A University of Kentucky-led research group is studying snake fungal disease across Kentucky to answer a question with high stakes for wildlife: Do infections caused by a snake-specific fungus reduce a snake's odds of surviving long enough to keep a population stable?
The disease is linked to the fungal pathogen Ophidiomycesophidiicola, which attacks keratin, the material that helps form and protect a snake's scales, said Steven Price, interim chair and professor of stream and riparian ecology in the Department of Forestry and Natural Resources, housed within the Martin-Gatton College of Agriculture, Food and Environment. Price has worked on the problem for the past 12 years.
The research, in collaboration with Virginia Tech, shows that infected snakes can develop skin lesions that resemble blisters or "rotted" scales. In some cases, the fungus can invade tissue beneath the scales and cause more extensive damage.
"We can detect it on the skin, and it can cause lesions," Price said. "Sometimes the fungus can invade underneath the scales and cause lumps or nodules, and we can see changes in behavior consistent with snakes trying to warm themselves up."
Snakes are ectotherms, meaning that when illness pushes them to induce a fever, they may spend longer periods basking to raise body temperature. Price said researchers also see shedding problems, including unusually frequent shedding and incomplete sheds that leave old skin stuck to the body.
Beyond skin and behavior, infections may affect internal physiology. Price noted evidence of stress-hormone disruption and reduced sex hormone levels in male and female snakes, patterns that suggest possible impacts on reproduction.
Even with these signs, linking disease to population decline is difficult, said Eleanor Lane, a Ph.D. student overseeing much of the research, because snakes are hard to find and even harder to count. Unlike some wildlife diseases that can be tracked through visible die-offs, snakes often die out of sight or are quickly scavenged. That challenge is a central reason the team is using intensive, long-term field methods.
"The only way you can figure that out is by catching a lot of snakes, marking them, swabbing them to see if the fungus is present, recording clinical signs, then recapturing individuals over time," Lane said. "That lets us estimate survival and test whether populations are changing."
The research group surveys both aquatic and terrestrial species, including venomous species such as the Eastern copperhead. Field sites span multiple Kentucky regions, including Robinson Forest in Eastern Kentucky, the Knobs Region, areas near Red River Gorge, a South Central Kentucky site near Mammoth Cave and an aquatic-snake site in Jessamine County. Price said the group does not share precise collecting locations to protect sensitive wildlife from harassment tied to recreational collecting.
Earlier work has shown high infection prevalence in some years in semi-aquatic snakes. Price and Lane said analyses led by a previous Forestry and Natural Resources graduate student found years in which more than 55% of tested individuals in certain snake groups carried the pathogen.
The research also focuses on how the disease spreads. Lane said evidence supports direct "snake-to-snake" transfer, with studies also indicating vertical transmission from mother to offspring in both egg-laying and live-bearing species. The fungus may also persist in the environment, creating a pathway for "environment-to-snake" exposure, especially in shared shelter sites such as hibernacula where many snakes congregate to overwinter or in refuges where snakes regularly shed skin.
Signs of snake fungal disease was first noted in a New Hampshire timber rattlesnake population in 2006, Price said, with Kentucky recording its first confirmed case in 2014. Price also pointed to population-genetic work suggesting the pathogen was introduced to North America relatively recently, with evidence of infections in museum specimens dating back to the mid-20th century.
For the current field season, the group is still processing diagnostic results that pair lab confirmation of the fungus with visible clinical signs. Even as those data come in, Price and Lane say the project's priority remains long-term monitoring, including measuring survival and determining whether infections are shifting snake populations over time.
