A form of the disease called sylvan yellow fever is transmitted in tropical jungles by other species of mosquitoes that live in trees. At the end of the 19th cent., yellow fever was highly prevalent in the Caribbean area, and a way of controlling it had to be found before construction of the Panama Canal could be undertaken. In 1900 a commission headed by Walter Reed and including James Carroll, Jesse Lazear, and Aristides Agramonte proved in Havana the theory of C. J. Finlay that yellow fever was a mosquito-borne infection. W. C. Gorgas , an army physician and sanitation expert, succeeded in controlling the disease in the Panama Canal Zone and other areas in that part of the world by mosquito-eradication measures. The later development of an immunizing vaccine and strict quarantine measures against ships, planes, and passengers coming from known or suspected yellow-fever areas further aided control of the disease.
Yellow fever begins suddenly after an incubation period of three to five days.
In mild cases only fever and headache may be present. The severe form of the disease commences with fever, chills, bleeding into the skin, rapid heartbeat, headache, back pains, and extreme prostration. Nausea, vomiting, and constipation are common. Jaundice usually appears on the second or third day. The patient then lapses into delirium and coma, often followed by death.