How easy is it to transfer mareks disease from property to property. I want to go visit my sister but her flock has been affected by mareks disease. She only has 3 hens left out of her flock. If I go visit her and spend time on her property how likely is it that I can then transfer Mareks back to my property and risk my flock? If changed clothes before returning home, changed shoes, and stay away from her chickens will that be ok?