A ranavirus-associated mass mortality event in an Illinois amphibian community [JMIH]

Ranavirus is an infectious pathogen affecting reptiles and amphibians associated with global amphibian population declines,and is one of two notifiable amphibian pathogens to the OIE. The purpose of this study was to determine the background prevalence of FV3-like ranavirus in amphibian communities at sites in east-central Illinois with recurrent outbreaks in Eastern Box Turtles (Terrapene carolina carolina). The Wood Frog (Rana sylvatica) was to be used as a sentinel species due to its reported ranavirus sensitivity. 20 R. sylvaticaindividuals of each life stage were to be sampled at eight vernal ponds using skin and oral swabs for adults and metamorphs, and lethal tissue sampling for tadpoles. However, a mass mortality event began while monitoring tadpoles. In response to the mortality event, we collected deceased individuals of any observed species over the next eight weeksat the original eight ponds and at an additional 15 sites wherever mortalities were observed. The event included over 3,000 observed individuals of six species. The highest number of mortalities were observed in R. sylvatica(n=752), Silvery Salamanders (Ambystoma platineum; n=303), and Chorus Frogs (Pseudacrisspp.; n=105). The viral isolate was classified as an FV3-like Ranavirus using sequence from several primer pairs, was detected at 10 of the 23 ponds sampled (44%), and infection prevalence ranged from 0% to 100%. Detection of this mortality event in progress highlights the need to continue monitoring this area for ranavirus in ectothermic vertebrates, as an event of this scale had not previously been observed within these sites.