Abstract

This study was designed to detect the reactions grossly and histologically on the lymphoid organs (Bursa of Fabricious, Spleen, Thymus) in 8 day old broiler chickens vaccinated with infectious bursal disease vaccine (Intermediate plus)-(Ceva- IBDL).The study revealed no clinical signs on post vaccination days 2, 4 and 6. Gross lesions were swelling of the bursa due to the edema which obviously appeared as yellowish transudate covering the serosal surface area, and the bursa appears congested, the longitudinal striation on the surface become more prominent and congested while small gray foci appear on the surface of spleen. Microscopically there is degeneration and necrosis of lymphocytes in the medullary area and lymphoid follicles, edema between lymphoid follicles, hyperemia, lymphocytic depletion and cystic cavities developed in the medullary area of the follicles. In spleen, there were degeneration and necrosis of reticuloendothelial cells in the germinal center of the white pulp, with hyperemia in spleen and thymus. It was concluded that the intermediate plus vaccine which used in this study induced severe pathological changes in the bursa and spleen and less in the thymus on post vaccination days 2, 4 and 6.