Introduction

Laboratories concerned with the diagnosis of dementia, and research into dementing conditions, will come into contact sooner or later with brain tissue from patients in whom the dementia is due to the presence of an infective agent. Concern about the possible presence of such microorganisms is one important reason for ensuring that good laboratory practice and carefully devised safety precautions are implemented wherever dementia diagnosis and research is undertaken. This chapter is concerned with discussion of the likely hazards and risks involved in this kind of work and the strategies for safe practice which should be in place.

The concept of hazard focuses on the level of danger associated with the particular agent under consideration, while risk depends not only on the nature of the hazard but also on the likelihood of exposure (ACDP, 1995a). Consideration of the hazards and their likely risk in relation to dementing illnesses forms the basis of the containment protocols which have been developed to limit the danger posed by these hazards. The general principles of containment need to be considered in relation both to the process which is under way, for example the examination of a biopsy or the conduct of an autopsy, and the setting in which that process takes place, for example the laboratory or the post-mortem room. Laboratories which specialize in examining dementia cases may well be part of a formally constituted brain bank that stores tissues for research purposes and also dispatches tissue samples to the wider research community (Cruz-Sánchez & Tolosa, 1995). Particular safety precautions may well apply to individual brain banks that focus on infective dementias (Bell & Ironside, 1997).