Yellow fever, an acute infectious disease affecting humans, monkeys, and several other small mammals, is found in tropical and subtropical zones in Africa and South America. Caused by a virus transmitted by several species of mosquito, yellow fever is characterized by the abrupt onset of headache, backache, rapidly rising fever, nausea, and vomiting. It also attacks the liver, producing the jaundice which gives it its name. Yellow fever causes death in 2-5% of cases, but survival confers lifelong immunity. Other than reduction of the fever, no specific treatment is available.

Yellow fever had been known on the coast of West Africa for centuries before the first epidemic occurred in the Western Hemisphere. The epidemic, reported in Barbados in 1647, probably resulted from the slave trade. The first epidemic in the United States occurred in New York City in 1668 and, by 1893, 135 major epidemics had occurred in North American...