a1 Yellow Fever Research Institute, Entebbe, Uganda.*
1. During the past eight years field investigations on the epidemiology of yellow fever have been carried out in Bwamba County, a small heavily-forested area in the extreme west of Uganda.
During the course of this work yellow fever virus has been isolated from a human case, from Aëdes (Stegomyia) simpsoni, Theo., and from a mixed lot of Aëdes spp. taken in uninhabited rain-forest.
As it is known that yellow fever is endemic among the monkeys of the Bwamba forests and that a high rate of immunity is shown by certain species that rarely descend to the ground, it was concluded that an arboreal mosquito was the most likely transmitter of yellow fever among monkeys, and an investigation of the arboreal mosquito fauna was begun.
* This Institute is supported jointly by the Medical Department of the Uganda Protectorate and the International Health Division of the Rockefeller Foundation.