Introduce a nation-wide program to fight against mosquitoes, and allocate a separate department to work on it, instead of the council.
I have traveled to Vietnam, where the weather is very similar to Sri Lanka, but most of the areas were successfully free of mosquitoes. As per my discussion with one of our tour guides, I learned that they grow lemongrass in their front and back yards to protect themselves from mosquitoes.
I suggest to do more research on this.
~ Dasun Abeywardana