Computational Epidemiology Laboratory, Institute for Scientific Interchange (ISI), Torino, Italy.|Department of Veterinary Science, University of Turin, Torino, Italy.|ICTEAM Institute, Université Catholique de Louvain, Louvain-la-Neuve, Belgium.|CNRS, UMR5558, F-69622 Villeurbanne, France.|Department of Civil and Environmental Engineering, Massachusetts Institute of Technology, Cambridge, Massachusetts, United States of America.|ICTEAM Institute, Université Catholique de Louvain, Louvain-la-Neuve, Belgium.|Sociology and Economics of Networks and Services Department, Orange Labs, Issy-les-Moulineaux, France.|Department of Civil and Environmental Engineering, Massachusetts Institute of Technology, Cambridge, Massachusetts, United States of America, Engineering Systems Division, Massachusetts Institute of Technology, Cambridge, Massachusetts, United States of America.|INSERM, U707, Paris, France, UPMC Université Paris 06, Faculté de Médecine Pierre et Marie Curie, UMR S 707, Paris, France, Institute for Scientific Interchange (ISI), Torino, Italy.