By Brian Stallard
Jul 19, 2015 04:06 AM EDT
(Photo : Pixabay)
It’s very rare for a disease to boast a 100 percent mortality rate. Rabies, for instance, is considered the deadliest disease in the world and even it has seen a handful of exceptionally lucky survivors. However, in the case of a new fungal disease sweeping through North American snakes, experts are reporting only death and more death.
“Reports of fungus on snakes started trickling in a few years ago, and there has been some concern that this represents a new emerging threat,” David Stern, a herpetologist at Auburn University recently explained in the University of Washington’s Conservation Magazine.
And there is certainly a lot of reason for concern. Fungal diseases have recently been ravaging amphibian populations across half the globe, and while that wouldn’t include snakes, it does set a precedent for taking fungal epidemics seriously.
Batrachochytrium dendrobatidis (Bd) infected frog goes rigid as the fungus causes its skin to overproduce keratin and harden. This disease functions very differently than snake fungal disease, but control and isolation concerns remain the same.
Scientists actually first started investigating the “snake fungal disease” (SFD), as it’s now called, in the early 2000s. Within that time, Florida wildlife officials reported disturbing mass deaths of pygmy rattlesnakes – first a clutch of 42, and later 59 more carcasses.
The damage the disease does is brutal and recognizable, with severe skin lesions, swelling, and contortion after an infection reaches the bones of its victims. This allowed experts to quickly catch on to the fact that SFD has already spread to at least 15 states, and affects everything from poisonous rattlers to garter snakes, rat snakes, and even rare ribbon varieties.
When researchers turned their attention to a small population of timber rattlesnakes in New Hampshire displaying these symptoms, they witnessed the disease kill more than 50 percent. The remaining survivors, while having been exposed to the disease, had never become infected themselves. That is to say, every snake that contracted the disease quickly died.
According to a study recently published in the journal Fungal Ecology, the fungus behind SFD survives by eating keratin – the stuff that makes up both human fingernails and snake scales. Normally happily residing in soil, the opportunistic fungus likely attacks snakes just exiting hibernation – a time when their immune system isn’t fully revved up, and they have a nice full set of scales for munching on.
“Mortality,” the researchers wrote, “appears to be 100 percent.”
The concern now is not that the disease is here, but that it’s prevalence is being underestimated. As any gardener or outdoorsman will know, snakes are by-nature tough to find in the wilderness. And if they can’t be surveyed, how will scientists ever know an epidemic is on hand until it’s too late? For now, it seems like we’ll just have to wait and see.
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