1. Clinic of Infectious Diseases at University of Udine, Udine, Italy
2. Sacro Cuore Hospital, Negrar, Italy
3. Amedeo di Savoia Hospital, Torino, Italy
4. University of Brescia, Brescia, Italy
5. F. Fallacara Hospital, Triggiano, Italy
6. Istituto Superiore di Sanità, Roma, Italy