No, CJD occurs in humans, and usually only in Libyan Jews. Mad Cow disease is a different prion that is somewhat similar to CJD. They are related, all spongiform encephalatic prions are related, doesn't make them the same. But loosely, when a human gets "infected" people tend to say its CJD because its easier. CJD has very close resemblance with the Mad Cow Desease. Sure, it's not exactly the same, but it's not too far-fetched either.