I don't eat beef in any great quantities except in meatballs or frankfurters etc. but since even gelatine is supposed to be a theoretical carrier I don't think I am at any less risk than somebody who eats it every day.

Meatballs and frankfurters (store bought ones at least) likely carry a higher BSE risk than a good steak. The process of "mechanical recovery" of meat used in meat balls and the like means you are far more likely to end up with the BSE infectious agent in the resulting "meat" than with a steak.