Rift Valley fever is a mosquito-borne, fever-causing viral disease that affects livestock and humans. The virus exists in regions of eastern and southern Africa where cattle are raised, but the virus has also been found in sub-Saharan Africa and Madagascar. In 2000, the most recent epidemic broke out in Saudi Arabia and Yemen, representing the first Rift Valley fever cases identified outside of Africa. Rift Valley fever is more virulent than the West Nile Virus and poses a potential threat to public health if introduced to the United States.
How do people get Rift Valley fever?
The bites of infected mosquitoes and possibly other bloodsucking insects can transmit Rift Valley fever to humans. Normally, the virus lies dormant in the eggs of Aedes mosquitoes. Periods of excessive rainfall or flooding allow the eggs to hatch infected mosquitoes that then feed on livestock and spread the virus. When other species of mosquitoes and other biting insects feed on infected livestock, they too can become infected with Rift Valley fever and perpetuate disease. A mosquito-borne epizootic (incidence of disease in a large number of animals) can easily lead to a human epidemic.
People can also contract Rift Valley fever if they are exposed to the blood or body fluids of infected animals, for example when slaughtering infected animals or touching contaminated meat during food preparation. Some laboratory workers have also been infected with Rift Valley fever through airborne transmission when handling laboratory specimens containing the virus.
Who is at risk for Rift Valley fever?
People who sleep outdoors at night in geographical regions where outbreaks occur are at risk for exposure to infected mosquitoes. International travelers who visit areas with Rift Valley Fever during outbreaks or sporadic cases increase their chances of getting Rift Valley fever. Animal herdsmen, veterinarians, slaughterhouse workers, and other people who work with animals in areas where Rift Valley fever is present have a higher risk of contracting the virus from an infected animal.
What are the symptoms of Rift Valley fever?
People with Rift Valley fever typically experience a mild, flu-like illness with sudden onset of fever, headache, muscle pain, backache, weakness, dizziness, and weight loss.
Symptoms of Rift Valley fever usually last from four to seven days; people generally get better after this time. However, some patients develop a more severe course of Rift Valley fever, resulting in eye disease, meningo-encephalitis (inflammation of the brain and surrounding tissue), or hemorrhagic fever (severe bleeding).
What is the treatment for Rift Valley fever?
Currently, there is no established course of treatment for people infected with Rift Valley Fever. Most people experience only a mild and short duration of disease and will not require any specific treatment. General supportive therapy is used to treat more severe cases of disease.
Nevertheless, the effectiveness of ribavirin, an antiviral drug, is being studied for the treatment of Rift Valley fever patients. Developing a vaccine for protection against Rift Valley fever in humans is also under investigation.
What complications can result from Rift Valley fever after recovery?
The most common complication resulting from Rift Valley Fever is inflammation of the retina (nerve layer that senses light and creates impulses that travel through a nerve to the brain). Approximately 1%-10% of affected patients experience some degree of permanent vision loss.
Can the disease be fatal?
Yes. Approximately 1 out of 100 people that become infected with Rift Valley fever die of the disease, according to the CDC. Most deaths occur in patients who develop hemorrhagic fever as a complication of Rift Valley Fever.
What’s the best way to avoid catching Rift Valley fever?
Protect yourself against exposure to infected mosquitoes by wearing long-sleeved shirts and trousers where appropriate, using bednets and insect repellant, and avoiding going outdoors during peak biting times, especially dawn and dusk. Do not sleep outdoors at night in regions where Rift Valley fever outbreaks can occur. Travelers should avoid visiting areas where Rift Valley fever epidemics may occur, and people should take appropriate measures against contracting the virus from potentially infected animals. Removing collections of stagnant water may reduce the incidence of RVF infection.
On the net:
CDC information: http://www.cdc.gov/ncidod/dvrd/spb/mnpages/dispages/rvf.htm
WHO information: http://www.who.int/mediacentre/factsheets/fs207/en/
