Are mutant mosquitoes the answer in Key West?

KEY WEST, Florida Tue Jul 24, 2012 12:37pm EDT

1 of 4. Aedes Aegypti mosquito feeding on blood is pictured in this handout photo from Oxitec Ltd. The Florida Keys has for years battled dengue fever, a potentially fatal virus with extreme flu-like symptoms that is spread by the Aedes Aegypti mosquito.

Credit: Reuters/Oxitec Ltd./Handout

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KEY WEST, Florida (Reuters) - When Hadyn Parry, chief executive officer of the British biotechnology company Oxitec Ltd, appeared at a Key West town hall meeting to present his plan to use genetically modified mosquitoes in the fight to eradicate dengue fever, he came up against familiar resistance.

Alarmed local residents at the April meeting raised the specter of their island paradise being turned into an experimental "Jurassic Park" for mutant mosquitoes.

"Have there been studies of what can happen if someone is bit by one of these mosquitoes?" said Key West realtor Mila de Mier. "Are we the subjects, the guinea pigs of this experiment?"

Wary of the potential threat to its vital tourism industry, the Florida Keys Mosquito Control unit spends $1 million a year on eradication efforts and is constantly on the lookout for dengue, a potentially fatal virus with extreme flu-like symptoms that is spread by the Aedes aegypti mosquito.

The prospect of saving taxpayer dollars prompted the Mosquito Control Board to propose implementing Oxitec's GM technology on an experimental basis.

But a group of residents, spearheaded by de Mier, has campaigned vociferously against the use of mutants and persuaded the city commission to reject the Mosquito Control Board's recommendation.

The board does not need city permission to proceed but the mutant mosquito release is on hold waiting for federal approval from the U.S. Food and Drug Administration.

MOSQUITO BIRTH CONTROL

Oxitec's GM technique involves introducing sterile males into the mosquito population so they mate with females thereby reducing the overall birth rate. One female mosquito can lay 70-80 eggs at a time and maybe 500 in its lifetime.

"If we upset the balance so there are more males that are sterile than their fertile equivalent, then the female has more chance of mating with one of ours," Parry told Reuters. "We call it birth control for insects."

The Aedes aegypti mosquitoes are very hard to eradicate, Parry said, noting that they are resistant to chemicals and like to inhabit spaces under homes where aerial spraying cannot reach them.

The Mosquito Control Board uses both helicopters and trucks to spray affected areas, notifying residents to keep pets inside.

Trucks can be heard in the early evening driving through neighborhoods as the powerful truck-bed sprayer releases chemicals. Helicopter spraying is usually used when larger areas of the Florida Keys need control of a mosquito infestation.

This method of control is labor-intensive and costly and involves dumping chemicals into the fragile Keys ecosystem. Oxitec says its solution is cheaper and environmentally more friendly and can be used in a very limited and surgical manner.

Because dengue is carried only by Aedes aegypti mosquito, the threat of infection can be determined easily by field traps. Aedes aegypti also has a very limited range, flying only a few hundred feet during its entire lifetime, so eradication efforts using sterile GM mosquitoes can be narrowed down almost street by street, said Parry.

YEARS OF RESEARCH

Oxitec says its GM solution stems from 10 years of research at the University of Oxford's Department of Zoology, led by Dr Luke Alphey. Successful outdoor trials in Brazil, the Cayman Islands and Malaysia have seen an 80 percent reduction in the Aedes aegypti population, it says.

Oxitec's partners in Brazil, Moscamed, inaugurated a factory in Bahia, Brazil, this month to scale up application of the technology with production of 4 million mosquitoes a week.

The company's strategy is an adaptation of 'sterile insect technique' pioneered after World War Two, which used radiation to sterilize the fruit fly, an agricultural pest. It was later used to eliminate the New World screw worm which affected cattle in the southern United States.

Alphey adapted the technique by replacing radiation bombardment with genetic engineering, said Parry.

Critics worry that eradicating one species of mosquitoes could have unintended consequences on the food chain and ecosystem. They launched an internet petition that has gathered more than 100,000 signatures and sent a letter to Florida Governor Rick Scott asking him to block the experiment.

They also argue that the city has not had a dengue case since 2010 when 67 cases were reported, and the last previous outbreak before that was in 1934.

But the possibility of dengue being spread by travelers from nearby Caribbean islands, where the disease is more common, makes the Keys especially vulnerable, along with the rest of south Florida.

About 20 percent of the homes in Key West have dengue carrying mosquitoes, according to evidence collected in local traps by the local mosquito control teams. In some areas it can get as high as 40 percent or more in the summer rainy season.

MOSQUITO CONTROL PLAN

Michael Doyle, director of the Florida Keys Mosquito Control District, said he has no concerns about Oxitec's GM technology based on the data presented to him, and plans to move forward if and when the FDA gives its approval.

The proposal involves an experiment similar to past releases in the Cayman Islands and Brazil, he said. A test run involving 5,000 to 10,000 males "to see how far they would fly" would be followed by a larger release "of one million or more in a small area of Key West to test if the releases significantly reduced the wild Aedes aegypti population."

If that was successful, millions more would be released throughout Key West.

It is not clear when approval might be granted, Doyle said. The FDA does not comment on individual permit applications, but an FDA representative told Reuters that no GM mosquitoes would be released "without appropriate federal regulatory oversight."

De Mier said she is not totally opposed to the idea, but wanted more information first.

"They're trying to scare us into acceptance because of dengue fever," she said. "We're more concerned about what they are not telling us. We're concerned about the possible environmental impact. Hurt our ecosystem, and that hurts our tourism and affects all of us."

De Mier said she and other residents like the idea of no more early morning helicopters spraying their neighborhood, so they would like to see an alternative happen.

"At the city commission meeting I got laughs and what not when I mentioned my fear of a Jurassic Park event happening in the Keys," she said. "But I also got everyone's attention and maybe made a few of them think about what could happen."

(Addtional reporting by David Adams; editing by Mohammad Zargham)

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