Bite back The lab breeding six-legged agents in the war on disease

Could a 'self-limiting' gene that kills off mosquitoes' female offspring reduce the spread of malaria, dengue fever and Zika?

- Sarah Johnson

In an unassuming building on an industrial estate outside Oxford, Michal Bilski sits in a windowless room with electric fly swatters and sticky tape on the wall, peering down a microscope. On the slide before him is a line of mosquito eggs that he collected less than an hour previously and put into position with a brush. Bilski manoeuvres a small needle filled with a DNA concoction and uses it to pierce each egg and inject a tiny amount.

"Each slide has between 50 and 100 eggs on it, and it takes from 15 minutes to half an hour to inject them all," he said. "Normally in a day we would inject between 500 to over 1,000 eggs."

Bilski, a research and development team leader for the biotechnology company Oxitec, is carrying out one of the early stages in the process of making genetically modified (GM) mosquitoes. It is hoped the insects that hatch will prove instrumental in the fight against diseases such as malaria, dengue fever, Zika and chikungunya, of which mosquitoes are vectors.

Last year, Oxitec released tens of thousands of GM mosquitoes in Djibouti, where there has been a resurgence of malaria caused by an invasive species. It was the first time such mosquitoes have been released in east Africa and the second time on the continent. It follows multiple releases of modified mosquitoes in Florida and Brazil to combat dengue fever, a neglected tropical disease.

The impact of these mosquitoes on malaria transmission could be significant, believes Lottie Renwick, head of strategy for Malaria No More UK. "They will play a really major role and be game-changing," she said, but added that the intervention needs to work alongside other tools such as mosquito nets and injections.