A while ago, I posted what was then my best understanding of the whole beef safety issue, which was basically that the rogue prions were believed to be confined to brain and spinal tissue, and that therefore beef butchered in manners which do not intermingle brain and spinal tissue with the meat or introduce it into the bloodstream (specifically, kosher and halal butchering) should be, if not perfectly safe, then at least very much safer to eat.
This turns out not to be the case. The following is relayed from my sister in the UK. (Emphasis, where used, is mine.)
"Dad's right about the nerve tissue in general being suspect. The brain and spinal cord stuff comes from the earlier British outbreak, and the main reason they came up with it was as a means of avoiding the alternative of declaring all British Beef unsafe. It was quite a cynical move, and a lot of people decided to treat all british beef as unsafe anyway, as did some european countries, much to the anger of the British government. In my opinion the cynics were right, as these declarations about what was and was not safe to eat were being heavily influenced by pressure from the food and farming industry at a time when no-one had even 100% identified how BSE was transmitted. There was general outrage when the minister for food and agriculture at the time, John Selwyn Gummer, decided to use his six year old daughter as a political gimmick and had her televised eating a hamburger."
So, in short, if you want to be completely safe, you must regard all beef as suspect. Meanwhile, NPR is reporting that the cause of the Yakima outbreak has been putatively traced to a cow or cows bought from a Canadian breeder, where they are asserted to have been given contaminated feed. (What imbecile came up with the idea of feeding ground-up bits of dead cow to cows, anyway? They're herbivores, for crissake. Ruminants, even.) According to NPR, efforts are under way to track down every cow that came from this breeder. Whether they'll succeed remains to be seen.
I'd share data on the actual infection rate of BSE and chances of contracting vCJD, except that to the best of my knowledge there IS no hard data on infection rates. To the best of my knowledge, it's still all guesswork. About all we seem to know so far is that, at our current state of understanding of the problem, if you contract vCJD, you will die.
(Random thought: I wonder if the biological structure of the BSE prion is always the same? If so, reason says it ought to be possible to develop a genegineered antibody to it, which could then be used to fairly quickly test for the presence of BSE prions in any beef.)