Before a business trip to England, I was putting pine straw (purchased at a home store) in my backyard garden.

I had P.I. but it did not 'bloom' 'until I was in England. Very Nasty reaction too.

Issue: Went to Dr office and told them I had P.I. - was given medicine that did not work - took a few days (extremely bad days of pain) until I found resolution.

Point is:  The UK does NOT have Poisen Ivy - at least that was what I was told by the doctors.  Using Internet, I provided a doctor info on PI and was finally given correct prescription.. 

Moral of the Story:  1) Carry tecnu or whatever remedy with you at all times ( it is extremely effective )  ; (2) Just because you tell a doctor something, doesn't mean he UNDERSTANDS it - ... It is all about CONTEXT!!