Chytridiomycosis Outbreak in a Chilean Giant Frog () Captive Breeding Program: Genomic Characterization and Pathological Findings.

Emerging infectious diseases in wildlife are increasingly associated with animal mortality and species declines, but their source and genetic characterization often remains elusive. Amphibian chytridiomycosis, caused by the fungus (), has been associated with catastrophic and well-documented amphibian population declines and extinctions at the global scale. We used histology and whole-genome sequencing to describe the lesions caused by, and the genetic variability of, two isolates obtained from a mass mortality event in a captive population of the threatened Chilean giant frog (). This was the first time an association between and high mortality had been detected in this charismatic and declining frog species. Pathological examinations revealed that 30 dead metamorphosed frogs presented agnathia or brachygnathia, a condition that is reported for the first time in association with chytridiomycosis. Phylogenomic analyses revealed that isolates (PA1 and PA2) from captive group with other isolates (AVS2, AVS4, and AVS7) forming a single highly supported Chilean clade within the global panzootic lineage of (GPL). These findings are important to inform the strengthening of biosecurity measures to prevent the impacts of chytridiomycosis in captive breeding programs elsewhere.