1. Microbiology and Virology Unit, University Hospital Città della Salute e della Scienza di Torino, Turin, Italy.
2. Department of Internal Medicine 4, Hospital de Santa Marta, Central Lisbon Hospital Centre, Lisbon, Portugal.
3. NOVA Medical School, Universidade Nova de Lisboa, Lisbon, Portugal.
4. Department of Medical Sciences, Unit of Infectious Diseases, University of Turin, Turin, Italy.