‘Super-mosquito’ to fight dengue carriers set for US trials

Genetically modified mosquitoes tested in Cayman to control viruses like dengue and chikungunya borne by fellow-mosquitos may be released in the Florida Keys as well under a proposal in the United States.

Researchers at the Cayman Mosquito Research and Control Unit are preparing for a bigger release of the genetically modified insects.

The Aedes aegypti, a species of mosquito that showed up in the Caribbean island of Cayman in 2002, carries dengue and chikungunya.

Dengue is all too common in India; and if successful in Florida they could eventually help South Asia too.

The genetically modified version of the male mosquito is sterile, so females that mate with them won't reproduce. The idea is to push out the non-modified males so mosquitoes reproduce at a much lower rate.

Oxitec, a British biotech company, developed the mosquitoes and first tested them in London's East End in 2010.

British and local researchers found that the 3.3 million genetically modified bugs released over 23 weeks in a small area of East End helped reduce the mosquito population in the test area by as much as 80 per cent.

The genetic modification uses a theory tested in the 1970s when mosquitoes were radiated to sterilise them; but the radiation killed most of the mosquitoes, according to research published in the journal Nature Biotechnology.

Alan Wheeler, with the Cayman Mosquito Research and Control Unit, said he has been in touch with his counterparts in Florida about what he sees as the success of the program here. ''The Keys have a very similar environment to what we have here,'' he said, ''and what works in the Keys works in Cayman and vice versa.

''We are planning to go ahead with a controlled release here,'' Wheeler added. He hopes the program will be ready this summer. Of course it will need a number of permissions for the mosquitoes to be actually released in the atmosphere.

The new release will still be a research trial, but Wheeler said it will be an operational trial. He said the larger scale trial expects to see a marked decline in mosquitoes. A site has not yet been selected for the new research trial, he said.

Oxitec researchers recently finished a trial in Panama, which they said knocked out 90 percent of the mosquito population in a small urban area west of Panama City.

Dengue is a dangerous, potentially deadly virus with no vaccine or treatment. It shows up in most tropical areas, and the World Health Organization reported more than 2.3 million cases in 2013, and 40 percent of the world's population is at risk. Cayman has had a handful of locally transmitted dengue cases in recent years.

Chikungunya is much more prevalent in Cayman, with 43 cases contracted locally in the past year. The chikungunya virus causes fever and severe joint pain. There is no treatment for the virus other than treating the symptoms.