Vol. 9, Special Issue 2, Part D (2025)

A study of Marek’s Disease (MD) in a poultry farm in the Ajmer region of Rajasthan, which had a prior outbreak history, involved the collection of 25 samples from a newly introduced flock six months after the previous incident. Microscopic examination of intestinal samples revealed severe pathological changes across multiple layers of the intestinal wall. Affected birds displayed enlarged intestines with thinning of the serosal surface, reflecting significant structural alteration. Histopathological findings highlighted extensive proliferation of pleomorphic lymphoid cells infiltrating the mucosa, submucosa, muscle layers, and subserosa. This infiltration caused widespread architectural disruption, compromising the integrity of the intestinal wall. The mucosal layer bore the brunt of the pathology, with tumor cell accumulation leading to morphological changes. Flattened villi were frequently observed, and in extreme cases, complete obliteration occurred due to aggressive lymphoid cell invasion. The mucosal glands exhibited varying degrees of damage, ranging from compression to cystic dilation, linked to lymphoid infiltration. Degeneration and loss of the normal epithelial lining of these glands further compounded the structural damage. These profound changes highlighted the invasive nature of MD and its capacity to disrupt normal intestinal function. This study underscores the critical need for continued surveillance and improved control measures, as MD remains a persistent threat to poultry health. The findings reveal the aggressive progression of MD in the intestines, providing vital insights into its pathogenesis and emphasizing the importance of early detection and intervention to mitigate its impact.