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Recommendations for Rift Valley Fever in Kenya
UPDATE 03-27-2007: Rift Valley Fever Outbreak in Kenya
The U.S.-bound refugees from Dadaab no longer need to have a 10-day waiting period before departure.
Thank you for your cooperation and support during this outbreak response.
In response to the Rift Valley Fever (RVF) outbreak in the Dadaab refugee camp and Eastern Kenya, the Centers for Disease Control and Prevention (CDC) has developed interim recommendations to prevent the importation of RVF into the United States by refugees.
Rift Valley Fever is a mosquito-borne viral disease that causes serious morbidity and mortality in persons and livestock. As of February 7, 2007, 512 human suspect cases and 140 deaths have been reported in Kenya, of which 25 probable cases, 7 suspect cases, 6 confirmed cases and 5 deaths have been reported in Dadaab. Cases have been reported from Hagadera, Ifo, and Dagahaley. Large animal die-offs among infected livestock have been reported throughout Eastern Kenya. A multi-agency, large-scale, internationally supported investigation is currently being conducted in Kenya. (For updates, see http://www.who.int/csr/don/en/)
Rift Valley Fever does not routinely occur in the United States; however, competent mosquito vectors exist in many parts of the United States, raising concern that mosquitoes could transmit and sustain RVF infection in the United States if imported by persons who are carrying the virus. Persons who are infected and have RVF virus circulating in the blood may not always have symptoms. By 10 days after infection, the viremia has usually resolved and the risk of transmission to competent mosquito vectors is extremely low; therefore, a holding period of 10 days would significantly reduce the risk of importation.
The following recommendations are being implemented overseas. They should be considered interim and may change as the investigation in Kenya evolves:
- Refugees from Dadaab camp should remain in the Nairobi Transit Center or another transmission-free area for 10 days before departure to the United States.
- During these 10 days, refugees should have temperatures checked and documented twice a day by the International Organization for Migration (IOM).
- Persons who have a fever should be examined and evaluated for possible RVF infection. Persons with symptoms like those of RVF should have testing performed by CDC-Kenya laboratory. They should not travel until RVF has been ruled out as a cause of illness. If RVF is confirmed, travel should be delayed until illness is completely resolved.
Frequently Asked Questions about Rift Valley Fever in Kenya
What is Rift Valley fever?
Rift Valley fever (RVF) is an acute, fever-causing viral disease that affects domestic animals (such as cattle, buffalo, sheep, goats, and camels) and humans. RVF is most commonly associated with mosquito-borne epidemics during years of unusually heavy rainfall. The disease is caused by the RVF virus, a member of the genus Phlebovirus in the family Bunyaviridae. The disease was first reported among livestock by veterinary officers in Kenya in the early 1900s.
Where is RVF found?
RVF is generally found in regions of eastern and southern Africa where sheep and cattle are raised, but the virus also exists in most countries of sub-Saharan Africa and in Madagascar.
How is RVF virus spread among animals?
An epizootic of RVF is generally observed during years in which unusually heavy rainfall and localized flooding occur. The excessive rainfall allows mosquito eggs, usually of the genus Aedes, to hatch. The mosquito eggs are naturally infected with the RVF virus, and the mosquitoes transmit the virus to the livestock on which they feed. Once the livestock are infected, other species of mosquitoes can become infected from the animals and can spread the disease. In addition, the virus may be transmitted by other biting insects.
How do humans get RVF?
Humans can get RVF through bites from infected mosquitoes and possibly other bloodsucking insects that serve as vectors. Humans can also get the disease if they are exposed to the blood, body fluids, or tissues of infected animals. Direct exposure to infected animals can occur during slaughter or through veterinary and obstetric procedures.
What are the symptoms?
RVF virus can cause several disease syndromes. Most people with RVF have either no symptoms or a mild illness associated with fever and liver abnormalities However, in some patients the illness can progress to hemorrhagic fever, encephalitis (inflammation of the brain), or ocular disease. Patients who become ill usually experience fever, generalized weakness, back pain, dizziness, and extreme weight loss at the onset of the illness. Typically, patients recover within 2 days to one week after onset of illness.
What is the incubation period for RVF?
The incubation period for RVF is approximately 2-5 days.
Are there complications after recovery?
The most common complication associated with RVF is inflammation of the retina. As a result, approximately 1%-10% of affected patients may have some permanent vision loss.
Is RVF ever fatal?
Approximately 1% of humans who become infected with RVF die of the disease. Case-fatality proportions are significantly higher for infected animals. The most severe impact is observed in pregnant livestock; RVF infection results in abortion of virtually 100% of fetuses.
How is RVF treated?
There is no established course of treatment for patients infected with RVF virus.
Who is at risk for RVF?
Studies have shown that sleeping outdoors at night in geographic regions where outbreaks occur could be a risk factor for exposure to mosquito and other insect vectors. Herdsmen, abattoir workers, and other individuals who work with animals in RVF-endemic areas (see map 2, attached) have an increased risk for infection. Persons in high-risk professions, such as veterinarians and slaughterhouse workers, have an increased chance of contracting the virus from an infected animal. International travelers increase their chances of getting the disease when they visit RVF-endemic locations during periods when sporadic cases or epidemics are occurring. Recommendations for travelers can be found at: http://www.cdc.gov/travel/other/2006/rift_valley_fever_kenya.htm
How is RVF prevented?
A person's chances of becoming infected can be reduced by taking measures to decrease contact with mosquitoes and other bloodsucking insects through the use of mosquito repellents and bednets. Avoiding exposure to blood or tissues of animals that may potentially be infected is an important protective measure for persons working with animals in RVF-endemic areas.
Source: http://www.cdc.gov/ncidod/dvrd/spb/mnpages/dispages/rvf.htm