I'd LOVE to find an answer to the question discussed in this thread. I got a really bad poison ivy rash on my right wrist 3 or 4 years ago (I'm pretty allergic, and got exposed to oil from one of the thick vines - it was nasty). The rash eventually went away with some steroid treatment, but ever since, I've felt a slight bit of itching there when I run hot water over the wrist.
Today, for the first time, the rash has actually come back. There are small blisters over a large area, the identical area to where I had the rash in the first place. I KNOW I haven't been re-exposed, so I can't fathom how this could even happen.
