Scientists to release genetically modified mosquitoes in Florida to combat dengue, Zika

It’s been a big week for the Aedes aegypti mosquitoes, and not necessarily a good one. On top of earning the moniker “worst animal in the world” from the Atlantic on Thursday, the insect will soon be the target of an early-stage elimination strategy in southern Florida involving genetically modified male mosquitoes. The goal? Reduce a mosquito population that causes 400 million infections across the globe each year.

The project was approved by the Florida Keys Mosquito Control District this week, just months after the UK-based biotech firm behind the plan, Oxitec, was granted an experimental use permit by the U.S. Environmental Protection Agency. The “promising new tool,” as the EPA referred to it in May, involves releasing large quantities of male Aedes aegypti mosquitoes that have been engineered to produce only male offspring.

The importance of that fact is that only female Aedes aegypti bite (a move required to produce eggs). So the modified male mosquitoes — or “frankensquitos” as some call them — are merely there to produce more harmless mosquitoes. Over time, the process reduces the population of the Aedes aegypti, thereby lowering the transmission of infections that are primarily spread by them, including Zika virus, chikungunya and — most recently in Florida — dengue fever.

Kevin Gorman, Oxitec’s global head of field operations, says the concept is simpler than it sounds. “We release males that go out and find females; and those wild females, once mated by our males, don’t produce any female offspring,” Gorman tells Yahoo Life. “So that’s the way we control the population.” Gorman says Oxitec has been releasing the mosquitoes for the last two years in Brazil, where it has led to a 95 percent reduction in the Aedes aegypti population.

A UK-based biotechnology firm has gained approval to release 750 million genetically engineered mosquitoes aimed at controlling the population. Here's why it could prove vital. (Photo: Getty Images)
A UK-based biotechnology firm has gained approval to release genetically engineered mosquitoes aimed at limiting the population of the bugs. Here's why it could prove vital. (Photo: Getty Images)

The plan in the Florida Keys, he says, will be on a dramatically smaller scale. While some news organizations wrote Thursday that the company was planning to release “750 million” of the genetically engineered mosquitoes, Gorman clarifies that the number is simply the limit set by the EPA. Oxitec is planning to equip technical leads in Florida with boxes that contain thousands, not millions, of self-releasing genetically modified mosquitoes.

Considering that it’s a small-scale, localized study, Gorman says it’s not likely to make an impact on virus transmission — at least not at this point. But ultimately, that’s the plan. “It’s about getting another tool in the toolbox for vector-control authorities so that they can choose which one to use when outbreaks strike,” says Gorman. “It’s really about being prepared for future events.”

When it comes to preparing for outbreaks of mosquito-borne illnesses, he says Florida is the No. 1 place of concern in the U.S. “It’s pretty much the gateway for the species into the U.S — the most southerly tropical state in the U.S., and as such it’s the one that is most threatened by these diseases,” says Gorman. “Every year it has some level of disease transmission.”

Floridians are currently battling another outbreak of dengue fever, a virus that was eliminated from the U.S. in 1946 before returning in the 1980s. In 2019, the Centers for Disease Control and Prevention recorded 1,183 cases overall. Florida not only reported the most cases (371) but was one of only three states where local transmission — rather than travel-related transmission — was reported.

Although many experts consider Oxitec’s tool to be an exciting potential solution, not everyone agrees. In the wake of the approval, many environmental activists and residents have spoken out expressing concern about what impact the genetically engineered mosquitoes may have. Dana Perls, food and technology program manager with environmental nonprofit Friends of the Earth said in a statement that the experiment will “needlessly put Floridians, the environment and endangered species at risk.”

Barry Wray, executive director of the Florida Keys Environmental Coalition, said in another statement that the mosquito control board was proceeding with an experiment that could be “damaging to environmental health and the economy.” Equally opposed was Jaydee Hanson, policy director for the International Center for Technology Assessment and the Center for Food Safety, who criticized the timing of the decision.

"With all the urgent crises facing our nation and the State of Florida — the Covid-19 pandemic, racial injustice, climate change — the administration has used tax dollars and government resources for a Jurassic Park experiment,” Hanson said in a press release. “Now the Monroe County Mosquito Control District has given the final permission needed. What could possibly go wrong? We don't know, because EPA unlawfully refused to seriously analyze environmental risks. Now without further review of the risks, the experiment can proceed.”

Although the experiment may be new to U.S. soil, the EPA notes in its May press release that it went through an “extensive evaluation” before Oxitec was granted permission to try it. This included evaluating safety risks. “Since only male mosquitoes will be released into the environment and they do not bite people, they will not pose a risk to people,” the EPA wrote. “It is also anticipated that there would be no adverse effects to animals such as bats and fish in the environment.”

The tool had been cleared in 2016 by the Food and Drug Administration, which conducted a thorough analysis of the technology and determined that the risk of adverse effects to people, animals and the environment was “negligible.”

Gorman says that concerns about safety, based on the FDA and EPA approval as well as a decade of experience with the tool, are unwarranted. “No one in Florida is going to be at risk from our mosquitoes — but they are at significant risk from mosquito-borne diseases,” says Gorman. “We’ve released over a billion mosquitoes over the last 10 years in Panama, Brazil, Grand Cayman and Malaysia, and we’ve never had one adverse effect on humans, the environment or animals.”

While the mosquitoes are reportedly set to be released in 2021, no exact locations in the Florida Keys have been chosen.

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