Outbreak of avian aspergillosis in colonial-bred chicks (Isa Brown) in southern Rio Grande do Sul - case report

ABSTRACT In this study we describe the epidemiology, clinical signs, and pathology of an outbreak of avian aspergillosis in alternative breeding in the southern region of Rio Grande do Sul, Brazil. Between the fifth and tenth day of life, 360 chicks from a flock of 4000 developed unspecific clinical signs and died. The birds were housed in a reused aviary litter, without previous treatment. In 11 six-day-old female ISA Brown chicks (Gallus gallus domesticus), necropsy revealed firm, yellowish-white, multinodular lesions extending from the pleura to the lung parenchyma. Histologically, a granulomatous, multifocal to coalescent pneumonia was observed. Granulomas were characterized by central necrosis, with heterophil and epithelioid macrophage infiltration and presence of countless Y-shaped intralesional septate hyphae morphologically compatible with Aspergillus spp. The diagnosis through isolation confirmed Aspergillus fumigatus. We highlight the importance of aspergillosis as a primary cause of diseases in the respiratory tract of young birds in alternative breeding. Measures to prevent aspergillosis mainly regarding the reuse of aviary litter are essential in poultry husbandry to prevent economic losses, reduce environmental contamination and mitigate the potential risk to public health.