**1. Introduction**

Prion diseases or transmissible spongiform encephalopathies (TSEs) are a group of chronic, progressive, and fatal neurodegenerative disorders that affect a variety of mammalian species. They include scrapie in sheep and goats, chronic wasting disease in deer and elk, bovine spongiform encephalopathy (BSE or so-called "mad cow disease") in cattle, and variant Creutzfeldt–Jakob disease (vCJD) in humans.[1] Since the term "prion" was coined by Dr. Stanley Prusiner in 1982,[2] the extensive research on prion diseases has investigated their molecular biology,[3] causes,[4] pathogenesis,[5] genetics,[6] types,[7] biochemical mecha‐ nisms,[8] and therapies,[9] among other aspects. A prion is a proteinaceous infectious particle that lacks nucleic acid.[7] Abnormal prions (PrPSc) are the pathologic isoforms of prions and are expressed in specified risk material (SRM) such as bovine central nervous system (CNS) tissue.[10] PrPSc has a high β-sheet content, is extremely resistant to heat and proteases, and is insoluble in non-denaturing detergents.[11, 12] Infection of prion diseases occurs naturally via

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the oral route as well as by blood transfusion and maternal routes.[13] This chapter reviews the research into two foodborne prion diseases, BSE and vCJD, related to their spread in cattle and humans, the contamination of SRM in meat, the relevant regulations, and the detection methods available for surveillance.
