I've learned to spot poison ivy from a mile away. I've never actually caught it but my wife and father are very allergic. Best thing is to learn to recognize it, then you can eliminate it from your yard. They sell all sorts of poison ivy killers but to be honest I think Roundup works just as good, you have to spray it every few days for a while. It often seems like it is unaffected but eventually it will turn yellow, then wither, and die out. The vine/roots will still be there, so you want to go back and spray that. Just when you think its gone, it will come back most likely in the same spot so you have to hit it again early in the season. It's best to do all this sooner or later, because once it gets into your yard it loves to keep spreading. It loves to climb fences and tree trunks as well.