THE discovery that a rare brain disease in cows can mutate into BSE has given new life to the theory that mad cow disease started out in cattle, rather than crossing over from sheep.
When BSE emerged in British cattle in the mid-1980s, the leading theory was that they had initially contracted the disease by eating feed containing the remains of sheep infected with scrapie. Both BSE and scrapie are caused by infectious prions, misshapen forms of a normal brain protein. Having made this species jump, BSE would have spread as cattle carcasses were processed into animal fodder and fed…
