Two species of mosquitoes commonly involved in sylvatic yellow fever transmission in Africa are Aedes furcifer and Aedes luteocephalus . This cycle occurs quietly in nature, because African monkeys do not become ill when infected with yellow fever virus. Although a great deal is known about the conditions required for the occurrence of yellow fever epidemics, it is not possible to predict exactly when or where an epidemic will occur. Environmental factors, factors related to the mosquito vector, and factors related to the host are all important. The amount of rainfall and the availability of mosquito breeding sites are both important.
Heavy rainfall contributes to the development of large mosquito populations.
Conversely, in areas that are continually dry, storing water close to homes may encourage breeding of Ae. For sylvatic transmission, monkeys must be present at least part of the year. 1.3.3 Mosquito Vector Factors Not all mosquitoes can transmit the yellow fever virus. It is very important to know where Ae. This peri-domestic mosquito is an avid human biter and is usually the primary vector in epidemics.