Detection of Adenoviruses in Free-Ranging Blanding's Turtles (Emydoidea blandingii), Painted Turtles (Chrysemys picta), and Red-Eared 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.