Interesting article in the Daily Mail, highlights the fact that this fatal disease is still baffling scientists, what is well publicized is that prions cannot be destroyed by man, therefore, it is conceivable that we are being exposed via almost anything, air, surgical instruments, blood products, water from buried BSE carcasses, vaccinations.
here is a link to the DM story:
http:www.dailymail.co.uk/news/article-1347003/How-mad-cow-disease-spread-air.html