Perhaps because "Mad Cow" disease has been an issue between the British public and medical experts for a few years now. The government has been telling people that there is nothing to worry about, everything is under control. The public questions the government's motives, and worries if they are really getting the real story. Well, now, after all those governmental reassurances that their health is not in danger, the US declares that they won't take blood from you if you've even VISITED there, much less, lived there. They Brits obviously would feel someone isn't telling them everything. In addition to the personal worry, they now feel as if they are from some third world pariah state, sanctioned by the US. Is their concern understandable? Meanwhile they are supposed to be reassured after statements like "We are dealing with a disease that may still be on the increase in terms of human disease, we are dealing with an organism that we cannot identify, and we are dealing with a disease that only causes symptoms several years after it is first transmitted." So much for reassurance.