Histologic Changes and Inclusion Bodies in Chickens Inoculated with an Ornithosis Agent

Ornithosis has been associated with pigeons, turkeys, ducks, geese, and, more rarely, chickens (7). In a previous report, the inoculated chickens were found to be a clinicially resistant host to the strains of ornithosis used (2). Infection was established in groups of White Leghorn chickens inoculated at 1 to 40 days of age with the C-1 strain of ornithosis of turkey origin. Afterward, the agent was recovered irregularly from subclinically infected birds. The agent was present in the blood, saliva, cloacal contents, and tissues for as long as 7 weeks after inoculation, the longest period tested. Only 3 of 212 inoculated chickens had clinical signs of disease. The important factors in establishing infection were organism dose and bird age. The studies indicated that no single technique, including clinical observation, isolation of organisms, gross lesions, or complement-fixing antibody response, was fully reliable for detection of the infection.