Rift Valley fever
Rift Valley fever (RVF) is an infectious disease primarily affecting livestock and, to a lesser extent, humans, predominantly in the Rift Valley region of eastern Africa. Caused by the RVF virus, it is transmitted to humans through bites from infected mosquitoes or through direct contact with infected livestock. The risk of transmission increases during the rainy season when mosquito populations surge, and those in close contact with animals—such as farmers, herders, and veterinarians—are particularly vulnerable. Symptoms of RVF typically resemble the flu, including fever, weakness, and body aches, with most individuals recovering within two weeks. However, more severe cases can lead to complications like bleeding, liver failure, and eye problems, which may result in permanent vision loss. Although less than 1% of infected individuals die from the disease, the mortality rate is higher in livestock. Current management focuses on symptom relief, as there is no specific antiviral treatment available. Preventative measures include avoiding mosquito bites and employing safety protocols when handling livestock. Various vaccines are currently under development to combat this disease.
Rift Valley fever
- ANATOMY OR SYSTEM AFFECTED: All
Definition
Rift Valley fever (RVF) is an infectious disease with flu-like symptoms that affects livestock (mostly) and humans in the Rift Valley region of eastern Africa. RVF comes from the RVF virus. Humans and animals get RVF either from a bite by infected mosquitoes or close contact with livestock infected with the RVF virus. While RVF is deadly in animals, the virus in humans is usually treated by helping to alleviate symptoms.
Causes
Both people and animals, such as goats, sheep, cattle, and other livestock, get RVF through the bite of a mosquito infected with the RVF virus. The threat of the virus is especially high during the rainy season or in rainier years when more mosquitoes hatch eggs. The mosquito eggs contain RVF, and then the mosquitoes born from them are infected. Persons, such as farmers, herders, veterinarians, and slaughterers, who work closely with livestock can also contract the disease through contact with blood or other bodily fluids and tissues or organs of infected animals. RVF may also be transmitted through drinking unpasteurized milk or consuming undercooked meat.
Risk Factors
The people at most significant risk of getting RVF are those who work directly or indirectly with livestock, especially persons who handle animal tissues or fluids. Heavy rains also increase the chance of humans and livestock being bitten by mosquitoes infected with the RVF virus. In regions in which there might already be a current outbreak of RVF, persons who sleep outdoors or travelers to the area are also at risk. There are several other risk factors for RVF. Laboratory and healthcare workers are at risk because of their contact with blood and pathogens. Individuals who are pregnant or who have immune system deficiencies may also have increased risk. Younger children and older adults are more likely to develop RVF. Finally, Indigenous peoples who continue cultural practices involving animal blood have an increased risk of developing RVF.
Symptoms
RVF symptoms are flu-like, including fever, weakness, aches, back pain, nausea, and dizziness. Some people also experience gastrointestinal issues and photosensitivity. Most people with RVF usually recover on their own within two weeks. In more serious cases, those infected can experience severe bleeding, liver failure, brain inflammation, and eye complications, such as inflammation of the retina. A small percentage of people who get eye complications may experience permanent vision loss. Less than 1 percent of people die from RVF. Often, the death rate can be attributed to other factors, such as other illnesses or infections. Infected livestock have higher death rates.
Screening and Diagnosis
RVF’s initial symptoms can be flu-like, but a blood test can determine if a person has RVF.
Treatment and Therapy
There is no specific treatment for RVF other than alleviating any flu-like symptoms. Several RVF vaccines, including live attenuated vaccines, inactivated vaccines, and deoxyribonucleic acid (DNA) vaccines, are in development and undergoing clinical trials.
Prevention and Outcomes
The most effective prevention against getting RVF is avoiding mosquito bites by using insect repellent, wearing long pants and long sleeves, and using a bed net while sleeping. Persons working with livestock that may be infected with the RVF virus need to take special precautions when coming into direct or indirect contact with animals and animal parts.
Bibliography
"About Rift Valley Fever (RVF)." CDC, 14 May 2024, www.cdc.gov/rift-valley-fever/about/index.html. Accessed 7 Oct. 2024.
Davies, F. Glyn, and Vincent Martin. Recognizing Rift Valley Fever. 17th ed., Rome: Food and Agriculture Organization of the United Nations, 2003.
Kapoor, Shailendra. "Resurgence of Rift Valley Fever." Infectious Diseases in Clinical Practice, vol. 16, no. 1, 2008, pp. 9-12.
Marquardt, William C., editor. Biology of Disease Vectors. 2d ed., New York: Elsevier Academic Press, 2005.
"Rift Valley Fever." World Health Organization (WHO), www.who.int/health-topics/rift-valley-fever#tab=tab‗1. Accessed 7 Oct. 2024.