Yellow Fever

• Yellow fever is a condition that mostly occurs in regions of Africa and South America.
• Yellow fever mostly causes mild disease. A small number of cases however can be fatal.
• Yellow fever treatments focus on fever reduction, hydration, and avoiding complications.
• The yellow fever vaccine can provide safe and effective protection against the condition.

Yellow fever is a condition caused by a virus that is transmitted through mosquito bites. It occurs mostly in regions of Africa and South America and mostly causes mild disease. Some cases however can be more severe and can even be fatal. In this guide by Ada’s medical team, you’ll find more information on yellow fever symptoms, the progression of the disease and possible prevention and treatment strategies.

Yellow fever is a condition caused by a virus. This virus can be transmitted by infected mosquitoes. Yellow fever usually occurs in certain regions in Africa, Central, and South America. Most cases are mild, but a small number of people develop severe symptoms which can be fatal.1

Yellow fever symptoms usually develop 3 to 6 days after you are bitten by an infected mosquito. These symptoms can include:2

• Fever
• Muscle pain
• Headaches
• Loss of appetite
• Nausea
• Vomiting

Not everyone who gets infected with the yellow fever virus develops symptoms of yellow fever. Those who do develop symptoms usually get better within 3 to 4 days. 

There is however a small number of people that fall ill again within 24 hours of recovering from the original symptoms. The symptoms that develop in this second phase are more severe and can be fatal for half of the patients that enter this phase. Some common symptoms are: 1

• High fever
• Jaundice (yellowing of the skin/eyes)
• Dark urine
• Abdominal pain
• Vomiting
• Bleeding from the mouth, nose, eyes, or stomach

The cause of yellow fever is a virus which can be transmitted through the bite of an infected mosquito. These mosquitoes are more common in forested regions in Africa, and Central and South America. The virus usually circulates between mosquitoes and animals that live in the forest. Humans can also get bitten by these mosquitoes and fall ill as well. There is a higher chance of getting bitten during the day. 1 2

People living in countries where yellow fever is present are at a higher risk of getting infected with the yellow fever virus, especially those close to forested areas, as the mosquitoes spreading the disease are more likely to be found there. People vacationing in these areas should also take their precautions against the virus. 2

Yellow fever symptoms usually last 3 to 4 days. Most people don’t experience any symptoms anymore after this period. There is a small number of people however that enter a second phase within 24 to 48 hours after recovering from the initial symptoms. Half of people also recover from this phase. For others, this last phase can be fatal within 7 to 10 days. 1

Yellow fever can be diagnosed through a blood test that detects antibodies against the virus. It is however important to inform your healthcare provider if you’ve received a yellow fever vaccine, as this can also cause an increase in the antibodies. If this test comes back positive, other more specific tests will be performed, as the antibody test can also be positive for other viruses of the same family, such as the West Nile virus and the virus-causing dengue. 3

Yellow fever treatment focuses on decreasing fever and avoiding dehydration as well as liver and kidney failure. In order to do so, you should rest, drink plenty of water, and follow the instructions of your healthcare provider.
"There is no specific antiviral medication for yellow fever, so treatment focuses on managing symptoms and supporting the body. Important: If you suspect you have yellow fever, do not take aspirin or other non-steroidal anti-inflammatory drugs (NSAIDs) like ibuprofen, as these can increase your risk of bleeding. Use only acetaminophen (paracetamol) for fever and pain, and seek medical attention immediately if symptoms worsen."1

The most effective form of prevention is getting the yellow fever vaccine. You only need one yellow fever shot for lifelong protection against the virus. The vaccine is safe and recommended for people living in or traveling to countries with a risk of yellow fever transmission. Yellow fever vaccine side effects are very rare. Only pregnant women, babies younger than 9 months, people with severe allergies to egg protein, and people with severe immunodeficiency are excluded from vaccination due to the possible risk of side effects.1
Other preventative measures which you can take are covering your skin with enough clothing and using mosquito repellents in order to avoid getting bitten. 

In order to prevent yellow fever outbreaks, governments, and healthcare organizations also monitor the risk of an outbreak and take measures to eliminate mosquito breeding sites.

Yellow fever is a viral condition that causes mild symptoms or no symptoms at all in most cases. In some cases, however, the condition can be fatal. Yellow fever is caused by a virus that is transmitted by mosquitoes and mostly occurs in regions of Africa and South America. A yellow fever vaccine is available for safe and effective protection against the condition.

Q: How does yellow fever spread? 

A: Yellow fever can spread through the bite of mosquitoes that are infected with the yellow fever virus. These yellow fever mosquitoes are most active during the day. 

Q: Is yellow fever still around? 

A: Although there are prevention and monitoring strategies in order to prevent yellow fever outbreaks, the condition is still present in certain regions of Africa and South America. 

Q: What happens when a person gets yellow fever? 

A: Most people that get yellow fever don’t notice any symptoms or only complain of mild symptoms accompanied by fever. These symptoms generally disappear after 3 to 4 days. A small number of people however develop severe symptoms 24 to 48 hours after the original symptoms have disappeared. In some cases, this can be fatal. 

Q: How do doctors treat yellow fever now? 

A: Yellow fever treatment focuses on reducing fever, staying hydrated, and avoiding possible complications. Vaccination in regions where the virus occurs is an important prevention strategy.