That’s true, but the areas with the most cases are NM and AZ. My state is more damp and our last human case was in 1984. Don’t know that climate is a factor but it might be.

To your point, as one descends from the Sierra Nevada to the east it becomes desert. Reno to the northeast of Lake Tahoe is not that far. I was thinking mostly that fleas do not seem to do well where it snows.