I heard an interesting story on the radio the other day while driving somewhere between Lafayette and Winamac, Indiana. NPR reported that a UK company called Oxitec had genetically modified a line of Aedes aegypti mosquitoes and released them into the wild. These are the pests responsible for the zika virus outbreak currently ravaging Central and South America, Mexico, a few western African countries, and numerous tropical islands. A few cases have been reported in the United States, but those are generally travelers returning from affected areas.
Oxitec is currently running a trial in Brazil, a country severely impacted by the Zika virus. The modified mosquitoes are engineered to need the antibiotic tetracycline to develop beyond adolescence. Male mosquitoes in the lab receive the antibiotic so they can reach adulthood and then are released into the wild. They breed with wild female mosquitoes, but the larvae, unable to access tetracycline, die before reaching adulthood. This could be important because the Aedes aegypti mosquitoes are also the carrier for dengue fever and chikungunya. Oxitec’s trial in Piracicaba, a city northwest of Sao Paolo, has reduced wild mosquito larvae by 82% compared to similar areas with unmodified populations. Oxitec is now expanding its trial cover a larger area in Brazil. It recently requested permission from the FDA to release the modified mosquitoes in the Florida Keys, another hot, humid area susceptible to mosquito-borne diseases.
As I've written before, other companies are developing genetically engineered mosquitoes that cannot carry malaria, but the Oxitec mosquitoes are the first to be released into the wild. In light of the public concern over the zika virus, it seems Oxitec’s breakthrough should be a welcome development. But genetically modified organisms are never without their critics. Various environmental groups have expressed concerns about releasing these insects into wild populations. Activists warn that the reduction of the Aedes aegypti mosquito could create a void into which other pests or insects could flow and could impact animals higher in the food chain like bats and spiders. These are real concerns that must be considered, but they should be weighed against the potential human damage caused by these mosquito-borne illnesses.
I'm interested to see where this goes. The zika virus is a real, immediate challenge for the countries affected by it. Dengue fever is another public health nightmare. There is no cure and no vaccine. In the past, the primary method of managing dengue fever has been through chemical mosquito control. The use of modified mosquitoes could help eliminate the responsible mosquitoes at a lower cost and without using as many chemicals, potentially saving a significant amount of money. I’m sure we’ll hear quite a bit more about this in the weeks and months to come as the data from the Oxitec trials is reviewed by scientists the world over. For now, hang on to that bug spray.