CJD is the disease that some people get when exposed to meat from cattle with BSE (bovine spongioform encephelitis??, I think), also commonly called "Mad Cow Disease." The article discusses genetic traits in humans, some of which were not know to previously by suspect to getting CJD.
The things about BSE, as I have understood to be the case, is that it will occur naturally in cattle, without being caused by outside sources. So, there is little to be done that can ensure we do not eat meat from cattle with BSE.