Surveillance of Ophidiomyces ophidiicola in Snakes, Primarily Eastern Wormsnakes (Carphophis amoenus), in Central Virginia, USA, Based on Swab and Tissue Sampling.

Ophidiomycosis, or snake fungal disease, caused by the pathogen Ophidiomyces ophidiicola, poses a growing threat to wild snake populations in North America. We surveyed snake populations in central Virginia, USA in 2021-22; no clinical signs of ophidiomycosis had been observed in a survey 2013-14. Across 82 individuals representing seven species, 16% tested O. ophidiicola-positive, including 17% of eastern wormsnakes (Carphophis amoenus), the most frequently encountered species. All O. ophidiicola-positive snakes exhibited skin lesions or abnormalities at the time of capture; no subclinical individuals tested positive. Among eastern wormsnakes, O. ophidiicola-positive individuals were significantly larger in mass and length but did not differ in body condition compared to O. ophidiicola-negative individuals, suggesting age-related infection accumulation. Swabs preserved in RNAlater, swabs preserved in sterile water, and tissue samples from tail tips yielded O. ophidiicola-positive rates of 9%, 5%, and 7%, respectively. The number of O. ophidiicola-positive snakes was too small to formally test for differences between sampling techniques; however, this study supports the use of both swab samples and tissues. We tentatively suggest emergence of O. ophidiicola in our study site sometime between 2014 and 2021, or environmental changes during this period that altered pathogen load and/or host immune status. Our results provide the most extensive dataset to date on O. ophidiicola prevalence in C. amoenus and underscore the need for continued monitoring in fossorial species.