Best way to do it is to use your DNA points to boost transmission types and devolve any symptoms as they mutate so nobody notices your infection until you get a message saying that there are no healthy people left in the world - that way they haven't started trying to cure it
Then once everybody is infected, devolve all your transmission types to boost DNA points and hit them with a string of symptoms along with some lethal symptoms and watch them all drop like flies
Use DNA points collected from deaths to boost drug resistance periodically as the cure progresses but you shouldn't need to evolve that too much before you anihilate everyone