1. MRC Prion Unit and Department of Neurodegenerative Disease, UCL Institute of Neurology, The National Hospital for Neurology and Neurosurgery, Queen SquareLondon WC1N 3BG, UK
2. Centre for International Health, ABCRCHealth Research Campus, Shenton Park, Curtin University, GPO Box U1987, Perth, WA 6845, Australia