Emergence of Ophidiomyces ophidiicola, Nannizziopsis barbatae and Paranannizziopsis in free-ranging Australian reptiles.

Abstract

Emerging fungal diseases pose a threat to reptiles globally. Increasing detections of onygenalean fungi, particularly Ophidiomyces ophidiicola, Nannizziopsis spp. and Paranannizziopsis spp. in clinically diseased free-ranging reptiles, indicate likely ongoing spread within wild reptile populations. These fungal pathogens have not previously been reported in free-ranging Australian reptiles, except for N. barbatae in select lizard species. We present 10 cases of onygenalean dermatomycoses in five free-ranging native Australian squamate species that presented to the Australia Zoo Wildlife Hospital between 2023 and 2024. Coastal carpet pythons (Morelia spilota mcdowelli) represented five of the cases, with O. ophidiicola, N. barbatae and P. australasiensis detected in this snake species. In addition, we confirmed O. ophidiicola in an eastern bandy-bandy (Vermicella annulata) and white-crowned snake (Cacophis harriettae), Nannizziopsis barbatae in an eastern water dragon (Intellagama lesueurii lesueurii), and Paranannizziopsis spp. in two eastern bearded dragons (Pogona barbata). Clinical presentations ranged from mild to severe dermatitis, with secondary outcomes of dysecdysis, stomatitis, emaciation and moribundity. Diagnoses were confirmed using a combination of histopathology, PCR, DNA sequencing and/or culture and barcoding. Our study reports the first known cases of Ophidiomyces ophidiicola and Paranannizziopsis in free-ranging Australian reptiles, and the first case of N. barbatae in a snake species globally. These cases represent an expansion of the known host and geographic range of onygenalean fungi into free-ranging Australian reptiles. Importantly, these fungi were associated with debilitating disease that could threaten native reptile populations if not promptly addressed.