In Brazil's case, as least, it's simpler than that.
Mosquito eradication used to be done at the federal level, with military like organization. It kept things in control.
A few years ago it has been re-assigned to municipalities. Not only are local authorities less equipped to handle it, but mosquitoes do not conform to city boundaries. If one city is doing a good job but it's neighbor isn't you're screwed.
There's probably lots to be done through technical advances, but most of this could be avoided using common sense.