I just read last night an interesting article about a field trial wherein genetically-modified male Aedes mosquitoes were released in an uninhabited forest somewhere in Malaysia to mate with mild female Aedes to produce larvae that eventually will die early without reaching its normal life span and therefore not reach adulthood. In effect, this will expect to decrease the Aedes population and cut down the incidence of dengue.
Anyway, the defense made were males have no capability to transmit dengue so the GM-mosquitoes will soon die without spreading dengue. If these GM-mosquitoes mate, the offspring eventually dies so the gene introduced to the modified mosquitoes are not passed on to future generations. So theoretically, it is believed that this is a safe move.
This debate will never end.
You can read more of this trial at The Independent website.