1. Department of Veterinary Public Health and Animal Pathology; Faculty of Veterinary Medicine; University of Bologna; via Tolara di Sopra 50 40064 Ozzano Emilia BO Italy
2. Department of Food Safety and Veterinary Public Health; Istituto Superiore di Sanità; Viale Regina Elena 299 00161 Roma Italy
3. Department of Animal Pathology, Prophylaxis and Food Hygiene; Faculty of Veterinary Medicine; University of Pisa; Viale delle Piagge 2 56124 Pisa Italy