Tuesday 25 October 2016

US closer to using genetically modified mosquitoes that could fight Zika

Julie Steenhuysen

Published 05/08/2016 | 22:32

The Zika virus can be carried by mosquitoes (AP)
The Zika virus can be carried by mosquitoes (AP)

The United States has taken another step toward clearing the way for a trial of genetically modified mosquitoes in Florida as a way of reducing populations of mosquitoes that carry the Zika virus.

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The US Food and Drug Administration said on Friday that a field trial testing Intrexon Corp's genetically engineered mosquitoes would not have a significant impact on the environment. The announcement came as Florida officials ramp up aerial pesticide spraying of a neighborhood in Miami. Florida is the first state to report local transmission of the virus.

Florida health authorities have identified 16 Zika cases spread by local mosquitoes and expect there may be more.

Pregnant women are most at risk from Zika, a virus spread by Aedes aegypti mosquitoes. U.S. health officials have concluded that Zika infections in pregnant women can cause microcephaly, a birth defect marked by small head size that can lead to severe developmental problems in babies.

The Zika outbreak was first detected last year in Brazil and has spread rapidly in the Americas.

Intrexon's Oxitec unit has been working for years to kick off a trial of the mosquitoes in the Florida Keys to assess the effectiveness of its mosquitoes to reduce levels of mosquitoes that carry diseases, including Zika, dengue, Yellow Fever and chikungunya.

The FDA has been reviewing Oxitec's application for use of its technology as an investigational new animal drug. Its environmental assessment helps clear the way for the company to begin a clinical trial in Key Haven, Florida that would assess whether the genetically modified mosquitoes will mate with local, wild mosquitoes and suppress their population over time.

Results of that trial would be used to support approval of the company's technology, a process that could take more than a year.

Oxitec's mosquitoes are genetically altered so their offspring die before they can reproduce. Trials in Brazil, Panama and the Cayman Islands have shown that the Oxitec mosquitoes can reduce local Aedes aegypti populations by more than 90 percent.


To begin the trial, however, the company must first await the results of a vote in the Nov. 8 general election seeking community approval for the trial.

Oxitec Chief Executive Hadyn Parry said in a conference call that the vote is non-binding, and the decision about whether to proceed is up to the Florida Keys Mosquito Control District, the local body responsible for mosquito control.

Community support in the vote is not guaranteed.

In Key Haven, a suburb of large, waterfront homes near Key West where the trial is slated to take place, yard signs have popped up declaring "no consent" to the release of genetically modified mosquitoes.

Kathryn Watkins, a Key Haven resident recruited by trial opponents, is seeking election to the board overseeing the Florida Keys Mosquito Control District.

"It just has everyone scared," Watkins said, adding that local residents see themselves as unwilling test subjects. "The genetically modified male has to mate with a wild female, and the wild female has to bite us in order to lay eggs," she said.

"They are using us in this trial without consent," she added.

As his company awaits the vote, Parry said he intends to ask the FDA for an emergency-use authorization that would make the product available to help battle Zika in the United States. The FDA has approved several diagnostic products under this designation.

But it is not likely to be granted under current statutes. FDA spokeswoman Theresa Eisenman said there is no "fast-track" designation for new animal drugs, and emergency-use provisions in the applicable law do not apply to animal drugs.

The World Health Organization has declared Zika a global health emergency, and has suggested that alternative approaches to fighting mosquitoes that carry the virus might be an important way to suppress mosquito populations.

Zika spread rapidly in Latin America and the Caribbean before local transmission began in the continental United States. Aedes aegypti mosquitoes thrive in warmer southern US states.

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