Blood infectivity, processing and screening tests in transmissible spongiform encephalopathy.

Surprising advances have been made in the areas of blood infectivity, infectivity removal and, especially, blood screening tests for transmissible spongiform encephalopathy (TSE) in the past few years. In fact, if anyone as recently as last year had suggested that a screening test for preclinical human infection might be available before the end of 2005, the statement would have been met with smiling disbelief. Nevertheless, it can be confidently predicted that the diagnostic misfolded 'prion' protein (PrP(TSE)) will soon be reliably detectable in blood during the symptomatic phase of disease, and it is highly probable that it will also be detectable in blood from at least a proportion of infected individuals during the preclinical phase of disease.