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17/06/2016, 17:00

Imagine there are no mosquitoes

The possibility of DNA-modified Aedes aegypti mosquitoes being released in Key Haven in the Lower Keys as a test to reduce the population of the species that carries Zika and dengue:

The word "trial" can imply something untested, but the Oxitec self-limiting mosquito does not fit that description. In fact, it is quite the opposite.

Extensive research and testing has been conducted by Oxitec and independent collaborators for more than 14 years. These efforts have led to four different countries granting regulatory safety approval for outdoor field trials or use of Oxitec's mosquito.

Since 2010, five such trials have taken place and the world's first program in partnership with a Brazilian municipality was launched last year and recently expanded. The Cayman Islands has also just announced it is starting a multi-phase rollout of Oxitec's self-limiting mosquito on Grand Cayman, with plans in place to help reclaim the entire island from the disease-carrying Aedes aegypti.

In 2016, Oxitec's solution has been recommended by the World Health Organization for deployment in operational conditions, and the Pan American Health Organization declared it will provide technical support for countries that wish to implement Oxitec's mosquitoes. Additionally the U.S. Food and Drug Administration released a preliminary finding of no significant impact for the investigational trial proposed in the Florida Keys, which followed a thorough environmental assessment review by the FDA and two additional agencies, the Environmental Protection Agency and the Centers for Disease Control and Prevention.

We are pleased by this support and findings from these agencies and regulatory bodies this year, as well as the local support and many positive statements made during the FDA's public comment period. Yet we have heard questions as well and want to make sure we address as many as possible.

The first is why have dengue cases increased in Brazil after our successful trials there? Our trials in Brazil covered small areas, between roughly 1,000 and 3,000 residents across no more than .15 square miles. Aedes aegypti mosquitoes fly only a few hundred yards in their lifetimes, making these defined regions quite good to test how successful Oxitec's self-limiting mosquito can be.

The results across all three trials showed an unparalleled 90 percent suppression of the local populations of disease-transmitting Aedes aegypti mosquitoes. Yet the trials were not designed to follow health outcomes in these small areas, and the outcome of any effect on disease incidence was not investigated.

In April 2015, Oxitec's first program in partnership with a municipality was launched to cover an area of 5,000 residents in the CECAP/Eldorado neighborhood of Piracicaba, Brazil. By year's end, the project had decreased the population of Aedes aegypti mosquitoes in the treated area by ~82 percent.

Additionally, as recently noted by the health secretary of Piracicaba, from July 2014 to 2015, CECAP/Eldorado had 133 dengue fever cases. From July 2015 to May 20, 2016, the same neighborhood had only seven confirmed cases. These favorable results led to the expansion of the project in May to protect an additional 60,000 people.

The second question is is it possible for the self-limiting gene of the Oxitec mosquito to be passed to humans through a bite? The answer is no.

Before we get into the science behind that definitive response, it should be noted that Oxitec sorts its mosquitoes to release males, and male mosquitoes do not bite (only female mosquitoes bite humans to get nutrients they need from blood to produce eggs).

Our sex-sorting methods are best in class and work extremely well, yet on the off chance that a female Oxitec self-limiting mosquito bites someone, it would be just like a bite from a wild Aedes aegypti. Why? The two proteins that have been stably integrated into the mosquito genome are non-toxic and non-allergenic and not found in female saliva, therefore they cannot enter the human blood stream during a bite. So not only are they non-hazardous to human health, humans are not exposed to them.

Importantly, the numerous diseases that the nonnative Aedes aegypti transmit present a very real danger to people around the world, including Keys residents and tourists, and our solution has proven effective in fighting this mosquito in multiple trials across the globe.

We feel passionately about the importance of controlling Aedes aegypti but we also want Keys residents to better understand the technology so they will feel completely comfortable with this trial. So keep the questions coming; we're here to answer them.

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