Most of the sick salamanders were lethargic, swam in circles, and were unable to remain upright. Red spots and swollen areas were also observed on the skin. Although there was evidence that other wildlife were in the area of the lake, only salamander carcasses were observed. USGS wildlife pathologists closely examined the salamanders for gross lesions, and affected tissues were examined by light microscopy for cellular changes. A virus was isolated in cell culture from the affected tissues.
Work is currently underway to further identify the viral isolate.
This is the third mortality event from which NWHC virologists have isolated a virus from salamanders this year. The other die-offs occurred in Maine and North Dakota. The significance of the isolates to general amphibian decline is unknown. In 1995, researchers at the University of Arizona reported a similar die-off of tiger salamanders in southern Arizona. These deaths were attributed to an iridovirus infection.