Someone (a nurse in fact), once asked me whether having an anti-virus programme on my computer had helped me to stop getting sick! Talk about the Twilight Zone! I stumbled though when trying to define what a real virus is.
Foot and mouth (hoof) disease is a virus, right? BSE is not though, right? I've read numerous articles on the subject, but not one adequately explained the nature of disease.

If you want a laugh read this over-confident EU report on BSE:
http://europa.eu.int/comm/food/fs/bse/bse20_en.html/