Science, Tech & Environment

Key West officials debate use of genetically modified mosquito to fight Dengue fever

This story is a part of

Human Needs

This story is a part of

Human Needs


Experts estimate that nearly 100 million people a year are infected with Dengue fever, a mosquito-borne virus. (Photo by James Jordan via Flickr CC.)

Researchers at the biotechnology company OxiTec have created a type of mosquito birth control by genetically sterilizing the males, a scientific breakthrough they say could help prevent Dengue fever from spreading in the United States.

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Experts estimate that nearly 100 million people are infected with Dengue annually, a 30-fold increase in the last 50 years. Without a vaccine or proven treatment, the virus appears likely to keep spreading.

Michael Doyle, executive director of the Florida Keys Mosquito Control District, said the disease was mostly eradicated in the United States in the 1930s. But in 2009, he started to see cases of it in Key West.

Symptoms of the mosquito-borne virus include high fever and intense joint and muscle pain.

"When Dengue arrived, we realized that we had to reduce these mosquito numbers en masse in order to prevent any further transmission," Doyle said.

Door-to-door checks and weekly treatments of the entire island by insecticide-spraying helicopters have so far been effective. The last case of Dengue in Key West was confirmed in November 2010.

But those same programs are also expensive. Doyle said the door-to-door checks alone cost more than $1 million.

"There’s about eight thousand properties in Key West," he said. "Our inspectors try to get to every one of those once a month to six weeks to dump out containers and treat with low toxicity insecticides."

The new technology created by OxiTech could change all that. By sterilizing the males, the gene-altering technology helps minimize the number of new mosquitoes who live through adulthood. 

Doyle said it would cost between $200,000 and $250,000 a year to buy the genetically modified mosquito eggs needed to start the sterilization process.

"If promises are true, then we would have better control for less money," he said.

But getting approval to use the new technology has fallen between the cracks of the U.S. government's regulatory system. It's unclear which federal agency, if any, has jurisdiction over it.

Because of that, Doyle said he could likely go ahead with the program without government approval. But doing so could lead to unknown consequences.

"What potential impacts could there be on the environment or on human health if one of the mosquitoes bit someone?" he asked. "Those are real questions that need to be answered with real facts, and unfortunately we have no one to look at the facts for us."

Luke Alphey, chief scientific officer at Oxitec, said Doyle had nothing to worry about. Regulatory agencies in several other countries, including Brazil and Malaysia, have already tested and approved the gene-modifying technology.

Alphey said a study done in the Cayman Islands showed that the modified mosquitoes did exactly what they were supposed to — reduce local mosquito populations — without any unwanted effects.

But critics of Oxitec are hesitent to support the company's research findings. They say it jumped into field testing without sufficient review and public consultation, according to a New York Times article.

"Even if the harms don’t materialize, this will undermine the credibility and legitimacy of the research enterprise," Lawrence Gostin, professor of international health law at Georgetown University, told the Times.