1. Department of Infectious, Parasitic and Immune-mediated Diseases, Istituto Superiore di Sanità, Rome, Italy
2. National Centre for Epidemiology, Surveillance and Health Promotion, Istituto Superiore di Sanità, Rome, Italy
3. E.A. 35.45, Faculte de Pharmacie, Chatenay-Malabry, France
4. Department of Internal Medicine, University of Florence, Florence, Italy