From a random mailing list that I'm on:
"I sit in the steam room at the gym occasionally. With a recent management change the steam room now gets so unbearably hot that my feet will literally scald if I sit too close to the heater. Whenever I sit in that damp room slightly larger than an elevator, the same thought goes through my head, "I wonder if this place is extremely clean or a cesspool of bacteria." I didn't pay close enough attention in rudimentary science class to know whether a room that hot and damp would kill bacteria or be the perfect incubator for it. Regardless, I figured it out today when the guy sitting in there blew his nose several times and wiped it on the seat. He was also trying to read a newspaper that was soaking wet from the steam, and I couldn't decide which of his behaviors was more eccentric."
I'm not as keen on the steam room myself for those same concerns - but the sauna was out of commission this AM. The Y seems to be pretty good about cleaning the whirlpool/steam/sauna rooms and I'm generally one of the first in there each day so I figure my odds are a little better.
I've read anecdotally that the heat helps with Lyme treatment - Borellia apparently doesn't survive much above 35-40C - so the thought is 70+C will help pasteurize me a bit at a time.
I'm doing a number of different things, so can't say that the heat is helping, but I've been feeling very good since the beginning of the year and it doesn't seem to hurt. But that could be the pro-biotics or the doubled up anti-biotic regime - my daily dose is no longer measured in mg, but in g.... :-)