An epidemic of BSE arose among cattle in the United Kingdom in the 1980's.
Prions cause proteins normally found in the brain to twist into an abnormal shape.
The abnormally shaped protein then induces other neighboring proteins to twist into the abnormal shape. Over time, large quantities of the abnormally shaped protein accumulate in the brain, and normal brain function is impaired. There is currently no treatment known to interfere with this process. Therefore, the only way to prevent prion-mediated diseases is to prevent introduction of the prion to begin with. Recently, a different prion disease was found in a few people in the United Kingdom.