1. Food and Agriculture Organization of the United Nations (FAO) Headquarters, Viale delle Terme di Caracalla, 00153 Rome, Italy
2. Department of Pathobiology and Population Sciences, FAO Reference Centre in Veterinary Epidemiology, World Organisation for Animal Health (WOAH) Collaborating Centre in Risk Analysis and Modelling, Royal Veterinary College, University of London, Hatfield, Herts AL9 9TA, UK