Transmissible Spongiform Encephalopathies (TSEs), also known as prion diseases, are neurodegenerative diseases that affect the central nervous system of both humans and animals. All TSEs are invariably fatal and are characterized by a long incubation period, slow progression and the presence of lesions in central nervous system tissues. In addition, a modified protein, known as a “prion”, PrPres or PrPsc (res=protease-resistant; sc=scrapie), has been detected in all affected animals. Prions accumulate in nerve cells, ultimately causing their death, and therefore play a key role in the development of the degenerative lesions.
To date, the following TSEs have been recognized in animals: scrapie of sheep, goats and mouflon, bovine spongiform encephalopathy (BSE), transmissible mink encephalopathy (TME), chronic wasting disease (CWD) of deer, feline spongiform encephalopathy (FSE). The best known and most common among these diseases are scrapie and bovine spongiform encephalopathy (BSE). Indeed, scrapie is quite common in Europe (and endemic in the United Kingdom), and BSE has received worldwide attention since a massive outbreak started in the UK in the mid-1980s, especially after it was recognized that the disease can be transmitted to humans, through the consumption of contaminated animal products, in the form of a new variant of Creutzfeldt-Jakob disease (nvCJD). Further information on other TSEs is available on the website of the National reference centre for animal encephalopathies (CEA), at the Istituto zooprofilattico di Piemonte, Liguria e Valle d’Aosta.