Oxitec is back in the Keys, meeting with local officials and hosting town hall meetings, including one on Tuesday, Feb. 20 at 1 p.m. in Marathon. The company is awaiting Environmental Protection Agency approval for trials to release genetically modified mosquitoes in the Florida Keys. It has already passed the Food and Drug Administration examination.

“We expect to be granted the permit by the EPA in the next few months. We can’t guarantee it, but we are expecting it,” said Dr. Derric Nimmo, Oxitec’s principal scientist. “And so we are back in the Keys to engage and help the communities understand what’s going on with the project.”

On Tuesday, the Marathon City Council signed a letter of support for research funding for this type of “vector control” research, but not in support of Oxitec specifically. The state Department of Health is collecting the letters to present to the Centers for Disease Control, which may have funding for research projects.

“We are standing on the sidelines right now,” said Phil Goodman, chairman of the Florida Keys Mosquito Control District. “We are always interested in new technology. In a perfect world, we would be interested in pursuing all three sterile technologies.”

Should approval be granted, and Oxitec receive federal funding, the location for the trials in the Keys would be a joint decision between Oxitec and the Florida Keys Mosquito Control District. This is of particular importance since the Key Haven neighborhood rejected a genetically modified mosquito release in its neighborhood in a non-binding referendum question in the 2016 general election. Precinct 11 voted 65 percent against the study. But in a second referendum question, for the entire county, 31 of 33 precincts approved an “effectiveness trial in Monroe County” of genetically modified mosquitoes by at least half a percentage point.

It’s likely that neighborhoods that approve of the technology trials, as detailed in the 2016 election results, will be heavily courted by Oxitec. For example, Ocean Reef voted 84 percent in favor. The Middle Keys ranged from a 56 percent approval at Kirk of the Keys precinct all the way up to 72 percent approval at Key Colony Beach City Hall precinct. Summerland Key and parts of Big Pine Key and Sugarloaf were also overwhelmingly in favor at near 67 percent.

“We are engaging all of these places to make sure they have the correct information and understand what’s happening,” Dr. Nimmo said.

Should the EPA approval happen, where to conduct the trial will be a science-based discussion; however. Goodman said if the FKMCD were to participate, its board would have to approve, and the location decision would be a joint one with Oxitec.

“We would need current data on where the best mosquito numbers are before we need a site,” he said, adding that it would have to be recent data in order to name a test site, a control site and have the use of a nearby facility.

“We feel we need to make a sterile technique to make significant strides in controlling mosquitoes in the Florida Keys, to feel like the Keys are safe,” said Goodman. “A few days of too much wind and too much rain and good control turns to bad control with the tools that we have now.”

The town hall meeting is Tuesday, Feb. 20 at 1 p.m. at Florida Keys Mosquito Control District headquarters on 107th Street in Marathon.

The Science

Right now, there are three methods of controlling mosquito population through sterilization. All three target the Aedes aegypti mosquito, the primary species responsible for transmitting human viruses.

  • The first method is the Wolbachia method, in which mosquitoes are released into the wild after being infected with a naturally occurring bacteria rendering them less able to produce. There have already been trials of this method in the Keys, and a $1.4 million trial is underway in Miami-Dade County. The FKMCD said the short Keys trial had positive results but was, by and large, inconclusive.
  • The second method is to irridate mosquitoes, releasing sterile males into the wild to mate with females, so no offspring are produced. This is the same methodology used to treat the recent screwworm outbreak in the Keys, which was eradicated in under a year without spreading to the mainland. However, treatment weakens the mosquito, making it a less effective method.
  • The third method is to release male mosquitoes that have been genetically modified. This is the Oxitec technology. Treatments of tetracycline allow the modified mosquito to reach adulthood so as to reproduce with a female, but turns on a “self-limiting” gene so offspring do not survive. The drug also turns on a “marker” gene so scientists can study the mosquito’s impact in the wild.

The genetically modified mosquito method has met with public resistance in the Keys. Dr. John W. Norris of Key West has opposed the technology, citing the possible creation of an antibiotic-resistant scenario that could pose a health threat to humans. Proponents of the technology welcome a way to fight vector diseases (transmitted through the bite of infected insects) such as dengue, Zika, yellow fever and chikungunya. Local veterinarian Dr. Doug Mader said he supports the technology 100 percent, as it will reduce the number of canine heartworm infections — he said he sees four or five a month in the Keys — also a mosquito-borne disease.

Oxitec reports it has positive regulatory findings from independent scientific reviews and regulators from around the world that conclude the genetically modified mosquitoes have no negative effects on human health, animal health or the environment.

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  1. “Dr. John W. Norris of Key West has opposed the technology, citing the possible creation of an antibiotic-resistant scenario that could pose a health threat to humans.”

    The Oxitec mosquito program continues to expand in Brazil where its use has been associated with a large reductions of dengue fever. It would seem like a no brainer for Dr. Norris and the anti-GMO NGO(s) that are likely behind him to go there (or contract with a local company) to collect samples in treated versus non-treated areas to document any increase in antibiotic resistant bacteria. However, Dr. Norris & friends don’t appear to want to approach the problem scientifically – perhaps because their goal is to stop the project for reasons that have little to do with the mosquitoes benefit versus supposed risk

    As a retired molecular biologist who has followed the Oxitec story for over two years (even buying a bit of stock in its parent company because I think their technology is sound) my sense is that the anti-GMO NGOs fear that success of the Oxitec mosquito will undermine their activism (and donations) in the agricultural arena.

  2. Once again morphd is blinded by his conflict of interest. Dr. Norris has in fact traveled to the Cayman Islands and collected data on tetracycline resistance there which is why he is concerned. In fact, a variety of physicians in the Keys are concerned about this and have signed a petition to Oxitec asking the company to allow their mosquitoes to be tested for tetracycline resistant bacteria. Oxitec has refused to conduct these studies as they have refused to conduct several studies requested by physicians and scientists.

    Unfortunately, Oxitec will not take a scientific approach when it comes to safety. In fact, Oxitec has systematically misinformed residents in the Keys by telling them they only release males and all the offspring of these mosquutoes die before reaching adulthood.
    This is simply false. In the Cayman Islands Oxitec has released 9 females out of 500 males released. In fact, the data clearly shows an initial increase in female mosquitoes in areas GMO mosquitoes were released. This increase in female mosquitoes can lead to an increase in mosquito-borne diseases such as dengue fever.

    Despite claims made here by morphd, Oxitec cannot provide any evidence of ever having reduced dengue fever in Brazil or elsewhere. According to Dr. Haroldo Bezerra, a public health entomology and vector control adviser to the Pan American Health Organization, “Results from epidemiological trials remain the primary missing information for assessment of the public health value of this product,” “Epidemiological studies must be carried out to assess the public health value of reducing vector populations through the application of [Oxitec’s mosquitoes].”

    As previously mentioned Oxitec’s mosquitoes can initially increase the risk of dengue fever. The other approaches, Wolbachia and irradiated mosquitoes, do not have such a risk and also do not have the risk of tetracycline resistance either. Wolbachia inhibits the replication of the virus responsible for dengue fever. Therefore, even if females are released using this technique these females would be unlikely to spread dengue fever when biting humans. The FAO has stated that irradiated mosquitoes will also have Wolbachia in order to prevent any females released from spreading dengue.

    However, Oxitec’s female mosquitoes are fully capable of spreading dengue fever to humans. Unlike irradiated mosquitoes Oxitec cannot use Wolbachia because the Wolbachia will be killed when Oxitec bathes their mosquitoes in tetracycline.

    It is quite clear that Oxitec’s mosquitoes pose the greatest safety risk of the methods mentioned here because they can initially increase the risk of dengue fever and increase the risk of tetracycline resistance among several other risks. This is the reason that Oxitec’s mosquitoes face resistance among health professionals in the Keys and the residents as well.

  3. I should also point out that veterinarian Dr. Doug Mader should be very concerned about Oxitec’s mosquitoes harboring tetracycline resistant bacteria. Tetracycline is often used in treating canine heartworms and tetracycline resistant bacteria could render tetracycline useless making it harder to treat patients.

    Dr. Mader should, however, be in favor of the Wolbachia option since, “In mosquitoes, it has been shown that the presence of Wolbachia can inhibit the transmission of certain viruses, such as Dengue, Chikungunya, Yellow Fever, West Nile, as well as the infectivity of the malaria-causing protozoan, Plasmodium and filarial nematodes.” Canine heartworms are caused by the filarial nematode Dirofilaria immitis. Therefore, Wolbachia can inhibit transmission preventing his patients from ever having canine heartworms.

    In comparison, Oxitec releases female mosquitoes, along with the males, which can transmit mosquito-borne diseases. This initial increase in female mosquitoes can initially increase mosquito-borne diseases. Therefore, Dr. Mader may initially see an increase in canine heartworms in his patients if Oxitec’s mosquitoes are released. Since Oxitec’s mosquitoes also likely harbor tetracycline resistant bacteria this could mean not just an increase in canine heartworms, but also tetracycline resistant bacteria in Dirofilaria immitis which means canine heartworms that cannot be treated with tetracycline.

    It is these type of concerns that have led physicians and residents in the Keys to oppose Oxitec’s mosquitoes in favor of better and safer options such as Wolbachia.

  4. How is Wolbachia safer? Its a living bacteria that has been put in a new environment. Most people should know what happens when you do this; they mutate at a faster rate. This has been documented with fruit flies in California. When first introduced into fruit flies it was detrimental causing reduced egg production. After a few years it had evolved to a point it was beneficial resulting in increased egg production. As it is a living reproducing organism its going to be difficult to stop if things go wrong. Another point is wolbachia does not block the viruses that cause disease transmission; it impairs it so but some virus can still be passed. What is a likely outcome of only impairing transmission; selection of more virulent strains of dengue Zika and chikungunya?

    • Wolbachia already naturally exists in the environment, unlike GM mosquitoes. In the example of the fruit fly given by John Jones, the Wolbachia in the fruit flies was discovered by Michael Turelli. The evolution was also discovered by Turelli, et al. as can be seen in, “From Parasite to Mutualist: Rapid Evolution of Wolbachia in Natural Populations of Drosophila”

      Yet, Turelli is a huge supporter of using Wolbachia in Aedes aegypti. From a Washington Post article:

      “We could tell everybody with a straight face that they already have this bacterium in their house,” said Michael Turelli, a University of California, Davis evolutionary biologist who collaborated with the Australians. “That helped get community buy-in.”

      For at least two decades — since crucial observations made by Turelli — scientists have eyed enlisting Wolbachia in the war against mosquito-borne diseases. In the late 1980s, Turelli and a colleague discovered Wolbachia in fruit flies in Southern California orange groves. After observing the reproductive advantage the bacterium provided the flies, they watched Wolbachia “spread through California like wildfire.”

      This rapid spread made a big scientific splash — inspiring researchers battling insect-borne diseases to search for Wolbachia strains that could protect against diseases.
      That work is now poised to pay off against dengue fever…

      Still, Turelli said Wolbachia carries a huge potential for dramatically reducing or even eliminating tropical diseases. As demonstrated in Australia, small releases of Wolbachia-carrying mosquitoes can quickly blossom, expanding outward in a wave that replaces that existing population. Calculations that Turelli will publish next month in the journal American Naturalist show that flipping the mosquito population in a small area — one square kilometer — will start a Wolbachia wave that could blanket an entire country “in years, not decades,” he said.

      “This is going to be a major industry,” Turelli predicted. “Many people are going to use Wolbachia to prevent the transmission of many diseases.”

      What John fails to recognize is that having Wolbachia spread is the whole point. Of course Wolbachia is going to try to survive and what better way to evolve than by increasing reproduction of the host so that Wolbachia spreads further? However, Wolbachia also must compete with other invaders using the same host such as dengue virus, zika, etc. and therefore it is an evolutionary advantage for Wolbachia to continue, and increase, it’s inhibition of viruses such as dengue, zika, etc. It would not seem likely that more virulent strains of dengue, etc. would occur. Viral inhibiting drugs have been used in HIV patients for 20 years without creating more a more virulent strain of HIV.

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