Abstract
Confirmatory diagnosis of invasive aspergillosis is paramount to ensure proper treatment and effective management of the disease in food and companion animals. Suspected invasive aspergilllosis in chickens was encountered at post-mortem. Morphological and molecular methods were employed to identify Aspergillus from samples collected from dead chickens at post-mortem. Morphologically, two species of Aspergillus were identified, namely Aspergillus fumigatus and Aspergillus flavus. Molecular identification based on polymerase chain reaction (PCR) and sequence analysis of the partial 5.8 S rRNA, complete internal transcribed spacer-2 and partial 28S rRNA sequences bolstered morphological identification to arrive at the confirmatory diagnosis of the disease. Various hotspots that differentiate A. flavus from A. fumigatus and from other Aspergillus species were identified based on multiple sequence analysis. Maximum likelihood phylogenetic tree showed that isolates from the same species were grouped in the same clade. It is important to correctly identify the Aspergillus species in order to efficiently manage the disease. Key words: Aspergillosis, chicken, morphology, molecular characterization.
Highlights
Aspergillosis is a severe fungal disease that affects a variety of domestic and wild birds that are kept in captivity
The most common etiologic agent is Aspergillus fumigatus but A. flavus, A. niger, A. nidulans, and other Aspergillus species or sometimes mixed infections can play a role in the disease (Barton et al, 1992; Perelman and Kuttin, 1992; Joseph, 2000; de Oca et al, 2017)
The numerous, cream coloured nodules observed at post-mortem are typical of aspergillosis which was further confirmed with the colony and cellular features of fungi isolated from samples collected from the affected organs of the carcass
Summary
Aspergillosis is a severe fungal disease that affects a variety of domestic and wild birds that are kept in captivity. The fungi ribosomal RNA (rRNA) genes (rDNA) comprising small subunit (SSU) 18S rRNA, 5.8S rRNA, large subunit (LSU) 28S rRNA, and internal transcribed regions 1 and 2 (ITS1 and 2) (Khot et al, 2009) are the most universal target for their molecular identification. Most molecular detection and characterization of fungi are based on analyzing the ITS 1, ITS2 and the 5 ́end of the 28S gene (Fell et al, 2000; Abliz et al, 2004; Hinrikson et al, 2005; Walther et al, 2013; Trubiano et al, 2016, Gade et al, 2017). This study seeks to use morphological and molecular methods to detect, identify and characterize the Aspergillus species involved in an infection observed in a poultry flock, and arrive at the confirmatory diagnosis of the disease
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