The information on this website is not a substitute for diagnosis and treatment by a qualified, licensed professional. At this point nvCJD has killed 24 people in Britain and one in France. Mad cow disease is a member of a family of rare diseases called transmissible spongiform encephalopathies, or TSEs. A prion is simply a particular kind of protein. All mammals have prions, and some non-mammalian species have them as well.
Prions are normal.
Without DNA, reproduction should not be possible. However, it is now becoming widely accepted that prions do reproduce themselves and do cause disease. The abnormal prions also cause other nearby prions to become folded into the same shape, thus creating more abnormal prions by a domino effect. Thus animals and humans can be carrying an infectious prion disease for months or years without showing any symptoms. Ruminants are animals that chew their cuds, including cattle, sheep, goats, deer and elk.