Science News - September 10, 2011

disease first arrived in caves near Albany, N. Y., it has spread to more than 190 sites in 16 eastern states— with suspected cases in two more, west of the Mississippi — and to four Canadian provinces. The disease’s toll now exceeds well over 1 million bats.

It’s “the most devastating wildlife disease in recorded history,” says biologist Thomas Kunz of Boston University.

Because species affected by the syndrome are all insect-eaters, their loss could foster the transmission of pest-borne diseases in forests, croplands and among people, Gabriela Chavarria of the U.S. Fish & Wildlife Service said in testimony June 24 before a U.S. House of Representatives subcommittee. A million bats can eradicate 3. 6 metric tons of insects per night, she reported. Others at the hearing cited estimates of bats’ annual pest-control benefits to agriculture alone at up to $53 billion.

But scientists aren’t just documenting the disease’s spread and potential devastation. Teams are now testing antifungal therapies and looking for lifestyle habits that might limit vulnerability. Several scientists have begun actively investigating why the fungus is killing bats in North America — while the same infection has left European counterparts virtually unharmed. Such research might help scientists target protection efforts.

Out of nowhere

The epidemic hit during the winter of 2005 to 2006. “But we didn’t know it at the time,” says Alan Hicks of the New York State Department of Environmental Conservation in Albany.

A year later, biologists stumbled upon caves harboring thousands of dead and dying bats. Affected animals tended to host a characteristic white dusting of fungal hyphae, extremely friable threadlike growths. As word of the mystery epidemic spread in early 2007, a photographer realized he had loads of pictures that he had taken a year earlier at a now-ravaged site near Albany. One photo from February 16, 2006, showed nascent evidence of the fungus.

Hoping to identify this pathogen,

Hicks and others immediately began
circulating pictures of affected animals
among researchers — “people who col-
lectively have probably looked at tens
of millions of bats,” Hicks says. “And to
a person, they all said: ‘I’ve never seen
anything like this.’ ”
Two years later, David Blehert of the
U.S. Geological Survey’s National Wild-
life Health Center in Madison, Wis., and
colleagues published data confirming
that this fungus — a member of the soil-
dwelling Geomyces — was new to science.

For its devastating impact, it would be named G. destructans. Unlike related fungi, this one doesn’t target the dead. Instead, G. destructans latches onto living bats in the dead of winter.

Bats living where the weather gets
cold either migrate or wait the win-
ter out by hibernating in underground
caverns and mines, often at tempera-
tures within 1 to 10 degrees Celsius
of freezing. As body temperatures
plummet and immune systems take a
winter break, these animals congregate
in closely packed masses of hundreds or
thousands. Biologists refer to the con-
gregation locales as hibernacula. And
it’s in these chilly chambers that the
cold-loving G. destructans finds its hosts.

White-nose misnomer The syndrome gets its name from the observation that infected bats often develop a thin mask of pale fungal fibers on their faces. “If you touch it, the fungus

Fungal surprise after first being identified in a bat colony near albany, n.y., in 2007 (locale shown in black), a white fungus has since spread to caves across the eastern United States and into canada. three cases are suspected in two states west of the mississippi river.