The agents responsible for transmissible spongiform encephalopathies or prion diseases target the central nervous system, but their unique nature and pathophysiology has meant that prion diseases have made an impact in disciplines as diverse as dentistry and transfusion medicine, in large measure because of their resistance to decontamination by conventional means.¹

In 1996, a new variant form of Creutzfeldt–Jakob disease (CJD) was described in the UK that preferentially affects young adults, resulting in a disease that often presents with psychiatric symptoms progressing to ataxia, dementia and terminating in akinetic mutism.² The cause of this disease was proposed to be oral exposure to the bovine encephalopathy (BSE) agent, and subsequent studies have only served to strengthen this link, with no credible alternative explanation having been proposed.^3–6 All human prion diseases are progressive and uniformly fatal neurodegenerative conditions, and, in the case of the acquired forms (iatrogenic CJD and kuru), associated with potentially very long incubation periods.⁷ Host genetics substantially influence these diseases: familial prion diseases are closely associated with mutations in the prion protein gene (PRNP), and the methionine /valine polymorphism at PRNP codon 129 appears to influence susceptibility, incubation period and in some respects disease phenotype.⁷

Our understanding of the pathogenesis of prion diseases has been greatly aided by the development of methods to detect and localise abnormal forms of the prion protein (PrPSc), which is the major, if not the sole, component of the infectious agent.⁷ Variations of standard immunohistochemical methods and Western blotting that use protease digestion and other discriminant steps to distinguish between the ubiquitous normal form of the prion protein (PrP^C) and PrP^Sc have been used. With such tools, the distribution of this protease-resistant …