By inoculating laboratory snakes with cultured O. ophiodiicola, a research team led by USGS National Wildlife Health Center microbiologist Jeffrey Lorch was able to prove definitively that the fungus was behind SFD.
SFD is reminiscent of other fungal diseases currently ravaging animals such as bats, with white-nose syndrome, and frogs, with chytridiomycosis. For some snakes, then, the stakes could not be higher.
"There is a fear that Ophidiomyces could drive at least some populations of snakes to extinction," said Lorch, in a statement.
It's still not certain exactly how the disease causes death in the wild, though Lorch thinks a number of factors combine to kill the animal.
"It could be due to predation or exposure if snakes are out and about when they shouldn't be," he said. "They could be getting secondary skin infections if bacteria get in."
Meanwhile, the mortality rate of FSD has been tough to peg, thanks to a lack of long-term data on the condition as well as the difficulty in studying the solitary, often inscrutable nature of snakes.
According to the USGS, the nine states in which SFD has been observed are Illinois, Florida, Massachusetts, Minnesota, New Jersey, New York, Ohio, Tennessee, and Wisconsin. But researchers suspect the disease may not be limited to those states.
Snakes the USGS has diagnosed with FSD include northern water snakes, eastern racers, the aforementioned massasauga rattlesnake, rat snakes, timber rattlesnakes, pygmy rattlesnakes, and milk snakes (see above photo).
Now that scientists have found the culprit behind SFD, they say they can concentrate on finding a way to try to manage the disease in at-risk snake populations.