Conspiracy theories are not unlike viruses. Mostly they circulate harmlessly on the fringes of society, but every now and then a mutation for increased transmissibility can lead to a mainstream outbreak with seriously damaging consequences in the real world.

It’s ironic then that a conspiracy theory about a real virus - the Zika epidemic currently affecting Brazil - is currently exhibiting just such break-out behaviour. The first outing I can find came via an obscure post on Reddit on 25 January. The location should have rung warning bells: it was in a sub-Reddit category titled “conspiracies”, sandwiched between 9/11 truther rants, and was written anonymously under the giveaway pseudonym “redditsucksatbanning”.

From Ebola to Zika, tiny mobile lab gives real-time DNA data on outbreaks Read more

It alleged that the UK-based small company Oxitec, which began releasing genetically engineered male-sterile mosquitoes in 2011 in north-eastern Brazil in order to combat dengue disease, may have inadvertently caused the Zika outbreak. Oxitec’s approach involves releasing non-biting males - which have been genetically engineered to carry a gene that is lethal to their offspring - to mate with wild females.

A scientific paper about the trials, conducted in the Brazilian city of Juazeiro in late 2011, confirmed that the local population of disease-carrying Aedes aegypti mosquitoes crashed by more than 90% during the trial, making Oxitec’s approach a far more promising form of control than conventional insecticide spraying. Aedes mosquitoes carry both dengue and Zika, so the same strategy could help tackle both diseases.



The Reddit post claimed to spot a correlation between the site of the GM mosquito releases and the location of the first Zika outbreaks in Brazil. This allegation was repeated on the fringe news site AntiMedia on 28 January, three days later. It included a handy map with a big red arrow indicating the mosquito release site in an area suspiciously close to the main Zika-affected sites.



Oops. There are two cities called Juazeiro in Brazil, and AntiMedia’s big red arrow was pointing at the wrong one, as the myth-busting science blogger Christie Wilcox quickly spotted. The Juazeiro where the GM mosquito releases had actually taken place was 300km away. Both cities are in turn rather a long way from the main Zika outbreak areas, which are located on the coast.



The timing was wrong too. Zika was first reported in Brazil in 2015, while the Oxitec mosquito releases began four years earlier. Moreover, Zika is thought to have come to Brazil from a 2013 outbreak in French Polynesia, which in turn spread from a 2007 outbreak in Micronesia. So the GM mosquitoes were effectively being blamed for causing a disease many thousands of miles away and several years before they were even released.



Russia’s international channel RT - always keen to push anti-GMO memes in order to advance Putin’s war against the West - was next to push the story on 30 January, adding pseudo-expert quotes from anti-biotech campaigners next to a republication of the erroneous maps identifying the wrong Brazilian city as the site of the mosquito release. Next up was the Daily Mail, which picked up the story on 31 January. “Are scientists to blame for Zika virus?” it asked, in a typically suggestive rhetorical question.



By then social media was beginning to buzz - friends of mine reported seeing the story posted on their Facebook timelines. It was then republished in further mutated form on 1 February by the environmental journalist Oliver Tickell, editor of the Ecologist website, under a new headline: “Pandora’s box: how GM mosquitos [sic] could have caused Brazil’s microcephaly disaster”.



Tickell quoted an “expert”, Dr Mae Wan Ho, fresh with a new theory. Dr Ho proposed that the DNA sequence used in genetically engineering Oxitec’s mosquitoes might somehow have jumped into the Zika virus and caused it to mutate into a more pathogenic form. Sounds plausible? The article seems impressively technical, quoting Dr Ho waxing lyrical on “integrated transposon vectors” and other sciencey-sounding language.



Scientific ignorance about Zika parallels Aids crisis in 1980s, say Brazilian experts Read more

The Ecologist failed to note Dr Ho’s real credentials, however. She is a decades-long anti-GMO activist who today divides her time between pushing anti-vaccine misinformation about MMR, bizarre ideas about about mobile phones causing cancer, and pseudo-scientific woo about homeopathy and “holistic” Chinese medicine.



Plus she made an elementary mistake: the mosquitoes couldn’t inadvertently insert additional DNA into the Zika virus genome, because Zika has no DNA - it’s an RNA virus. That’s a different type of molecule, Dr Ho. Moreover, the DNA sequence in question is 8400 bases long, almost as long as the entire Zika virus genome. Dr Ho’s purported mechanism is a biological impossibility and the Ecologist story is science fiction.



The real-world damage this kind of nonsense can cause is serious. Oxitec’s GM mosquito approach could potentially shield millions of Brazilians not just from Zika but from dengue too. It could even protect the Rio Olympics. But this won’t be allowed to happen if the conspiracy theory continues to snowball: already the Brazilian authorities are delaying approval for Oxitec to scale up deployment.



There are historical precedents too. Myths circulating in Nigeria severely hampered efforts to eradicate polio during the early 2000s. Worse, HIV/Aids denialism during the Mbeki government’s tenure in South Africa is estimated to have caused over 300,000 preventable deaths. Mbeki reportedly caught the Aids denial virus off the internet. I can only hope that no-one in the Brazilian government reads the Daily Mail or the Ecologist, or countless innocent lives may yet be lost.

