Article Insects, us & the future

It’s simple - we, er, genetically modify the mosquitoes

A look into how genetic engineering could save us from widespread dengue fever.

Dengue fever has swept rapidly across the globe since 2012. A record-breaking number of infections have been reported by the World Health Organisation, which estimates that 100 million people could be infected this year.

You may not have heard of dengue fever, but it is the fastest-growing mosquito-borne disease in the world and has an economic cost on a level with malaria. It is estimated that 500,000 people with severe dengue require hospitalisation every year and about 2.5% of those infected die.

Dengue fever is primarily transmitted by a species of mosquito called Aedes aegypti and can cause severe flu-like symptoms. A typical Aedes mosquito will travel no more than 500 metres and rarely lives longer than a month. But with the help of intercontinental man-made transport, Aedes aegypti eggs have hitchhiked as far as the Cayman Islands, Brazil and, most recently, the United States.

Despite the global spread of these mosquitoes, ways to exterminate them are still fairly primitive. Mosquitoes lay their eggs in water, so one method is to put larvicides (insecticides that specifically target the larval life stage of an insect) into the water where mosquitoes are found. Another is to kill them in flight by spraying insecticides into the air. Both methods are time-consuming, costly and harmful to other species in the surrounding environment.

The mosquitoes are spreading fast, which means dengue infections are on the rise. In the mid-70s, Brazil declared it had no Aeges aegipti. Now it spends $1 billion a year trying to get rid of them. With no approved vaccinations for dengue, the world needs a solution. One that can safely find its way into homes and schools. And a solution that safeguards other species, native and beneficial to their surrounding ecosystems.

According to Oxitec -  a biotech company devoted to insect control  -  genetic engineering is the answer.

Oxitec has come up with a way to genetically modify Aedes mosquitoes to require an artificial chemical to develop beyond the larval stage. Oxitec’s genetically modified male eggs (3 million of which can be transported within the size of a small coffee cup) are treated with the chemical and strategically released into areas highly populated with Aedes mosquitoes. If these males find a mate, the trait will be passed onto their offspring and without a source of the chemical in the natural environment, their offspring will never develop into adults. More genetically modified males are then released and this results in a decline in the mosquito population, serving as a control to the transmission of dengue fever.

The advantage of using male mosquitoes is that they don’t bite, it is only the females that need the protein in blood to develop eggs, so releasing males into the wild won’t cause any harm to the surrounding inhabitants.

A 2010 field trial carried out by Oxitec in the Cayman Islands hosted the release of genetically modified male mosquitoes and successfully reduced the population of the Aedes aegypti by 80%. Now Oxitec is going through the process of trialling on a bigger scale, in more densely populated areas, and is confident that this process will be essential to preventing continued widespread growth of the disease.

However, there is a lot of stigma around genetically modified organisms (GMOs) and some groups, such as the Non-GMO Project, show a concern that research and development into this new technology will have negative repercussions on the natural food chain.

Hadyn Parry, CEO of Oxitec, argues that, “our fear of the technology distracts from the need to tackle global problems, such as hunger and disease”. He believes that the debate over GMOs has become too political and that activist groups are not evaluating the benefits of GM technology.

Damn science, you scary. The fact that humans now have the power to genetically modify other species to kill off their own kind is alarming. But it looks like, whether we like it or not, we’re about to witness some world-class scientific research. And if in the process it can help prevent life-threatening, widespread disease then I support it.

Hopefully, genetic engineering and other technological advances in future years to come will be used responsibly for essential purposes and to control widespread diseases such as dengue fever. And I hope that the inevitable disputes between participating scientists and groups such as the Non-GMO Project can communicate effectively to safeguard a beneficial future for this remarkable new technology.

_Follow Dave on Twitter @__mynameisdave

Header image attribution (Ramón Portellano)

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