Before Zika strikes, county considers mutant mosquitoes
The Bayou City’s teeming mosquito population spawns in dark, wet nooks and carries a slew of deadly tropical diseases that could ravage the region.
So Houston is pondering a sneak attack, something akin to a Trojan Horse. Harris County officials are negotiating with a British biotech company, Oxitec, to create and release mutant mosquitoes genetically engineered so that after they’re set loose in the wild, offspring die, and the mosquito population dwindles.
Deric Nimmo, principal scientist at Oxitec, said it is a paradigm shift — “the release of mosquitoes to control mosquitoes.”
If an agreement is finalized, Harris County could become one of the first locations in the United States to use the mosquitoes, going far beyond the chemicals and public-awareness campaigns the county has long relied upon.
However, the proposition is controversial: Experts say the method is
unproven and that if one mosquito vanishes, another could take its place and carry the same diseases. A proposed trial in a Florida Keys suburb never got off the ground amid residents’ concerns about genetic engineering.
Phil Lounibos, a professor at the University of Florida who studies mosquitoes and the diseases they carry, sees promise in Oxitec’s approach but has reservations. He said the question remains whether it can produce the public health benefits the company promises.
Oxitec spun off from Oxford University 15 years ago to commercialize proprietary strains of insects, namely mosquitoes. The hope is that they can help reduce populations of Aedes aegypti mosquitoes, which carry the Zika virus, dengue fever and chikungunya, among other deadly illnesses. The mosquitoes are common in the Houston region.
Oxitec inserts a “selflimiting gene” into a male mosquito and releases several into the environment. Those mosquitoes then mate with females — Oxitec claims their special males out-compete normal males — and the resulting offspring die before they become adults. Over time, the overall population of the Aedes mosquito declines.
Male mosquitoes do not bite and can’t spread disease.
Still in trial phase
The company has conducted field trials in Brazil, Panama and the Cayman Islands and says it has reduced the Aedes mosquito populations by up to 90 percent in each location.
“It looks like we’re going
to do or plan to do some sort of trial initially to test out the system,” Nimmo said.
Oxitec has yet to try out its technology in the U.S.
In August, the Food and Drug Administration gave the green light to a proposed field trial in Key Haven, a Florida Keys suburb, finding that it would have no significant impacts on human health, animal health or the environment. Monroe County residents voted in a nonbinding resolution in favor of working with Oxitec. But Key Haven residents voted nearly 2-to-1 in November against the trial.
The company is looking for another location in Monroe County, Nimmo said. According to the FDA, even after a field trial, Oxitec would still have
to demonstrate that its product is safe and effective before it can be marketed commercially.
Monroe County encompasses the Keys, where dengue fever was first found to be locally transmitted after decades of absence in the U.S.
“I really hope that we’re able to get permission to go ahead this year,” Nimmo said. “We’re ready.”
According to the FDA, if Oxitec wanted to conduct a field trial in Harris County, the company would have to submit an environmental assessment to the agency.
Another complication: Regulatory authority over Oxitec’s mosquitoes would then likely shift to the Environmental Protection Agency.
Mustapha Debboun, director of the Harris County Mosquito Control Division, said working with Oxitec could provide another tool in the fight against Zika and other mosquito-borne illnesses.
“We’re not abandoning the tried-and-true” approaches, said Harris County Precinct 4 Commissioner Jack Cagle, who has been leading the efforts. “We’re willing to see — What can we add to the tried-and-true that can make this better, especially considering that the triedand-true has some flaws?”
Year-round threat
Unseasonably warm weather has prompted the division to boost staff during winter months. It has seven investigators now, compared to four, and two additional public education staffers, Debboun said.
In August, officials nearly doubled the number of Aedes mosquito traps across the county to 134. Harris County also continues to partner with Microsoft to develop hightech traps that will sense and nab only certain species of mosquitoes, like those that carry Zika or dengue, and eventually hopes to utilize drones to find and target hot spots.
After receiving a federal grant, the county hopes by May to start research on whether mosquitoes in the region that could carry Zika are developing resistance to certain pesticides. The county also will use that money to test more mosquitoes for Zika, Debboun said.
“The crucial part of all this is to find out if the mosquito has the virus in it,” he said.
Debboun cautioned that while mosquito season is traditionally thought of as between June and October, people can contract mosquito-borne diseases all year, especially during a year like this one with unseasonably warm temperatures.
In February, he said, the county found evidence of West Nile virus circulating in mosquitoes. That marked the earliest month on record.
And though there have been no documented cases of Zika in the Houston region yet, some parts of the area are particularly vulnerable, experts say.
That’s one reason why surveillance for mosquito-borne diseases doesn’t stop, said Salvador Rico, inspection supervisor for the Harris County Mosquito Control Division.
‘Do the best we can’
In addition to combing Harris County for breeding grounds, Rico’s team responds to complaints from residents. During peak mosquito season last summer, the team handled up to 20 complaints a day from all over the county.
On a recent Friday, Rico responded to a complaint at a home in Idylwood. He walked around the house, looking at flower pots and buckets, emptying water from several where it had built up. He looked for tears in the screen where mosquitoes could get into the home.
He didn’t find any obvious problems, but if there had been, he would have treated the sites with chemicals to kill the bugs. Inspectors also test samples for a range of viruses to see if a more concerted chemical campaign is necessary.
“It’s impossible for us to be everywhere,” he said. “We try to do the best we can.”