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PIRACICABA, Brazil — From its gleaming, year-old factory in this southeast Brazilian city, Oxitec, a British biotech firm, has built a thriving business releasing tens of millions of genetically engineered mosquitoes to protect populations from illnesses like dengue, chikungunya, and Zika.

But the company sees its future here not just in big factories but in a new business model centered on miniature labs, where mosquito eggs can be raised and released into neighborhoods. These mosquitoes carry a gene that causes their offspring to die before reaching maturity, with the goal of reducing vector-borne diseases.


Last November, Oxitec introduced its first “mobile production unit” in Juiz de Fora, an inland city of 500,000. Eggs from the Piracicaba factory are raised in mosquito hatcheries crammed inside the 40-foot rectangular lab that could pass for a white shipping container, condensing the work of a high-tech Silicon Valley-esque facility into just a single room.

In coming months, the company said, it hopes to finalize contracts with another handful of Brazilian cities, beginning with interventions that cover areas with as few as 10,000 residents.

“There are 5,000 municipalities [in Brazil] that have serious issues with chikungunya and dengue,” said Jorge Espanha, Oxitec’s general manager for Brazil. “We have to adapt our solution to our mobile production units.”

That’s a 180-degree turn for the company, which has spent the last half-decade scaling up its Piracicaba operation to support its biggest insect deployment in Brazil. Now, its focus has turned to scaling down its operation and replicating its Juiz de Fora experiment.


The company is betting that through this more diffuse strategy, it can move faster to scale up — or down — in locations where people are threatened by vector-born illnesses.

The modularity also helps with a quirk of the mosquito business: population interventions require larger numbers of mosquitoes at the beginning and fewer during what’s called the “maintenance stage,” which aims simply to keep newly reduced population sizes below natural levels. Mobile units have enough lab space to meet that need, the company hopes.

“If your demand decreases by 50 percent after the suppression phase,” said Karla Tepedino, the director of production and distribution for Oxitec in Brazil, “why would I build a huge factory that produces what I need in the suppression phase but when I’m in maintenance phase it produces more than that?”

Widespread use of the mobile units, Oxitec says, would make its product vastly more cost-effective for governments at all levels hoping to contract the firm for vector control. And a lower price point, Espanha said, could lead to a sea change in the way Brazil fights vector-borne illness.

Still, critics say, Oxitec’s mosquitoes haven’t been shown to work at a nationwide scale — and so if Brazil goes all-in for mobile labs, it may be a gamble.

A “mobile production unit” outside the Oxitec factory complex in Piracicaba, Sao Paulo, Brazil. Karla Tepedino/Oxitec

Mosquito supply and demand

The manufacturing process for all of Oxitec’s mosquitoes in Brazil begins at the Piracicaba factory, a Silicon Valley-esque facility in layout and technology. The company’s roughly 130 Brazil-based employees share the space with rogue insects that hover over desks and land on cafeteria room lunch trays, where they’re routinely zapped with tennis racket-shaped electric swatters.

It’s there that scientists hatch billions of male Aedes aegypti mosquitoes over the course of a given year, each containing a self-limiting gene that causes their offspring to die before reaching maturity.

The ultimate goal is to drastically reduce mosquito populations and the diseases — including Zika, dengue, and chikungunya — that they spread. In the Cayman Islands, for instance, where Oxitec’s latest intervention began in 2016, mosquito populations fell by 62 percent.

Presently, the bugs are hatched, fed, sorted by sex, and transferred to distribution units from the Piracicaba facility. But it’s all those tasks that the company now hopes the trailer units can take on.

Oxitec, while declining to cite specific negotiations, says plans are in the works for another handful of cities in which it can begin deploying mobile units and attempting to control mosquito populations. And if cities decide to pull out of projects, scale up, or scale down, there’s been little waste.

“This is the other beauty of it,” said Tepedino. “If you decide to build a factory for any reason, you can just put those mobile units there while we’re building the facility.”

A cheaper solution?

And the cost argument is central to Oxitec’s pitch to prospective host communities.

An Oxitec-commissioned study released last month indicated that the 2 million cases of illnesses spread by Aedes aegypti mosquitoes in 2016 — namely dengue, chikungunya, and Zika — cost Brazil more than $730 million in economic productivity.

Oxitec says the mobile units could be a lower-cost way to combat that problem for cash-strapped countries and municipalities not capable of signing contracts that can fund factory-scale operations.

But some remain skeptical of Oxitec’s strategy, billed as a near-panacea for a country that has twice claimed to have wiped out its Aedes aegypti population only to see it return with a vengeance. Research in the field has accelerated quickly in recent years, and skepticism of such interventions is common among local populations and the science community alike.

“Results from epidemiological trials remain the primary missing information for assessment of the public health value of this product,” Dr. Haroldo Bezerra, a public health entomology and vector control adviser to the Pan American Health Organization, told STAT. “Epidemiological studies must be carried out to assess the public health value of reducing vector populations through the application of [Oxitec’s mosquitoes].”

From Oxitec’s perspective, things seem simpler: Brazil has tried before, notably in the 1940s and 1950s, to eradicate its Aedes aegypti population, only to see the insects make a resurgence.

To Espanha and Oxitec, that history indicates that a shift in Brazil’s vector-control approach is needed.

“They are already spending the money,” Espanha said, “but it seems that the solution is still not there.”

  • “Oxitec, a British biotech firm, has built a thriving business releasing tens of millions of genetically engineered mosquitoes to protect populations from illnesses like dengue, chikungunya, and Zika.”

    Pharmaceutical PSYOPS at it’s most blatant. Protect populations? Zika, a relatively benign respiratory infection, had been a staple in Brazil for generations, before 2015 when Oxitec released it’s first hordes of GMO mosquitoes in North Eastern Brazil, which became the epicenter of the first ever epidemic of microcephalic newborns anywhere in history.. And we’re to buy the story that they’re really in production of Frankenstein bugs as a preventative?

  • Keys Physician Presenting Bacterial Health Concern February 20th at FKMCD Prior to Antibiotic Dependent GM Mosquito Upper Keys Release

    Physicians petitioned for bacterial safety cultures on the Oxitec antibiotic dependent mosquito in 2016. Physicians embrace technology and have ample experience nothing is completely safe. Petitioners want risk benefit analysis and accept reasonable imperfection but are not prone to blind acceptance. The cultures requested would not delay any trial, but would address the physician safety concern. The request was declined by the company with release now being planned in an upper Keys location not as yet identified.

    Petitioners worry about the spreading of antibiotic resistant bacteria into the homes of immunologically incompetent patients we treat; ie those with diabetes, asthma, on chemotherapy, etc. Petitioners know it is only a matter of time before mosquito borne illnesses return to the Keys. Keys physicians want testing now and an end to delays.

    Physicians petitioned for data as to bacteria identification and sensitivity to antibiotics carried by the Oxitec antibiotic dependent insects. Cultures very similar to throat or urine cultures. These antibiotic dependent mosquitoes are raised in baths of the antibiotic tetracycline. This antibiotic is classified by the World Health Organization as a ‘highly important’ antibiotic. The mass use of any antibiotic promotes resistant bacteria to that and possibly other antibiotics. The mosquito being used is meant to get where spraying cannot reach, such as inside of homes and businesses. It is here physicians concerns arise. What risk is there of humans infection from any antibiotic resistant bacteria left behind on surfaces by these antibiotic dependent mosquitoes?

    Keys physicians petitioned to have that culture data factored into any release and to delay the release if the data was not provided. Excuses for denial were received and felt weak. Gaining physician support just required data and appropriate risk benefit analysis.

    Data denied, Keys physicians turned to the Cayman Islands were these antibiotic dependent insects are deployed now. The Cayman Ministry of Health was battling actively 3 mosquito borne illnesses (Zika, Dengue, and Chikungunya) and turned to all options for control. Keys physician would likely have done the same under the same circumstances, but our circumstances were different. Keys physicians were screening for mosquito borne illnesses, but luckily not battling those diseases actively. Keys physicians were and are battling actively daily antibiotic resistant bacteria here. Cayman Island physicians were battling these bacteria as well. They had data on this concern as well. Some of the Cayman data is linked below. It demonstrates an anomaly Keys physicians expected. Cayman Island Ministry of Health data demonstrates an anomaly in the antibiotic tetracycline resistance that stands out in human Staph aureus infections.

    Our islands have an issue with Staph aureus infections. Where all other antibiotics of significant resistance in this Staph are dropping by an impressive percentage in resistance during an aggressive Pan American Health Organization (PAHO) guided Cayman campaign, tetracycline did not decline in Staph aureus. Cayman data does not place blame on the Oxitec insects as other factors could be responsible, but it was predicted by the petitioners. This remembering there have been releases with pauses since 2009 in the Caymans. Now we await data divided between release area and rest of the Caymans to see if the release area is a resistance cluster. We are very grateful to the Mosquito Research and Control Unit of the Cayman Ministry of Health for their hospitality during a site visit and freely sharing their data. More data to come.

    Antibiotic resistance is as significant a threat to human health as mosquito borne illnesses. Keys physicians do not accept a key statement by Dr Nimmo the Oxitec Spokesperson related to not providing the data. We do not accept the United States government would refuse the cultures physicians seek. These cultures are safety testing. Also, we are working with the goal of submitting the Cayman data to publication, to the EPA and to The National Antibiotic Resistance Monitoring System (NARMS) arm of the FDA. FDA and EPA have rules for data. Antibiotic dependent insects are new technology and FDA admitted it was not the most appropriate place for oversight.

    Please take the time to review and share the video linked. I will be presenting the concern and this data at the Sterile Insect Training of the Florida Keys Mosquito Control District on February 20th. This to clarify our desire for risk benefit analysis on this subject. Please freely comment back.

    • Dr. Norris,

      The tetracycline is not used for its antibiotic properties but to bind to a receptor protein that serves as part of a switch to keep the GM mosquito’s ‘self destruct’ gene turned off so that it can be bred in the lab. How relevant is the concentration used for mosquito rearing to the promotion of tetracycline resistance in bacteria that aren’t even growing inside humans or farm animals?

      Tetracycline is an old antibiotic, being in existence for more than half a century. There is already a fair amount of tetracycline resistance in the environment. See for example Wang et al 2017 “Tetracycline Resistance Genes Identified from Distinct Soil Environments in China by Functional Metagenomics” or Sanderson et al 2016 “Antibiotic resistance genes as an emerging environmental contaminant.” Even if use of the GM mosquito were to increase numbers of tetracycline resistant bacteria, how relevant would any increase be in the background of existing resistance levels?

      Importantly, according to an article from a New Zealand dermatology group, tetracycline may not even promote the bacterial resistance you highlight (google: “Tetracycline Author: A/Prof Amanda Oakley, Dermatologist, Hamilton, New Zealand, 1997. Updated in July 2016.”) “It is important to note that the use of tetracyclines does not increase Staphylococcus aureus resistance.”

      Will a risk benefit analysis consider the above factors or only serve to increase the public’s fear of biotechnology? There are a number of activists who’ve made a career out of opposing biotechnology and at least some of them, like Jeffery Smith and Andrew Kimbrell, appear to be active behind the scenes doing what they can to undermine the GM mosquito, which has demonstrated substantially greater efficacy than pesticide spraying and other measures in controlling populations of the dangerous Aedes aegypti mosquito in Brazil and Cayman. Are you truly up against a genuine risk or just playing their fool?

      As mentioned elsewhere, I’m a retired molecular biologist who has followed this story for over two years. The technology looked promising enough that I purchased some stock in Oxitec’s parent company (a small fraction of my portfolio and not a recommendation as it is a high-risk investment not for the fainthearted).

    • I recognize other bring up elements of what you post morphd. It is ironic to question what is called ‘sterile insect technique’ for risk of infectious resistant bacteria.

      Tetracycline is defined by WHO as a ‘highly important’ antibiotic for human health. It is first line drug in STD therapy and is a mainstay in MRSA as well as many other infections.

      Alexander Fleming stated in his Nobel Prize 1945 acceptance speech for discovering antibiotics on page 93 last 3 paragraphs to beware the ignorant man who under doses himself with antibiotics promoting the bacteria to resistance. He gives example the ignorant man under treating himself, his wife catching the resistant bacteria and dying. He asks who is responsible for the victims of the ignorant man.

      As far of how important in a world of resistance, we questioned that too. We asked it be studied. When denied, we looked to the Cayman Islands for their data during years of release. The Caymans were very generous. Their data shows, what it showed. The initial data is what is discussed. Blogs like this do not tend to allow links so I did not place link here. But to see it go to keywstdoctor with a dot com and look at bottom of page for link. It says judge for yourself.

      As far as breeding public fear about biotech, are you kidding. The public should not trust a science community that denies data for expedient political philosophy. They can trust a community that is honest. Physicians questioned the use of a ‘highly important’ antibiotic as fertilizer for insects that man programmed to require it? Doing this as the WHO called for an end to antibiotic use in healthy animals in 2017. The company is creating how many different insect species dependent on the antibiotic technology. This technology is meant to get into our patient’s homes. We asked for risk benefit analysis.

      With that said I am personally very impressed even at a 62% reduction stated by the MRCU. The question is not genetic engineering. The question is why did they not use something else to turn their lethal switch. Look at the inside of the cargo container they use to grow the insects. It reminds me of an hospital room but with little bacterial controls. See the images.

      Listen, I am no fan of Naled etc but that does not mean we as physicians want what at its UNLIKELY EXTREME another tobacco. How many experts and physicians pushed cigarettes in the 1940s and 1950s? So initial data is what it is. More to come. Time is a premium for Zika, Dengue etc. as well as our daily battle with antibiotic resistant bacteria.

      WHO states 700,000 humans die a year from bacterial resistance with that number rising nearly 15 times by 2050 to 10,000,000 dead a year. 200,000 of those perinatal. Mosquitoes are quotes 725,000 die a year now with no clear projections over the same time period. Those projections without the antibiotic dependent insects of how many types? How does this antibiotic dependent tech change both sets of numbers?

      As a physician, I personally have screened, diagnosed and treated these issue and don’t expect that to change. I’m in no lab. No golden God’s in my world. My house call bag is pretty worn. I’m just an island doctor worried about the people I serve from all the above. Trust with verification is a Reaganism I follow.

      Physicians petitioned in 2016. We wanted this answered then. Is there a resistant and transferable plasmid? Why not screen the insect livestock as you would food livestock for their human consumption? Read our petition. We are pro technology but none of us have seen a tool without a negative. Let release area data show whatever it does and factor it in to future releases.

      As a biologist I’m sure you can recognize need for data when a question is before you and ethical need to follow it where it leads. This all in humble opinion.

  • What could be the unintended consequences of this? Are there animals, plants or something else that depend on adult mosquitoes? I hate mosquitoes & have a somewhat allergic reaction to the bite so I wish they would disappear but of those unintended consequences I worry about & what about a little further down the line such as the animals &/or plants that are dependant on the first line animals &/or plants that eat the adult mosquitoes of which there would be far fewer of (thankfully). Please get rid of hornets & wasps too while you are at it LOL. I wish.

    • It’s a valid concern- it would seem as though such free manipulation of mosquito populations could have drastic downstream effects on the ecosystem. They are effectively changing the initial conditions of a very chaotic system… so it’s hard to figure out what will happen as a result until it has already happened.

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