In this Brazilian farm town where legions of people have suffered from dengue fever, a campaign is fighting back, releasing swarms of mosquitoes engineered to wipe out their own species.

As workers open plastic containers allowing millions of newly hatched Aedes aegypti mosquitoes to spread their wings and flutter into the sky, it seems counterintuitive. After all, this is the same pesky bug that transmits the dengue virus through a human-to-mosquito-to-human cycle that's surprisingly difficult to break.

The traditional defense is to kill these flying vectors with chemical insecticides. But that hasn’t worked in Brazil or other tropical countries where dengue is a leading cause of illness and fatality.

Last year, Brazil reported 1.4 million cases of dengue, which is endemic in three of the 12 host cities for this summer’s World Cup. There is no vaccine. The most severe form of the illness, dengue hemorrhagic fever, can lead to shock, coma and death.