Yellow Fever Mosquito

Lore & Background

The yellow fever virus is mainly transmitted through the bite of the yellow fever mosquito Aedes aegypti, but other mostly Aedes mosquitoes such as the tiger mosquito (Aedes albopictus) can also serve as a vector. Like other arboviruses, Yellow fever virus is taken up by a female mosquito when it ingests the blood of an infected human or another primate. Viruses reach the stomach of the mosquito, and if the virus concentration is high enough, the virions can infect epithelial cells and replicate there. From there, they reach the haemocoel and from there the salivary glands. When the mosquito next sucks blood, it injects its saliva into the wound, and the virus reaches the bloodstream of the bitten person. Transovarial transmission and transstadial transmission of yellow fever virus within A. aegypti are indicated. This infection of vectors without a previous blood meal seems to play a role in single, sudden breakouts of the disease. In the "urban cycle", only the yellow fever mosquito A. aegypti is involved. It is well adapted to urban areas, and can also transmit other diseases, including Zika fever, dengue fever, and chikungunya. The urban cycle is responsible for the major outbreaks of yellow fever that occur in Africa. Except for an outbreak in Bolivia in 1999, this urban cycle no longer exists in South America.

In Their Own Story

The female Aedes aegypti mosquito takes up the yellow fever virus when she ingests the blood of an infected human or another primate. The virus reaches her stomach, and if the concentration is high enough, the virions infect epithelial cells and replicate there. From there, they reach her haemocoel and then her salivary glands. When she next sucks blood, she injects her saliva into the wound, and the virus reaches the bloodstream of the bitten person. This urban cycle is responsible for the major outbreaks of yellow fever that occur in Africa.

Reader's Guide

The yellow fever mosquito Aedes aegypti is found throughout the tropics and subtropics. It is well adapted to urban areas. It breeds in artificial containers. The female requires a blood meal for egg development. The mosquito is a daytime biter. Control measures include reducing the population of the transmitting mosquitoes. In areas where yellow fever is common, early diagnosis of cases and immunization of large parts of the population are important to prevent outbreaks.

Did You Know?

• The yellow fever virus was the first human virus to be isolated, in 1927.
• Yellow fever originated in Africa and spread to the Americas starting in the 17th century with the European trafficking of enslaved Africans.
• In about 15% of people infected with yellow fever, within a day of improving the fever recurs, abdominal pain occurs and liver damage begins, causing yellow skin.
• The yellow fever mosquito Aedes aegypti can also transmit other diseases, including Zika fever, dengue fever, and chikungunya.
• Transovarial transmission of yellow fever virus within A. aegypti is indicated, meaning a female mosquito can pass the virus to its eggs.