1865 check this site out , you'll become a cwd expert, some of the most interesting articles are about baiting and feeding, so game farms feed their animals, like cattle farmers feed thier cows and they get madcow disease, those animals are in close proximity to each other and the disease is contaigous, i don't know how things would be different in the wild, but i'd be willing to bet that the farm that slayer's talking about has to detroy the rest of their animals.
http://www.cwd-info.org/index.php/fuseaction/about.main