1. Departamento de Patología Animal, Facultad de Veterinaria, Universidad de Zaragoza, Spain
2. Departament de Medi Ambient, Principality of Andorra
3. Moredun Research Institute, Bush Loan, Penicuik, Edinburgh, Scotland EH26 0PZ, UK
4. Department of Parasitology and Infectious Diseases, University of Veterinary Medicine, Komenskeho 73, 041 81 Kosice, Slovakia