Dengue virus is transmitted by Aedes mosquitoes, primarily Aedes aegypti and Aedes albopictus.
Aedes aegypti (pictured left) is considered a domestic mosquito as it lives in close association with humans, breeding in artificial containers around houses and it is responsible for the majority of dengue transmission.
The transmission cycle for dengue is human - mosquito – human. Importantly, mosquitoes do not naturally carry the dengue virus but must acquire it from a dengue infected person before they can transmit it to another person.
Only female mosquitoes bite, requiring the blood for egg production, and therefore only female mosquitoes transmit pathogens. A female mosquito may acquire dengue virus after ingesting blood from a person sick with dengue. It takes about 12 days for the mosquito to be capable of transmitting the virus to a new person. During this time the virus replicates inside the mosquito body, spreading until it reaches the mosquito’s salivary glands. The virus is then injected with the saliva into a human whenever the mosquito takes a blood meal. Given that most mosquitoes live less than 30 days, only relatively old mosquitoes (those at least 12 days old) can transmit dengue virus to humans.