1. Department of Anatomy, Physiology and Animal Sciences, Faculty of Veterinary Medicine, University of Forestry, Sofia, Bulgaria
2. Department of Medical Microbiology, Faculty of Medicine, Medical University of Sofia, Sofia, Bulgaria
3. Department of Pathology, Parasitology and Parasitic Diseases of Animals, Diseases of Aquatic Animals and Bees, National Diagnostic and Research Veterinary Medical Institute “Professor G. Pavlov,”Sofia, Bulgaria³
4. Department of General Animal Husbandry, Faculty of Veterinary Medicine, Trakia University, Stara Zagora, Bulgaria
5. National Reference Laboratory for Fish, Mollusc and Crustacean Diseases, National Diagnostic and Research Veterinary Medical Institute “Professor G. Pavlov,”Sofia, Bulgaria