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What is yellow fever?

Yellow fever is a viral disease that is transmitted by the Aedes aegypti mosquito. Although it is a rare disease, many countries require that visitors have the yellow fever vaccination prior to entering the country.


Symptoms usually occur within three to six days after exposure and may include:

  • Flu-like symptoms (for example, fever, headache, vomiting and backache)
  • Slow and weak pulse
  • Bleeding of the gums
  • Bloody urine
  • Jaundice

Risk factors

Yellow fever can affect both sexes, and all ages and races. A certain type of mosquito, Aedes aegypti, is most often responsible for transmitting the virus. Generally, yellow fever only occurs in certain areas of Africa and South America. In South America (especially Brazil), infections occur sporadically, and usually among forestry and agricultural workers. In Africa, infections occur primarily in the tropical areas of western and central Africa, but also in urban locations as well as jungle regions.

Types of treatment

Treatment is aimed at controlling the symptoms, and includes rest, fluids and use of medicines to help relieve fever and aching.

Other instructions

Certain medications should be avoided, such as aspirin or nonsteroidal anti-inflammatory drugs, which may increase the risk for bleeding. People with yellow fever should be protected from further mosquito exposure (for example, they should stay indoors or under a mosquito net) during the first few days of illness, so they do not contribute to the disease transmission cycle.


There is a vaccine available for yellow fever. Because transmission of yellow fever no longer occurs within the United States, it is important for travelers to talk with their healthcare providers about the need to be immunized prior to visiting areas where yellow fever still exists.

It is believed that people who have had yellow fever develop lifelong immunity.

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