In a dank limestone cave below eastern Iowa, a single hibernating bat harbors a fungus called Geomyces destructans, state wildlife officials announced Wednesday.

This might not be newsworthy if it was any other fungus, but G. destructans happens to cause white-nose syndrome (WNS), a devastating epidemic that has killed nearly 7 million American bats since 2006. And until now, it had never been found in Iowa — raising fears that it's on the verge of exploding across the U.S West.

The WNS outbreak began six years ago in New York, and earlier this year federal authorities confirmed it has spread to Alabama and Missouri, with a suspected case as far as western Oklahoma. The Iowa report is tentative, since only low levels of the fungus were found on a single bat, with no signs of full-blown WNS.

But since G. destructans is so fast and fatal — it has a 100 percent mortality rate at some sites — bat experts are wary of underestimating it. "The level is so low it's difficult to say what this detection means," says Daryl Howell of the Iowa Department of Natural Resources. "It may be at a level low enough that it may not infect the bats at all, or it could be just the beginning of an outbreak that we will see in the future."

Either way, the discovery of G. destructans will be a game-changer at Iowa's Maquoketa Caves State Park. "We now go from trying to prevent the fungus from getting into the cave to trying to prevent it from getting out," Howell says.

WNS spreads mainly from bat to bat, although scientists think hikers and spelunkers inadvertently help it spread among caves when fungal spores stick to their clothes, shoes and equipment. The caves at Maquoketa had been closed to the public for the past two years as a precaution against this, but the Iowa DNR decided earlier this year to open them, citing new funding to hire staff and install decontamination mats. That decision will stand even though G. destructans has been detected, parks bureau chief Kevin Szcodronski says in a statement.

"Education is probably the most effective tool we have to prevent the spread of the disease," he says, noting that Maquoketa staff will teach visitors about the spread of WNS, explaining why they shouldn't visit other caves with any clothing or gear that was used there. The park is also adding mats with a decontamination solution at cave entrances, hoping to kill any fungal spores on visitors' shoes as they arrive or leave. "We were fortunate in that the Legislature appropriated enough money for us to be able to offer this kind of service to the public," Szcodronski says. "We simply didn't have the funding the previous two years to be able to do this."

But while keeping the Maquoketa caves open could raise public awareness about WNS, some conservationists say it's too risky. "Opening a tourist cave when white-nose syndrome was documented in a neighboring state was questionable, but keeping a known contaminated cave open to a high volume of tourists is irresponsible," says Mollie Matteson, a bat specialist with the Center for Biological Diversity, in a statement released Wednesday. "Iowa state park officials need to reconsider their decision to open Maquoketa, in particular, because Iowa, along with Missouri and Oklahoma, now represents the western front of this catastrophic epidemic."

It remains unclear how exactly WNS kills bats, but it typically wakes them up from hibernation too early, sending them on futile midwinter hunts for food. Scientists only recently traced the disease to G. destructans, a fungus that's native to Europe but doesn't kill bats there. It's now deemed an invasive species in North America, where it may have been accidentally imported on a traveler's clothes or equipment.

WNS is undeniably an ecological problem, threatening not only common species like little brown bats, but also endangered ones like gray bats. Yet it could also have dire consequences for the U.S. economy, since bats play a key role in controlling insect populations — from disease carriers like mosquitoes to agricultural pests like beetles and flies. According to the CBD, bats eat enough bugs to be worth $22 billion annually to American farmers. "The spread of this pathogen to Iowa is terrible news for our bats and for us," Matteson says. "It's a disaster for farmers, too, who depend on bats to control crop pests by eating millions of insects."

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