Respiratory (especially pulmonary) and urinary infections ofCryptosporidiumin layer chickens

Abstract

Respiratory (especially pulmonary) and urinary infections of Crypto‐sporidium were diagnosed in four of 26 chickens from a layer flock. Macroscopically, the lungs had various degrees of yellowish white pneumonic foci. Occasionally caseous exudates were present in the lungs and air sacs. Histologically, there was marked epithelial hyperplasia in the air capillaries, atria, parabronchi, secondary bronchi and trachea. Cryptosporidia were detected on the epithelial cell surface or in the lumens of them in the lungs. Macrophages containing cryptosporidia were frequently seen in the lumens and walls of air capillaries and atria and in the cavities of parabronchi and secondary bronchi. Cellular infiltration was observed in the interstitium. Aspergillosis or bacterial infection was also present in the lungs and air sacs. The ureters and collecting ducts, collecting tubules and distal convoluted tubules of the kidneys demonstrated marked hyperplasia of epithelial cells associated with cellular infiltration. Cryptosporidial attachment on the epithelial cell surface of them were noted. Ultrastructurally, trophozoites, schizonts and macrogametocytes of Crypto sporidium were recognised in the lungs, kidneys and ureters. This study suggests that Cryptosporidium may induce bronchopneumonia with epithelial hyperplasia and may invade the urinary tract of chickens that are infected with other infectious agents.