Aspergillosis is a non-contagious and infectious systemic mycotic disease of birds caused by Aspergillus species. The common etiological agents isolated from cases of aspergillosis in birds include Aspergillus fumigatus Aspergillus flavus, Aspergillus terreus, Aspergillus niger and Aspergillus versicolor¹, among which Aspergillus fumigatus is a major respiratory pathogen of birds². It has been reported that acute aspergillosis in young chicks can cause higher morbidity and mortality while chronic form particularly in adults cause sporadic morbidity and mortality³. Aspergillosis in ostriches was reported previously but most of them were case reports using conventional method of diagnosis⁴. However, a study from Iran suggests that the ostriches which had undergone prolonged treatment with chloramphenicol and enrofloxacin lead to development of pulmonary aspergillosis⁵. Mixed infection with A fumigatues, A. niger and A. flavus in 3–8-week-old ostriches was also reported⁵. Further, it is reported that A. fumigatus can produce various toxins viz., gliotoxin, helvolic acid, fumagillin and aflatoxin-like substances which cause death of the bird by their immunosuppressive properties⁶.

A male 10-year-old ostrich exhibited anorexia, reduced movements and dullness for two weeks at Nawab Wajid Ali Shah Zoological Park, Lucknow, Uttar Pradesh. Symptomatic treatment with antibiotics and immunomodulators were administered but the condition of the bird deteriorated eventually followed by sudden death. Systematic necropsy examination of the carcass was conducted and samples intended for histopathological and microbiological examinations including small tissue pieces of lungs, air sacs, liver, kidneys, spleen, heart, brain, proventriculus and intestinal parts were collected in 10% neutral buffered formalin as well as on ice. Tissues were processed in routine manner for histopathological examination. The fungal organism in the tissue sections was demonstrated by the periodic acid schiff (PAS) staining⁷. Tissue triturates from the nodular lesions in lungs and air sacs was cultured on Sabouraud Dextrose Agar (SDA) at 37°C for 24 to 36 hours, and the obtained fungal culture was stained with lactophenol cotton blue which revealed the fungal morphological features². DNA was isolated from the fungal culture as well as from nodular tissues using genomic DNA kit (Qiagen, USA) following manufacturer’s guidelines. The isolated DNA was subjected to ITS region-based PCR as previously described².

Macroscopically, severe pleuritis with multiple focal to coalescing caseo-necrotic nodules along with severe consolidation of lung lobes was observed (Fig. 1). The air sacs were cloudy and thickened with multiple greenish white hard nodules (Fig. 2). Histopathological examination of the lung sections depicted multiple granulomatous nodules with central caseo-necrotic areas surrounded by inflammatory cells predominantly lymphocytes, macrophages and heterophils (Fig. 3). A very few multinucleated giant cells around the caseo-granulomatous lesions were found. Fungal structures like septate branching hyphae were detected around the periphery of the lesions (Fig. 4). Further, the fungal hyphae was confirmed by PAS staining (Fig. 5). Other organs did not reveal any specific histological changes except for parenchymal degeneration and vascular changes. Microscopic examination of lactophenol blue-stained smears prepared from culture isolates revealed uniseriate and columnar conidial head with chains of globose to subglobose conidia. The conidiophores were short, smooth, and terminating in flask-shaped vesicles, with a single row of phialides characteristic of Aspergillus fumigatus (Fig. 6). The identification of A. fumigatus was further confirmed through the PCR by amplification of the ITS 1 region with an amplicon size of 350 bp.

Aspergillosis is the most prevalent fungal infection of the respiratory system in birds, and it is associated with a high rate of morbidity and mortality⁸, these are ubiquitous fungal pathogens that exist in warm and humid conditions. The disease primarily occurs by the inhalation of asexual spores into lungs especially chicks. Recent studies revealed that they resist intracellular killing by alveolar macrophages. The most common aetiology for aspergillosis in poultry includes A. fumigatus and A. flavus⁶. Previously, aspergillosis in ostriches was confirmed by isolation of A. fumigatus^6,8, A. niger and A. flavus⁴ from affected birds. The gross and histopathological findings in the present study are in agreement with previous studies^4,9. Culture isolation and PCR detection of this pathogen in the present study was well correlated with previous reports^2,9. Most of the cases, previously were reported in the ostrich chicks and very few from adult ostriches. Present case report places on record on incidence of aspergillosis in an adult male ostrich.

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