1. School of Veterinary Medical Sciences, University of Camerino, Via Circonvallazione 93/95, 62024 Matelica (MC), Italy
2. Department of Biopathological and Hygiene of Animal and Food Productions, Section of Parasitology, Faculty of Veterinary Medicine, University of Perugia, Via San Costanzo 4, 06126 Perugia, Italy
3. Department of Veterinary Pathology, Diagnostic and Clinics, Section of Experimental Science and Applied Biotechnologies, Faculty of Veterinary Medicine, University of Perugia, Via San Costanzo 4, 06126 Perugia, Italy
4. Department of Microbiology, Immunology and Pathology, Faculty of Veterinary Science, University of Colorado States, 200 West Lake Street 1644, Fort Collins, Colorado, U.S.A.