I wonder if the ecology is out of balance, leading to larger mosquito populations than people would have seen a few thousand years ago. If the bird and bat population were five times, ten times larger, or if the swamps were less foul from plants adapted to the area (instead of invasives), maybe that would have made the problem less severe.
I don’t know about elsewhere but the local Salish peoples would shear specially bred dogs with very light fur. Something like Samoyed fur, but more fine. They’re probably extinct now.