_1736051173 20250105042613000 Rovedar Daryoushbabazadeh@gmail.com Rovedar Journal of World’s Poultry Science J. World's Poult. Sci. 2980-7999 12 15 2024 3 4 Buddhimali Yashodhara Iluppalla Gamage https://orcid.org/0000-0003-3416-7194 Introduction: Marek’s disease (MD) is a major threat to the poultry industry worldwide and significantly affects production and economic stability. In this context, an outbreak in a commercial poultry farm in Naththandiya, Sri Lanka, served as a crucial alarm to avian health management. The clinical signs found during this outbreak not only highlight the virulence of MD virus but also raise questions regarding the effectiveness of the current control measures. Case report: The outbreak was found in a commercial poultry farm with 4500 Brown Leghorn female chickens including 2500 of 14 weeks old chickens, and 2000 of 6 weeks old chickens in Naththandiya, which was characterized by marked mortalities of 15-20 chickens/day in elder chickens and 35-40 chickens/day in 6 weeks old chickens. The older chickens have been vaccinated with the oral Infectious Bursal Disease (IBD) vaccine at 3 weeks and 11 weeks of age and also with Fowl Pox vaccine at 8 weeks of age. The younger chickens have been given only IBD vaccine at 3 weeks of age. The outbreak showed a wide range of clinical signs, including swollen and closed eyes, nasal discharge, respiratory distress, and anorexia. The post-mortem examination revealed pathognomonic lesions such as grey-white foci of neoplastic tissue in the liver, lungs, and kidneys, enlargement of the sciatic nerve with loss of cross striations, visceral organ enlargement such as liver, kidney, and spleen which indicates the presence of MD virus along with secondary infections caused by Escherichia coli (E. coli). Histopathological examination and bacterial culture confirmed the MD and E. coli infections respectively. Conclusion: This outbreak highlights the importance of vigilant surveillance, proactive management, and continuous review of vaccination protocols to control the transmission of Marek’s disease effectively. 12 15 2024 76 80 https://creativecommons.org/licenses/by/4.0 10.58803/jwps.v3i4.49 https://jwps.rovedar.com/index.php/JWPS/article/view/49 https://jwps.rovedar.com/index.php/JWPS/article/download/49/73 https://jwps.rovedar.com/index.php/JWPS/article/download/49/73 10.3390/ani14020250 10.1186/s13567-016-0404-3 Nair V. Marek's Disease in Poultry. In: Abuelo A, Boyle AG, Brandão J, Brutlag A, Carnevale J, Carney P, Davidson G, Eide M, Ramirez A, Swayne DE, editors. MSD Veterinary Manual. 11th ed. Merck & Co., Inc.: Rahway, NJ, USA; 2024. Available at: https://www.msdvetmanual.com/poultry/neoplasms-in-poultry/marek-s-disease-in-poultry. World Organisation for Animal Health. Manual of Diagnostic Tests and Vaccines for Terrestrial Animals. 13th ed. 2024. [Updated 2024 July 26]. Available at: https://www.woah.org/fileadmin/Home/eng/Health_standards/tahm/3.03.09_MAREK_DIS.pdf. Nair V. Avian Leukosis in Poultry. In: Abuelo A, Boyle AG, Brandão J, Brutlag A, Carnevale J, Carney P, Davidson G, Eide M, Ramirez A, Swayne DE, editors. MSD Veterinary Manual. 11th ed. Merck & Co., Inc.: Rahway, NJ, USA; 2024. Available at: https://www.msdvetmanual.com/poultry/neoplasms-in-poultry/avian-leukosis-in-poultry. 10.1016/B978-0-444-52512-3.00183-2 Wallner-Pendleton E. Marek's Disease in Chickens. PennState Extension. 2023 Feb 16. Available at: https://extension.psu.edu/mareks-disease-in-chickens. Boehringer Ingelheim. Marek's Disease? Not in our chicken houses. [Internet]. 2010-2024 Boehringer Ingelheim International GmbH. [cited 2024 Oct 22]. Available at: https://www.boehringer-ingelheim.com/in/animal-health/livestock/poultry/mareks-disease-poultry-chicken. Brisbane Bird & Exotics Veterinary Services. Association of Avian Veterinarians. Marek's Disease. [Internet]. [cited 2024 Oct 22]. Available at: https://www.bbevs.com.au/sites/site-7755/documents/AAV-Mareks-Disease.pdf. Environmental Health & Safety Office at Yale University. Biological Safety Manual. [Internet]. 2020 August. [cited 2024 Oct 22]. Available at: https://ehs.yale.edu/sites/default/files/files/biosafety-manual.pdf. Expert System for Poultry. Disease Control and Management - Marek's Disease (MD). [Internet]. Tamil Nadu Agricultural University. [cited 2024 Oct 23]. Available at: http://www.agritech.tnau.ac.in/expert_system/poultry/DiseaseControlAndManagement-mareks. 10.1002/9781119511816 10.2147/VMRR.S376795 Fujimoto Y, Nakagawa M, Okada K, Okada M, Matsukawa K. Pathological studies of Marek's disease. I. The histopathology on field cases in Japan. Jpn J Vet Res. 1971 Jun; 19(1): 7-26. PMID: 4335918. Available at: https://pubmed.ncbi.nlm.nih.gov/4335918/. Adedeji A, Abdu P, Akanbi O, Luka P. Molecular and pathological investigations of Marek’s disease outbreaks in vaccinated poultry farms in Plateau State, North Central-Nigeria. Veterinaria Italiana. 2022 Nov 18; 58(1): 77–85. Available at: https://doi.org/10.12834/VetIt.2442.15397.1. 10.3390/ani12050540 10.1590/18069061-2015-0001 Tilley S, Frame DD, Bland MC. MAREK'S DISEASE (MD, Range Paralysis, Gray Eye). Agriculture. [Internet]. UtahStateUniversity COOPERATIVE EXTENSION. 2013 June. Available at: https://ucanr.edu/sites/aves/files/336233.pdf. 10.1177/1040638714522462 10.1371/journal.pone.0303371 10.1080/03079450500059255 10.1186/s12917-015-0493-7 10.5455/ajvs.285162 Khan A, Khatoon N, Akram M, Noor-un-Nisa, Khan A, Waheed S. Histopathological study of spleen infected by Marek’s Disease Virus (MDV) in broiler chicken. Ceylon Journal of Science. 2021: 50(1): 97- 10.4038/cjs.v50i1.7851 Basavaraju M, Gunashree B. S. Escherichia coli: An Overview of Main Characteristics. In: Marjanca Starčič Erjavec, editor. Escherichia coli - Old and New Insights. IntechOpen:2022. doi: 5772/intechopen.105508. 10.4172/2325-9590.1000238 10.1186/s13567-020-00746-4