1. Division of Clinical Neurology, Nuffield Department of Clinical Neurosciences, Weatherall Institute of Molecular Medicine, University of Oxford, Oxford OX3 9DS, UK
2. Department of Zoology, University of Oxford, South Parks Road, Oxford OX1 3PS, UK
3. Department of Infectious Disease Epidemiology, School of Public Health, Faculty of Medicine, Imperial College London, Medical School Building St Mary’s Campus, Norfolk Place, London W2 1PG, UK
4. Department of Statistics, University of Oxford, St Giles’, Oxford OX1 3LB, UK
5. Department of Microbiology and Immunology, Rega Institute for Medical Research, KU Leuven - University of Leuven, Leuven B-3000, Belgium