In the global rush to find a way to stop the spread of the Zika virus, a new player has emerged: a genetically modified mosquito whose developers claim it could be a game-changer.
Although initial reports of the mosquito's ability to halt the disease seem promising, the GM bug is still a new weapon in the world's anti-mosquito arsenal, and many factors could determine whether it will really succeed.
The mosquito, a product of the British biotechnology company Oxitec, is designed to reduce populations of Aedes aegypti mosquitoes, the species best known for carrying dengue fever, chikungunya, yellow fever and now Zika.
It uses a relatively simple concept: Oxitec has introduced a "self-destruct" gene into its mosquitoes, which causes new generations of the bugs to die before they reach adulthood. Releasing batches of the modified insects and allowing them to mate in the wild can reduce mosquito populations.
There is some irony here: The biotech firm in effect is giving the mosquito a birth defect — the same thing the mosquito is suspected of doing to people. The Zika virus, transmitted as the blood-sucking insect travels from person to person, is thought to be behind a surge in microcephaly, in which babies are born with abnormally small skulls and brains.
The Oxitec mosquito has had field trials in several countries. The biggest is in Brazil, the epicenter of the Zika crisis. Brazil is the first country in which the GM mosquito has been approved for limited use as a control method.
The company's reports have been glowing — that its GM insect has cut Aedes aegypti populations by 90 percent in its trials.
"Certainly people seem to be very happy with the results so far," said CEO Hadyn Parry.
However, there are concerns: For instance, would there be negative side effects to eliminating Aedes aegypti populations in the wild? Some experts believe that could create an ecological "hole," which another species would eventually fill, with uncertain implications.
On the other hand, conventional forms of mosquito control, such as pesticides, raise environmental concerns, too, and also are difficult to use with uniform success.
An Australian research project has turned to a different kind of altered mosquito with great success, said Phil Lounibos, a University of Florida mosquito expert.
The researchers have infected their Aedes aegypti mosquitoes with a bacterium called Wolbachia, which is naturally found in other insects but not usually in mosquitoes. The bacterium — which can be passed down to new generations in the mosquito's eggs — reduces the insects' ability to become infected with dengue fever, preventing them from transmitting the disease to humans. Theoretically it could have a similar effect on Zika.
The benefit of this tactic is that it doesn't wipe out mosquito populations, it just renders them less effective at spreading disease. So, it avoids the ecological concerns associated with removing an entire species from an ecosystem, Lounibos said.
The skeeter is in field trials in Vietnam, Indonesia, Colombia and Brazil.
"One of the benefits of the Aussie technique ... is that the Wolbachia is a naturally occurring bacterium that is not regarded as GM," Lounibos said, which sidesteps the hot-button issue of gene modification.
Public fears have not seemed much of a problem in most places, but there has been resistance in the Florida Keys, where Oxitec has proposed a field trial of its mosquito.
Many of these fears have centered on whether the insect's genetic modifications make it safe for the environment and safe for humans who might be bitten by it.
A bigger hurdle to GM mosquitoes may be regulatory. In any country where the insect might be useful, government approval is required — first for field testing, then again for regular use.
Lounibos predicted that with success in Brazil, the bug will find an easier path to approval in other countries, especially as the Zika virus continues to spread in the Americas.