I'm sure you recognize the shiny leaves. It's poison ivy. Perhaps you found it in a handful of weeds as you gardened. Perhaps you brushed against it while strolling in you local wildlife center. Maybe... Maybe your CAT rubbed it on your face! HISSSSS
How do we cats do that? Easy. According to the John Hopkins University Student Health and Wellness Center, only humans and other primates are sensitive to the nastiness in poison ivy, a chemical called urushiol.
http://www.jhu.edu/~shcenter/poisonivy.html
According to Mohan JE, et al, at the Department of Biology, Duke University, climate change may make poison ivy into a bigger problem for you. We already know that CO2 stimulates growth in plants. Mohan says, '... high-CO2 plants produce a more allergenic form of urushiol. Our results indicate that Toxicodendron taxa will become more abundant and more "toxic" in the future, potentially affecting global forest dynamics and human health'.
http://www.ncbi.nlm.nih.gov/pubmed/16754866?dopt=Abstract