Respiratory Tract Pathology of the B1 Strain of Newcastle Disease in Chickens

Lymphoid infiltration and lymphoid follicles have been reported to be commonly associated with Mycoplasma gallisepticum infection (1, 4). Lymphoid follicles in the air sacs were considered by Johnson (2) to be diagnostic for Mycoplasma infection. Jungherr (3) reported that in Newcastle disease there is hyperplasia of the lung alveolar wall cells and mononuclear infiltration with fibroblastic proliferation following chronic infection. This report concerns the respiratory-tract lesions caused by the B1 strain of Newcastle disease virus.