Pandora’s box: how GM mosquitos could have caused Brazil’s microcephaly disaster (The Ecologist)
1st February 2016
Aedes Aegypti mosquito feeding on human blood. This is the species that transmits Zika, and that was genetically engineered by Oxitec using the piggyBac transposon. Photo: James Gathany via jentavery on Flickr (CC BY).
In Brazil’s microcephaly epidemic, one vital question remains unanswered: how did the Zika virus suddenly learn how to disrupt the development of human embryos? The answer may lie in a sequence of ‘jumping DNA’ used to engineer the virus’s mosquito vector – and released into the wild four years ago in the precise area of Brazil where the microcephaly crisis is most acute.
These ‘promiscuous’ transposons have found special favour with genetic engineers, whose goal is to create ‘universal’ systems for transferring genes into any and every species on earth. Almost none of the geneticists has considered the hazards involved.
Since August 2015, a large number of babies in Northeast Brazil have been born with very small heads, a condition known as microcephaly, and with other serious malformations. 4,180 suspected cases have been reported.
Epidemiologists have found a convincing correlation between the incidence of the natal deformities and maternal infections with the Zika virus, first discovered in Uganda’s Zika Valley in 1947, which normally produces non-serious illness.
The correlation has been evidenced through the geographical distrubution of Zika infections and the wave of deformities. Zika virus has also been detected in the amniotic fluids and other tissues of the affected babies and their mothers.
This latter finding was recently reported by AS Oliveira Melo et al in a scientific paperpublished in the journal Ultrasound in Obstetrics & Gynecology, which noted evidence of intra-uterine infection. They also warn:
“As with other intrauterine infections, it is possible that the reported cases of microcephaly represent only the more severely affected children and that newborns with less severe disease, affecting not only the brain but also other organs, have not yet been diagnosed.”
The Brazilian Health Minister, Marcelo Castro, says he has “100% certainty” that there is a link between Zika and microcephaly. His view is supported by the medical community worldwide, including by the US Center for Disease Control.
Oliveira Melo et al draw attention to a mystery that lies at the heart of the affair: “It is difficult to explain why there have been no fetal cases of Zika virus infection reported until now but this may be due to the underreporting of cases, possible early acquisition of immunity in endemic areas or due to the rarity of the disease until now.
“As genomic changes in the virus have been reported, the possibility of a new, more virulent, strain needs to be considered. Until more cases are diagnosed and histopathological proof is obtained, the possibility of other etiologies cannot be ruled out.”
And this is the key question: how – if indeed Zika really is the problem, as appears likely – did this relatively innocuous virus acquire the ability to produce these terrible malformations in unborn human babies?
Oxitec’s GM mosquitoes
An excellent article by Claire Bernish published last week on AntiMedia draws attention to an interesting aspect of the matter which has escaped mainstream media attention: the correlation between the incidence of Zika and the area of release of genetically modified Aedes aegypti mosquitos engineered for male insterility (see maps, above right).
The purpose of the release was to see if it controlled population of the mosquitos, which are the vector of Dengue fever, a potentially lethal disease. The same species also transmits the Zika virus.
The releases took in 2011 and 2012 in the Itaberaba suburb of the city of Juazeiro, Bahia, Northeast Brazil, about 500 km west of ther coastal city of Recife. The experiment was written up in July 2015 in the journal PLOS Neglected Tropical Diseases in a paper titled ‘Suppression of a Field Population of Aedes aegypti in Brazil by Sustained Release of Transgenic Male Mosquitoes’ by Danilo O. Carvalho et al.
An initial ‘rangefinder of 30,000 GM mosquitos per week took place between 19th May and 29th June 2011, followed by a much larger release of 540,000 per week in early 2012, ending on 11th February.
At the end of it the scientists claimed “effective control of a wild population of Ae. aegypti by sustained releases of OX513A male Ae. aegypti. We diminished Ae. aegypti population by 95% (95% CI: 92.2%-97.5%) based on adult trap data and 78% (95% CI: 70.5%-84.8%) based on ovitrap indices compared to the adjacent no-release control area.”
So what’s to worry about?
The idea of the Oxitec mosquitoes is simple enough: the males produce non-viable offspring which all die. So the GM mosqitoes are ‘self-extinguishing’ and the altered genes cannot survive in the wild population. All very clever, and nothing to worry about!
But in fact, it’s not so simple. In 2010 geneticist Ricarda Steinbrecher wrote to the biosafety regulator in Malaysia – also considering a release of the Oxitec mosquitoes – with a number of safety concerns, pointing out the 2007 finding by Phuc et al that 3-4% of the first generation mosquitos actually survive.
The genetic engineerig method employed by Oxitec allows the popular antibiotic tetracycline to be used to repress the lethality during breeding. But as a side-effect, the lethality is also reduced by the presence of tetracycline in the environment; and as Bernish points out, Brazil is among the world’s biggest users of anti-microbials including tetracycline in its commercial farming sector:
“As a study by the American Society of Agronomy, et. al., explained, ‘It is estimated that approximately 75% of antibiotics are not absorbed by animals and are excreted in waste.’ One of the antibiotics (or antimicrobials) specifically named in that report for its environmental persistence is tetracycline.
In fact, as a confidential internal Oxitec document divulged in 2012, that survival rate could be as high as 15% – even with low levels of tetracycline present. ‘Even small amounts of tetracycline can repress’ the engineered lethality. Indeed, that 15% survival rate was described by Oxitec.”
She then quotes the leaked Oxitec paper: “After a lot of testing and comparing experimental design, it was found that [researchers] had used a cat food to feed the [OX513A] larvae and this cat food contained chicken. It is known that tetracycline is routinely used to prevent infections in chickens, especially in the cheap, mass produced, chicken used for animal food. The chicken is heat-treated before being used, but this does not remove all the tetracycline. This meant that a small amount of tetracycline was being added from the food to the larvae and repressing the [designed] lethal system.”
So in other words, there is every possibility for Oxitec’s modified genes to persist in wild populations of Aedes aegypti mosquitos, especially in the environmental presence of tetracycline which is widely present in sewage, septic tanks, contaminated water sources and farm runoff.
‘Promiscuous’ jumping genes
On the face of it, there is no obvious way in which the spread of Oxitec’s GM mosquitos into the wild could have anything to do with Brazil’s wave of micrcophaly. Is there?
Actually, yes. The problem may arise from the use of the ‘transposon’ (‘jumping’ sequence of DNA used in the genetic engineering process to introduce the new genes into the target organism). There are several such DNA sequences in use, and one of the most popular is known as known as piggyBac.
As a 2001 review article by Dr Mae Wan Ho shows, piggyBac is notoriously active, inserting itself into genes way beyond its intended target: “These ‘promiscuous’ transposons have found special favour with genetic engineers, whose goal is to create ‘universal’ systems for transferring genes into any and every species on earth. Almost none of the geneticists has considered the hazards involved …
“It would seem obvious that integrated transposon vectors may easily jump out again, to another site in the same genome, or to the genome of unrelated species. There are already signs of that in the transposon, piggyBac, used in the GM bollworms to be released by the USDA this summer.
The piggyBac transposon was discovered in cell cultures of the moth Trichopulsia, the cabbage looper, where it caused high rates of mutations in the baculovirus infecting the cells by jumping into its genes … This transposon was later found to be active in a wide range of species, including the fruitfly Drosophila, the mosquito transmitting yellow fever, Aedes aegypti, the medfly, Ceratitis capitata, and the original host, the cabbage looper.
“The piggyBac vector gave high frequencies of transpositions, 37 times higher than mariner and nearly four times higher than Hirmar.”
In a later 2014 report Dr Mae Wan Ho returned to the theme with additional detail and fresh scientific evidence (please refer to her original article for references): “The piggyBac transposon was discovered in cell cultures of the moth Trichopulsia, the cabbage looper, where it caused high rates of mutations in the baculovirus infecting the cells by jumping into its genes …
“There is also evidence that the disabled piggyBac vector carrying the transgene, even when stripped down to the bare minimum of the border repeats, was nevertheless able to replicate and spread, because the transposase enzyme enabling the piggyBac inserts to move can be provided by transposons present in all genomes.
“The main reason initially for using transposons as vectors in insect control was precisely because they can spread the transgenes rapidly by ‘non-Mendelian’ means within a population, i.e., by replicating copies and jumping into genomes, thereby ‘driving’ the trait through the insect population. However, the scientists involved neglected the fact that the transposons could also jump into the genomes of the mammalian hosts including human beings …
“In spite of instability and resulting genotoxicity, the piggyBac transposon has been used extensively also in human gene therapy. Several human cell lines have been transformed, even primary human T cells using piggyBac. These findings leave us little doubt that the transposon-borne transgenes in the transgenic mosquito can transfer horizontally to human cells. The piggyBac transposon was found to induce genome wide insertionmutations disrupting many gene functions.”
Has the GM nightmare finally come true?
So down to the key question: was the Oxitec’s GM Aedes aegypti male-sterile mosquito released in Juazeiro engineered with the piggyBac transposon? Yes, it was. And that creates a highly significant possibility: that Oxitec’s release of its GM mosquitos led directly to the development of Brazil’s microcephaly epidemic through the following mechanism:
1. Many of the millions of Oxitec GM mosquitos released in Juazeiro in 2011/2012 survive, assisted, but not dependent on, the presence of tetracycline in the environment.
2. These mosquitos interbreed with with the wild population and their novel genes become widespread.
3. The promiscuous piggyBac transposon now present in the local Aedes aegyptipopulation takes the opportunity to jump into the Zika virus, probably on numerous occasions.
4. In the process certain mutated strains of Zika acquire a selective advantage, making them more virulent and giving them an enhanced ability to enter and disrupt human DNA.
5. One way in which this manifests is by disrupting a key stage in the development of human embryos in the womb, causing microcephaly and the other reported deformations. Note that as Melo Oliveira et al warn, there are almost certainly other manifestations that have not yet been detected.
6. It may be that the piggyBac transposon has itself entered the DNA of babies exposed in utero to the modified Zika virus. Indeed, this may form part of the mechanism by which embryonic development is disrupted.
In the latter case, one implication is that the action of the gene could be blocked by giving pregnant women tetracycline in order to block its activity. The chances of success are probably low, but it has to be worth trying.
No further releases of GM insects!
While I am certainly not claiming that this is what actually took place, it is at least a credible hypothesis, and moreover a highly testable one. Nothing would be easier for genetic engineers than to test amniotic fluids, babies’ blood, wild Aedes mosquitos and the Zika virus itself for the presence of the piggyBac transposon, using well established and highly sensitive PCR (polymerase chain reaction) techniques.
If this proves to be the case, those urging caution on the release of GMOs generally, and transgenic insects bearing promiscuous transposons in particular, will have been proved right on all counts.
But most important, such experiments, and any deployment of similar GM insects, must be immediately halted until the possibilities outlined above can be safely ruled out. There are plans, for example, to release similarly modified Anopheles mosquitos as an anti-malarial measure.
There are also calls for even more of the Oxitec Aedes aegypti mosquitos to be released in order to halt the transmission of the Zika virus. If that were to take place, it could give rise to numerous new mutations of the virus with the potential to cause even more damage to the human genome, that we can, at this stage, only guess at.
Oliver Tickell edits The Ecologist.
A new ridiculous rumor is spreading around the internets. According to conspiracy theorists, the recent outbreak of Zika can be blamed on the British biotech company Oxitec, which some are saying even intentionally caused the disease as a form of ethnic cleansing or population control. The articles all cite a lone Redditor who proposed the connection on January 25th to the Conspiracy subreddit. “There are no biological free lunches,” says one commenter on the idea. “Releasing genetically altered species into the environment could have disastrous consequences” another added. “Maybe that’s what some entities want to happen…?”
For some reason, it’s been one of those months where random nonsense suddenly hits mainstream. Here are the facts: there’s no evidence whatsoever to support this conspiracy theory, or any of the other bizarre, anti-science claims that have popped up in the past few weeks. So let’s stop all of this right here, right now: The Earth is round, not flat (and it’s definitely not hollow). Last year was the hottest year on record, and climate change is really happening (so please just stop, Mr. Cruz). And FFS, genetically modified mosquitoes didn’t start the Zika outbreak.
Background on Zika
The Zika virus is a flavivirus closely related to notorious pathogens including dengue, yellow fever, Japanese encephalitis, and West Nile virus. The virus is transmitted by mosquitoes in the genus Aedes, especially A. aegypti, which is a known vector for many of Zika’s relatives. Symptoms of the infection appear three to twelve days post bite. Most people are asymptomatic, which means they show no signs of infection. The vast majority of those who do show signs of infection report fever, rash, joint pain, and conjunctivitis (red eyes), according to the U.S. Centers for Disease Control. After a week or less, the symptoms tend to go away on their own. Serious complications have occurred, but they have been extremely rare.
The Zika virus isn’t new. It was first isolated in 1947 from a Rhesus monkey in the Zika Forest in Uganda, hence the pathogen’s name. The first human cases were confirmed in Uganda and Tanzania in 1952, and by 1968, the virus had spread to Nigeria. But since then, the virus has found its way out of Africa. The first major outbreak occurred on the island of Yap in Micronesia for 13 weeks 2007, during which 185 Zika cases were suspected (49 of those were confirmed, with another 59 considered probable). Then, in October 2013, an outbreak began in French Polynesia; around 10,000 cases were reported, less than 100 of which presented with severe neurological or autoimmune complications. One confirmed case of autochthonous transmission occurred in Chile in 2014, which means a person was infected while they were in Chile rather than somewhere else. Cases were also reported that year from several Pacific Islands. The virus was detected in Chile until June 2014, but then it seemed to disappear.
Fast forward to May 2015, when the Pan American Health Organization (PAHO) issued an alert regarding the first confirmed Zika virus infection in Brazil. Since then, several thousand suspected cases of the disease and a previously unknown complication—a kind of birth defect known as microcephaly where the baby’s brain is abnormally small—have been reported from Brazil. (It’s important to note that while the connection between the virus and microcephaly is strongly suspected, the link has yet to be conclusively demonstrated.)
Currently, there is no vaccine for Zika, though the recent rise in cases has spurred research efforts. Thus, preventing mosquito bites is the only prophylactic measure available.
The recent spread of the virus has been described as “explosive”; Zika has now been detected in 25 countries and territories. The rising concern over both the number of cases and reports of serious complications has led the most affected areas in Brazil to declare a state of emergency, and on Monday, The World Health Organization’s Director-General will convene an International Health Regulations Emergency Committee on Zika virus and the observed increase in neurological disorders and neonatal malformations. At this emergency meeting, the committee will discuss mitigation strategies and decide whether the organization will officially declare the virus a “Public Health Emergency of International Concern.”
GM to the Rescue
The mosquito to blame for the outbreak—Aedes aegypti—doesn’t belong in the Americas. It’s native to Africa, and was only introduced in the new world when Europeans began to explore the globe. In the 20th century, mosquito control programs nearly eradicated the unwelcome menace from the Americas (largely thanks to the use of the controversial pesticide DDT); as late as the mid 1970s, Brazil and 15 other nations were Aedes aegypti-free. But despite the successes, eradication efforts were halted, allowing the mosquito to regain its lost territory.
Effective control measures are expensive and difficult to maintain, so at the tail end of the 20th century and into the 21st, scientists began to explore creative means of controlling mosquito populations, including the use of genetic modification. Oxitec’s mosquitoes are one of the most exciting technologies to have emerged from this period. Here’s how they work, as I described in a post almost exactly a year ago:
While these mosquitoes are genetically modified, they aren’t “cross-bred with the herpes simplex virus and E. colibacteria” (that would be an interkingdom ménage à trois!)—and no, they cannot be “used to bite people and essentially make them immune to dengue fever and chikungunya” (they aren’t carrying a vaccine!). The mosquitoes that Oxitec have designed are what scientists call “autocidal” or possess a “dominant lethal genetic system,” which is mostly fancy wording for “they die all by themselves”. The males carry inserted DNA which causes the mosquitoes to depend upon a dietary supplement that is easy to provide in the lab, but not available in nature. When the so-called mutants breed with normal females, all of the offspring require the missing dietary supplement because the suicide genes passed on from the males are genetically dominant. Thus, the offspring die before they can become adults. The idea is, if you release enough such males in an area, then the females won’t have a choice but to mate with them. That will mean there will be few to no successful offspring in the next generation, and the population is effectively controlled.
Male mosquitoes don’t bite people, so they cannot serve as transmission vectors for Zika or any other disease. As for fears that GM females will take over: less than 5% of all offspring survive in the laboratory, and as Glen Slade, director of Oxitec’s Brazilian branch notes, those are the best possible conditions for survival. “It is considered unlikely that the survival rate is anywhere near that high in the harsher field conditions since offspring reaching adulthood will have been weakened by the self-limiting gene,” he told me. And contrary to what the conspiracy theorists claim, scientists have shown that tetracycline in the environment doesn’t increase that survival rate.
Brazil, a hotspot for dengue and other such diseases, is one of the countries where Oxitec is testing their mozzies—so far, everywhere that Oxitec’s mosquitoes have been released, the local populations have been suppressed by about 90%.
Wrong Place, Wrong Time
Now that we’ve covered the background on the situation, let’s dig into the conspiracy theory. We’ll start with the main argument laid out as evidence: that the Zika outbreak began in the same location at the same time as the first Oxitec release:
Though it’s often said, it’s worth repeating: correlation doesn’t equal causation. If it did, then Nicholas Cage is to blame for people drowning (Why, Nick? WHY?). But even beyond that, there are bigger problems with this supposed correlation: even by those maps, the site of release is on the fringe of the Zika hotspot, not the center of it. Just look at the two overlaid:
The epicenter of the outbreak and the release clearly don’t line up—the epicenter is on the coast rather than inland where the map points. Furthermore, the first confirmed cases weren’t reported in that area, but in the town of Camaçari, Bahia, which is—unsurprisingly—on the coast and several hundred kilometers from the release site indicated.
But perhaps more importantly, the location on the map isn’t where the mosquitoes were released. That map points to Juazeiro de Norte, Ceará, which is a solid 300 km away from Juazeiro, Bahia—the actual site of the mosquito trial. That location is even more on the edge of the Zika-affected area:
The mistake was made initially by the Redditor who proposed the conspiracy theory and has been propagated through lazy journalistic practices by every proponent since. Here’s a quick tip: if you’re basing your conspiracy theory on location coincidence, it’s probably a good idea to actually get the location right.
They’re also wrong about the date. According to the D.C. Clothesline:
By July 2015, shortly after the GM mosquitoes were first released into the wild in Juazeiro, Brazil, Oxitec proudly announced they had “successfully controlled the Aedes aegypti mosquito that spreads dengue fever, chikungunya and zika virus, by reducing the target population by more than 90%.”
However, GM mosquitoes weren’t first released in Juazeiro, Bahia (let alone Juazeiro de Norte, Ceará) in 2015. Instead, the announcement by Oxitec was of the published results of a trial that occurred in Juaziero between May 2011 and Sept 2012—a fact which is clearly stated in the methods and results of the paper that Oxitec was so excited to share.
A new control effort employing Oxitec mosquitoes did begin in April 2015, but not in Juaziero, or any of the northeastern states of Brazil where the disease outbreak is occurring. As another press release from Oxitec states, the 2015 releases of their GM mosquitoes were in Piracicaba, São Paulo, Brazil:
Following approval by Brazil’s National Biosafety Committee (CTNBio) for releases throughout the country, Piracicaba’s CECAP/Eldorado district became the world’s first municipality to partner directly with Oxitec and in April 2015 started releasing its self-limiting mosquitoes whose offspring do not survive. By the end of the calendar year, results had already indicated a reduction in wild mosquito larvae by 82%. Oxitec’s efficacy trials across Brazil, Panama and the Cayman Islands all resulted in a greater than 90% suppression of the wild Ae. aegypti mosquito population–an unprecedented level of control.
Based on the positive results achieved to date, the ‘Friendly Aedes aegypti Project’ in CECAP/Eldorado district covering 5,000 people has been extended for another year. Additionally, Oxitec and Piracicaba have signed a letter of intent to expand the project to an area of 35,000-60,000 residents. This geographic region includes the city’s center and was chosen due to the large flow of people commuting between it and surrounding neighborhoods which may contribute to the spread of infestations and infections.
Piracicaba, for the record, is more than 1300 miles away from the Zika epicenter:
So not only did the conspiracy theorists get the location of the first Brazil release wrong, they either got the date wrong, too, or got the location of the 2015 releases really, really off. Either way, the central argument that the release of GM mosquitoes by Oxitec coincides with the first cases of Zika virus simply doesn’t hold up.
Scientists Speak Out
As this ludicrous conspiracy theory has spread, so, too, has the scientific opposition to it. “Frankly, I’m a little sick of this kind of anti-science platform,” said vector ecologist Tanjim Hossain from the University of Miami, when I asked him what he thought. “This kind of fear mongering is not only irresponsible, but may very well be downright harmful to vulnerable populations from a global health perspective.”
Despite the specious allusions made by proponents of the conspiracy, this is still not Jurassic Park, says Hossain.
“We have a problem where ZIKV is spreading rapidly and is widely suspected of causing serious health issues,” he continued. “How do we solve this problem? An Integrated Vector Management (IVM) approach is key. We need to use all available tools, old and new, to combat the problem. GM mosquitoes are a fairly new tool in our arsenal. The way I see it, they have the potential to quickly reduce a local population of vector mosquitoes to near zero, and thereby can also reduce the risk of disease transmission. This kind of strategy could be particularly useful in a disease outbreak ‘hotspot’ because you could hypothetically stop the disease in its tracks so to speak.”
Other scientists have shared similar sentiments. Alex Perkins, a biological science professor at Notre Dame, told Business Insider that rather than causing the outbreak, GM mosquitoes might be our best chance to fight it. “It could very well be the case that genetically modified mosquitos could end up being one of the most important tools that we have to combat Zika,” Perkins said. “If anything, we should potentially be looking into using these more.”
Brazilian authorities couldn’t be happier with the results so far, and are eager to continue to fight these deadly mosquitoes by any means they can. “The initial project in CECAP/Eldorado district clearly showed that the ‘friendly Aedes aegypti solution’ made a big difference for the inhabitants of the area, helping to protect them from the mosquito that transmits dengue, Zika and chikungunya,” said Pedro Mello, secretary of health in Piracicaba. He notes that during the 2014/2015 dengue season, before the trial there began, there were 133 cases of dengue. “In 2015/2016, after the beginning of the Friendly Aedes aegypti Project, we had only one case.”
It’s long past time to stop villainizing Oxitec’s mosquitoes for crimes they didn’t commit. Claire Bernish, The Daily
MFail, Mirror and everyone else who has spread these baseless accusations: I’m talking to you. The original post was in the Conspiracy subreddit—what more of a red flag for “this is wildly inaccurate bullsh*t” do you need? (After all, if this is a legit source, where are your reports on the new hidden messages in the $100 bill? or why the Illuminati wants people to believe in aliens?). It’s well known that large-scale conspiracy theories are mathematically challenged. Don’t just post whatever crap is spewed on the internet because you know it’ll get you a few clicks. It’s dishonest, dangerous, and, frankly, deplorable to treat nonsense as possible truth just to prey upon your audience’s very real fears of an emerging disease. You, with your complete lack of integrity, are maggots feeding on the decay of modern journalism, and I mean that with no disrespect to maggots.
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