1. MRC Prion Unit and Department of Neurodegenerative Diseases, UCL Institute of Neurology, National Hospital for Neurology and Neurosurgery, Queen Square, London WC1N 3BG, UK
2. Papua New Guinea Institute of Medical Research, PO Box 60, Goroka, Eastern Highlands Province, Papua New Guinea
3. International Health Research, Curtin University, Room 108, Shenton Park Campus, GPO Box U1987, Perth, Western Australia 6845, Australia