04 January 2013

Taking Down Malaria and Dengue with Genetically Modified Mosquitoes Sparks Debate

Hayden Parry is a scientist who is developing genetically modified male mosquitoes who are as a way to reduce the number of female mosquitoes capable of carrying malaria and dengue. His TED talk sets up the problem of mosquito control and the deadly impacts of malaria and dengue in the global south. The development of the sterile male mosquitoes at Oxford University has been tested in the Caymen Islands, Malaysia and Brazil.
And what's the result? Well, the result has been very good. In about four months of release, we've brought that population of mosquitos — in most cases we're dealing with villages here of about 2,000, 3,000 people, that sort of size, starting small — we've taken that mosquito population down by about 85 percent in about four months. And in fact, the numbers after that get, those get very difficult to count, because there just aren't any left. So that's been what we've seen in Cayman, it's been what we've seen in Brazil in those trials.
A long post in the PLOS public health blog by Viet Le discusses the possibility of implementing Parry's idea and suggests an alternative. Le, as does Parry in his talk, points out that people are resistant to the idea of introducing genetically modified mosquitoes much in the same way that they are in regards to genetically modified crops. "Environmentalists are uneasy about the ecological consequences of both introducing GM mosquitoes and eradicating entire mosquito populations (keep in mind, both A. aegypti and A. albopictus are species not native to the US)," writes Le. "And as one Key West resident quoted in the New Yorker bluntly put it, “You are not going to cram something down my throat that I don’t want. I am no guinea pig.”"


Parry concludes his talk by addressing concerns about genetic modifications to mosquitoes by illustrating how it is in fact different than GM crops.
We have G.M. crops, we have pharmaceuticals, we have new vaccines, all using roughly the same technology, but with very different outcomes. And I'm in favor, actually. Of course I am. I'm in favor of particularly where the older technologies don't work well or have become unacceptable. And although the techniques are similar, the outcomes are very, very different, and if you take our approach, for example, and you compare it to, say, G.M. crops, both techniques are trying to produce a massive benefit. Both have a side benefit,which is that we reduce pesticide use tremendously. But whereas a G.M. crop is trying to protect the plant, for example, and give it an advantage, what we're actually doing is taking the mosquito and giving it the biggest disadvantage it can possibly have, rendering it unable to reproduce effectively. So for the mosquito, it's a dead end.

Chris Sweeney beat the New Yorker to the punch when he reported on the use of genetically modified mosquitoes to address the emerging problem n Florida's Big Pine Key for the Miami New Times. At the time, many of the concerns stemmed from a lack of evidence as to whether introducing sterile male mosquitoes would lead to a decrease in the female population and the incidence of dengue. Sweeney wrote:
Few peer-reviewed scientific journal articles have been published demonstrating the effectiveness and safety of genetically modified mosquitoes when released in the wild. Articles that have been published include an Oxitec staffer among the authors, and there are no independent, third-party studies under way. 
Opponents, including the Conchs at the real estate office, hone in on the Cayman experiment because it's the furthest along. About four years ago, Oxitec and the Cayman mosquito control authority collaborated on an experiment without providing much information to the scientific community or local residents about the release. In November 2010, Oxitec took the stage at a medical conference in Atlanta and delivered findings from what was the first field trial of genetically modified mosquitoes. Some researchers in the crowd were surprised that, all of a sudden, a British biotech company was announcing it had released its mutant mosquitoes in the wild without consulting the larger research community. 
In response, the prestigious journal Science published a news article that took a biting tone as it questioned whether the company had rushed to release its mosquitoes in the Cayman Islands, and suggested that the hastiness and off-the-radar style of the experiment had strained Oxitec's ties with funders, including the Bill & Melinda Gates Foundation. This past January, researchers at Germany's Max Planck Institute published a paper in the journal PLoS Neglected Tropical Diseases implying that Oxitec exploited a weak regulatory environment in the Cayman Islands to do the experiment with minimal oversight and little effort to inform the locals that millions of genetically modified organisms were being let loose in their back yard.
Environmental group Friends of the Earth, one of Oxitech's harsher critics, says the company has not "been open and honest with the local communities about the possible risks its technology pose." Helen Wallace of GeneWatch UK took that sentiment a step further when she said in a statement that Oxitec's Cayman experiment shows that the "British scientific establishment is acting like the last bastion of colonialism, using an overseas territory as a private lab." 
In addition to these transparency complaints, opponents fret over a few lab-based studies showing that 3 percent of the Oxitec mosquitoes survived into adulthood despite possessing the self-destruct gene. Oxitec CEO Hadyn Parry tells New Times that this hasn't happened when they're released in the wild, nor is it likely that such mosquitoes can live long enough to transmit diseases. As for Oxitec's opaqueness, Parry says the company never denies an interview and welcomes reporters into its laboratories and has even shared confidential data with activist groups to quell further uproar. 
The results from the Grand Cayman study were made available in early September. The trial was successful in suppressing the incidence of dengue by 80%, said the press release. "We believe our approach can be integrated into many existing vector control programmes and we look forward to working with communities around the world to help combat mosquitoes that spread disease," said Parry in the release. Parry told Sweeney that he hopes to publish the findings in a peer reviewed journal this coming year.

Debates over whether to employ the sterile male mosquitoes in Florida continue. An additional hurdle to a US trial is the FDA who has yet to approve the use of the genetically modified mosquito. Meanwhile, residents are more than happy to see trials continue in other countries.

"Why the rush here?" said Key West resident Joel Biddle, who caught dengue in 2009, to the AP. "We already have test cases in the world where we can watch what is happening and make the best studies, because wouldn't it be wonderful if we could find out how it can be fail-safe — which it is not right now. It's an open Pandora's box."

Permissions