Thursday, February 4, 2016

Zika outburst associated with release of genetically-modified mosquitoes in Brazil

The internet and public health institutions are a-buzz with the reports that the astronomical upsurge in incidences of Zika, might have been associated with the release of genetically-modified mosquitoes into Brazil last year by a British firm.

The seriousness of this suggestion can hardly be exaggerated, and the accusations and counter-accusations are hard-hitting and desperate.

But the facts won't go away.

It is indeed true that OXITEC in 2015 released genetically-modified mosquitoes into some regions in Brazil in a well-intended effort to curb mosquito-borne diseases such as dengue fever and malaria. (The experiment started in 2012). It is also true,despite bare-faced denial by fierce apologists, that the presence of even trace amounts of the antibiotic tetracycline can disrupt the death-mechanism programmed for the larvae of the modified mosquitoes.  If this happens, the expected drastic decrease in mosquito population might only be temporary, blossoming with a vengeance soon after. Worse, the resulting poorly-characterized GM modified mosquitoes could now dominate the population - in which case anything can happen! That tetracycline can have such an impact is confirmed in an in-house confidential report of OXITEC itself, now leaked and posted on the internet.

It is known that Brazil is one of the topmost users of tetracycline in the world; and that the area which now forms the epicentre of the Zika outbreak largely coincided with the area the GM mosquitoes were released in 2015.  Between October 2015 and now, over 4000 babies with microcephaly has been recorded in Brazil.

However, it is also true that the surge in mosquitoes, and the corresponding surge in incidence of Zika, might be due to other causes.  As pointed out by the WHO: “conditions associated with this year’s El Nino weather pattern are expected to increase mosquito populations greatly in many areas.” 

In the above-cited press statement, WHO's Dr Chan pointed out that Zika, ordinarily known to be a mild condition, first assumed terror status when it produced neurological complications in French Polynesia.  At that time the virus was co-circulating with dengue fever.  It is not yet clear what is further interacting with the virus in Brazil that could be producing what the WHO boss described as "heart breaking burden" for affected families and communities.

The dicey situation is now further exacerbated by the suggestions to combat the current Zika scourge by the release of more genetically-modified mosquitoes!

Here are some relevant extract from the article from Antimedia Organization:

"The particular strain of Oxitec GM mosquitoes, OX513A, are genetically altered so the vast majority of their offspring will die before they mature — though Dr. Ricarda Steinbrecher published concerns in a report in September 2010 that a known survival rate of 3-4 percent warranted further study before the release of the GM insects. Her concerns, which were echoed by several other scientists both at the time and since, appear to have been ignored — though they should not have been.
Those genetically-modified mosquitoes work to control wild, potentially disease-carrying populations in a very specific manner. Only the male modified Aedes mosquitoes are supposed to be released into the wild — as they will mate with their unaltered female counterparts. Once offspring are produced, the modified, scientific facet is supposed to ‘kick in’ and kill that larvae before it reaches breeding age — if tetracycline is not present during its development. But there is a problem.
Aedes aegypti mosquito. Image credit: Muhammad Mahdi Karim
According to an unclassified document from the Trade and Agriculture Directorate Committee for Agriculture dated February 2015, Brazil is the third largest in “global antimicrobial consumption in food animal production” — meaning, Brazil is third in the world for its use of tetracycline in its food animals. 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:
“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.”"

Read the entire article at