Mosquito trial in dengue fever battle

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OXFORD, England, Nov. 11 (UPI) -- A field trial in the Caribbean using genetically altered mosquitoes to combat the spread of dengue fever has been a success, researchers say.

The use of the genetically modified insects to sabotage wild Aedes aegypti mosquitoes, which spread the viral fever, took place on the island of Grand Cayman, NewScientist.com reported.

By the end of the six-month trial on a 40-acre plot, populations of the native insects had plummeted, researchers said.

"It's a proof of principle, that it works," says Angela Harris of the Grand Cayman Mosquito Control and Research Unit.

The MCRU conducted the trial with U.K. company Oxitec that bred the modified mosquitoes.

Oxford-based Oxitec breeds millions of males carrying an altered gene that is passed on when they mate with females. The lethal gene prevents the larva and pupae from growing properly and causes them to die before adulthood, breaking the insects' life cycle.

In the six months of the trial, the researchers released 3.3 million males in batches of 50,000.

"Males don't bite, so no one gets sick," says Harris.

Dengue fever infects 50 million people annually and kills 25,000. In the past year, dengue has reappeared in the United States for the first time in 65 years, and in southern Europe, NewScientist.com reported.