Granulomatous ventriculitis caused by Pythium insidiosum in a rosella (Platycercus eximius)

Ventriculite granulomatosa causada por Pythium insidiosum em uma rosela (Platycercus eximius)

Pythiosis is an infectious disease caused by the oomycete Pythium insidiosum and can affect various systems/tissues, including cutaneous, digestive and respiratory tracts. The disease has been reported in horses, cattle, sheep, goats, dogs, and cats; in birds, there are only two cases. This report describes the anatomopathological and immunohistochemical findings of pythiosis in a captive rosella (Platycercus eximius) that presented with weight loss and death. Macroscopically, multiple white nodules up to 0.5 cm in diameter were observed in the ventricular wall. Multifocal severe heterophilic and granulomatous ventriculitis was observed, associated with hyphae measuring 2 to 6 µm in diameter, with nearly parallel walls, occasionally septate and branched. The hyphae were strongly outlined in black in Grocott-Gomori silver methenamine (GMS), lightly stained by periodic acid-Schiff (PAS), and were positive by immunohistochemistry (IHC) using a polyclonal anti-Pythium insidiosum antibody. The diagnosis of ventriculitis caused by P. insidiosum in a rosella was established by anatomopathological findings and confirmed by IHC. This seems to be the first report of pythiosis in psittacines and the third in birds.

INDEX TERMS:
Digestive infection; oomycete; pathology; psittaciformes; pythiosis