White nose syndrome has been identified as a newly arrived fungus that attacks a bat’s nose and wings. (US Fish and Wildlife Service)
The deadly white nose syndrome in bats has been linked to a fungus that most likely came from Europe. Carol Meteyer is a wildlife pathologist with the U.S. Geological Survey. She tells host Bruce Gellerman that the fungus attacks bats while they’re hibernating and erodes layers of skin and hair follicles on their wings.
GELLERMAN: Scientists report they have definitively identified the cause of a mysterious disease that’s been devastating colonies of bats. The disease was first discovered in upstate New York in 2006, and has spread to 19 Eastern U.S. states and four Canadian Provinces.
The deadly disease has a name - White Nose Syndrome - but the cause has baffled scientists - until now. Turns out, it’s a fungus: Geomyces destructans. It’s a cold loving fungus that can kill up to 90 percent of the bats in a colony while they hang and hibernate during the winter.
Carol Meteyer is a pathologist with the U.S. Geological Survey at the National Wildlife Health Center, and a member of the team that made the breakthrough discovery. We reached Dr. Meteyer at her office in Madison, Wisconsin.
METEYER: The reason it’s called White Nose Syndrome is because the fungus can infect the skin of the muzzle, but it’s actually causing the most major damage of the wing membrane. And that wing membrane is of critical importance to the survival of bats that hibernate.
GELLERMAN: So it’s the bat wings that are being infected, not just the nose.
METEYER: It’s primarily the bat wings. And the bat wings are critical during hibernation. They help maintain hydration or water balance. They help maintain the warmth of the bat - the body temperature of the bat - probably gas exchange, because they have gone from their heart from beating, maybe 1,000 times per minute when they’re flying, to the heart beating three times per minute when they’re hibernating. So they’re not breathing very often, and so there is transpiration or some respiration through that wing membrane as well.
GELLERMAN: How is it killing the bats?
METEYER: Animals that hibernate as part of their survival strategy have their immune system down regulated or their immune system goes into hibernation as well. So the bats, when they’re in hibernation in these caves, have very little immune response to any type of pathogen that might find them.
Usually these pathogens have evolved with the bats and probably also hibernate but Geomyces destructans, White Nose Syndrome, grows at the ideal temperature of the bat’s skin when it’s hibernating and it erodes through their skin without even being recognizing until they come out of hibernation in the spring.
GELLERMAN: It erodes their skin. It’s basically flesh-eating?
METEYER: You could call it that. It produces enzymes. So it colonizes that skin's surface, it begins to erode through that epidermis or the protective upper level of skin and it actually gets down into the connective tissue. And the wing membrane of bats is incredibly delicate. There’s one cell layer on top, there’s one cell layer on the bottom, and then there’s just a fine connective tissue, lace network that has nerves and blood vessels, but you could almost see through it. That’s how delicate those wing membranes are.
GELLERMAN: So where did this Geomyces destructans, this fungus, come from?
METEYER: The evidence that we have points to a new introduction of this organism from Europe. After we had determined and isolated this fungus from White Nose Syndrome, done the genetics, named it - it’s a new fungus - folks in Europe said: "Well, we have been seeing white noses on our bats for a number of years, in many different countries."
GELLERMAN: But those bats haven’t been dying.
METEYER: They haven’t been dying. That’s the intriguing part of this. You know, we assume that when bats hibernate, they do not have an immune system. That’s probably not any different in Europe than it is here. However, the hibernation period may be shorter in Europe than it is in upstate New York or Canada. So they may not be in those caves with immune suppression long enough to have this fungus really have the devastating effect that it has on our northeastern bats.
So, maybe they get a little bit of an infection, but they arouse, they can feed, you know, spring time comes earlier, and their immune system can clear this fungus from the wing membrane. We did publish a study this summer where we had bats that were severely affected with White Nose Syndrome when they aroused in early May, brought them in to rehabilitation, provided them with food, water and warmth, and they completely recovered.
GELLERMAN: Well, can we spray them with a fungicide or can we inoculate them, or will they just evolve immunity?
METEYER: The question of evolved immunity is a tricky one. Hibernating animals have evolved the strategy to conserve energy and not have a functioning immune system during winter. As far as treating bats, spraying bats - the environment that they’re in, in those caves - is so delicate. If they start spraying the caves to disinfect them, they’ll throw off that ecological balance that's evolved over eons, and one of the problems might be that since Geomyces destructans is the newcomer on the block, it may be the only one to survive. And some of these antibiotics, they are toxic, especially fungicides. You might spray it on the bat but you could kill the bat by spraying it. So it’s something that is being worked on and being investigated, but it’s not going to be a quick fix.
GELLERMAN: We’ve been talking with Dr. Carol Meteyer, she’s a wildlife pathologist with the U.S. Geological Survey, about the mysterious and now known cause of the catastrophic disease known as White Nose Syndrome in bats. Thank you so very much.
METEYER: Oh, you’re welcome. Thanks for inviting me.
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