Cross-continental emergence of Nannizziopsis barbatae disease may threaten wild Australian lizards

Abstract

Members of the genus Nannizziopsis are emerging fungal pathogens of reptiles that have been documented as the cause of fatal mycoses in a wide range of reptiles in captivity. Cases of severe, proliferative dermatitis, debility and death have been detected in multiple free-living lizard species from locations across Australia, including a substantial outbreak among Eastern water dragons (Intellagama lesueurii) in Brisbane, Queensland. We investigated this disease in a subset of severely affected lizards and identified a clinically consistent syndrome characterized by hyperkeratosis, epidermal hyperplasia, dermal inflammation, necrosis, ulceration, and emaciation. Using a novel fungal isolation method, histopathology, and molecular techniques, we identified the etiologic agent as Nannizziopsis barbatae, a species reported only once previously from captive lizards in Australia. Here we report severe dermatomycosis caused by N. barbatae in five species of Australian lizard, representing the first cases of Nannizziopsis infection among free-living reptiles, globally. Further, we evaluate key pathogen and host characteristics that indicate N. barbatae-associated dermatomycosis may pose a concerning threat to Australian lizards.

Nidoviruses in Reptiles: A Review

“…Consequently, the disease risk that reptile nidoviruses pose to wild populations of reptiles is largely unknown. Worldwide the number of reptile species listed as threatened continues to increase (24) and emerging or reemerging infectious diseases including various fungi (25)(26)(27), bacteria (28) and viruses (29)(30)(31) are cause for concern. Infectious disease is rarely a single contributing factor in known plant and animal extinctions, with the exception being amphibian panzootics caused by chytrid fungus (Batrachochytrium dendrobatidis) (32)(33)(34), yet understanding the risk they pose may be critical in preventing ongoing population declines.…”

The epidemiology and genomics of a virulent emerging fungal pathogen in an Australian reptile

“…Nannizziopsis barbatae was first identified in captivity in 2009 (14), and remained confined to captivity until, in 2013, two-free living eastern water dragons (Intellagama lesueurii) from locations separated by 30 km across Brisbane (Queensland, Australia) were identified with proliferative dermatitis, necrosis, ulceration and emaciation (15). Nb has since emerged in a growing number of phylogenetically and ecologically distant free-living lizards (2 x agamid species and 2 x skink species) across Australia (6 sites in Qld, 1 site in NSW and 1 site in WA) (15) and is known to cause disease in 9 species (data combined from captive and wild cases, see Table S1). This recent emergence in the wild, followed by a rapid expansion of its geographical distribution and host range, indicate that this fungal pathogen may present a pressing new threat to Australia's herpetological biodiversity.…”

“…This recent emergence in the wild, followed by a rapid expansion of its geographical distribution and host range, indicate that this fungal pathogen may present a pressing new threat to Australia's herpetological biodiversity. While we know that Nb causes untreatable severe dermatomycosis (15), mitigating its impact will require a thorough understanding of its ecology.…”

“…The copyright holder for this preprint this version posted October 24, 2021. ; https://doi.org/10.1101/2021.10. 22.465237 doi: bioRxiv preprint Taking advantage of its recent emergence in a long-term study population of eastern water dragons (15) and using an innovative combination of comparative genomics and spatiotemporal autocorrelation models, we assess the potential threat that Nb may pose to Australia's herpetological biodiversity.…”

“…Members of the fungal genus Nannizziopsis are well known to the pet trade as primary pathogens that cause serious cutaneous and systemic fatal disease in a diverse range of reptiles across the world (10)(11)(12)(13). Nannizziopsis barbatae was first identified in captivity in 2009 (14), and remained confined to captivity until, in 2013, two-free living eastern water dragons (Intellagama lesueurii) from locations separated by 30 km across Brisbane (Queensland, Australia) were identified with proliferative dermatitis, necrosis, ulceration and emaciation (15). Nb has since emerged in a growing number of phylogenetically and ecologically distant free-living lizards (2 x agamid species and 2 x skink species) across Australia (6 sites in Qld, 1 site in NSW and 1 site in WA) (15) and is known to cause disease in 9 species (data combined from captive and wild cases, see Table S1).…”