Mosquito-Borne Human Viral Diseases: Why Aedes aegypti?

Abstract

Although numerous viruses are transmitted by mosquitoes, four have caused the most human suffering over the centuries and continuing today. These are the viruses causing yellow fever, dengue, chikungunya, and Zika fevers. Africa is clearly the ancestral home of yellow fever, chikungunya, and Zika viruses and likely the dengue virus. Several species of mosquitoes, primarily in the genus Aedes, have been transmitting these viruses and their direct ancestors among African primates for millennia allowing for coadaptation among viruses, mosquitoes, and primates. One African primate (humans) and one African Aedes mosquito (Aedes aegypti) have escaped Africa and spread around the world. Thus it is not surprising that this native African mosquito is the most efficient vector of these native African viruses to this native African primate. This makes it likely that when the next disease-causing virus comes out of Africa, Ae. aegypti will be the major vector to humans.

Figure 1.

Phylogenetic relationship of flaviviruses transmitted to humans by mosquitoes. Red indicates African origin, blue Asia, and green Australia. “Origin” refers to where the virus was first isolated. Simplified from Gaunt et al. This figure appears in color at www.ajtmh.org.