Further info:
We are informed by friends that the slaughtering and butchering requirements of both kosher and halal are such that there is no risk of brain or spinal tissue getting into the bloodstream and hence into the meat. Since brain/spinal tissue is the infection vector for BSE, it follows that kosher or halal beef from even an infected cow should be safe, or at the least very much safer. So if the risk of BSE concerns you, buy your beef from a kosher or halal butcher, or from the supermarket's kosher section if you have a supermarket near you with a kosher section.