Was Zika outbreak caused by genetically modified mosquitoes?

Aedes Albopictus
An Aedes albopictus female mosquito obtaining a blood meal from a human host. Under experimental conditions the Aedes albopictus mosquito, also known as the Asian tiger mosquito, has been found to be a vector of West Nile virus. Aedes is a genus of the Culicine family of mosquitos. Photo: CDC/ James Gathany

Much has been said about zika virus and the release of genetically modified mosquitoes, but most reports state their cases in black and white. In reality diseases and their spread often inhabit a murky grey area somewhere between the two extremes.

Zika virus was first discovered in Uganda in 1947. It spread to many African countries but not a single case of microcephaly was noted. Not one. It moved out of Africa, still causing the mild flu like symptoms we associate with it today but again there were no recorded cases of microcephaly associated with it.

So what changed? Did anything change? Is it just a case of less medical reporting in Africa? Or maybe immunity to zika having been exposed to it, in the case of women, before reaching childbearing age.

Scientists are saying that something in the mosquitoes has changed as they traversed the globe. The World Health Organisation has not mentioned the release of genetically modified mosquitoes in the area most affected by cases of microcephaly and therefore seems to feel it has no bearing on the steep rise in microcephaly cases.

For almost 70 years Zika has done its thing, causing itchy rashes and a mild flu-like illness, then, all of a sudden babies in Brazil are being born with little brain matter and this has now been scientifically linked  to the virus.

In 2015, British company Oxitec announced that they had completed a field trial of a genetically modified mosquito:

Releases of the genetically engineered Oxitec mosquito, commonly known as ‘Friendly Aedes aegypti’, reduced the dengue mosquito population in an area of Juazeiro, Brazil by 95%, well below the modelled threshold for epidemic disease transmission.

Juazeiro is the exact same area where microcephalic babies started to be born later that year. Coincidence? Maybe, but it should be taken into account that the company had released GM mosquitoes in Brazil before, three years before in 2012 according to The Guardian. Could this second release of adulterated mosquitoes be having an effect on the microcephaly rates in the area?

Zika virus

Oxitec have refuted any link between their work and the Zika outbreak, and the company have actually been asked to expand their work in Brazil to help tackle the outbreak, opening a new mosquito facility in Piracicaba.

Chief executive Hadyn Parry labelled the claims as ‘simply untrue’.

“All vector control solutions – insecticides, traps, and ‘sterile’ mosquitoes get deployed in areas with a high incidence of disease to help stop the spread of the disease at its source.

“The fewer the mosquitoes, the lower the risk of disease. Our approach has proven to be more effective than the alternatives with a lower environmental impact.” – Oxitec Chief Executive, Haydn Parry

Discussing the expansion of its Brazil project, an Oxitec spokesman said: “We are delighted Piracicaba is encouraged by our strong results and expanding the program.”

“Our new facility will support the roll out of our groundbreaking vector-control across the heart of the city and beyond.

“As the principal source for the fastest growing vector-borne infection in the world in Dengue Fever, as well as the increasingly challenging Zika virus, controlling the population provides the best defense against these serious diseases for which there are no cures.” – Oxitec spokesman

Piracicaba’s health secretary, Pedro Mello, has also defended the company, claiming their work had helped protect the local population from different viruses including Zika.

“The initial project in CECAP/Eldorado district clearly showed that the ‘friendly Aedes aegyptisolution’ made a big difference for the inhabitants of the area, helping to protect them from the mosquito that transmits dengue, Zika and chikungunya.

“It is important to remember that in dengue year 2014/15 CECAP/Eldorado had 133 cases of dengue, the highest incidence in the city of Piracicaba.

“In 2015/2016, after the beginning of the Friendly Aedes aegypti Project, we had only one case.

“With this result, in addition to extending the project for another year in CECAP/ Eldorado, we decided to expand the use of the friendly Aedes aegypti to the central area of Piracicaba.”

– Pedro Mello, Piracicaba Secretary of Health

Notre Dame biological sciences professor, Alex Perkins, is among the many scientists have supported the British firm, telling Business Insider UK: “It could very well be the case that genetically modified mosquitoes could end up being one of the most important tools that we have to combat Zika.

“If anything, we should potentially be looking into using these more.”

“Judas” animals

The problem with genetic modification is the possible unanticipated side effects. The use of ‘Judas‘ animals is not unheard of. Sterile goats fitted with radio transmitters were introduced into the Galapagos island to stop the spread of wild goats wiping out flora found nowhere else on the planet. More recently Sweden has introduced Judas racoon dogs to halt the spread of the animal that they feel threatens local wildlife. Both of these cases involved getting rid of something that was introduced and was/is affecting indigenous flora and fauna. They are animals that were captured, sterilised and released back into the wild no longer able to reproduce but capable of leading hunters to others of the same species in order to eradicate them.

Mosquitoes are rather different, it would be impossible to trap and individually sterilise the males to prevent impregnation of the females, so a different approach was adopted.

OX513A was the name given to the modified male mosquitoes that were released in Brazil. They were bred in a lab in the UK and modified to require tetracycline, an antibiotic, to stay alive and destined to die if they didn’t get a regular supply of it.

All well and good so far.

Except they didn’t all die without the Tetracycline. The Department of Biosafety, Ministery of Natural Resources and Environment of Malaysia (sic) reports that 3-4% of the GM mosquitoes don’t actually die, they go on breeding and reproducing at their usual alarming rate. 

In theory at least a mosquito that bit a person or animal that had tetracycline in their bloodstream would survive and possible thrive, but more importantly why did 3-4% of the released mosquitos survive? What ongoing and unexpected effects could that have on mosquitoes and the humans they bite?

Eleonore Pauwels, a member of the Science and Technology Innovation Program at the Woodrow Wilson International Center for Scholars in Washington, D.C. speaking at an event in Washington in February said:

“We now have the power to hijack evolution.Many people think it’ll be efficient and predictable. But that’s not the case here. We need to know how to talk about to the public, so they understand the risks.”

At the same event, called by President Obama to call for funds to fight the zika virus, Kevin Esvelt, a genetic researcher at MIT’s Media Lab is quoted as saying:

“It is not something that we should do lightly — to deliberately alter the traits of a wild population. Even with something like a mosquito, which most of us are probably not very fond of, there might be unexpected ecological side affects.”

One also has to ask the question as to why Colombia, a neighbour of Brazil has recorded more than 20,000 cases of zika but has only reported a small increase of microcephaly related to zika. (up to April 16th 2016)

Mosquitoes are food for a wide variety of animals and birds and the knock on effect on those animals is unknown, as is the effect of those mosquitoes getting into the human food chain by the same mechanism.

In 2012, after the first release by Oxitec genewatch.org published a report into ongoing concerns and risk assessments of Oxitec’s ‘experiments’.

“No risk assessment was published for public scrutiny or consultation prior to releases of GM mosquitoes in the Cayman Islands or Brazil. In Malaysia only a summary was published. GeneWatch has obtained copies of the risk assessments in the UK because they must be provided by Oxitec when exporting GM mosquito eggs for open release for the first time to a given country. In no case did the company correctly follow this notification procedure, with the result that there was no independent scrutiny of whether these risk assessments met the required European standards.

“Oxitec has repeatedly referred to its GM mosquitoes as sterile, when this so-called sterility is partial and conditional. The GM mosquitoes do breed and most die at the larval stage: the extent to which their offspring survive to adulthood is one of many factors which influences the efficacy and safety of this approach.” – Genewatch report

The debate over genetically modified insects, animals and foodstuffs will continue to rage, with the scientific community split over whether the advantages outweigh the problems, both the known and the unknown.

It seems slightly out of whack that a small group of elite scientists get to decide on matters that could potentially affect all of us. The problem with releasing genetically modified insects back into the wild is that unlike goats and racoon dogs they can’t be tracked, trapped, recalled or eliminated in numbers large enough to eradicate any unforeseen problems their release has created, and this in itself is a major problem of releasing genetically modified insects of any kind.