The first record of Heterakis gallinarum as a cause of fatal nodular typhlitis in golden pheasants (Chrysolophus pictus) in India

Background: Heterakidosis is one of the most prevalent parasitic diseases in birds, the caecae of a variety of wild and domestic birds are infected with these nematodes. In pheasants, nodular typhlitis is a lethal disease caused mainly by infection with Heterakis isolonche alone or in conjunction with Heterakis gallinarum. H. gallinarum has long been recognized to infect birds with low pathogenicity, with only a few fatal cases previously reported. Case description: This paper describes a case of fatal nodular typhlitis due to H. gallinarum in a male and female pair of adult golden pheasants (Chrysolophus pictus) from a zoological garden in Uttar Pradesh, India. Findings/treatment and outcome: The caecum had multiple serosal and mucosal nodules, the majority of which were found to contain various stages of parasites embedded in the center along with the free forms in the caecal contents. Histopathologically, these nodules were generally represented by granulomas centered on necrotic parasite debris, with the occasional reactive fibrous hyperplastic tissue reaction. Based on the morphology and nematode-specific internal transcribed spacer (ITS) ITS1-5.8 rRNA-ITS2 region-based PCR, the nematode was identified as H. gallinarum. The presence of H. gallinarum was further confirmed by sequencing the ITS region followed by phylogenetic analysis. According to the author’s best knowledge, this is the first instance of H. gallinarum being linked to nodular typhlitis in pheasants in India. Conclusion: Our findings confirm that H. gallinarum, other than H. isolonche, can induce severe nodular typhlitis with a fatal outcome in pheasants.