A prion is a misfolded protein that can make other proteins of the same kind misfold. Prion diseases are rare, and they affect animals as well as people. The best known are scrapie in sheep and goats, bovine spongiform encephalopathy (BSE, also called mad cow disease) in cattle, and chronic wasting disease (CWD) in deer, elk and moose. A few others have been described in mink, zoo animals and cats. Animal prion diseases usually spread through contaminated feed or through contact with infected animals and their surroundings.
Eating beef from cattle with BSE caused variant CJD in people, mostly in Britain in the 1990s. Scrapie and CWD have not been linked to human disease, though scientists keep studying whether CWD could ever affect people. If you want to read about one disease, start with chronic wasting disease, BSE or scrapie. For the wider picture, see causes and risk, what a prion is and all prion diseases.
Explore
- BSE (mad cow disease)BSE in cattle explained plainly: what it is, the controls that exist now, the link to variant CJD in people, and what the risk looks like today.
- Chronic wasting disease (CWD)Chronic wasting disease in deer and elk, explained plainly: where it is found, how it spreads, what is known about risk to people, and advice for hunters.
- ScrapieScrapie in sheep and goats explained plainly: signs, how it spreads, the role of genetics, eradication programmes, and what is known about risk to people.