Aspergillosis in 41 wild bird species in the eastern United States: a 22-year retrospective review

Abstract

Aspergillosis is the most commonly and widely reported fungal infection in birds. Disease development is often secondary to stressors that cause immunocompromise, and it is typically regarded as a disease of captivity. We retrospectively evaluated data from 133 birds diagnosed with aspergillosis at the Southeastern Cooperative Wildlife Disease Study from 2001-2023 to assess diversity and relative frequency across avian taxa, gross and histologic lesion patterns, and comorbidities. Of 10 taxonomic orders represented, Charadriiformes (shorebirds; n = 35) and Accipitriformes (raptors; n = 32) were most common. Among them, the laughing gull (Leucophaeus atricilla; n = 20) and bald eagle (Haliaeetus leucocephalus; n = 14) were infected most commonly. Gross lesions were most frequent in lung (n = 80), air sac (n = 71), or celomic cavity lining (n = 42). Four distinct gross lesion patterns were identified: 1) tan caseous plaques (n = 106), 2) hollow masses lined with mold (n = 26), 3) red pulmonary nodules (n = 15), and 4) necrotic brown plaques (n = 3). Histologically, fungal hyphae were most common in lung (n = 107) and air sac (n = 49). Comorbidities were diagnosed in 67 birds with a spectrum of viral (n = 19), bacterial (n = 11), parasitic (n = 6), other fungal (n = 4), and non-infectious (n = 50) causes. Six birds each were diagnosed with highly pathogenic avian influenza or salmonellosis. Twenty-two birds were emaciated. Free-ranging birds are susceptible to myriad stressors that can predispose them to the development of aspergillosis.

Keywords: Aspergillus; Charadriiformes; aspergillosis; birds; fungi; mycoses; raptors.

Figure 1.

Gross lesions attributed to avian aspergillosis. A. The celomic cavity lining and air sac wall in a laughing gull (Leucophaeus atricilla) is effaced by firm, round, caseous, yellow-tan plaques. B. A cross-section of the mediastinum in a bald eagle (Haliaeetus leucocephalus) is expanded by a large hollow mass lined with gray-green Aspergillus spp. mold. C. The right caudal thoracic and abdominal air sacs in a red-tailed hawk (Buteo jamaicensis) are effaced by round, nodular, brown-gray plaques (arrowheads). D. The lung in a black vulture (Coragyps atratus) is effaced by a well-demarcated, firm, dark-red nodule.

Figure 2.

Heterophilic granulomas associated with avian aspergillosis. A. Aspergillus spp. conidiophores have uniseriate conidial heads. The upper two-thirds of the vesicle are lined by roughly parallel phialides that give rise to chains of conidia. B. Fungal hyphae are argyrophilic, 3–10-µm, parallel-walled, septate, with dichotomous acute-angle branching. Grocott methenamine silver stain. C. Lung parenchyma is expanded and effaced by a large, round, heterophilic granuloma with a core of necrotic heterophils surrounded by a rim of macrophages and multinucleate giant cells. H&E. D. Faint negatively stained fungal hyphae are sometimes visible along the margin of the heterophilic core. Rare multinucleate giant cells are scattered throughout the histiocytic rim (arrowheads). H&E.