1. Infection Research Group, Glasgow Dental Hospital & School, 378 Sauchiehall Street, Glasgow G2 3JZ, Scotland, UK;
2. National Creutzfeldt-Jakob Disease Surveillance Unit, Western General Hospital, Edinburgh EH4 2XU, Scotland, UK; and
3. Eastman Dental Institute for Oral Health Care Sciences, University of London, 256 Gray’s Inn Road, London WC1X 8LD, UK;