抄録
Groups of broiler and layer chicks were experimentally infected with 400, 20,000 and 1,000,000 oocysts of Cryptosporidium baileyi at either 2, 16 or 30 days of age. Clinical signs were not observed in any of the infected birds and there was no significant effect on weight gain compared to uninfected controls. Tissues examined histologically at 2, 5, 7, 14, 21 days post-infection (DPI) revealed the presence of parasites in the Bursa of Fabricius and cloaca between 7 and 14 DPI, and occasionally in the caeca and trachea. Hypertrophy and hyperplasia of the lining epithelial cells, particularly in the bursa, were the main histological changes observed. A marked heterophil response with acute inflammatory exudate and bursal cast formation was seen in some of the heavily challenged birds.
