1. Unit of Infectious and Tropical Diseases, San Matteo Hospital Foundation, Pavia, Italy;
2. Department of Clinical, Surgical, Diagnostic and Pediatric Sciences, University of Pavia, Pavia, Italy;
3. Clinical Epidemiology and Biometric Unit, San Matteo Hospital Foundation, Pavia, Italy;
4. Instituto de Recursos Naturales y Agrobiología de Salamanca, Consejo Superior de Investigaciones Científicas, Salamanca, Spain;
5. Department of Infectious Diseases, WHO Collaborating Centre for the Epidemiology, Detection and Control of Cystic and Alveolar Echinococcosis, Istituto Superiore di Sanità, Rome, Italy