Histopathology
The most critical histopathological finding in liver sections of diseased birds was the presence of inclusion bodies in the hepatocytes (Figure 2), appearing as large basophilic intranuclear inclusion bodies surrounded by a pale halo. Many hepatocytes were degenerated and swollen with vacuolated cytoplasm. Infrequently, necrosis of scattered hepatocytes occurred. Moreover, there was lymphocytic and heterophilic hepatitis. These inflammatory infiltrates appeared clearly around the central vein. Additionally, there was widening and infiltration of sinusoids with lymphocytes, heterophils, and histiocytes (Figure 3).
Histopathological sections of testicles from infected birds revealed degeneration of spermatozoa, spermatids, Sertoli cells, and Leydig cells. In the interstitial tissue, there was intertubular hemorrhage and large vacuoles. Also, there was dilation of seminiferous tubular lumens that contained necrotic debris and were devoid of spermatozoa, a lesion reported for the first time in the present study (Figure 4).