I wonder if they have the same variation in reactions that people do? My sister was hyper reactive to poison ivy and I have never had a rash, despite romping everywhere she went as kids, and as an adult trekking through the woods without even knowing what it looked like. i am sure Ive contacted it, though... My sister would get the rash and then spread it all over herself through just the secondary contact. It can cause a reaction in mucas membranes, too.
I do think it could kill a chicken if she had an internal reaction, but that is just supposition. I have nothing to back it up.