Pathological alterations and molecular identification of Marek’s disease in chicken

Marek’s Disease (MD) in chickens, caused by the oncogenic avian herpesvirus known as Marek’s Disease Virus (MDV), poses significant challenges to the poultry industry. This study was aimed at the molecular detection of MDV in afflicted chickens focussing on the gross and histopathological changes. The diagnosis was confirmed by cytological analysis of touch impression smear of the visceral organs with tumour like lesions. Employing polymerase chain reaction (PCR) technique, the presence of the virus was detected in various tissues. Pathological examination revealed characteristic lesions such as lymphoproliferative tumours in various organs including the spleen, liver, kidney, proventriculus, heart and ovary. On microscopic examination, visceral organs revealed densely populated parenchyma with infiltration of pleomorphic lymphoid cells. Out of 70 samples, 17 cases tested positive for MD. The findings provide valuable insights into the occurrence, pathology and diagnosis of MD in chickens, contributing to better disease management strategies and control measures of this economically important poultry disease. Keywords: Marek`s disease, cytology, lymphocytes, methyl green-pyronine