Clinical, mycological and pathological findings in turkeys experimentally infected by Aspergillus fumigatus

International audience ; Experimental aspergillosis was obtained in 15 one-day-old turkeys by intra-air sac inoculation of a spore suspension of 3-day-old A. fumigatus culture (CBS 144.89) containing 107 spores. Ten additional turkey poults were used as controls. Infected and non-infected animals were closely observed at least twice a day for the appearance of clinical signs and were sequentially sacrificed at days 1, 2, 3, 5 and 7 post-inoculation. In the infected group, most lung tissues and air sac swabs were culture positive from day 1 to day 5. One day post-inoculation, air sac membranes were multifocally and moderately to severely thickened by an edema and covered by an exudate. A small number of germinating conidia was present in the superficial exudate, giving already rise to small radiating hyphae. Lung lesions were mild, dominated by a diffuse congestion and a mild hererophilic infiltration. From two to 3 days post-inoculation, air sac membranes were more severely affected and several granulomas were observed. Both granulomas and exudates were rich in germinated conidia and hyphae. Pulmonary lesions consisted in a diffuse pneumonia. Five days post-inoculation, lesions of the air sac membranes progressed to a severe, multifocal, heterophilic and granulomatous inflammation. Seven days post-inoculation, a reduction of the severity of the diffuse pneumonia was detected. Concomitantly, the fungal elements were mainly observed as fragmented tubules in the cytoplasm of multinucleate giant cells. The present study demonstrated that healthy turkey poults might be able to withstand exposure to 107 A. fumigatus spores.