Definition of Yellow fever

Yellow fever: An acute systemic (bodywide) illness caused by a virus called a Flavivirus. In severe cases, the viral infection causes a high fever, bleeding into the skin, and necrosis (death) of cells in the kidney and liver. The damage done to the liver from the virus results in severe jaundice which yellows the skin. Hence, the "yellow" in "yellow fever."

Yellow fever once ravaged port cities in the United States. (A viewer writes in: "This disease was prevalent in the deep south, not just in the seaports. My grandparents lived through an epidemic of yellow jack in central Mississippi around 1900, and they were a long way from the seacoast.")

Today yellow fever is most common in tropical areas of Africa and the Americas. The virus of yellow fever is transmitted in most cases by a bite of a mosquito. In urban settings, yellow fever may be transmitted from person to person by the Aedes aegypti mosquito. In the jungle, yellow fever is transmitted from monkeys to people by mosquitoes that breed in tree-holes in the rainforests. The diagnosis of yellow fever is made by observation or, if need be, by culturing the virus from a blood sample.

There is no cure for yellow fever, although antiviral medications may be tried. Non-aspirin pain relievers, rest, and rehydration with fluids decrease discomfort. The disease usually passes within a few weeks.

Yellow fever can be prevented by vaccination. The yellow fever vaccine is a live attenuated (weakened) viral vaccine. It is recommended for people traveling to or living in tropical areas in the Americas and Africa where yellow fever occurs. Because it is a live vaccine, it should not be given to infants or people with immune-system impairment.

The vaccine is based upon classic medical research done under Dr. Walter Reed. When yellow fever broke out among U.S. troops in Cuba in 1900, Dr. Reed, a member of the Army Medical Corps, headed a commission of physicians on yellow fever. They discovered that the fever was transmitted by the Aëdes aegypti mosquito which breeds near houses (and also transmit dengue). Reed's team later showed that the mosquito injected a virus that caused the dread disease. Sanitary engineers eradicated the mosquito and freed Cuba of yellow fever in 1902 (the year of Reed's death from appendicitis).

The vaccine against yellow fever is also based on the work of Max Theiler. Dr. Theiler, from South Africa, worked at the Rockefeller Foundation (now the Rockefeller University) in New York. In 1929 Theiler contracted yellow fever (not an uncommon experience among those studying the disease) but recovered and became immune to it. The following year Theiler discovered that yellow fever can be transmitted to white mice, which are easy to handle and are available by the thousand at small cost. This was a critical finding for the production of the vaccine. In 1951, Max Theiler (1899-1972) was awarded the Nobel Prize in Physiology or Medicine "for his discoveries concerning yellow fever and how to combat it."

Common Misspellings: yellow feaver