Fungal Disease May Threaten Snakes Worldwide

This is a northern water snake (Nerodia sipedon) with crusty and thickened scales overlaying raised blisters as a result of a fungal skin infection. (USGS National Wildlife Health Center/D.E. Green)

(CN) – A potentially fatal fungus found in more than two dozen snake species in Europe and the United States could be lethal to serpents across the globe, a new study finds.

The report, published Wednesday in the journal Science Advances, suggests that given the scope of the snake fungal disease caused by Ophidiomyces ophiodiicola, future surveys should operate under the assumption that all species harbor the pathogen.

“This really is the worst-case scenario,” said lead author Frank Burbrink, an associate curator at the American Museum of Natural History. “Our study suggests that first responders shouldn’t just be looking for certain types of snakes that have this disease, but at the whole community.

“All snakes could become infected, or already are infected.”

The disease has been found in 23 wild snake species in the United States, mainly in milk snakes, garter snakes, vipers and rat snakes in the eastern part of the nation. It was also recently discovered in three species commonly found in Europe.

The virus primarily affects snakes’ skin, forming lesions that expand rapidly and can cover a large portion of the body. While molting can resolve many cases, the reptiles can die from the infection.

Certain behavioral changes the snakes experience while combating the disease, like basking for longer periods of time while molting, expose them to starvation, lethal environmental exposure and predation.

“Some of the most devastating wildlife diseases ever documented, such as white-nose syndrome in bats and chytridiomycosis in amphibians, are caused by fungal pathogens,” said Jeffrey Lorch, a microbiologist with the U.S. Geological Survey. “These diseases have had such great impacts because they affect multiple species, and it now looks like the same is true of snake fungal disease.”

Projecting the disease’s potential impact is challenging because wild snakes can be difficult to locate and monitor.

The team created a model based on the evolutionary history, physical traits and ecology of known infected species and examined it using a neural network to search for associations that could be used to predict which species might be vulnerable to the virus.

Based on their results, the team suggests that all 98 groups of snakes in the eastern U.S. could be susceptible. Their findings also indicate that the epidemic could extend across the globe.

“The data for our model may not be perfect, but it will tell you if there’s even a weak association between a characteristic – for example, eating a certain type of animal or living in a particular environment – and the potential to get this disease,” Burbrink said. “And in this study, our model found no association other than ‘you are a snake’.”

The team hopes that their findings can be used to inform efforts to limit the spread of the disease.

“Scientists have learned a lot about research and monitoring needs from 25 years of studying the effects of chytrid fungi on amphibians, and those lessons tell us that prevention is the best policy,” said Karen Lips, a professor of biology at the University of Maryland, College Park.

“Researchers need to work with decisionmakers to prevent snake fungal disease from spreading, survey museums and field sites to determine the current distribution of the disease, run trials in the lab, and start working on treatments.”

 

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