Histological study of Broiler chicken liver infected with Marek’s Disease (MDV)

In chicken the Marek's disease virus (MDV) is able to cause a variety of syndromes and pathological symptoms. In order to conduct the histopathology, the liver was obtained from broiler chicken in poultry estate, near Gadap, Sindh, the age of birds was 07-10 weeks. Birds had diarrhea, dropping of wings, weight loss, a grey abdomen, anorexia and keel (breastbone) was prominent and protruded out. The disease had a daily mortality rate 0.16 to 0.20 percent of the flock. On postmortem the infected liver was swollen and had lesions, a portion was removed and kept in 10% formalin for 3 days in glass vials and then send to Parasitology Section, Department of Zoology, University of Karachi. Different concentrations of ethanol were used to dehydrate tissue later embedded in paraffin wax at 52°C for 4 days, 10 µm sections were stained with haematoxylin and eosin (H & E). The prepared slides were then observed under the microscope (> × 40) and examined for any histological findings. It was observed that several neoplastic foci pleomorphic cells were beginning to occur and it was infiltrated with lymphomatous lesions consisting of lymphoblast and mostly elongated and small to medium sized lymphocytes. These lesions are later transferred into tumor cells and infiltrate different organs and tissues. The occurrence of MDV in 07-10 weeks old broiler chicken even after vaccination could be due to poor biosecurity conditions.