Yellow fever

Medical Specialties: Allergy/immunology, Internal medicine

Clinical Definition

Yellow fever is a serious, potentially-fatal viral infection transmitted by mosquitoes. Travelers to endemic areas, especially in South America and tropical sub-Saharan Africa, may be candidates for vaccination against yellow fever. If a person is bitten by an infected mosquito, symptoms usually develop within one week.  

In Our Own Words

Yellow fever is mosquito-borne tropical viral illness that can be fatal. Cases range from mild fevers to severe disease. It is one of the so-called viral hemorrhagic fevers, meaning it has the potential to be dire, with infected patients not surviving despite care in the ICU. After three or four days, most patients recover in the remission stage. For patients who don’t go into remission, the patient can become toxic, with multi-organ failure and bleeding. Nearly half of these severely affected patients die.


Yellow fever gets its name from jaundice, which is the yellowing of the skin and one of the most common symptoms. Mosquitoes pick up the virus by feeding on humans or other primates and then spread the disease. Though many patients infected with yellow fever virus have no symptoms at all, about 15 percent of cases will develop aches and fever. There is a vaccine available for yellow fever, and among travelers to endemic areas, there have been few cases since vaccine introduction after World War II.

Relevant Conditions
  • Viral hemorrhagic fevers
  • Mosquito-borne viral disease
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  • Centers for Disease Control (CDC) and Prevention. "Yellow fever." Accessed July 2013.
  • University of Maryland Medical Center. "Yellow fever." Accessed July 2013.
  • World Health Organization. "Yellow fever." Accessed July 2013.
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