What is yellow fever?

Yellow fever is a potentially fatal disease that is widespread in certain parts of Africa and South America. Symptoms appear 3 to 6 days after infection and can include nausea, vomiting, fever, headache, chills and muscle pain.

After a few days, people appear to recover, but some will develop more serious symptoms, including bleeding, jaundice (a yellowing of the eyes and skin) and organ failure.

Who’s at risk?

You can get the yellow fever virus from the bite of an infected mosquito. There are countries in Africa, Central America, and South America that are endemic for yellow fever.

Mosquito swarm outdoors in jungle

What are the symptoms?

The yellow fever virus has an incubation period of 3 to 6 days. Although some individuals may not display any symptoms, those who do may experience fever, muscle pain, headache, loss of appetite, and nausea or vomiting. In most cases, these symptoms will resolve on their own within 3 to 4 days.

However, a small percentage of individuals will enter a more severe and toxic phase within 24 hours of the initial symptoms subsiding. This phase can affect multiple organ systems, including the liver and kidneys, and is characterized by a return of high fever. Jaundice, abdominal pain, dark urine, and vomiting may also occur, with bleeding from the mouth, nose, eyes or stomach being possible. This toxic phase can be fatal, with approximately half of the patients dying within 7-10 days.

Needles over map

How can yellow fever be prevented?

If you are travelling to an endemic region, the yellow fever vaccine is safe, affordable and a single dose provides life-long protection against yellow fever disease.

How is yellow fever treated?

At present, there is no targeted antiviral medication for yellow fever. However, hospital care to manage symptoms such as dehydration, fever, and liver and kidney failure can improve outcomes. Additionally, antibiotics can be used to treat any concurrent bacterial infections.

To prevent yellow fever, it is recommended to take personal preventive measures such as wearing clothing that covers most of the skin and using mosquito repellents. However, it's important to note that mosquitoes that transmit yellow fever are active during the daytime, so bed nets treated with insecticide may not be as effective as they are for other diseases that are transmitted at night.