PIRACICABA, Brazil— Cecilia Kossman grabs a pint-sized plastic container from the back of her van, shakes it, then quickly dumps its contents out of the window, releasing about 1,000 genetically engineered mosquitoes into the city’s streets.
The tiny winged critters are mutated versions of Aedes aegypti, the notorious mosquito that has infected millions of people around the world with dengue, Yellow fever, Chikungunya and more recently Zika.
But Kossman’s mosquitoes don’t bite. They’re male and they carry a gene that makes it impossible for their offspring to reach adulthood. The mutant mosquitos are trojan horses, deployed on a mission to exterminate their own species.
“Their job now is to mate with regular females,” says Kossman, a biologist for Oxitec, a Britsh bioengineering company. She says Aedes females can mate only once in their life, so if they choose the wrong partner and mate with a GM mosquito, they’ll effectively be neutralized and the overall mosquito population will decrease by one family.
“It’s a new idea,” Kossman says as she gets ready to release another batch of modified mosquitoes. “We are eliminating mosquitoes by releasing other mosquitoes into the city.”
Piracicaba is a quiet town in the state of Sao Paulo that’s known for its world class ping pong center. But now it’s gaining new fame as the world’s largest testing ground for the so-called “friendly aedes,” the bioengineered mosquito designed to kill off its own species.
The mosquitos were invented by Oxitec, a British firm that thinks GM mosquitoes can be powerful tools to eradicate dangerous viruses such as dengue and zika, as well as a series of agricultural plagues.
The company recently got FDA approval to develop its mosquito project in the U.S., and hopes its experiences in Brazil will help them to successfully deploy the “friendly aedes” in South Florida, if residents in the Keys allow it.
But not everyone is comfortable with the thought of fighting mosquitoes with mutant mosquitoes. In Brazil, Oxitec´s “Friendly Aedes” scheme has been met with some resistance from environmentalists and skeptical scientists who say the town was never consulted on the project and more research is needed to better understand the potential drawbacks and unintended consequences of releasing a new type of insect.
“We need to see more data,” said Jose Maria Ferraz, an ecology professor at Brazil’s University of Campinas and a former member of CTNBio, the government regulatory commission for biological products.
Ferraz thinks Brazil rushed into experimenting with the GM mosquitoes without fully understanding what it was getting itself into.
“This mosquito was approved by a commission that relied on data compiled by the same company who profits from promoting its use,” he says.
Oxitec insists its technology is safe. The company says it’s been designing GM mosquitoes since the early 2000s, and testing them in different parts of the world with positive results.
Oxitec set up shop in Piracicaba in the spring of 2015, at the invitation of the city’s own major at a time when the town was reeling from a dengue epidemic.
The genetically manufactured mosquito was first tested in a neighborhood on the outskirts of the city known as CECAP, home to 5,000 people. It was an area that was one of the hardest hit by the 2015 dengue outbreak.
“We used to have up to eight people per day here, vomiting and with fever,” said Maria Tonossi, a health worker at the local public clinic. “But now we don’t really have any people coming with those symptoms. I think the mosquito has really helped us to do our work.”
The number of dengue cases in CECAP dropped from 133 cases in the 2014-2015 season to just 12 this past season. Oxitec believes that this is related to the thousands of GM mosquitoes they released in the neighborhood each week, which led to a drastic drop in the local population of Aedes Aegypti.
According to Oxitec CECAP had 82% less aedes mosquitoes than another non-treated area of the city, after the first nine months of the program.
“Those numbers tell us that the project is working,” says Kossman, the biologist
But others think there is not enough data to tell just how helpful the gm mosquito was in reducing Dengue, or the Aedes Aegypti population.
Professor Ferraz notes that the city government has also been fumigating in the CECAP area, and increasing programs that urge people to eliminate mosquito breeding sites.
“There could be many factors involved,” Ferraz said. “To get a better sense of what happened you would need to compare this neighborhood with a place that has similar characteristics.”
Ferraz also worries about the unintended effects of eliminating Aedes aegypti, which could just be replaced by another type of mosquito known as Aedes albopictus. That could lead to a situation where one vector for diseases is simply replaced by another, he said.
Oxitec employees say their program in Piracicaba has not led to an increase in the population of albopictus mosquitoes. And in any event, the company says the albopictus feeds primarily off animal blood, so it doesn’t pose as much of a threat to humans.
But a memo written by a member of Brazil’s biological regulatory commission in 2014 proposes another theory.
“Scientific studies show that until the 18th and 19th centuries, albopictus was the species that bit people most frequently in the daytime in Asian cities,” the report reads. “It has the aggressiveness and potential to once again occupy that niche.”
Critics of the project are also concerned that the offspring of GM mosquitoes might actually survive if the eggs are laid in water that is contaminated with tetracycline, an antibiotic that is used as medicine for farm animals, and is also used in the Oxitec lab to help its GM mosquitoes survive.
The company says that its mosquitoes are raised in water with very high concentrations of tetracycline, a condition that cannot occur outside the lab environment.
Despite the controversy, Piracicaba plans to push ahead with the GM mosquito. The city plans to expand the “friendly Aedes” project to an additional 13 neighborhoods by the end of this year, covering an area that’s home to about 60,000 residents. It will be the largest deployment area ever for a genetically modified animal.
Oxitec meanwhile is planning to set up a new production facility in Piracicaba, so it can breed up to 60 million mosquitoes per week. The company is also setting its sites on the lucrative U.S. market.
In November the Florida Keys town of Key Haven will vote on a referendum on whether or not to incorporate Oxitec’s GM mosquitoes into its arsenal of zika fighting tools. The same courtesy wasn’t extended to the people of Piracicaba. But Oxitec says it has tried to provide information about its project to the local population.
“The whole region is taking a look at this to see if it works,” said Veruska Segura, a resident of the nearby town of Limeira who dropped by a public info booth that the company runs in Piracicaba’s lone shopping mall. “We had 20,000 cases of dengue in my town…and that’s very expensive for the local health system.”
Oxitec’s employees stress that their genetically engineered mosquito is not a magic bullet for dengue or zika, rather another means of combating those illnesses.
Kossman, the biologist who supervises the mosquito’s release in Piracicaba, says that globalization has helped Aedes aegypti to move easily from one place to another, in cars, ships, and planes, which makes it a very difficult species to eliminate in the 21st century. So she thinks cities should use everything at their disposal to fight the mosquito.
“We know that one technology on its own is not going to save us,” Kossman said. “But the more tools you have at your disposal the better. The important thing is to fight the mosquito and the diseases it carries.”