Ophidiomycosis is related to seasonal patterns of reproduction, ecdysis, and thermoregulatory behavior in a free‐living snake species

Abstract

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.

Characterisation, prevalence and severity of skin lesions caused by ophidiomycosis in a population of wild snakes

“…In contrast to Lind et al 44 , who found no link between sex or reproductive status and Oo detection in pygmy rattlesnakes ( Sistrurus miliarius ), we observed that male grass snakes had a higher likelihood of presenting with skin lesions compared to females. Since male snakes are more active, ranging over larger distances while searching for suitable females during the breeding season 48 , they may have an increased likelihood of ventral scale scarification and exposure to Oo in the environment.…”

“…The increased occurrence of traumatic injuries in snakes with skin lesions observed in this study suggests a higher frequency of encounters with predators, therefore supporting the theory of increased basking behaviour in snakes with ophidiomycosis and subsequent higher risk of predation 12 . It has been suggested that such behaviour might relate to higher frequencies of thermoregulatory postures 44 , or to the increased metabolism needed to promote sloughing required for clearing fungal infections 3 . While puncture wounds are highly suggestive of predation, the cause of tail damage and lacerations, which were classed as predation injuries in this study, is less certain, although may still be linked to predation 45 , 46 .…”

Ophidiomyces ophidiicola in free-ranging and captive snakes in the Czech and Slovak Republics

“…In addition, the disease may progress to multifocal skin lesions, granulocytic inflammation and necrotic foci. The symptoms are often accompanied by frequent and defective moulting and, eventually, the emergence of risky behaviour in the form of behavioural fever (Lorch et al 2015, Lind et al 2022). The disease sometimes becomes chronic and affects the muscular and deeper body layers, with a tendency to form granulomas (Lorch et al 2016).…”

Health Assessment of Free-Ranging Eastern Indigo Snakes (Drymarchon Couperi) From Hydrologic Restoration Construction Sites in South Florida, Usa

“…In reptiles, plasma corticosterone levels may be more indicative of chronic stress than hematologic values (Hunt 2019). Elevated corticosterone levels have been reported in green sea turtles ( Chelonia mydas ) with fibropapillomatosis (Aguirre et al 1995), fence lizards ( Sceloporus occidentalis ) with plasmodiasis (Dunlap and Schall 1995), and pygmy rattlesnakes ( Sistrurus miliarius ) with ophidiomycosis (Lind et al 2023). Because these reports compare naturally infected individuals to noninfected individuals, it cannot be determined whether infection caused elevated plasma corticosterone or if preexisting chronic stressors triggered an exaggerated corticosterone response, inducing immunosuppression, and allowed for these infections to occur.…”