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Pathology of experimental chlamydiosis in chicks
1Department of Comparative Pathology, Faculty of Veterinary Medicine, Hokkaido University, Sapporo, Japan.
Insights
Chicks experimentally infected with Chlamydia psittaci developed acute septicemic lesions, primarily affecting the respiratory system and multiple organs. This study details the clinical, gross, and microscopic pathology associated with the infection.
Area of Science:
- Veterinary Pathology
- Avian Infectious Diseases
- Microbiology
Background:
- Chlamydia psittaci is an important avian pathogen.
- Understanding the pathogenesis of Chlamydia psittaci in poultry is crucial for disease control.
Purpose of the Study:
- To investigate the pathological effects of Chlamydia psittaci inoculation in one-day-old chicks.
- To characterize the clinical, gross, and microscopic lesions induced by experimental Chlamydia psittaci infection.
Main Methods:
- One-day-old chicks were experimentally inoculated with Chlamydia psittaci via air sac, trachea, or esophageal injection.
- Clinical signs, gross lesions, and histopathological changes were evaluated.
- Immunohistochemistry was used to detect chlamydial antigens.
Main Results:
- Air sac and tracheal inoculation induced acute chlamydial septicemic lesions, including hepatomegaly, splenomegaly, and airsacculitis.
- Histopathology revealed fibrinopurulent inflammation, serositis, endoarteritis, and hepatic necrosis.
- Chlamydial antigens were detected in various organs, indicating widespread infection and multiplication within host cells.
Conclusions:
- Experimental inoculation of Chlamydia psittaci into the air sac and trachea causes severe systemic disease in young chicks.
- The study provides detailed pathological findings, highlighting the importance of early diagnosis and intervention for Chlamydia psittaci infections in poultry.
Abstract:
Twelve one-day-old chicks were experimentally inoculated with Chlamydia psittaci derived from turkeys. Acute chlamydial septicemic lesions were induced by the inoculation into the air sac and trachea. No lesions were produced by the esophageal injection. Clinically, the affected chicks showed emaciation and mouth breathing, and were inactive while some birds died. Grossly, they had hepatomegaly, splenomegaly and airsacculitis. Histopathologically, fibrinopurulent airsacculitis, pneumonia and bronchitis, multiple fibrinous serositis in the hepatic and splenic capsules, peri- and epicardium, and mesenterium, focal endoarteritis in the aortae, activation of reticuloendothelial cells in the spleen, and hepatic necrosis were noted. Immunohistochemically, chlamydial antigen granules were present in the cytoplasm of epithelial cells of the respiratory system, hepatocytes, macrophages in the air sac, lung, serous membrane, liver, spleen, aortae, reticuloendothelial cells in the spleen, and mesothelial cells in various organs or tissues. Chlamydial multiplication in the cells of the organs or tissues involved was preceded to form the lesions.