Infectious and Tropical Diseases Unit, Department of Medicine and Surgery, University of Insubria-ASST-Sette Laghi, Varese, Italy

Correspondence to Paolo Antonio Grossi, Professor of Infectious Diseases, Department of Medicine and Surgery - University of Insubria, Director of Infectious and Tropical Diseases Unit, ASST-Sette Laghi, Viale Borri, 57, Varese 21100, Italy. Tel: +39 0332 393075; fax: +39 0332 393080; e-mail: [email protected]