Millions of genetically modified mosquitoes could be released in the Florida Keys if British researchers win approval to use the bugs against two extremely painful viral diseases.
Never before have insects with modified DNA come so close to being set loose in a residential U.S. neighborhood.
"This is essentially using a mosquito as a drug to cure disease," said Michael Doyle, executive director of the Florida Keys Mosquito Control District, which is waiting to hear if the Food and Drug Administration will allow the experiment.
Dengue and chikungunya are growing threats in the U.S., but some people
are more frightened at the thought of being bitten by a genetically
modified organism. More than 130,000 people signed a Change.org petition
against the experiment.
Even potential boosters say those responsible must do more to show that
benefits outweigh the risks of breeding modified insects that could bite
people.
"I think the science is fine, they definitely can kill mosquitoes, but
the GMO issue still sticks as something of a thorny issue for the
general public," said Phil Lounibos, who studies mosquito control at the
Florida Medical Entomology Laboratory.
Mosquito controllers say they're running out of options. With climate
change and globalization spreading tropical diseases farther from the
equator, storm winds, cargo ships and humans carry these viruses to
places like Key West, the southernmost U.S. city.
There are no vaccines or cures for dengue, known as "break-bone fever,"
or chikungunya, so painful it causes contortions. U.S. cases remain
rare.
Insecticides are sprayed year-round in the Keys' charming and crowded
neighborhoods. But Aedes aegypti, whose biting females spread these
diseases, have evolved to resist four of the six insecticides used to
kill them.
Enter Oxitec, a British biotech firm that patented a method of breeding Aedes aegypti with fragments of genes from the herpes simplex virus and E. coli
bacteria as well as coral and cabbage. This synthetic DNA is commonly
used in laboratory science and is thought to pose no significant risks
to other animals, but it kills mosquito larvae.
Oxitec's lab workers manually remove modified females, aiming to release
only males, which don't bite for blood like females do. The modified
males then mate with wild females whose offspring die, reducing the
population.
Oxitec has built a breeding lab in Marathon and hopes to release its mosquitoes in a Key West neighborhood this spring.
FDA spokeswoman Theresa Eisenman said no field tests will be allowed
until the agency has "thoroughly reviewed all the necessary
information."
Company spokeswoman Chris Creese said the test will be similar in size to Oxitec's 2012 experiment in the Cayman Islands,
where 3.3 million modified mosquitoes were released over six months,
suppressing 96 percent of the targeted bugs. Oxitec says a later test in
Brazil also was successful, and both countries now want larger-scale projects.
But critics accused Oxitec of failing to obtain informed consent in the
Caymans, saying residents weren't told they could be bitten by a few
stray females overlooked in the lab.
Instead, Oxitec said only non-biting males would be released, and that
even if humans were somehow bitten, no genetically modified DNA would
enter their bloodstream.
Neither claim is entirely true, outside observers say.
"I'm on their side, in that consequences are highly unlikely. But to say
that there's no genetically modified DNA that might get into a human,
that's kind of a gray matter," said Lounibos.
Creese says Oxitec has now released 70 million of its mosquitoes in
several countries and received no reports of human impacts caused by
bites or from the synthetic DNA, despite regulatory oversight that
encourages people to report any problems. "We are confident of the
safety of our mosquito, as there's no mechanism for any adverse effect
on human health. The proteins are non-toxic and non-allergenic," she
said.
Oxitec should still do more to show that the synthetic DNA causes no
harm when transferred into humans by its mosquitoes, said Guy Reeves, a
molecular geneticist at Germany's Max Planck Institute.
Key West resident Marilyn Smith wasn't persuaded after Oxitec's
presentation at a public meeting. She says neither disease has had a
major outbreak yet in Florida, so "why are we being used as the
experiment, the guinea pigs, just to see what happens?"
