Bovine spongiform encephalopathy (BSE), commonly known as "mad cow disease," is a fatal disease that strikes the nervous system of cattle.
BSE is part of a group of diseases called prion diseases that occur in both animals and humans. The main animal forms are chronic wasting disease in deer, scrapie in sheep, and mad cow disease. In humans, there are three different prion diseases: Creutzfeldt-Jacob disease (CJD), also named sporadic CJD (sCJD), Gerstmann-Straussler-Scheinker disease, and fatal familial insomnia. In 1996, another form of CJD was identified; it has since been named "variant CJD" (vCJD). This variant form of CJD has been linked to the consumption of meat products infected with BSE.
Currently, no vaccine or treatment exists to treat BSE, and affected animals display a variety of neurological symptoms before they die (think of television reports showing cows having trouble standing up).
An animal with outward symptoms of BSE may survive for 2 weeks to 6 months, though it may have carried the disease for up to 8 years. BSE has an incubation period (the time between infection and development of symptoms) ranging from 30 months to 8 years, which is a long time for a disease to remain undetected.