Transmissible spongiform encephalopathies and the safety of naturally-derived biologicals

Late in 1986, a new neurodegenerative disease, referred to as bovine spongiform encephalopathy (BSE), was recognized in domestic cattle in southern England. Since then, tens of thousands of cases have been confirmed throughout the U.K. and the disease has also appeared sporadically outside of the British Isles. BSE belongs to a group of rare, progressive and fatal disorders of the central nervous system of animals and man caused by anomalous infectious agents whose properties are not yet full understood. Consequently, fears were raised about the possibility that the disease might constitute a possible health risk for humans. Minimization of potential contamination has thus become an issue of growing interest. This short review summarizes the main aspects of the problem together with the procedures developed to sterilize preparation of biologicals even from sources containing potentially high levels of contamination.