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Safe Handling of Transmissible Spongiform Encephalopathies Specimens in the Histopathology Laboratory

Abstract Creutzfeldt-Jakob disease (CJD) is the most common form of the human transmissible spongiform encephalopathies (TSEs), a term that describes a fatal degenerative condition of the central nervous system, and has a worldwide death rate of about 1 case per million people per year. Approximately 90% of CJD cases are classified as sporadic, whereas approximately 10% are familial. It is the <1% of CJD cases that result from iatrogenic exposure from direct inoculation, implantation, or transplantation of infectious material that concern laboratory personnel. A consistent theory of TSEs is that a normal neuronal membrane protein-prion protein encoded by a gene on chromosome 20 and composed solely of protein becomes altered to a protease-resistant form accumulates in brain and the central nervous system and is exhibited by the replacement of normal neurons (photo A), with microscopic vacuoles (photo B) the feature from which TSE derives its name. Prions have exceptional resistance to chemical and physical decontamination methods. The infective agent is not inactivated by tissue fixatives or common disinfectants, and some infectivity may survive standard laboratory autoclaving methods (e.g., 121°C for 15 min). Therefore, it is prudent for the histopathology laboratory to take a precautionary approach for safe handling and processing of brain specimens from known or suspected cases of CJD to protect against possible TSE transmission to laboratory personnel (The J Histotechnol 30:81, 2007). Submitted February 15, 2007; accepted with revisions March 20, 2007.