Yellow fever (also called yellow jack or sometimes black vomit or American Plague) is an acute viral disease. It is transmitted by the bite of mosquitoes (the yellow fever mosquito, Aedes aegypti
, and other species). Yellow fever is an important cause of hemorrhagic illness in many African and South American countries despite existence of an effective vaccine. The yellow refers to the jaundice symptoms that affect some patients.
Yellow fever has been a source of many devastating epidemics. Yellow fever epidemics broke out in the 1700s and 1900s in Italy, France, Spain, England, and the United States. Three hundred thousand people are believed to have died from yellow fever in Spain during the 19th century. French soldiers were attacked by yellow fever during the 1802 Haitian Revolution; more than half of the army perished from the disease. Outbreaks followed by thousands of deaths occurred periodically in other Western Hemisphere locations until research, which included human volunteers (some of whom died), led to an understanding of the method of transmission to humans (primarily by mosquitos) and development of a vaccine and other preventive efforts in the early 20th century.
Despite the breakthrough research of Cuban physician Carlos Finlay, American physician Walter Reed, and many others over 100 years ago, non-vaccinated populations in many developing nations in Africa and Central/South America continue to be at risk. As of 2001, the World Health Organization (WHO) estimates that yellow fever causes 200,000 illnesses and 30,000 deaths every year in unvaccinated populations.
The map below is from the World Health Organization and gives a general distribution of the problem. Do not make your own assessment from this map, but rather discuss the issue with your doctor prior to travel.