Department of Ecology and Evolutionary Biology, Princeton University, Princeton, New Jersey, United States of America.|Maxwell Institute for Mathematical Sciences, Department of Actuarial Mathematics and Statistics, Heriot-Watt University, Edinburgh, United Kingdom.|Department of Plant Sciences, University of Cambridge, Cambridge, United Kingdom.|International Federation of Red Cross and Red Crescent Societies, Geneva, Switzerland.|MRC Centre for Outbreak Analysis and Modelling, Department Infectious Disease Epidemiology, Imperial College, London, United Kingdom.|School of Public Health, University of Michigan, Ann Arbor, Michigan, United States of America.|Maxwell Institute for Mathematical Sciences, Department of Actuarial Mathematics and Statistics, Heriot-Watt University, Edinburgh, United Kingdom.|Centre for the Mathematical Modelling of Infectious Diseases, London School of Hygiene & Tropical Medicine, London, United Kingdom.|Department of Ecology and Evolutionary Biology, Princeton University, Princeton, New Jersey, United States of America.|Department of Integrative Biology, Oregon State University, Corvallis, Oregon, United States of America.|Department of Ecology and Evolutionary Biology, Princeton University, Princeton, New Jersey, United States of America.