My OEGB pullet, Missy, has been showing SOME symptoms of Marek's. I'm not sure. It's been 2 weeks, and she can't walk or see very well. All the other birds in my flock are perfectly fine, soooooo........ How long would Marek's take to kill a bird? She might not have Marek's, but I want to be ready and prepared when the time comes. And if it hasn't killed by now, it may not be Marek's. Please answer quick!