CWD isn't bound by climates. All it needs is a warm blooded host(s) to proliferate. It is predominant in areas that allow baiting and where penned deer or ruminates for that matter are kept in close proximity to one another. . The reason you don't see it in the north is because deer densities are usually much lighter, so one doesn't have that overcrowded, close animal to animal contact like southern climes where overpopulation is prevalent.