627,000 deaths per year: that's a good figure. Malaria, the deadly illness caused by infected mosquitoes, is on the retreat, thanks to medical treatments that have reduced mortality rates by 42% since 2000. Among African children, the mortality rate has dropped even more: 54%. Even so, one African child dies of malaria every minute, according to the World Health Organisation.

It's not that NGOs and aid organisations don't try hard enough to prevent the parasite-infected mosquitoes from biting humans: it's just that keeping every one of the tiny insects away with nets and insecticides is very hard work.

What if all that mosquito-chasing wasn't necessary? What if the insects killed themselves? That's the idea behind Oxitec, an Oxford-based biotech company. It breeds sterile male mosquitoes for release in affected areas. As male mosquitoes always do, they'll find the females and mate with them – but because they're sterile, the offspring will die. "We're using mosquitoes' biological urge to our advantage", Oxitec chief executive Hadyn Parry tells Guardian Sustainable Business.

This is how Oxitec's pioneering mosquito intervention works: scientists breed both males and females on trays in the company's three factories; one in Oxford, two in Brazil. At the stage between larvae and fully developed insects, the mosquitoes are separated and the males, easy to identify thanks to their larger size, are kept. The separation can either be done on site or in the area where the sterile mosquitoes will be dispatched on their mission. "A coffee cup holds about 3m eggs, so it's inexpensive to send", explains Parry.

Oxitec's sterile Romeos are genetically modified mosquitoes; their code has been changed to make sure the genetic material they give their female partners doesn't result in offspring. The Oxitec scientists have also added a forensic marker – a colour – to their insects, which makes it easy for scientists and doctors tracking mosquito-borne diseases to establish where the sterile mosquitoes are active and how far they travel.

Letting the deadly mosquitoes kill each other softly seems a sensible solution, especially since Oxitec reports that the process has no environmental effects. Of course, it also saves humans in affected areas from constant exposure to insecticides. "People use insecticides to prove that they're doing something, even if it's not very successful", says Parry. "And you can only use insecticides in homes that are permanently open, as they often are in the African countryside. In cities, where people close their windows and doors, you can't use them." According to Oxitec, the cost of its sterile males is low as well.

To date, Oxitec has chosen to focus primarily on mosquitoes carrying dengue fever, an illness causing high fever, muscle pains and severe skin rashes. That's because the dengue virus is carried only by one mosquito species. "Genetically modified mosquitoes are much more applicable for diseases like dengue because malaria is carried by so many different kinds of mosquitoes", explains Dr Thomas Walker, a lecturer at the Department for Disease Control at the London School of Hygiene and Tropical Medicine. "Another potential drawback is that the sterile males may not be as fit as regular males." In other words, the killer males may not mate with the females as regular males are faster and fitter.

But with dengue infecting some 50 million people per year, combating its carriers is a large and potentially rewarding task in itself. Oxitec, aware of many people's fundamental opposition to genetic modification, has opted for a business strategy that involves first getting government approval. Brazil's health regulator has already certified the sterile mosquitoes as safe; next, Oxitec will go to the US Food and Drug Administration. The company believes these approvals, and the low production and shipping cost, will help make its genetically modified insects a straightforward sell – and it's easy to see how a fix that involves the killers killing themselves would be an attractive choice to NGOs and governments. The obvious question is whether they'd want to spend money on fighting dengue, a less dangerous disease. If not: can Oxitec's killer mosquitoes become an effective solution to malaria as well?

Meanwhile, researchers are exploring another new approach: infecting mosquitoes with a virus in a process similar to vaccinations. When the mosquitoes later contract the disease virus, it will have no effect on them, and they won't spread it to humans. According to Walker, sterile mosquitoes work best in isolated areas, for example islands, where new mosquitoes don't keep coming in. "The key question is, will lab-grown mosquitoes be able to compete with mosquitoes born in the wild?" he explains. "What Oxitec is doing is good from a disease point of view. Whether people think it's a good idea depends on their attitude towards genetic modification."

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