Rickochet been there done that. Drove a tow truck for a few years, we got a call about a trailer down a hillside. Wasn't loaded properly, and it came off the truck. Tore up a lot of ground, we were tramping up and down that hillside for many trips. Later learned that hillside was covered in poison oak. I got it on 65-75% of my body. Dr's office gave me steroids, and some cream that was supposed to help, it didn't do much. Lower 1/2 was far worse that my upper half. I am very familiar with poison oak, and stay away from it as much as possible.
I also caught the stuff last year when I was digging up a sprinkler head next to the fence by the poison oak. I knew what the roots were from, and I did my best to clean the oils off my hands and tools before I took a leak. Apparently I didn't do a good enough job. That was the time I learned of Zanfell. Holy shit that made life better, poison oak cleaned up faster than any other time.