevention: What Can You Do?

• Animals can be vaccinated against Rift Valley fever
• Humans should avoid unnecessary, close contact with animals and their body parts and should always make sure to reduce the chances for mosquito bites (wear light colored, long clothing; use mosquito repellent; sleep under mosquito nets, etc.)

Rift Valley Fever In the News

• Rift Valley Fever outbreak kills 21 in western Niger
• Outbreak: Rift Valley Fever reported in Niger, Mali

Sources:
https://www.cdc.gov/vhf/rvf/
http://www.who.int/mediacentre/factsheets/fs207/en/