1. Unit of Infectious Diseases, Cardinal Massaia, 14100 Asti, Italy
2. Unit of Oncology and Haematology, Candiolo Cancer Institute, FPO-IRCCS Strada Provinciale 142, 10060 Candiolo, Italy
3. Department of Medical Sciences, Infectious Diseases, University of Turin, 10126 Turin, Italy
4. Department of Oncology, Stem Cell Transplant Center, Città della Salute e della Scienza Hospital, 10100 Turin, Italy
5. Microbiology and Virology Unit, University Hospital Città della Salute e della Scienza di Torino, 10100 Turin, Italy
6. Intensive Care Unit, IRCCS Candiolo, 10100 Candiolo, Italy
7. School of Medicine, Tufts University, Boston, MA 02111, USA