Evidence of Ranavirus Infections among Sympatric Larval Amphibians and Box Turtles

Ranaviruses are emerging as serious pathogens across ectothermic taxa, recently causing mass die-offs including entire chelonian populations. Amphibians may serve as reservoirs for chelonian infections. To assess this idea and determine whether chelonians in the Midwest are infected with (or at risk for) ranavirus infections, we tested for presence of ranavirus infections among sympatric larval amphibians (N = 135) and Eastern Box Turtles (Terrapene carolina carolina, N = 132) earlier and later in the Box Turtle active season (between May and October 2009) in south-central Indiana. Three larval amphibians (2.2%; one Ambystoma sp. and two unidentifiable anuran larvae) and four Box Turtles (3.0%) tested positive for a ranavirus. Ranavirus infections were found in both early-season pond breeders (anurans) and then later-season pond breeders (salamanders), spanning the Box Turtle active period, but we did not detect mass die-offs. The majority (75%) of our ranavirus-positive Box Turtles were found later in the season. This represents the first documented case of ranavirus infection among a Box Turtle population in the Midwest and one of the few studies reporting ranaviruses across wild sympatric taxa. Our results suggest that ranaviruses persist sublethally in both larval amphibians and individual Box Turtles, allowing them to serve as reservoirs for this disease. Future studies should include sampling of all sympatric herpetofauna and investigate prevalence and persistence of the viruses to understand better the risks of cross-contamination.