1. Clinical Epidemiology Unit, Department of Epidemiology and Preclinical Research, National Institute for Infectious Diseases Lazzaro Spallanzani IRCCS, 00149 Rome, Italy
2. Medical Center, Comunità di S. Patrignano, 47853 Coriano, RN, Italy
3. Infectious Disease Unit, Hospital of Rimini “Gli Infermi”, 47923 Rimini, Italy