Conspiracy theories surrounding the Zika virus have begun to surface online, with various ideas about the 'truth' behind the outbreak being posted. Here are the most prevalent theories being thrown around – and why they are wrong.

The virus comes from genetically modified mosquitos

This theory suggests the Zika virus outbreak is the result of mosquitos genetically modified by British company Oxitec. The GM mosquitoes in question, Aedes aegypti, have been engineered so that when they breed with the normal population, none of the mosquito offspring survive. This is, apparently, a bid to control harmful populations of mosquitoes carrying dengue fever.

Conspiracy theorists point out that these GM mosquitoes were tested in Brazil, and they say the Zika virus was somehow introduced to the mix. One 'redditor' (a poster on said that some of the GM-mosquito offspring survived and became more susceptible to Zika.

Zika virus
The Zika virus is spread by mosquitoes Jaime Saldarriaga/Reuters

But this is nonsense. GM mosquitos cannot reproduce, and those that survived into adulthood cannot suddenly become infected with the Zika virus. Further to that, the Zika virus has been around for more than 60 years, having been first isolated in Uganda in 1947. It found its way from Africa and moved westwards, with cases in Micronesia, French Polynesia and Chile. It was first identified in Brazil in May 2015.

Some of the theorists claim Oxitec's initial testing took place in the same area as the location of the initial Zika outbreak in Brazil last year. This is not the case – the two sites are around 200 miles apart. Another testing site, which began in 2015, is about 800 miles from the epicentre, as Discover magazine has pointed out.

In reality, GM mosquitos could actually help to curb the spread of the Zika virus.

Zika is a biological weapon

This conspiracy theory has been floating the internet around without any real basis from where it came from: possibly something to do with secret Rockefeller laboratory experiments or the Illuminati. It appeared because of a screenshot showing how you can buy the Zika virus online. And technically you can – you have to have credentials, legal documents and valid research purposes. Essentially, you cannot just buy the Zika virus online.

Birth defects are from TDAP vaccine

Zika virus
Pregnant women waiting to be seen by a doctor at the Alonso Suazo clinic in Tegucigalpa, Honduras Orlando Sierra/AFP

Anti-vaxxers have jumped on the Zika virus outbreak to claim that birth defects linked with it are actually the result of the TDAP vaccine, which is given to pregnant women and protects against diphtheria, pertussis and tetanus. The vaccine was recommended to women following outbreaks of whooping cough worldwide. Newborns cannot have the vaccine, so it is instead given to women in the later stages of pregnancy to ensure the baby is protected.

A number of conspiracy reports suggest that because the link between microcephaly – where the head and brain of babies are abnormally small – and the Zika virus has not been proven, it is a cover-up story. While the link between microcephaly and the Zika virus has not been confirmed, the idea that the TDAP vaccine results in birth defects is wrong – and potentially dangerous.

Women in other countries also get the TDAP vaccine, but there has not been a vast increase in microcephaly cases. It has been suggested this was a 'bad batch' of TDAP. Unfortunately for anti-vaxxers, the vaccine is given to women in the later stages of pregnancy after the head has developed – and heads do not 'un-develop'.

The Zika virus has been invented to make everyone take a vaccine

Channel 4\'s Utopia, in which a \'vaccine\' to a fake outbreak was set to be distributed by a covert organisation to reduce the global population Channel 4

This conspiracy theory is probably the most convoluted. It says that the Zika virus does not actually exist – or at least it is not causing birth defects – and that the outbreak is a massive ploy to make sure everyone takes the vaccine that would eventually be developed for it. What the vaccine would actually do is a point of debate online, but some suggest it would cause mass-sterilisation that would reduce the global population – a similar situation to that seen in Channel 4 series Utopia.

The theory has been particularly popular among anti-vaxxers. This may be because it came from a man called Jon Rappoport – a HIV denier and anti-vaccination advocate. As Tara C Smith writing for Science Blogs sums up: "What's wrong with it? Pretty much everything. Rappoport has made a meta-conspiracy theory, claiming the increase in microcephaly is caused not by Zika, but by a combination of pesticide use and manufacturing, the Tdap and GMO mosquitoes mentioned above, mosquito sprays, and poverty/sanitation/malnutrition (the boogeymen of every anti-vaccine advocate).

"Like many science deniers, he's taking the parts of the research that fit his biases ... and ignoring the parts he doesn't–that if there is an increase in microcephaly, Zika might be a driving force. In his mind, the virus is irrelevant and just a mechanism to make the public into "sheep" who will fall in line with government recommendations."

Why conspiracy theories emerge

July 20, 1969: Buzz Aldrin walks on the surface of the moon.  Neil  Armstrong, taking the photo,  is reflected in his visor
The first Moon landing has long been considered by some to be a hoax Nasa

Conspiracy theories about the Zika virus were always likely to surface – there are a lot of unknowns involved making it a prime target for people wanting to present a different narrative away from mainstream organisations. Research from 2014 showed that conspiracy theories emerge whether there is an explanation for something or not. A study by researchers from the University of Kent showed conspiracy theories appear to form from a "self-sustaining world view composed of a network of mutually supported beliefs".

Indeed, recent research by David Robert Grimes from the University of Oxford looked at how long a conspiracy could be maintained in relation to how many people were involved. In it, he concedes that presenting conspiracy theorists is largely a pointless exercise.

"Not everyone who believes in a conspiracy is unreasonable or unthinking," he said. "I hope that by showing how eye-wateringly unlikely some alleged conspiracies are, some people will reconsider their anti-science beliefs. This will of course not convince everyone; there's ample evidence that belief in conspiracy is often ideological rather than rational, and that conspiracy theories thrive in an echo chamber.

"This makes challenging the more odious narratives much more difficult. If we are to address the multitudinous difficulties facing us as a species, from climate change to geo-politics, then we need to embrace reality over ideologically motivated fictions. To this end, we need to better understand how and why some ideas are entrenched and persistent among certain groups despite the evidence, and how we might counteract this."