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Genetically Modified Mosquitoes Join The Fight To Stop Zika Virus

Larvae of genetically modified <em>Aedes aegypti</em> mosquitoes are pictured through a microscope viewfinder. The larvae will die before reaching adulthood.
Nelson Almeida
AFP/Getty Images
Larvae of genetically modified Aedes aegypti mosquitoes are pictured through a microscope viewfinder. The larvae will die before reaching adulthood.

The rapid spread of the Zika virus has raised interest in a British company that has developed a genetically modified mosquito. Oxitec has produced a genetically engineered line of the Aedes aegypti mosquito, the mosquito that carries dengue fever and chikungunya. Those tropical diseases have become common in Latin America and are now showing up in Florida.

Aedes aegypti also carries Zika, a disease whose symptoms include fever, like dengue. It has also been linked to a birth defect, microcephaly in children born to women infected with Zika.

In Brazil, in the wake of mounting concern over Zika, Oxitec has announced it is expanding a program to release genetically modified Aedes aegypti mosquitoes in Piracicaba, a city about 100 miles northwest of Sao Paulo.

The company breeds and releases into the wild male mosquitoes that don't produce viable offspring. When females mate with the GMO males, they lay eggs that hatch but the larvae die before adulthood. Oxitec says trials conducted in Brazil and other countries over the past decade show releasing bioengineered male mosquitoes can reduce the wild Aedes aegypti population by 90 percent.

<em>Aedes Aegypti</em> looks for a meal.
/ Courtesy of Oxitec
Courtesy of Oxitec
Aedes Aegypti looks for a meal.

In Piracicaba, the company says trials that started in April have reduced wild mosquito larvae by 82 percent. Oxitec has signed an agreement with the city to build a new mosquito production facility in the city and expand the trials to cover an area with up to 60,000 residents.

In this country, Oxitec is currently awaiting FDA approval to conduct trials of its genetically modified mosquitoes in the Florida Keys. After an outbreak of dengue fever in Key West several years ago, county officials and Oxitec agreed to see if releasing the genetically modified mosquitoes here can help control the Aedes aegypti population. Many local residents have expressed concerns about the consequences of releasing genetically modified mosquitoes into the environment.

There have been a handful of Zika cases reported in the U.S., including three in Florida. So far, none were contracted locally. All were recently returned travelers believed to have contracted Zika overseas. But there are concerns that Zika, like dengue and chikungunya, could spread to warm climes in the U.S., like South Florida.

The good news is that although there have been sporadic local outbreaks of dengue fever in the U.S., it hasn't become widespread. One reason, health officials say, may be because of good local mosquito control programs.

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As NPR's Miami correspondent, Greg Allen reports on the diverse issues and developments tied to the Southeast. He covers everything from breaking news to economic and political stories to arts and environmental stories. He moved into this role in 2006, after four years as NPR's Midwest correspondent.