Though rattlesnakes once occupied much of the US, humans have shrunk their populations—and now an insidious fungal disease is doing further damage. Ophidiomyces ophiodiicola surfaced here roughly 10 years ago, and it has since been found in nine eastern states, reports the AP. The eastern massasauga rattlesnake in Illinois is under attack, New Hampshire's rattlesnakes have suffered a population loss of 50%, and Vermont's venomous timber rattlers are down to two nesting sites. "I think potentially this could overwhelm any conservation effort we could employ to try to protect this last remaining population," says Vermont Department of Fish and Wildlife biologist Doug Blodgett. "We don't have any control over it."
Snake fungal disease can cause crusty scales, abnormal molting, swelling, and more, according to the National Wildlife Health Center. Part of what's so mysterious about the fungus: Scientists don't know if it originated abroad or has always been here and is only now causing issues. And it doesn't have a uniform effect: The mortality rate for infected massasauga rattlesnakes is 80% to 90%; while all of Massachusetts' five rattlesnake populations have been hit by the fungus, it's not experiencing the high mortality rate. "It does seem to be a disease that has different effects in different areas," confirmed a microbiologist with the center. There are no reports of the fungus infecting humans, according to the Northeast Partners in Amphibian and Reptile Conservation, but anyone who touches an infected snake should wash with care afterward. (Read more snakes stories.)