Detection of Adenoviruses in Free-Ranging Blanding’s Turtles (Emydoidea blandingii), Painted Turtles (Chrysemys picta), and RedEared Sliders (Trachemys scripta elegans) in Illinois, USA

Morbidity and mortality associated with adenoviruses (AdVs) have been reported in multiple taxa, including chelonians. Adenoviruses of a distinct testudinoid origin have been detected in both managed and free-ranging turtles in North America and Europe; however, the prevalence and impact of AdVs in free-ranging turtle populations have yet to be determined. A multispecies investigation to detect novel or existing AdVs in Blanding’s turtles (Emydoidea blandingii; n=1,359), painted turtles (Chrysemys picta; n=270), and red-eared sliders (Trachemys scripta elegans; n=205) was performed across four counties in Illinois (with one site reaching into Wisconsin), USA, from 2016 to 2022. Sequence-confirmed AdVs were detected in Blanding’s turtles (1.8%; n=24), painted turtles (13.0%; n=35), and red-eared sliders (8.8%; n=18). Ten AdVs, including 5 novel AdVs, were detected across the three species, with each species having 3–6 AdVs detected. Three AdVs were probably prey related, whereas the remaining seven AdVs were probably host-adapted AdVs, based on the absence of clinical signs of disease. The majority of AdVs detected were testadenoviruses; however, the siadenovirus Sulawesi tortoise adenovirus (STADV) was sequence confirmed in 1 Blanding’s turtle, 15 painted turtles, and 10 red-eared sliders, all of which were free of clinical signs of disease. These results provide a baseline for the presence and diversity of AdVs in free-ranging turtles in Illinois, including evidence for a North American reservoir for STADV.