Leveraging preserved specimens of Nerodia to infer the spatiotemporal dynamics of Ophidiomyces ophidiicola via quantitative polymerase chain reaction

<em>Ophidiomyces ophidiicola </em>(<em>Oo</em>) is a fungal pathogen and the causative agent of ophidiomycosis that has affected multiple snake taxa across the United States, Europe, and Asia. Ophidiomycosis<em> </em>has often been referred to as an emerging infectious disease (EID), however its status as an EID has recently come under debate. <em>Oo </em>infections have been confirmed in wild snake populations in Texas; however, it is unknown if the pathogen is novel (i.e., invasive) or endemic to the state. To address this knowledge gap, we conducted surveys for <em>Oo </em>among preserved <em>Nerodia </em>deposited at three university museums in Texas. First, we visually assessed snakes for signs of infection (SOI), and if SOI were present, we sampled the affected area. We then used quantitative polymerase chain reaction to diagnose the presence of <em>Oo </em>DNA on areas with SOI and used these data to evaluate spatiotemporal patterns of <em>Oo</em> prevalence. We also tested for significant spatial clusters of <em>Oo </em>infection using a Bernoulli probability model as implemented in the program SatScan. We found that the proportion of snakes exhibiting SOI was constant over time while the prevalence of <em>Oo </em>DNA among those SOI increased across space and time. Within these data, we detected an incidence pattern consistent with an introduction and then spread. We detected six spatial clusters of <em>Oo </em>infection, although only one was significant. Our results support the hypothesis that <em>Oo </em>was an emerging, novel pathogen to Texas snakes. These data narrow the knowledge gap regarding the history of <em>Oo</em> infections in Texas and establish a historical record of confirmed <em>Oo </em>detections in several counties across the state. Thus, our results will guide future research to those areas with evidence of past <em>Oo</em> infections but lacking confirmation in contemporary hosts.