Snake Disease: Fungus Causing Widespread Skin Infections Has Been Found
Researchers from the U.S. Geological Survey (USGS) have found the culprit behind a deadly skin infection spreading among snake populations in the eastern half of the U.S. Now that they have definitively proven a fungus called Ophidiomyces ophiodiicola is to blame, researchers can start working toward a cure, according to a release.
This skin infection, known as snake fungal disease (SFD), has plagued numerous species including northern water snakes, eastern racers, massasauga rattlesnake, rat snakes, timber rattlesnakes, pygmy rattlesnakes, and milk snakes. External abnormalities associated with SFD include opaque infected eyes, thickened crusty or discolored scales, scabs and blisters. For some infected species, such as the massasauga rattlesnake in Illinois, the disease is almost always fatal. Other species are not as severely affected--but because the disease can linger in the atmosphere, it can drive some species to extinction: "Unlike many bacterial and viral pathogens, fungal spores can live in the environment without a host," Jeffrey Lorch, who is a microbiologist at the USGS National Wildlife Health Center, Madison, Wisconsin, said in the release. "And that means that as the host population declines, the fungus can persist in the environment, which could potentially mean it could drive hosts to extinction."
In a recent study, USGS researchers experimentally infected captive-bred corn snakes (Pantherophis guttatus) with pure cultures of O. ophiodiicola. As a result, all infected snakes developed gross lesions identical to those observed in wild snakes. Researchers then extracted the same strand of O. ophiodiicola from infected lesions to treat snakes.
In addition to physical changes, researchers found that infected snakes also had an increased white blood cell count and increased frequency of molting, among other abnormalities such as anorexia and migrating to a different location in the enclosure. While snakes may be responding like this as a way of fighting the infection, abnormal behaviors may also contribute to increased mortality rates.
Researchers are still unsure exactly how the disease causes death in the wild. "It could be due to predation or exposure if snakes are out and about when they shouldn't be. They could be getting secondary skin infections if bacteria get in," noted Lorch in an article by Discovery.
In total, SFD has been documented in nine states including Illinois, Florida, Massachusetts, Minnesota, New Jersey, New York, Ohio, Tennessee, and Wisconsin. However, the skin infection is hard to study due to snakes' solitary and cryptic (camouflage) nature.
Their study was recently published in the journal mBio.
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