Many medical professionals have said Lyme disease isn’t in Colorado. It is, though. My last tick bite was on the 4th of July trail and I had a huge bull’s eye rash, which my PCP missed.
My Lyme doctor said several years ago that ticks carrying Lyme disease are prevalent in the Tetons.
I don’t know if they’re surviving the harsh temps in winter or reintroduced every spring by migratory birds. My bet is surviving harsh winters like they do in Canada.
I don’t think there are enough birds, possums, etc. to eat all of the ticks. They have lots of babies. And the eggs can get infected before they hatch. So they can be infectious upon the first blood feeding. I never saw a tick on my arm so I guess it was a nymph.