What is yellow fever?

Yellow fever is a viral disease caused by the bite of a mosquito. Many countries still require visitors to be vaccinated for it before entering.

Yellow fever is found mainly in certain areas of Africa, Central America, and South America. In certain parts of South America, infections happen less often. They occur usually among forestry and agricultural workers or in travelers to jungle areas. But recent outbreaks have been reported in and around major cities in Brazil. In Africa, infections happen most often in the tropical areas of western and central Africa. But they also happen in cities and jungle areas.

What causes yellow fever?

Yellow fever is caused by a virus (flavivirus). The virus is passed on to people through the bite of an infected mosquito. Mosquitoes can bite during the day and at night.

What are the symptoms of yellow fever?

People infected with this virus may have minimal or no symptoms, while others may have severe symptoms. Each person may have slightly different symptoms. The following are the most common symptoms:

• Fever

• Flu-like symptoms, such as headache, nausea and vomiting, and backache

• Bleeding of the gums

• Bloody urine

• Yellowing of the skin or eyes (jaundice)

Symptoms usually happen within 3 to 6 days after you are exposed to the virus. Symptoms may look like other health problems. Always see your healthcare provider for a diagnosis.

How is yellow fever diagnosed?

Your healthcare provider will ask about your past health and travel history for dates and exact locations. You will also need a physical exam. Blood tests can also help with a diagnosis.

How is yellow fever treated?

Treatment will depend on your symptoms, age, and general health. It will also depend on how severe the condition is.

There is no specific medicine for yellow fever, so treatment is aimed at controlling your symptoms. This includes rest and plenty of fluids. You may also need to take medicine to help relieve fever and aching. You should not take aspirin or nonsteroidal anti-inflammatory medicines such as ibuprofen or naproxen. These may raise the risk of bleeding.

You should protect yourself from mosquitoes during the illness. This may mean staying indoors or under a mosquito net. This will help keep you from passing the disease on to other people and uninfected mosquitoes.

What are possible complications of yellow fever?

Most people who get yellow fever do not have complications. They may not even know they have had the disease. Some people who get it may have some weakness and fatigue for a few months after symptoms go away. If severe disease happens, death is possible.

What can I do to prevent yellow fever?

A vaccine is available for yellow fever. The disease no longer happens in the U.S. But talk with your healthcare provider to see if you need the shot before visiting areas where yellow fever still exists. People who have had yellow fever develop lifelong immunity. The CDC advises the vaccine for people 9 months and older who are traveling to or living in areas at risk for yellow fever in Africa and South America. Some countries require proof of vaccination before entering. The CDC also provides a list of conditions and factors that increase a person's risk for a serious adverse event after vaccination.

Not being bitten by mosquitoes is another important part of preventing yellow fever. Use mosquito repellant that contains DEET and cover exposed skin when traveling in areas where yellow fever occurs. Use DEET cautiously in small children. Always follow label instructions. Wear long-sleeved shirts and long pants when outside. Use screens on windows and mosquito netting over beds.

When should I call my healthcare provider?

Call your healthcare provider right away if your symptoms get worse or you have new ones.

Key points about yellow fever

• Yellow fever is a disease caused by a virus passed on through the bite of an infected mosquito.

• Yellow fever happens only in certain areas of Africa, Central America, and South America.

• The disease can cause flu-like symptoms, slow and weak pulse, bleeding of the gums, bloody urine, and yellow skin (jaundice).

• Treatment is aimed at controlling the symptoms. It includes rest and plenty of fluids. You may also need to take medicine to help relieve fever and aching. Serious symptoms need medical care and close monitoring.

• A vaccine is available to prevent yellow fever. You may need it before traveling to some tropical countries in Africa, Central America, or South America.

Next steps

Tips to help you get the most from a visit to your healthcare provider:

• Know the reason for your visit and what you want to happen.

• Before your visit, write down questions you want answered.

• Bring someone with you to help you ask questions and remember what your healthcare provider tells you.

• At the visit, write down the name of a new diagnosis and any new medicines, treatments, or tests. Also write down any new instructions your healthcare provider gives you.

• Know why a new medicine or treatment is prescribed and how it will help you. Also know what the side effects are and when you should report them to your healthcare provider.

• Ask if your condition can be treated in other ways.

• Know why a test or procedure is recommended and what the results could mean.

• Know what to expect if you do not take the medicine or have the test or procedure.

• If you have a follow-up appointment, write down the date, time, and purpose for that visit.

• Know how you can contact your healthcare provider if you have questions.