health

Yellow fever is an infectious disease caused by a virus that is transmitted
to humans by mosquitoes.
Yellow fever is a disease caused by yellow fever virus, a member of the
flavivirus (FLAY-vih-vy-rus) group of viruses. The disease gets its name
because it often causes jaundice*, which tints the skin yellow, and a high
fever. Yellow fever also can cause kidney failure and uncontrolled bleeding,
or hemorrhaging (HEM-rij-ing). Many cases produce only mild illness,
but severe cases of yellow fever can be fatal. Once someone has survived
the disease, the person has lifetime immunity* against it.
Yellow fever afflicts both humans and monkeys and has been known
since at least the 1600s. The disease is not spread by person-to-person
contact. It is transmitted by several different species of mosquitoes; a
person can contract yellow fever only from the bite of a mosquito that has
bitten an infected person or monkey.
The disease once caused epidemics* in the Americas, Europe, and the
Caribbean, but at the beginning of the 21st century the disease occurred
almost exclusively in South America and Africa. Each year, outbreaks lead
to an estimated 200,000 cases and 30,000 deaths worldwide. Vaccines
against the virus were developed in 1928 and 1937, and mosquitoeradication
programs made great progress in controlling the disease.
The last recorded outbreak of yellow fever in the United States was in
New Orleans in 1905. However, lapses in prevention programs in Africa
and South America allowed yellow fever to once again become a serious
public health issue on those continents.