Panama Considers Sterilizing Mosquitoes to Combat Dengue

Weeks after Panama’s Health Minister, Javier Diaz, declared that the country was experiencing a “dengue epidemic,” Panama approved the evaluation of a novel tool to combat the dengue mosquito. It involves mass-rearing large numbers of male mosquitoes that are genetically modified so that their offspring cannot reproduce, which reduces the population.

Panama is collaborating with Oxitec, a British company that is currently waiting for approval from Spanish authorities to use the same technique in Spain to control the olive fly.

Oxitec has built upon the Sterile Insect Technique (SIT), which has been used for more than 50 years in the United States according to the International Atomic Energy Agency. Using SIT, the males have traditionally been sterilized by being exposed to radiation. However, Oxitec’s sterilization process instead relies on genetic manipulation of the insect’s genome. According to their web site:

“One major problem [with SIT] is that irradiating insects can damage their health … Oxitec’s innovative new genetic methods have the ability to improve mating competitiveness of the ‘sterile’ males and will enable a greater range of insects to be used in SIT programmes. Using genetic modification, a ‘sterile’ factor has been inserted into the insect’s genome, which ensures that whilst the modified insects do have offspring they will not survive to the reproductive stage.

Oxitec’s genetically modified insects don’t require radiation to be made sterile, so the males are fitter — in effect, more ‘attractive’ to females — than irradiated insects. This enables a much more cost-effective and successful release programme.”

Lat year an Oxitec trial in Brazil carried out in an urban environment achieved a 96% suppression of the dengue mosquito.

Concern over Panama’s growing number of cases has highlighted the need for new, more effective ways of controlling the dengue mosquito, Aedes aegypti, which transmits the disease.

Following a recommendation from Panama’s National Biosafety Committee, and formal approval from the Ministries of Agricultural Development and Commerce and Industry, an open-field evaluation of Oxitec’s mosquitoes will be conducted by the Gorgas Institute.

“Dengue fever is a growing concern in Panama, and the tools we have for controlling the dengue mosquito are limited and increasingly ineffective,” said Nestor Sosa, director of the institute. “There is a real need to explore additional, more effective technologies for combatting this pest and tackling the dengue problem.”

The evaluation will begin this spring in a residential suburb of the Arraijan District, west of Panama City, and is expected to run for several months. In previous evaluations of Oxitec’s mosquitoes, dengue mosquito populations in the Cayman Islands and in Brazil were supressed by over 90% in the area of release. The Arraijan District suffers from a high incidence of dengue fever, with dengue cases in Panama as a whole tripling between 2012 and 2013.

“Oxitec’s approach has already shown great promise. It’s a technology that is completely specific to the dengue mosquito we are targeting, and by helping to reduce our reliance on chemical pesticides, it could also be beneficial for the environment,” Dr. Sosa said. “We’ve worked closely with Oxitec and with local communities here in Panama to bring this project to the evaluation stage, and I’m delighted that we’re now able to take this next step. People in Panama know as well as anyone the toll that dengue fever can exact on a community: this exciting new technology may offer real hope for a future free from dengue.”

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