Modelling Aspergillus fumigatus infections in racing pigeons (Columba livia domestica).

In vivo modelling of aspergillosis in birds allows the evaluation of control measures and the study of host-pathogen interactions. In this study the impact of the use of different inoculation routes and immunosuppression on the course of an infection with Aspergillus fumigatus in racing pigeons (Columba livia domestica) was examined. A. fumigatus conidia were inoculated in the thoracic air sac, lung or trachea in immunocompetent or immunosuppressed pigeon squabs. Immunosuppression was induced by three dexamethasone injections before inoculation. Mortality in the A. fumigatus-inoculated groups varied between 1/4 and 4/4. The highest and more acute mortality was seen in immunocompetent pigeons inoculated in the thoracic air sac and in pigeons inoculated in the thoracic air sac or lung after immunosuppression. Pigeons inoculated in the lung or inoculated intratracheally after immunosuppression developed an aspergillosis infection with a slower course of disease and more prominent clinical symptoms. Using microsatellite length polymorphism, it was confirmed that all mycoses were caused by the inoculated strain except for one isolate in a dexamethasone-treated pigeon. In conclusion, inoculation in the lung is selected as the preferred model for chronic aspergillosis in pigeons, and inoculation in the thoracic air sac as the preferred model for acute aspergillosis. The use of immunosuppressed birds seems to be contra-indicated due to the risk of opportunistic infections.