1. Institute of Infectious and Tropical Diseases, University of Brescia, 25123 Brescia, Italy
2. Unit of Infectious Diseases, “Magna Graecia” University, 88100 Catanzaro, Italy
3. Department of Pathology, School of Medicine, Emory University, Atlanta, GA 30322, USA
4. Division of Infectious Diseases, San Gerardo Hospital, University of Milano-Bicocca, 20900 Monza, Italy