[1] Erasmus MC, Dept Epidemiol & Biostat, NL-3000 DR Rotterdam, Netherlands
[2] Mesos Med Ctr, Dept Neurol, Utrecht, Netherlands
[3] Western Gen Hosp, UK Natl CJD Surveillance Unit, Edinburgh EH4 2XU, Midlothian, Scotland
[4] Univ Utrecht, Med Ctr, Dept Pathol, Utrecht, Netherlands
[5] Univ Hosp Marques Valdecilla, Dept Neurol, Santander, Spain
[6] Erasmus MC, Dept Internal Med, Rotterdam, Netherlands