Amphibian ranavirus and chytridiomycosis infections are reportable to the OIE due to their impacts on population stability. Both pathogens have been detected in clinically affected individuals in Illinois.1-4 The state-endangered silvery salamander (Ambystoma platineum) is considered a species of conservation concern; however, information on baseline silvery salamander health and pathogen susceptibility has not been reported. The purpose of this study was to characterize the health and disease status of silvery salamanders through physical examination and PCR screening for ranavirus and chytridiomycosis. Adult silvery salamanders (n=84) were captured at 10 ponds in Vermilion County, Illinois during spring emergence in March, 2016. A frog virus 3-like ranavirus was detected in seven individuals (8.3% prevalence). Ranavirus occurrence was significantly associated with the presence of raised skin nodules (p=0.02). From May 1 to June 22, approximately 300 silvery salamander larvae, representing over 80% of the larval population, were found dead. Gross necropsy findings included hemorrhages and subcutaneous edema. A frog virus 3-like ranavirus was PCR amplified from liver and kidney samples (n=50, 100% prevalence). Surviving metamorphs (n=14) were captured in June. Five individuals tested PCR positive for ranavirus (35% prevalence). Two displayed hemorrhages, one had traumatic injuries, and two were aclinical. This study demonstrates that disease may pose a threat to silvery salamander conservation in Illinois, and underscores the need for continued health assessment in this species. This health assessment framework can be applied to other imperiled salamander populations to assess threats to conservation, and monitor for emerging infectious diseases such as Batrachochytrium salamandrivorans.
The authors thank the herpetologists at the Illinois Natural History Survey for their assistance with salamander trapping and sample collection.
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