White-nose syndrome, the deadly fungus that has killed millions of bats in the eastern U.S. and Canada, has been found in dead bats in Northeastern Minnesota's Soudan Underground Mine.

The Minnesota Department of Natural Resources reported the finding Wednesday.

Several hundred bats have been found dead near the main entrance to the mine since January, and a sample sent to a federal wildlife laboratory confirmed the cause was white-nose syndrome.

It’s the first time bats have been confirmed as dying from the disease in Minnesota.

The bats that flew out during below-zero temperatures were freezing to death immediately after leaving the mine, said Jim Essig, manager at Lake Vermilion-Soudan Underground Mine State Park.

“You don't normally see a lot of surface activity when it’s 30 or 40 below zero,” Essig said Wednesday. “Bats were coming to the surface and dying from exposure... in a few minutes.”

Bats continue to leave the mine, but because the weather has been warmer of late, the bats are getting farther from the entrance before dying of starvation and exposure.

As many as 15,000 bats spend their winters in the labyrinth of underground shafts and tunnels in the mine, by far the largest colony in Minnesota. Experts said as many as 90 or even 100 percent of those bats may perish within a few years. In eastern caves and mines where bats spend the winter, called hibernacula, entire colonies have been wiped out in less than a year.

The fungus was first detected in the mine in 2013, but scientists say it often takes two to three years for the disease to start killing bats.

White-nose syndrome was first observed in North America in 2007 in a cave in upstate New York. The fungal disease spread fast, and has now has been found in 27 states and five Canadian provinces.

It's possible some species could become “functionally extinct” within a few years, according to the U.S. Fish and Wildlife Service, which has called the disease the worst wildlife health crisis in the nation’s history.

The northern long-eared bat this year was formally placed on the endangered species list as threatened, offering federal protection for one of the species most affected by the disease. Little brown bats also are hard-hit.

Both little brown bats and northern long-eared bast have been found dead near the mine.

“Minnesota has seven species of bats, four of which hibernate during the winter and are at greatest risk of contracting the disease,” said Gerda Nordquist, a bat expert and mammalogist in the DNR’s Ecological and Water Resources Division.

It's not clear how the disease has spread so quickly, but it's believed that it is transmitted both between bats and from one cave to another in the footwear or clothing of people who visit caves.

“We’ve been following the recommended procedures to try to protect the bats from white-nose syndrome,” Essig said in a statement Wednesday. “Now that it’s here, we will continue to do everything we can at our parks to prevent human transport of fungal spores to other sites.”

Jeremy Coleman, white-nose syndrome coordinator for the U.S. Fish and Wildlife Service, said the behavior seen at Soudan is classic for a major outbreak of the disease.

“Given the observed mortality and behavior.... What you are starting to see now is the very rapid spread into the (regional) bat population,” Coleman said Wednesday.

Bats already had been dying from the disease just north of Minnesota, near Atikokan, Ontario, as well as in southern Wisconsin and Iowa. Experts say those caves and mines are close enough for Minnesota bats to come in contact with infected bats from those locations.





Fuzzy nose

White-nose syndrome is named for the fuzzy white growth of fungus observed on the faces of infected bats. Those infected die from the disease, which causes wounds to the wing tissue as well as dehydration and starvation. It often first shows up as unusual behavior, such as flying during the day in summer or leaving caves during their usual winter hibernation, when no bugs are present for them to eat.

That appears to be what happened in Soudan, where bats would normally never leave the mine in winter.

Bats can live more than 30 years in the wild but have a very low reproductive rate, which means it is very difficult for populations to rebuild after the disease hits, Nordquist said.

Experts say they are considering options to try to keep the disease out of specific caves, but once it enters it is impossible to eradicate.

The loss of bats, the only flying mammal, is considered troubling because bats play an important role in many ecosystems. A single bat can eat more than 1,000 mosquitoes in a single night. Bats are considered important agriculturally because of the huge number of insects they can keep away from crops, and in forested areas for reducing the number of tree-damaging bugs.

White-nose syndrome is not known to pose a threat to humans, pets, livestock or other wildlife.

The fungus also has been detected in Forestville/Mystery Cave State Park in southeastern Minnesota, but bats have not been found dead there as of yet.

Nordquist encourages anyone who sees a sick or dead bat to submit a Bat Observation Report on the DNR’s website, dnr.state.mn.us/reportbats.





Research underway, but no cure yet

Research continues to bring better understanding of white-nose syndrome, and scientists are beginning to see promising results that could eventually help treat affected bats. But so far nothing has been found to stop or even slow the bat disease that is spreading across North America.

“We’re hoping for the best… There are some potential good news stories to come, to have impacts in time,” Coleman said.

A wildlife veterinarian at the University of Wisconsin confirmed the disease kills bats by causing their bodies to overheat, burning energy too quickly and at a time - in winter - when no insects are present to replace the lost calories.

Experts at the University of Minnesota are working on microbes found in the Soudan mine to see if they might be used to treat against the disease, Nordquist said. Finding antifungal compounds from the mines where bats are affected could be a breakthrough, Coleman said.

In one Vermont cave where a quarter-million bats died a few years ago from white-nose syndrome, a few bats have returned. Scientists are trying to find out why they survived when others did not. They also are looking at why the disease doesn’t kill bats in its native Europe.

Last May the U.S. Forest Service and partners released bats in Missouri that had contracted white-nose syndrome the previous fall but were treated with a bacterium over the winter and survived. The treated bats will be monitored to see if they remain healthy. Early results show promise at thwarting the disease and even reducing it in infected bats, although researchers haven't figured out how to treat more than a few bats at a time.

In another study, University of California Santa Cruz researchers last April published the results of laboratory studies that showed how bacteria found naturally on some bats inhibited growth of the fungus that causes the disease. It's not clear how the bacteria works or why some bats have it and others don't.

Researchers also are working to find fungicides that might kill the fungus that causes white-nose syndrome. And scientists at UC San Francisco and Brown University recently figured out the likely way that white-nose syndrome breaks down tissue in bats, opening the door to potential treatments.