1. Division of Public Health, Infectious Diseases and Occupational Medicine, Department of Medicine, Mayo Clinic , Rochester, Minnesota , USA
2. Department of Infectious Disease, ASST FBF SACCO Fatebenefratelli , Milano, Lombardia , Italy
3. St. Elizabeth's Medical Center, A Boston University Teaching Hospital , Brighton, Massachusetts , USA
4. Institute for Infectious Diseases, University of Bern , Bern , Switzerland