Prion Positivity Detected by Real-Time Quaking-Induced Conversion (RT-QuIC) in the Cadaver of an Elderly Woman Subjected to Forensic Autopsy.

Prion diseases are fatal neurodegenerative disorders. Previous studies have indicated the presence of "prion carriers" who remain asymptomatic, but scrapie prion protein (PrP(Sc)) has begun to accumulate in the brain. Indeed, we identified an undiagnosed case of prion disease in a cadaver used for the anatomical practice of medical students. These findings suggest that cadavers for autopsy may occasionally include prion carriers. In the case of forensic autopsy, staff cannot sometimes obtain the background information of the dead bodies, and the risks for exposure to prions can be higher than in other autopsies. To ensure the safety of forensic staff, we conducted prion screening tests on the brains of the cadavers. One case demonstrated positive results in the real-time quaking-induced conversion (RT-QuIC) assay, which amplifies abnormal prion proteins in vitro. This result indicates that asymptomatic cases exist not only in cadavers but also in living individuals. The risk of prion infection via medical procedures including autopsy is not high, but prions are lethal pathogens that are difficult to decontaminate. Medical staff should consider that the cadaver or patient can be a prion carrier regardless of whether they are symptomatic or asymptomatic. This type of prion investigation allows us to obtain information on pre-symptomatic cases of prion disease, which could contribute to enhanced medical safety and provide new insights into human prion diseases.