Image of the Week: Aedes aegypti
This week, there has been growing concern over the outbreak of the Zika virus in Brazil. Now detected in over 20 countries, the World Health Organization will convene an emergency committee to discuss the spread of the disease. The virus has been linked to birth defects, notably microcephaly (abnormal smallness of the head), so pregnant women are most at risk. Here, we take a look at the mosquito that carries the Zika virus…
Our image this week shows the Aedes aegypti mosquito, a vector that can transmit tropical diseases including dengue, chikunguna, yellow fever, West Nile fever, and Zika.
Aedes aegypti are now present on all continents except Antarctica. Originating in Africa as primarily a forest species, the mosquito has spread with globalisation and trade, and has adapted to urban environments.
Surprisingly, these mosquitoes don’t fly very far – on average about 400 metres during their adult lifespan, according to WHO. Partially as a result of drought in Brazil, Aedes aegypti have been able to breed within households as more people are storing large containers of water indoors.
So how can these mosquitoes transmit diseases like Zika? An infected female Aedes aegypti passes on the virus after biting an infected person and then biting another, uninfected person.
Female mosquitos use protein from human blood to help their eggs develop. The eggs can hatch into larvae in less than a day, and this larvae then takes around four days to develop into pupae. Adult mosquitoes will emerge two days after that. Once an adult mosquito has bitten a person and extracted blood, it lays its’ eggs. And the cycle starts again.
While Aedes aegypti are adept at transmitting the Zika virus, there are ways we can attempt to halt the spread. The Wellcome Trust-funded company Oxitec have developed an innovative solution to control Aedes aegypti. By releasing genetically modified male mosquitoes whose offspring will die before they become mature adults, the number of mosquitoes could be dramatically reduced.