Monday, July 30, 2012

Eradicating Dengue Through Genetically Motified Mosquitoes?

More on mosquitoes - this time in terms of fighting dengue fever, for which we have no treatments nor cures to fight this disease, and effects at least 50 million people a year.

After posting recently about malaria and mosquitoes, (see "Ending Malaria") Micheal Specter's article caught my attention, too.  Especially the ethical ramifications of entering a genetically modified species to fight a deadly disease verses the ramifications of using insecticide. I don't have any answers, but found the article well worth thinking through.

Micheal Specter writes for the New Yorker magazine. In the current edition (July 9, 2012) he writes an article about dengue fever, "The Mosquito Solution." The online article is for members only (although the link gives an abstract), so I'll give a very brief summery and direct you to a newsstand, library, or a friend to read the article. He does provide a commentary on what has occurred sense at "Mosquitos and Nimbyism" (July 11, 2012) along with a summery of his original article. He has also been interviewed on NPR's "The Takeaway".

Dengue fever is transmitted through the bite of the female Aedes aegypti mosquitoes. Aedes aegypti are a subspecies of mosquito that came to the America's about 200 years ago on the slave ships out of Africa. Biologically speaking, Aedes aegypti is a new comer that hasn't established a biological importance in the food chain (there are other mosquito subspecies in the Americas, and if the Aedes aegypti disappeared, there is extremely unlikely to be ecological disaster across the ecosystem).

Enter the British firm Oxitec. Oxitec has developed a way to modify the male Aedes aegypti so that none of their offspring survive (the article gives more details about how this works). The basic idea is simple, the genetically modified male Aedes aegypti mates with the wild female. The female lays eggs, the eggs hatch, but before the larvae can fly, the genetic mutation takes over, killing them all.

Enter Brazil. Historically, Brazil has had large outbreaks of dengue fever. There is not a family or even a household who has not felt the effects of dengue fever. Oxitec set up a research site in Brazil to test their genetically modified male Aedes aegypti. People were thrilled. The Oxitec mosquitoes were cheaper than using insecticides, the government was thrilled. And it seems to be working.

Enter Key West. Key West had a dengue fever outbreak in 2009 in which less than a 100 people were effected. Currently, Key West is trying to eradicate the Aedes aegypti (and other mosquitoes) through insecticides. The mosquito control officials would love to try Oxitec's genetically modified mosquitoes. In part, this program would cost less than the insecticides they are currently using. The mosquito control officials also think it is more "green" in that it only effects the Aedes aegypti rather than everything. The Key West citizens are not so certain: "We don't want to be guinea pigs or lab rats!"

So, while Brazil is building a factory to produce genetically modified male Aedes Aegypti, in Key West nearly a hundred thousand people have signed a petition to prevent Oxitec from even a small experiment.

To conclude, here are some facts that Michael Specter presents:
There are some known facts, however: male mosquitoes don’t bite; they live less than two weeks and travel, on average, only seventy-five yards; Aedes aegypti mate with no other species, and right now, the region is trying to eliminate them anyway, but with chemicals—which are more expensive than Oxitec mosquitoes, and far from environmentally benign. In addition, as an invasive species that arrived on slave ships in the Americas little more than two hundred years ago, Aedes plays no significant role in the food chain. There is, of course, another theoretical catastrophe to consider: a dengue epidemic in Key West. So far the city has largely been spared, but the region, as Oxitec’s chief scientist Luke Alphey told me when I spoke with him for my article, is “living in a sea of dengue.”*

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