Science News - September 10, 2011

American bats would explain the continent’s pandemic, Willis says. His team expects to publish its findings soon.

Best case is slow recovery

In the meantime, scientists are anxious to find a treatment. Plenty of medicines for fungal infections in people can kill G. destructans — at least in the test tube, notes Alison Robbins of the Cummings School of Veterinary Medicine at Tufts University in North Grafton, Mass. That knowledge has led her and others to investigate the potential of terbinafine, an active ingredient in many athlete’s foot medicines, to treat white-nose syndrome. This drug has been used safely in children around the world, she notes.

Last year, she dabbed it on bats that were temporarily taken from roosting in a hibernaculum. “But just the disturbance of doing that killed them,” Robbins says. So she and bat physiologist DeeAnn Reeder of Bucknell University in Lewisburg, Pa., turned to lab studies, applying terbinafine onto wings of infected bats as a cream or spray. It didn’t save them.

Robbins also tried injecting terbinafine directly into white-nose-infected little brown bats that she brought back to her lab from a cave in Virginia. All bats that were handled and kept warm following the disruption, whether treated or not, survived longer than those that went straight back into hibernation without any care from Robbins’ team. But none survived hibernation more than roughly 100 days, Robbins says. Few made it even that long. The stress, especially from handling, was enough to kill them. Still, she says, she hasn’t given up on terbinafine.

The bats’ 600-kilometer road trip to Massachusetts probably contributed to their stress. Unfortunately, Robbins says, the Virginia colony was the closest of any significant size. As recently as 2008, some 10,000 bats used to hibernate about 50 kilometers from her facility. By 2009, the syndrome had culled that population to 117. This past fall, just 14 bats returned.

Insect-eating bats simply don’t do well in captivity, Robbins says, but scientists

Scientists documenting white-nose
syndrome’s spread often have to climb
through caves and abandoned mines
over piles of dead bats.

may need to keep small numbers alive in
the lab until a workable treatment can be
found. “We have to try to figure out how
to make it work,” she says. “At this point,
there’s nothing to lose.”
Kunz has been focusing on another
survival strategy: making bats’ summer
digs more hospitable.

In spring, hibernating females awake and take flight to maternity colonies. These sites can be the ridgepoles of barns, somebody’s attic or a natural site. In contrast to winter, when they hunker down in near-freezing accommodations, females seek ultrawarm homes in summer where they nestle together, conserving their bodies’ energy for pregnancy and lactation. But as white-nose has taken its toll, Northeastern maternity populations have plummeted. This June, Kunz visited a trio of summer lodges that used to host bet ween 800 and 1,200 bats each. Two were empty and the last housed just 38.

Concerned that some communities
are losing too many bodies to main-
tain crucial spring warmth, his group
designed what it calls roost modules.
Outfitted with oodles of baffles, these
wooden structures can be inserted into
buildings, creating bat incubators. He
has installed them at two sites. Unlike
neighboring populations that contin-
ued to dwindle perilously, colonies with
roost modules seem to have stabilized
at 30 percent of the original colony size,
Kunz says. “I’m now collecting data on
genetic variation in the survivors to see
if they show signs of genetic resistance.”
Because effective treatments for the
disease are lacking, some scientists have
pinned their hopes on the evolution of
such resistance among American bats.
Biologist Sébastien Puechmaille of
University College Dublin suspects
European bats have already evolved
such a resistance, explaining their sur-
vival. “It appears the fungus has been in
Europe for a long time. And when I say a
long time, I mean thousands — if not tens
of thousands — of years,” he says.