Bat disease’s quick spread to western North America ‘a terrifying mystery’

Bat experts in Western Canada are shocked by the way white nose syndrome – a deadly fungal disease that's killed more than six million bats in the east – has jumped across the continent.

The U.S. Geological Survey confirmed recently that a sick bat found by hikers near Seattle, just south of the border with British Columbia, had died from white nose syndrome (WNS). It is the first recorded occurrence of the disease in western North America.

The disease is linked to a white fungus, which can look like frost on the muzzles of infected bats. The fungal growth attacks the bats as they hibernate, disrupting sleep, causing them to fly during the day, depleting fat reserves and leading to dehydration and death. It was initially detected in eastern New York in 2007. Since then it has spread to 28 states and five provinces, but until last week hadn't been found west of Manitoba or Kansas.

Moving by short geographic jumps, WNS wasn't expected to reach the West Coast for another five or 10 years and its sudden appearance in the Pacific Northwest has startled experts.

"I think it's a bit of a terrifying mystery as to how it could move so far," Craig Willis, a bat specialist at the University of Winnipeg, said Tuesday.

"It's been gradually moving west. In Canada, I would have expected the next site to see it is a place in central Manitoba," said Dr. Willis, who has been monitoring large hibernating colonies for the first sign of the disease in his province.

He said WNS fungus could have jumped to Washington on the boots, clothing or climbing ropes of someone who'd been in an infected bat cave in the East. Or it could have been introduced by a bat that reached North America by ship from Asia.

Because the infected Washington bat is a genetically distinct western species, it is clear the animal itself didn't ride across North America on a train or truck.

Purnima Govindarajulu, a small-mammal specialist at the B.C. Ministry of Environment, said the detection of the disease in the Seattle area is shocking.

"I was devastated when I first heard," she said. "This is a very major, unexpected discovery."

Dr. Govindarajulu said B.C. authorities were already taking steps to prepare for a possible WNS outbreak, but have now rushed that strategy forward.

"We thought we had more time. We are ramping up our responses right now. It's been crazy, the past few days. We are scrambling to speed up all our responses," she said.

Dr. Govindarajulu urged members of the public to call the Ministry of Environment if they see bats behaving strangely, such as flying during daylight, or if they find dead bats.

She said WNS isn't a health threat to humans, but people should avoid touching dead bats with their bare hands because of the chance of exposure to rabies or other diseases.

She said it is probable WNS is already infecting bats in British Columbia.

"That is the general feeling," Dr. Govindarajulu sais. "When we talk to disease experts … their response is if you are detecting it in a wild animal, the disease has been here at least for a year, maybe more."

Mark Brigham, professor of biology at the University of Regina and author of Bats of British Columbia, said the appearance of WNS in Washington is bad news for bats all along the West Coast.

"The fact that it's only one [infected bat] is better than if it were hundreds, but the fact that it's there at all is very scary," he said. "If it's there in Washington, in my humble opinion that means it's effectively all up and down the West Coast."

Dr. Brigham said there are several species of bats in British Columbia that are vulnerable to WNS, but it isn't known how fast the disease will spread in the province.

In eastern North America, he said, bats often hibernate in huge colonies. In British Columbia, they hibernate in much smaller, more scattered colonies, which may slow cross-contamination, but few of the sites are known so it will be difficult to detect what's happening.

Dr. Brigham said there is currently no known method to inhibit the spread of WNS. "As of right now, there is absolutely nothing we can do to stop it," he said. "The fungus likes cold, wet conditions and … Seattle at this time of the year is cool and wet, as is Vancouver and much of B.C."