The World Health Organization and other global health groups have responded to rumors that the recent outbreak of Zika virus stemmed from the release of genetically modified mosquitoes in Brazil. Experts are dismissing the notion, saying there is no evidence to support that GM mosquitoes had anything to do with the rampant spread of the virus, which causes birth defects. Although the rumor has all the sensationalism of a science fiction thriller, the facts simply don’t add up.
So, how did the theory get started in the first place? British biotechnology company Oxitec did genetically engineer mosquitoes to fight dengue fever and other diseases carried by the same species which spreads the Zika virus. Those genetically modified mosquitoes were, in fact, released in Brazil. However, a logical look at the timeline of the Zika virus illustrates how it’s impossible for those mosquitoes to have caused it. Initial cases of the Zika virus in humans were discovered nearly seven decades ago in Uganda, and it’s popped up other places as well.
Small outbreaks occurred in other parts of the world prior to the recent boom in South America. In 2007, the small island nation of Yap in the West Pacific Ocean was home to 100+ cases. Five years later, some 28,000 cases were reported in French Polynesia – a significant event, since that makes up 11 percent of the population there. Both of those outbreaks took place before Oxitec’s genetically modified mosquitoes were released.
Health experts also claim that, even if the timeline fit, the genetically engineered mosquitoes wouldn’t have survived to transmit the Zika virus. Oxitec engineered the mosquitoes by instilling a self-destruct gene into male mosquitoes, which they pass on through reproduction, causing their progeny to die off in as little as 12 weeks. The third prong of the GM-mosquito conspiracy theory is geography, but that doesn’t hold up either. Oxitec’s mosquitoes were set free in two locations – Juazeiro and Jacobina – which are both quite a distance from Camaçari, where initial cases of Zika were reported in May 2015. The tiny winged insects, however persistent they can seem, do not typically travel more than 440 meters, so it’s highly unlikely that any of the GM mosquitoes could have made it hundreds of miles from their release sites to Camaçari.
Although health experts around the globe agree that genetically modified mosquitoes didn’t start – or accelerate the spread of – the Zika virus, it’s possible that gene editing techniques could help end the outbreak. In fact, the technology Oxitec used to engineer mosquitoes to fight dengue and other diseases has potential applications for Zika. MIT posited this notion earlier this week, saying researchers are close to determining a method of using gene drive technology to block mosquitoes from carrying the virus or to eradicate the species altogether.