US Food and Drug Administration finds ‘no significant’ environmental impact of experimental release of insects after 15 Zika infections were reported in Miami

A release of genetically engineered mosquitoes that it is hoped could help combat the spread of the Zika virus has been approved in Florida by the US Food and Drug Administration (FDA).

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On Thursday, Florida officials said the same species of mosquito had transmitted 15 Zika infections in the Wynwood neighborhood of Miami, the first cases to be caused by mosquitoes in the mainland US.

Hadyn Parry, chief executive of Oxitec, the company that created the genetically altered insects, said he was “really pleased” by the FDA approval of the experimental release, and called on authorities to grant Oxitec emergency authorization to release the insects in Miami as a control measure.

“We’re really pleased today,” said Parry. “Aedes aegypti is public enemy No 1. It is exclusively a human vector, it lives in and around the home, if you go into the center of town that’s where it is.”



Oxitec, a spinoff from a project at Oxford University, was recently purchased by Intrexon, the corporation that produces non-browning “Arctic” apples and fast-fattening “AquaBounty” salmon. The FDA announcement nearly clears the way for it to release the mosquitoes in an experimental trial on Key Haven, a small island in the Florida Keys. One obstacle remains, however: the voters of Monroe County.

In November, roughly 52,000 voters will decide if they want the trial to go forward. The referendum will not be legally binding, but most members of the elected Florida Keys mosquito control board have said they will abide by voters’ wishes. The trial has been hotly contested, with many residents vocally opposed to the mosquitoes’ release.

Aedes aegypti is believed to be primarily responsible for the transmission of Zika, a primarily mosquito-borne disease believed to cause birth defects including microcephaly, by which children are born with abnormally small heads and severe, lifelong developmental problems.

The Oxitec Florida trial would run for between six and 22 months, with a goal of determining whether wild Aedes aegypti females, the gender that bites, will mate with the company’s “OX513A” males, which are designed to produce offspring which do not fully mature, thus undercutting the mosquito population.

It is not clear how many engineered mosquitoes could be released. Parry said it could vary from 20 to 100 mosquitoes per person on the island.

The FDA announcement on Friday was a finding of “no significant” environmental impact, from a review of Oxitec data on whether releasing the mosquitoes would have any knock-on effect, for example in the food chain. Thousands of public comments were also considered. Parry declined to say how much Oxitec mosquitoes would cost local municipalities, if the FDA approved wide release.

Whether Keys voters approve the mosquito, however, may eventually prove irrelevant. Oxitec is releasing the insects on a trial basis in Panama, Brazil and the Cayman Islands, and has applied for experimental release permits in Sri Lanka and India.

Oxitec is developing another species of mosquito, the Aedes albopictus, Parry said. Like Aedes aegypti, it is capable of transmitting zika, dengue fever and chikungunya.