1. Department of Medical Sciences, Infectious Diseases, University of Turin, 10124 Turin, Italy
2. Department of Public Health and Paediatrics, University of Turin, 10124 Turin, Italy
3. Stem Cell Transplant Center, AOU Citta’ Della Salute E Della Scienza, 10126 Turin, Italy
4. Unit of Infectious Diseases, Cardinal Massaia, 14100 Asti, Italy
5. School of Medicine, Tufts University, Boston, MA 02111, USA