Some are ancient, but have adapted to thrive in some human environments, but have spread well past their original areas by colonialism, slave trade, shipping, and war. The idea that modern mosquitoes are some "natural" ecosystem element is pretty funny. Perhaps they have destroyed the habitat that once existed and driven out competing species which once fit into the niche, but they are in most places relatively modern in ways other biting flies are not. The growing effects of malaria are not only on humans, but other animals including both chimps and reptiles as well.
Anopheles/Aedes/Culex mosquitos are the grey goo of insects, driving other flies, midges, and even mosquitos (which local fish and larval predators have evolved with) to exinction. Treat them like the infection they are.
I remember someone moaning about how we had driven a species to extinction.
We're a funny lot, really. I've learned not to take us too seriously; especially the folks that take themselves very seriously.
Nobody was much concerned when we eradicated another infectious virus. Unlike Smallpox there was no "military rationale" for keeping copies on ice, so Rinderpest is gone. It appears that its close human relation, Measles, will be around for a long time though because "I don't believe in facts" trumps "My child has died of a preventable disease". So that's certainly evidence for you're "We're a funny lot" theory.
250 million people have malaria, and 600k, mostly children die from it yearly.
And yet, I see a lot more people defending the mosquitos than the humans.