10 Feb 2016

Scientists explore new technology to wipe out Zika mosquitoes

From Checkpoint, 6:08 pm on 10 February 2016

As health authorities in Colombia confirm that the Zika virus can be fatal, scientists are exploring new genetic engineering technology that could wipe out the species of mosquito which carries the virus forever.

The technology, which snips through genes to force a genetic change, could make the mosquito unable to spread disease or drive it to extinction by affecting the way it reproduces.

Speaking to Checkpoint with John Campbell, Kevin Esvelt, a gene drive researcher at MIT, said the technology might be just months away - but whether it was the right thing to do was a question for the people and countries affected.

Of the 3500 species of mosquito, only about 12 spread human diseases - in particular, the Aedes aegypti vector.

“There are two species that spread Zika and dengue and Chikungunya and yellow fever - note that dengue and yellow fever kill roughly 60,000 people between them per year.

“They’re fairly nasty on their own, never mind the new plague of Zika,” he said.

Gene drives of this sort are not quick fixes and can be very expensive, but could be a quicker and more effective solution than a vaccine, which targets the virus rather than the carrier.

The question, however, is whether using genetic engineering to eradicate these species could harm the affected countries’ ecosystems: Aedes aegypti serve as one of many food sources for bats and may also be useful for pollinating flowers.

“Is the ecosystem going to notice? We don’t know. Probably not, but we don’t know for sure,” said Dr Esvelt.

The mosquitos are native to North Africa and Eurasia, but, in much of the world, are invasive, introduced species.

“This means ecologically, they’re very unlikely to be required. They’re probably not doing anything important - in fact, they’re disruptive invaders,” said Dr Esvelt.

“In Hawaii, for example, they’re helping to drive native birds extinct by spreading bird parasites.”

The challenge, therefore, would be to get rid of the mosquito in regions where it is introduced while minimising the damage in North Africa and Eurasia.

In either case, the ecological outcomes were hard to predict exactly, said Dr Esvelt, though British company Oxetic had carried out small-scale trials, funded by the Bill and Melinda Gates foundation, to locally suppress populations of mosquitos.

The data from those experiments could help them to predict what might happen on a larger scale, Dr Esvelt said.

“You can look at those ecosystems and say, ‘is it different with most of those mosquitos gone?’ If not, then we’re probably fine.”