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Genetically Modified Mosquitoes​ Might Save Us From Dengue Fever

The release of the Frankenbugs may actually be one of the few human attempts to play god that won't blow up in our faces.
January 26, 2015, 9:09pm

Photo via Flickr user Wm Jas

According to an Associated Press story published yesterday, the U.S. Food and Drug Administration is currently debating a plan to control insect-born disease on the 44 inhabited islands in the Florida Keys by releasing millions of genetically modified mosquitos into the local wilds. These discussions are only the latest developments in a project that's been stalled by years of regulatory heel-dragging and protest. But we can only hope they result in the release of the Frankenbugs, which may actually be one of the few human attempts to play god that won't blow up in our faces—fingers crossed.

Officials hope to use the mosquitoes to control potential outbreaks of dengue fever. Spreading out of Southeast Asia in the 1950s, this mosquito-born disease causes flu-like symptoms as well as a rash, mild bleeding, and aches and pains so severe that it's earned the nickname "bone-break fever." Although not always a death sentence, the disease and secondary infections can prove fatal.


Dengue is not the only mosquito-born disease. Of the few hundred species that feast on man blood, several carry everything from chikungunya to malaria to lymphatic filariasis, Rift Valley and West Nile fevers, and various forms of encephalitis. The Aedes aegypti species that transmits dengue is also a vector for yellow fever. But dengue, for which there is no vaccine, is of special concern as over the past half-decade it has increased in prevalence thirty-fold, now infecting up to 100 million and killing at least 20,000 a year. The mosquitoes carrying the disease have started adapting to resist insecticides and changing their feeding habits to avoid protective nets.

As of 2009 dengue, thought all but eradicated, has returned to the Keys with a vengeance, infecting nearly 100 people by 2010 (the largest outbreak since 1934) and creating a lingering health threat that many fear will scare off the tourists upon whom the local economy depends.

Rather than try to control this problem with poison, Oxitec, a British company created by a few dozen University of Oxford Scientists in 2002, drew the attention of Keys officials with the offer to cheaply and effectively decimate dengue-carrying populations through genetic engineering.

In a lab, the scientists implant a new gene into non-biting male mosquitoes (only the females feast on our flesh) that causes the production of a protein that will kill them without constant treatment in the lab. These males then mate with females (who produce one litter of eggs in a lifetime) in the wild and pass along their self-destruct genes to the offspring. So long as the males strong enough to outbreed their competitors are constantly released into the wilderness, they can collapse local dengue-carrier populations in weeks. Then, as they die of protein buildup, their aberrant genes die with them, leaving no permanent changes to wider Aedes aegypti populations—all for far less than the cost of pesticides. They can even track the spread of their mutant progeny thanks to another spliced gene, which gives the monsters a fluorescent glow.


"In the target area we could suppress the population [of carriers] even to zero levels," Oxitec Chief Science Officer Dr. Luke Alphey told CNN last summer. "I hope that [this technique] will become a major part of control of major pest insects. If we could reduce, even in some countries, the burden of diseases like dengue… that would be fantastic. We're just at the dawn of genetic control."

Officials in the Keys, tired of spending $1 million a year (a tenth of their pest control budget) on iffy pesticides, watching residents ignore best-practice precautions, and tempted by the $200,000 to $400,000 per year price tag offered by Oxitec, started exploring the release of genetically modified mosquitoes all the way back in 2009. They first announced their desire to release the freak bugs and submitted plans for test dispersions for USFDA review and approval in 2012.

"The science of it, I think, looks fine," Michael Doyle of the Florida Keys Mosquito Control District told the Associated Press that year. "It's straight from setting up experiments and collecting data."

"This is safe, and it's been proven," he reiterated to Al Jazeera in 2013. "In terms of allergenicity and health issues, the FDA is looking into that, so I put it in their hands."

Locals are not nearly as hyped as Doyle about releasing the bugs of Dr. Moreau into their backyards, passing an ordinance requesting further testing on the technique before its use and creating a petition to block moves to advance the project. Their concerns, shared by many environmental activists, involve the risks inherent in introducing a modified organism into a complex and ever-changing environment. While in the lab the mosquitos appear safe, many fear unintended consequences. Consequences that could include creating an environmental gap that welcomes in nastier mosquito species, forcing dengue to evolve to be even heartier, or finding that the genetic modification does not kill all the mosquitoes' progeny and that humans are allergic to the resistant spawns' bites.


Local and international environmentalists also argue that Oxitec has never produced any good data on or invited any high quality independent review of their technique by respected scholars. (Emails and phone calls to Oxitec have not been returned. We will update when and if they respond.)

"The reduction figures from their trials cannot be verified," Dr. Helen Wallace of Greenwatch UK told CNN last year, "and they have not proved a positive impact on disease."

Yet despite all the talk about how unprecedented and risky releasing genetically modified insects in America would be, there's actually a good amount of precedent and study on this issue in the US and abroad—including reviews of Oxitec from outsiders—spanning well over a decade.

The US, the first nation to mess with mosquito genetics in 1998 and learn to pass on modifications to their progeny in 2000, actually came pretty close to releasing pink bullworms with tweaked DNA in October 2001. We released a batch on a fenced-off patch of Arizona cotton fields that fall, but never took the tests further because we found it was easier at the time to sterilize bugs using radiation—a technique in use since WWII using logic similar to Oxitec's process, but which could never sterilize mosquitoes without also making them too weak to mate.

Since then, scientists have pursued pest control and diseases via gene splicing vigorously, breeding malaria parasite-resistant mosquitoes or variations of malaria-carrier species that produce only non-biting male offspring or progeny that cannot fly, to name a few projects. Most of the feedback from these tests suggests the process is relatively safe and highly effective.


Oxitec has been trying to prove that in the field across the world for the past few years. In 2010, they launched their first tests, releasing millions of mosquitoes into the wild in target regions in the Cayman Islands and Malaysia. As of 2014, they had released over 70 million modified mosquitoes, most recently in Panama, with reduction rates of at least 80 percent and no clear adverse effects on the environment or failure of modified bugs to die to this point.

Their operations in Brazil, which started as tests in 2011 but evolved into a commercial program (the first state-sanctioned mass dispersion of modified insects in the world) in 2014, have proven popular with locals and received praise and verification from local, independent researchers.

Much of the doubt about Oxitec's spliced skeeters in the Keys and beyond stems not so much from the lack of promise and evidence behind their technique, but from the company's track record of community engagement. Despite the success of their first test in the Caymans, the company earned widespread condemnation for failing to inform the locals of their bugs' release until after the fact. That's actually a huge no-no in the accepted code of scientific ethics for work involving genetic modifications. So a similar silence in the Keys understandably irked locals.

Many are especially upset by the fact that the path Oxitec has taken (seeking FDA approval to test their bugs) will allow them to release the insects without local consent—a really poor procedural message for a company with a bad track record to send to a population that's on edge.

A good part of the local resistance also stems from a knee-jerk resistance to the introduction of anything that's been genetically modified. That sort of intransigence is hard to overcome—even by pointing out that, because the Aedes aegypti is actually an invasive species with no real unique and irreplaceable role in the local environment, its eradication by a spliced bug whose mutation will not effect any other species and will vanish after it dies upon completing its task, might actually be an environmental good (especially when compared to annual pesticide dumps).

Resistance to the monster mosquitoes seems to be waning though. Signatures on the petition fell off after 2012, and in 2013 an independent survey commissioned by Doyle's office found that over half of Keys residents supported using the lab-bred mosquitoes to fight dengue. As the science and support behind the Oxitec technique becomes clearer, especially given Brazil's endorsement and experience over the past year, it seems more and more likely that the FDA will finally approve the release of these flying freaks. True, things could go very Syfy channel at the last minute. But for now that seems like a(n infinitely small) risk worth taking.

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