White-nose syndrome has gone down to Georgia, wildlife authorities announced Tuesday, marking the 22nd U.S. state hit by a wildlife epidemic that has already killed about 6 million American bats. The news comes just one day after the fungal disease was confirmed in South Carolina, and just two weeks after it showed up in Illinois.
The disease — named after a white fuzz that grows on infected bats — made its Peach State debut at two caves in the state's northwestern corner, according to a joint statement by the Georgia Department of Natural Resources, the National Park Service and the U.S. Fish and Wildlife Service. Fifteen tri-colored bats with visible symptoms were found late last month at Lookout Mountain Cave in Chickamauga and Chattanooga National Military Park, followed by several more at Cloudland Canyon State Park's Sitton Cave on March 5.
A bat from each site was then sent for testing at the Southeastern Cooperative Wildlife Disease Study in Athens, which confirmed that both had white-nose syndrome (WNS). These cases represent the disease's first known foray into Georgia, but it was likely just a matter of time. WNS was confirmed last year in northeastern Alabama and in southern Tennessee, not to mention one day ago in South Carolina.
"We've been expecting the discovery of WNS in Georgia after it was confirmed in Tennessee and Alabama counties last season," says DNR wildlife biologist Trina Morris. "Still, I don't think anyone can prepare themselves to see it for the first time."
After appearing in a single New York cave seven years ago, WNS has now spread to 22 U.S. states and five Canadian provinces, killing 5.7 million to 6.7 million bats along the way. It's caused by a cold-loving cave fungus called Geomyces destructans, which is able to infect bats as they hibernate because the deep sleep lowers their body temperatures. There's no evidence it affects humans or any other animals, but its spores can cling to our clothes, shoes and caving equipment, potentially letting the fungus hitch a ride to new caves on unsuspecting spelunkers. In fact, that may help explain where it came from.
The spread of white-nose syndrome since 2006. Click map to enlarge. (Image: FWS)
G. destructans is related to cave fungi found in Europe, and since there's no similar epidemic in European bats, scientists think it may be an invasive species that kills American bats due to a lack of evolved immunity. Rather than killing the animals directly, it wakes them up too early from hibernation, causing them to fly outside in winter and search fruitlessly for insects. Infected bats are often found with empty stomachs and depleted fat reserves, suggesting they starved to death. There is no known cure or treatment for WNS, so biologists instead focus on slowing down its spread.
Since the arrival of WNS in Georgia was expected, the state DNR has been conducting more bat surveys while limiting the number of scientific trips into caves, part of an effort to both increase monitoring and reduce contamination. The agency's biologists have been working with cavers, cave owners and conservation groups to raise awareness about limiting cave exploration, as well as the proper ways to disinfect clothes and equipment.
Still, the disease is mainly spread from bat to bat, and even cave closures may not be enough. South Carolina's infected bat lived in a remote area that's closed to the public, for example, and those in Georgia's Chickamauga and Chattanooga National Military Park were found in caves that have been off-limits since 2009 because of WNS. Sitton Cave at Cloudland Canyon is normally open to the public, but was closed for the winter to avoid disturbance of its hibernating inhabitants. Only six dead bats were found in that cave, according to the DNR, yet roughly a third of its 1,600 bats showed signs of WNS. The disease has a mortality rate as high as 100 percent in some bat colonies.
WNS is known to affect at least nine different bat species, eight of which live in Georgia. Two are federally endangered — the Indiana bat and the gray bat — and one, the small-footed myotis, is deemed a "species of concern" by state officials. And the loss of any insect-eating bat is of concern, both because they eat disease-spreading bugs like mosquitoes and because they regulate populations of agricultural pests. According to a 2011 study, insectivorous bats save the U.S. agricultural industry about $3 billion every year. Many U.S. bat populations are already in decline due to habitat loss, the Georgia DNR points out, and their ability to rebound is limited by low reproduction rates.
"Some bat populations were beginning to recover due to conservation efforts to protect caves and other critical habitats," Morris says. "WNS now threatens these populations with significant declines that they may not be able to recover from."
Related white-nose syndrome stories on MNN:
- Fungus has killed 6 million bats, U.S. says
- White-nose syndrome hits endangered gray bats
- Deadly bat disease crosses Mississippi River