Skip to Main Content

Florida is one step closer to field trials of genetically engineered mosquitoes that could slow the spread of diseases like Zika.

The Food and Drug Administration issued its final environmental assessment Friday, finding that a proposed field trial to test the mosquitoes is effectively safe for both humans and the environment.


FDA’s decision is not a final approval — Oxitec, the company who created the mosquitoes, now awaits the decision of the Florida Keys Mosquito Control District, which oversees mosquito management. 

In light of FDA’s findings and increasing numbers of locally acquired cases of Zika infection, Oxitec CEO Haydn Perry urged a state of emergency-type declaration be considered to get the field trial underway quickly, suggesting that should efforts fail in Florida, the company would reluctantly look to other communities for its first US trials. The Keys have the infrastructure needed to do the work, Perry said, and going anywhere else would likely require significant ramp-up.

“I think the pathways that would enable emergency use should be looked at, because the crisis is here and now. It would be an awful shame if in two or three years time we looked back and said why didn’t we do this when we had it in our hands,” he said during a Friday press conference.


A public comment period following the preliminary findings yielded more than 2,600 public comments, including those opposing the plan. In November, residents of the Florida Keys will vote in a nonbinding referendum on whether or not to proceed with the field trial.

Phil Goodman, chairman of the mosquito board, said the board could vote to allow the field trial, regardless of the outcome of the referendum on the November ballot.

“I would vote to move forward” before the referendum, Goodman said.

When Oxitec’s genetically engineered Aedes aegypti mate with regular mosquitos in the wild, the offspring die before they are able to reproduce, thus decreasing the total mosquito population and the spread of diseases such as dengue, chikungunya, and possibly Zika. In field trials in Brazil, the Cayman Islands, and Panama, the population of mosquitos in the experimental areas dropped by about 90 percent within six to nine months. And according to Oxitec, in one treated location, incidence of dengue fell by 90 percent while in the nontreated area, incidence fell by about 50 percent. Based on field trial results, work continues in Brazil, Panama and the Cayman Islands.

The proposed US trial has two goals, as outlined in the environmental assessment: see if the genetic modification in the engineered mosquitos is passed on to offspring, and determine if the offspring actually die earlier as intended.

In the trial, mosquitoes would be released in Key Haven into an experimental zone. The trial would also include a buffer zone and a control zone on the island. The zones would not be physically divided by barriers like nets, but Aedes aegypti only travel in an area encompassing a few hundred meters on average in their lifetime, so they should not migrate from one area to the other, said Oxitec spokesman Matthew Warren. Egg traps in both the experimental and control zones would help compare the mosquito populations.

Oxitec’s mosquito is the first genetically engineered animal to be approved by the FDA for use in an open-release field trial, said FDA officials.