Features of the Manifestation of Marek's Disease in Poultry Farms of the Rostov Region, Russian Federation
The authors carried out monitoring studies to examine the epizootic process features and the manifestation of clinical signs and pathological changes in Marek’s disease in various poultry farms in the Rostov region. The disease was most often in chickens aged 1.5 to 6 months. Two forms of the disease were registered: classical (nervous) - 63.3% of cases, and tumor (visceral) - 36.7% of cases. There was an unequal manifestation of symptoms of the disease, because of the different state of natural resistance and immunological reactivity of sick birds. The main clinical signs of Marek’s disease in chickens included: oppression; loss of appetite; development of paresis and paralysis; violation of movement coordination; cachexia; anemic crest, earrings and visible mucous membranes; change in the shape and constriction of the pupil; depigmentation of the iris of the eyes; partial or complete loss of vision; lameness; damage to the feather follicles; and the formation of tumors on the skin. The mortality rate of birds with nervous lesions was 70%. The surviving birds died within 1–2 months from the development of neoplastic changes in the internal organs. The main pathological changes in Marek’s disease were thickening and destructive changes in nerve fibers; and neoplastic changes in the parenchymal organs, lungs, intestinal mesentery, gastrointestinal tract, muscle tissue and skin. Most often, the disease was registered in the personal subsidiary plots of citizens. It manifested itself in massive epizootic outbreaks, usually in a nervous form with a high morbidity and mortality. In poultry farms, the disease was recorded extremely rarely. As a rule, it manifested itself in a tumor-like form, in isolated cases among a small percentage of poultry.
Keywords: poultry, chickens, Marek’s disease, clinical signs, pathological changes
 Nuraliyev, Y. R. and Kochish, I. I. (2017). Marek’s Disease in the Infectious Agent Reservoir of Poultry Industry – Household Farms. Bulletin of Omsk State Agrarian University, vol. 4, pp. 162–169.
 Bessarabov, B. F., et al. (2007). Infectious Diseases of Animals. Moscow: Koloss.
 Payne, L. N. and Venugopal, K. (2000). Neoplastic Disease: Marek’s Disease, Avian Leukosis and Reticuloendotheliosis. Revue Scientifique et Technique, vol. 19, pp. 544–564.
 Bakulin, V. A. (2006). Bird Diseases. St. Petersburg: Publisher Bakulin V. A.
 Kulyashbekova, S. K., Borisov, A. V. and Drygin, V. V. (2008). Marek’s Disease. Vladimir: Transit-X.
 Dzhulardov, G. V. (2009). Biological Properties of Natural Isolators of the Marek Disease Virus Circulating in the Russian Federation. (PhD thesis, D.I. Ivanovsky Research Institute of Virology Russian Academy of Sciences, 2009).
 Kennedy, D. A., et al. (2017). Industry-Wide Surveillance of Marek’s Disease Virus on Commercial Poultry Farms. Aviandiseases, vol. 61, pp. 153-164.
 Venugopal, K. (2000). Marek’s Disease: An Update on Oncogenic Mechanisms and Control. Research in Veterinary Science, vol. 69, pp. 17–23.
 Heidari, M., et al. (2016). Marek’s Disease Virus Immunosuppression Alters Host Cellular Responses and Immune Gene Expression in the Skin of Infected Chickens. Veterinary Immunology and Immunopathology, vol. 180, pp. 21–28.
 Kurnenkova, E. V. and Kulyashbekova, S. K. (2008). Determination of the Marek’s Disease Virus Infectious Activity. Proceedings of the Federal Centre for Animal Health, vol. 6, pp. 300–306.
 Kulyashbekova, S. K. (2008). Peculiarities of Marek’s Disease Vaccine Technology. Proceedings of the Federal Centre for Animal Health, vol. 6, pp. 477–498.
 Tambiev, T. S., Garinina, E. R. and Filipsky, O. I. (2019). Disinfection of External Objects in Broiler Poultry. International Research Journal, vol. 11-1, pp. 149–152.
 Jarosinski, K. W., et al. (2006). Marek’s Disease Virus: Lytic Replication, Oncogenesis and Control. Expert Rev Vaccines, vol. 5, pp. 761–772.
 Afonyushkin, V., Yushkov, Y. and Gorodov, V. (2005). Results of using the Computer Modeling for Developing a PCR-System Being Optimal for Screening Technologies of Marek’s Disease Control. Siberian Herald of Agricultural Science, vol. 2, pp. 69–74.
 Glisson, J. R., et al. (2008). A Laboratory Manual for the Isolation, Identification and Characterization of Avian Pathogens (5th ed.). Athens: American Association of Avian Pathologists.