Florida Keys residents appear to be gaining momentum in their campaign to prevent Oxford-based Oxitec in the UK from releasing genetically engineered mosquitoes to help control the population of wild mosquitoes that can carry Dengue fever.
What Are Oxitec's Genetically Engineered Mosquitoes?
The Dengue virus is carried by Aedes aegypti mosquitoes. Oxitec has engineered these mosquitoes with a gene activator that responds to the antibiotic tetracycline. The activator remains silent when the mosquitoes are regularly feed the antibiotic. However, once tetracycline levels fall in the mosquito, the activator gene turns on and "floods the system" by activating lots of unnecessary genes. These additional active genes overload the biological processes in the mosquito and they die as a result. The activator gene is not a toxic molecule. It is just its presence at high concentrations in the mosquito that is disruptive, like "throwing a wrench in the machine."
The Oxitec mosquitos also express a fluorescent protein derived from jellyfish that make them easy to identify.
Why the Concern About Dengue?
Dengue fever is a very serious disease that has been virtually wiped out in Florida due to vigilent control of the mosquito population. However, in 2009, Florida had its first case of Dengue in 79 years. Just under 100 cases were identified in 2009 and 2010. In other parts of the Caribbean there are several thousand cases a year so it is an ongoing threat. There is no specific treatment to cure Dengue.
How Do Oxitec's Mosquitoes Control the Native Population?
The trick to reducing the population of native mosquitoes is to release a large number of the male mosquitoes with the lethal activator gene. These mate with the local population of female mosquitoes. The larvae produced from these couplings have the same activator gene as the engineered mosquito. Since the larvae don't have access to tetracycline to keep the activator silent, though, they soon die which reduces the population of the next generation of mosquitoes. The released male mosquitoes also die off rapidly after doing their thing with females.
Oxitec Mosquitoes Have Been Released Before
The Florida release of the mosquitoes would not be the first for Oxitec. The company has released the mosquitoes previously. In the fall of 2009 they did the open air release of the engineered mosquitoes in the Cayman Islands, and followed up with a larger study the next summer. The company was criticized for pursuing the studies under somewhat of a "hushed" process but Oxitec emphasized that the releases were done in conjunction with Mosquito Research and Control Unit (MRCU) of the Cayman Islands and claim that the lack of newsworthiness is the only reason few outside the Cayman Islands knew of it. The company reported an 80% reduction in the Aedes aegypti mosquito population in the 16-hectare test site where the mosquitoes were released.
In contrast to the relatively little notoriety of the Cayman release, the proposed release in Florida Keys is generating quite a commotion. An online petition started in March has gathered over 100,000 signatures, and the growing concern of the residents was covered in the latest issue of Nature. For a more background on the Florida situation, take a look at the detailed article in the Miami New Times News.
Lack of Clear Regulatory Guidelines
One of the important issues this situation has brought to light is the lack of regulatory oversight for these sort of genetically engineered organisms. Criticism that Oxitec has approached field testing of the mosquitoes with too much secrecy should, perhaps, be tempered by the fact there are not clear guidelines how to proceed with this sort of testing. In all cases, it seems that Oxitec has worked with local authorities to obtain the necessary approvals to proceed with the testing.
With the current plan in Florida, they are working with Florida Keys Mosquito Control District, who in March 2010, applied to the USDA to get import approval to move forward with the release. Eighteen months later in they were notified that the USDA does not have jurisdiction over the matter since it not related to agriculture or livestock.
Reportedly, the Florida Keys Mosquito Control District have subsequently contacted multiple government agencies, including the Centers for Disease Control and Prevention, the U.S. Department of Agriculture, and the Environmental Protection Agency to try to find the one that has responsibility for this sort of program. None have accepted jurisdiction. Oxitec and the Mosquito Control District are waiting to hear from the FDA. If they also do not claim responsibility, then perhaps no approval is required to proceed. This uncertainty regarding how the release is being controlled is what makes the residents of the Florida Keys anxious that it could happen without notice.