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Informed and effective management of emerging infectious diseases can be improved by a clear understanding of host–pathogen–environment interactions. Impacts of the seasonal environment on pathogen dynamics and host responses are poorly described in most reptile host–fungal pathogen systems. Here, we describe seasonal patterns of ophidiomycosis, a disease caused by the fungus Ophidiomyces ophidiicola (Oo), in a population of pygmy rattlesnakes, Sistrurus miliarius, in central Florida. We used field observations of gross clinical signs of disease in combination with qPCR on skin swabs to examine the seasonal prevalence of Oo and patterns of clinical presentation in hosts. We monitored thermoregulatory behaviors, ecdysis, and reproductive status in free‐living snakes to examine seasonal associations between infection and host coping responses. Both the prevalence of Oo and clinical signs of disease varied strongly with the season (winter high and summer low). In both seasons, the presence of clinical signs was a strong predictor of the presence of Oo as identified by qPCR on skin swabs (78% probability across seasons). Snakes with clinical signs of disease were more likely to be observed exhibiting thermoregulatory behavior or in ecdysis compared to non‐clinical snakes across seasons. The prevalence of Oo was not significantly different in pregnant snakes compared to other reproductive categories, but pregnant females were less likely to exhibit clinical signs of disease compared to males. Our results highlight strong seasonal patterns in both host clinical signs and Oo prevalence and support the efficacy of using gross clinical signs of disease in combination with qPCR on skin swabs to assess disease dynamics in free‐living snakes. We also identify ecdysis and thermoregulatory behaviors as components of the seasonal disease‐coping response and highlight the need to examine these behaviors as potential drivers of seasonal infection outcomes in reptiles afflicted with fungal pathogens. [ABSTRACT FROM AUTHOR]

Emergent diseases may result in population declines by inducing mortality directly or through sublethal effects on host reproduction. Snake fungal disease (SFD) is an emerging threat to biodiversity, but the sublethal impacts of disease on host fitness are poorly characterized. The cryptic nature of most snakes makes direct assessment of the fitness consequences of SFD challenging. In such contexts, measurement of sex steroids that correlate positively with seasonal reproductive investment may be useful in inferring the scope of disease impacts. To test the hypothesis that SFD is associated with reproductive suppression, we measured testosterone and estradiol in free‐ranging pygmy rattlesnakes with varying clinical signs of SFD. We also used real‐time PCR to validate the relationship between clinical signs and Ophidiomyces ophiodiicola (Oo) DNA presence on the skin. Infected males had lower testosterone compared to uninfected males during summer spermatogenesis and the fall breeding season. Infected females were less likely to have elevated estradiol compared to uninfected females during spring vitellogenesis. Approximately 85% of individuals with clinical signs were positive for Oo DNA. Our findings are consistent with the hypothesis that coping with SFD comes at a cost to the reproductive success of afflicted individuals, and that seasonal sex steroids may be valuable early indicators of sublethal effects. Snake fungal disease (SFD) is associated with suppression of sex steroid hormones in Pygmy rattlesnakes, Sisturus miliarius. Steroid suppression in infected males and females was only evident during seasonal reproductive events. SFD infection likely has associated sublethal reproductive costs in male and female rattlesnakes. [ABSTRACT FROM AUTHOR]