It's not completely true that the mosquitos don't carry things here. We do have something called Tularemia [1] (Harpest). Also it seems the first mosquitos for the season are more potent that later during the year.

And for personal anecdotal evidence, my wife gets more problems with mosquitos here than I do. When we visit her home country I get more problems than she does.

[1] https://en.wikipedia.org/wiki/Tularemia