Simply saying "unintended consequences" means doing nothing, ever.
WHO says "severe dengue is a leading cause of serious illness and death among children in some Asian and Latin American countries." After we don't have so many dead kids, some of them can grow up, and you can ask them how they feel about whatever unintended consequences there are.
There are always consequences, both intended and otherwise. It's best to go in with eyes open, having considered every possible consequence of our actions, and make a cost-benefit decision.
When human lives are at stake, notably the millions lost to malaria, dengue, and other mosquito-borne illnesses, the unintended consequences had better be pretty massive to make a difference.
E.g. Rabbits in Australia http://en.wikipedia.org/wiki/Rabbits_in_Australia#Biological...