Yellow Fever Virus: General Overview
- Publish Date: 2016/02/24 - (Rev. 2018/04/27)
- Author: Thomas C. Weiss
- Contact : Disabled World
Outline: Information regarding Yellow Fever, a virus transmitted through the bite of an infected mosquito, and found in subtropical and tropical areas of Africa and South America.
Yellow fever virus is found in subtropical and tropical areas in Africa and South America. The virus is transmitted to people through the bite of an infected mosquito. Yellow fever is a very rare cause of illness in American travelers. Illness ranges in severity from a self-limited febrile illness to severe liver disease with bleeding.
Yellow fever, (yellow jack, yellow plague, bronze john), is an acute viral disease. The disease is caused by the yellow fever virus and is spread by the bite of an infected female mosquito. It infects only humans, other primates, and several species of mosquitoes. In those with severe disease, death occurs in about half of people without treatment.
A safe and effective vaccine against yellow fever exists and some countries require vaccinations for travelers.
Yellow fever causes 200,000 infections and 30,000 deaths every year - with nearly 90% of these occurring in Africa.
Yellow fever disease is diagnosed based upon a person's symptoms, physical findings, laboratory testing and travel history, to include the potential of exposure to mosquitoes that are infected. There is no particular treatment for yellow fever - care is based on the symptoms the person is experiencing. Steps to prevent yellow fever virus infection include using insect repellent, getting vaccinated and wearing protective clothing.
Symptoms of Yellow Fever
Most people infected with yellow fever experience no illness, or only mild illness. In people who develop symptoms, the incubation period is usually three to six days. The initial symptoms include:
- Back pain
- Severe headache
- General body aches
- Sudden onset of fever
The majority of people improve following initial presentation. After a brief remission of hours to a day, around fifteen percent of people progress to develop a more severe form of the disease. The severe form is characterized by jaundice, a high fever, bleeding and eventually - shock and failure of multiple organs.
Treating Yellow Fever
No particular treatments have been found to benefit people with yellow fever. Whenever possible, people with yellow fever should be hospitalized for close observation and supportive care. Treatment is symptomatic. Fluids, rest and the use of pain relievers and medication to reduce fever might relieve symptoms of fever and aching.
Care should be taken to avoid some medications such as nonsteroidal anti-inflammatory drugs (NSAID's) and aspirin, which may increase a person's risk of bleeding. People with yellow fever should be protected from additional exposure to mosquitoes for up to five days after the onset of fever. By doing so, yellow fever virus in the person's bloodstream will be unavailable to uninfected mosquitoes, therefore breaking the cycle of transmission and decreasing the risk to the people around the infected person.
The Outcome of Yellow Fever
Most people who are infected with yellow fever will be asymptomatic, or have mild disease with complete recovery. In people who become symptomatic but recover, fatigue and weakness might last for a number of months. Among people who develop severe disease, twenty to fifty percent might die. People who recover from yellow fever usually have lasting immunity against subsequent infection.
Preventing Yellow Fever
Clearly, people in areas where yellow fever exists should avoid contact with mosquitoes. Additional prevention suggestions are presented below:
- Use Insect Repellent:
When you go outside, use and EPA-registered insect repellent such as ones containing DEET, IR3535, picaridin, or oil of lemon eucalyptus on skin that is exposed. Even a short period of time outside may be long enough to be bitten by a mosquito.
- Wear Proper Clothing:
When weather permits wear long-sleeves, long pants and socks. Mosquitoes might bite through clothes that are thin, so spraying clothes with repellent containing permethrin or another EPA-registered repellent for extra protection. Clothing pre-treated with permethring is commercially available. Mosquito repellants containing permethrin are not approved for application directly to a person's skin.
- Be Aware of Peak Mosquito Hours:
The peak biting times for many mosquito species is dusk until dawn. Aedes aegypti; however, feeds during the daytime. Take additional care to wear protective clothing and use repellant during daytime as well as during the early morning and evening hours. Remaining inside places with air-conditioned rooms or screens – especially during peak biting times, will also cut the risk of mosquito bites.
Yellow Fever Vaccine Recommendations
Vaccination for yellow fever is recommended for people aged less than nine months who are traveling to, or living in, areas at risk for yellow fever virus; most notably in Africa and South America. Yellow fever vaccine might be required for entry into certain nations. Yellow fever vaccine is available - but only at designated vaccination centers.
For most people who are traveling, one dose of yellow fever vaccine provides long-lasting protection. A booster dose of the vaccine is not needed. Some travelers; however, might require a booster dose. Certain nations may also require a booster dose of the vaccine.
Reactions to yellow fever vaccine are usually mild and include muscle aches, headaches and low-grade fevers. There have been reports of rare yet serious events after yellow fever vaccination. The events include life-threatening allergic reactions, disease affecting a person's nervous system, as well as disease affecting certain internal organs. Testing may be performed to look for certain serious adverse events.
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