Going after blood. Aedes agepti mosquitoes can breed in just a cap full of water and are the primary transporters of the dengue virus. [Image credit: James Gathany]
On Aug. 30, 2009, Mila De Mier, a realtor from Key West, Fla., stopped at a Staples in Washington, D.C. and printed all 3,766 pages of a petition intended for the Food and Drug Administration. At noon she was in the FDA’s Dockets Management offices, handing over the document and its attached 112,000 signatures. De Mier had travelled from Key West to the nation’s capitol and didn’t want her work to get lost in the shuffle.
Two weeks later, she called the FDA to check on the petition’s status. De Mier was told that its label, “Say NO to genetically modified mosquitoes,” made her package look suspicious. It was sent to security because they worried it actually contained genetically modified mosquitoes. When it was cleared, security shredded the entire document. So De Mier reprinted all 3,766 pages, travelled back to D.C. and submitted the whole thing again.
De Mier is worried about a plan — supported by the Florida Keys Mosquito Control District — to use genetically modified male mosquitoes to decrease population of Aedes aegypti mosquitoes responsible for transmitting dengue fever.
The virus that causes dengue fever is a hitchhiker that makes its way from humans to mosquitoes and back to humans again. The cycle is sustained by the Aedes aegypti female, who feeds on human blood to provide nutrients for her offspring. Her unsuspecting bite, if ridden with the dengue virus, results in headaches, aching joints and a rash. Dengue had not been seen in Key West since 1934. But between 2009 and 2011, there were 92 cases of the infectious disease, reminding residents that life in the tropics can come with a bite.
Currently, there is no dengue in the Florida Keys, but that war wasn’t easy to win. The outbreak in 2009 prompted health officials to use everything in their arsenal. The inspectors used helicopters to spray the island with an ecologically-friendly mosquito-killing liquid, marched door-to-door overturning open containers and handed out fliers and DVDs teaching residents how to prevent their homes from becoming a mosquito breeding haven.
“I don’t think anyone else in the world did all that we did,” says Coleen Fitzsimmons, a biologist at the Florida Keys Mosquito Control District. She credits the fact that there is no dengue in the Keys to this extensive and time consuming effort but says the number of Aedes aegypti mosquitoes flying around is still as high as it was in 2009, and that could result in a whole new outbreak. Even though the District killed the dengue-carrying population, Aedes aegypti mosquitoes continually migrate to the Keys, and this keeps the population strong.
Fitzsimmons wants to plan ahead and lean less on a chemical approach to fighting dengue: “With the Environmental Protection Agency limiting the amount of products we can use to kill mosquitoes, we are continuously working with a limited number of materials, and mosquitoes become resistant to the products.” Luke Alphey, co-founder of the Oxitec research company, has invented a method providing just the alternative Fitzsimmons and her colleagues are seeking. His idea is to prevent dengue fever by collapsing the Aedes aegypti population of mosquitoes that spread it. “It’s been called birth control for mosquitoes,” says Alphey.
Without any current cases of dengue, De Mier believes it more responsible to wait for peer-reviewed literature before implementing the Oxitec technology. “I’d like to make one thing clear,” says De Mier. “I am not anti-science.” She recalls that in 2010, when the technology was first presented to the residents, it was called “sterile male release,” and nothing was said about the insects being genetically modified. De Mier thinks that Oxitec is interested in testing its product in the U.S. to establish credibility, allowing them to market their product to even more countries.
De Mier and Key West residents aren’t the only ones expressing doubt. Phil Lounibos, an ecologist and mosquito behavior expert at the University of Florida in Gainesville, worries that there isn’t enough evidence to prove that they will stop or prevent dengue from resurfacing. “There is only a loose correlation between a reduced number of mosquitoes and a reduced number of dengue cases,” he adds. His reasoning points to Singapore, a country in which the government heavily regulates mosquito control to keep the Aedes aegypti population low. Despite low numbers of the mosquitoes, cases of dengue continue to pop up in Singapore.
Oxitec’s genetically modified mosquitoes have already been tested in Malaysia, Brazil and the Cayman Islands. “We are extremely careful about considerations concerning human health and well-being,” says Alphey, “and even if we weren’t, the regulators would make us consider these things.” He explains that the tool is species-specific — only affecting the Aedes aegypti population — making it “quite eco-friendly.” It is the kind of tool useful for a farmer getting rid of one pest without affecting any other organisms beneficial to his crop. Results of Oxitec’s trials have been published in Nature Biotechnology.
For Lounibos, the data from the previous research suggests that social variables are also involved. He says, “The results from experimental trials that Oxitec completed in Malaysia and the Cayman Islands are not particularly strong, although that may be related to a lack of community involvement at these sites.” On the other hand, Lounibos thinks Oxitec’s recent success in Brazil is the result of a stronger effort to engage that community. He recognizes that Oxitec faces a huge challenge in Florida where “resistance to [genetic modification] is pretty strong.”
The Florida Keys Mosquito Control District hired Michael Cobb, a social scientist at North Carolina State, to survey the public opinion. He was struck by the success of De Mier’s petition campaign, noting that, “If there are only 20,000 or so residents in Key West, Florida, why did so many persons, supposedly outside of the community, seem concerned with the cause?” Cobb’s survey of 800 people showed that while 61 percent of the participants supported the District’s use of genetically modified mosquitoes, only 18 percent opposed it, and 21 percent felt neutral toward the matter.
Perhaps public opinion cannot be captured by a singular petition or survey. Tamara Laine, a film documentarian from New Jersey, travelled to Key West in 2011 hoping to capture both sides of the story. “It’s very polarizing,” she says. “It feels like people are either for it because they think it is perfect technology, or they are extremely against it because they think there are unknown repercussions.”
Gregory Lanzaro, a vector biologist at University of California, Davis thinks opposition to using genetically modified mosquitoes comes from a general distrust of having scientists tinker around with nature. He believes the Oxitec method is “a good technology” than can improve human health, and reduce the impact insecticides can have on the environment. He says the specificity of the tool is what makes it so harmless. “This is a system that is incorporated into a genome, the only way it will move from one organism to another is through mating and you aren’t going to get a mosquito mating with a grasshopper.”
Scott Weaver, a virologist at the University of Texas Medical Branch in Galveston, also believes that Oxitec’s technology is worthwhile. He says, “One of the main problems with dengue research is there are no animals, even non-human primates or monkeys that respond the way humans do to the virus. This makes it very difficult to test vaccines.” A recent dengue vaccine study in Thailand showed promising results in animals but in the human testing trials proved ineffective for providing protection against a strain of the disease. Weaver cautions that simply reducing the number of mosquitoes is not enough. He thinks emphasis should be placed on choosing the right release site so that the mosquitoes that are actually carrying the viruses are killed.
Mila De Mier’s petition sits in a government office in D.C. — a neat, hand-delivered pile of opposition. Beside it might sit the Florida Keys Mosquito Control District’s request, sent in 2011, to release the genetically modified Aedes aegypti mosquitoes, a push to explore new science. The two together — an interface of science and society.