New gene-editing tools may help wipe out mosquito-borne diseases

In the age-old war of human versus mosquitoes, the bugs have been winning.

At least 700,000 people die every year from mosquito-borne diseases such as malaria, dengue, West Nile and yellow fever.

Global trade and climate change have helped disease-carrying species become established in places like Florida, California and Texas. In parts of the U.S., dengue is now a persistent problem. Last year, for the first time in decades, Florida and Texas reported locally-acquired malaria cases. Maryland also had a case.

But by using bioengineering, scientists have developed tools they believe may help control and possibly eradicate mosquitoes that carry dengue, malaria and other diseases. Andrea Leal, the head of mosquito control in the Florida Keys says, "The good news is we've got these emerging technologies that show great promise in reducing Aedes aegypti mosquitoes."

The Aedes aegypti mosquito loves to feed on people and it's become a significant health threat across the southern U.S. Leal's agency became the first in this country to partner with a company, Oxitec, that's testing a new means of mosquito control.

Using gene editing, Oxitec has developed male mosquitoes that, when they mate, produce female offspring that don't survive to adulthood. Females are the mosquitoes that bite, spreading dengue and other diseases.

Over the last three years, Oxitec released limited numbers of its bioengineered male mosquitoes in the Florida Keys. Oxitec hasn't released the results of those trials yet. But, in a 2022 study in Brazil, the company showed the technology reduced populations over 90 percent in some areas. Brazil approved Oxitec's request to market it commercially.

The company's CEO Grey Frandsen says, "Now the product is being deployed in every state in Brazil, including in the heart of the Amazon where the Amazon tourism authority has selected Oxitec to deploy around tourism sites because they are, in essence, rejecting the need to deploy chemical pesticides."

Along with Oxitec, many research organizations are now focused on using gene editing to combat mosquitoes. A major plus is it can be used on any species, including those that transmit malaria. Oxitec is working on three species of malaria mosquitoes and is in talks about conducting trials in Uganda.

Eric Caragata, an entomologist at the University of Florida, says there's growing evidence that gene editing technology will be an important tool in reducing the spread of dengue, malaria and other diseases. "If you use a product like that," he says, "you have the potential to drastically reduce the number of mosquitoes that are in an area and hopefully that would be accompanied by a decrease in the number of cases."

At the University of California San Diego, Omar Akbari is using gene editing to target a mosquito species that carries malaria. He calls gene editing a "game changer" that he believes if scaled up and maintained, can wipe out the Aedes aegypti mosquito from North America. "I think it's going to be difficult but I don't think it's impossible," he says, "because they have been eradicated before using insecticides. And these are new technologies."

In the U.S. and elsewhere, there's been public resistance and concerns about the possible environmental impact of releasing bioengineered mosquitoes. The three years of trials in the Keys were conducted to show state and federal regulators that the technology is environmentally safe and effective.

And in recent years, Frandsen has seen a shift in the questions his staff gets from the public. He says, "The question is no longer 'Do these technologies have a role?' 'Are these technologies appropriate for communities?'" he says. "The questions we're getting now is 'How quickly can we get these technologies to new communities that need it the most?'"

Oxitec is hoping to receive approval from the U.S. Environmental Protection Agency and make its mosquito control technology available commercially in the U.S. within the next two years.

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