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Swarms of Genetically-Modified Mosquitoes Will Take a Bite Out of Dengue Fever

“It is like a live insecticide.”

by Ben Richmond
Apr 12 2014, 1:00pm
Image: Wikimedia Commons

In order to fight dengue fever, which is spread by Aedes aegypti mosquitoes, counterforces of genetically-modified mosquitoes are being released in unprecedented numbers in Jacobina, Brazil.


The mosquitoes are all non-biting males that have been modified to carry two genes that makes them and their progeny dependent on the antibiotic tetracycline, the absence of which in the wild will prevent the next generation from reproducing.

“It is like a live insecticide,” Aldo Malavasi, the president of the Brazilian company Moscamed that’s raising and testing the GM mosquitoes in Jacobina, told The Global Post. The other newly-added gene is a marker that shows up on a special light so the spread of the GM mosquitoes can be monitored.

So sure: mosquitoes, chemical failsafes, and a lab-grown species separated out by gender. The comparisons to Jurassic Park stop there, but it's good to get these things out of the way.

The dengue virus has been a big problem in Brazil and around the world. Last year the country reported 1.4 million cases of the disease, for which no vaccine exists, and worldwide, cases of dengue have experienced a 30-fold jump since the 1960s. It infects an estimated 390 million people per year across the globe, and in its most severe form, dengue haemorrhagic fever can lead to shock, acute pain, coma, and death.

Obviously there are concerns about releasing a genetically-modified animal into the wild. “They are even harder to recall than plants are if anything goes wrong,” Helen Wallace, director of GeneWatch, said.

But the initial trials of fighting mosquitos with GM mosquitos thus far have been positive. After a series of contained evaluations, GM mosquitoes were first released into the great Brazilian outdoors in the February of 2011. In the December of that year, Dr. Margareth Capurro of the University of Sao Paulo lead another suppression trial that gave more evidence that genetic modification was working where mosquito nets and pesticides weren't.

“When we started the trial we were seeing Aedes aegypti in about half of the traps we set in and around people’s homes. Now we see hardly any,” Capurro said in 2012. “Comparing the area of release to the adjacent area where no releases were made, we have reduced the population of Aedes aegypti by 85 percent. We are very excited by the result”

There's pressure on public health officials to contain dengue quickly, as the virus is endemic to three of the 12 World Cup cities, which will attract visitors from across the globe. While dengue can't spread human-to-human, the growth of international travel has been a boon for the virus, as people get bit, and carry the virus home, where it can be spread by other vectors, like a newly arrived East-Coast resident, the Asian tiger mosquito .

“Most dengue is moved around by people not mosquitoes,” Phil Lounibos, an expert on insect ecology and behavior at the University of Florida, said. “Even in places with good mosquito control, they can’t control dengue because so many infected people are walking around and just a few mosquitoes will maintain endemic dengue.”

It's actually the forces of globalization that brought the Aedes aegypti from its native Africa to Brazil, which is why researchers want to target it in particular. By changing the gene of a single species, the scientists hope to leave the hundreds of thousands of endemic mosquitoes that are part of the South American ecosystem alone. And, naturally, to keep people from dying.

Front page image: Flickr/Sanofi Pasteur