The newly identified fungus found in devastated bat colonies along the eastern United States has been confirmed in Europe — but, surprisingly, in an apparently healthy bat.
During intensive monitoring last March of places bats hibernate, researchers near Perigueux, France, found a mouse-eared bat with white powdery patches on its body. A research team headed by bat expert Sébastien J. Puechmaille of University College Dublin reported in December's online Emerging Infectious Disease Journal that analysis of swabs of fungal growths from the bat's nose confirmed Geomyces destructans, the fungus that apparently has whisked away more than a million bats from caves in the Northeast United States.
But the French bat was alive.
Although sleeplessness and starvation are known to accompany white-nose syndrome's symptoms in American bats, researchers reported that the French bat "was in good condition," weighing 24 grams, which, they write, was "more than the expected average for a post-hibernating bat [of its species] despite having Geomyces destructans growth on its snout."
Three possibilities explain this, researchers say; the first being that the bat represents the vanguard of a dangerous infectious wave of white-nose that now threatens all European bats. But they hedge this ghastly scenario against the possibility that the fungus may not be the cause of death in white-nose syndrome, as suspected, but merely an opportunistic infection afflicting bats already hurting from some yet undiscovered malady.
But Alan Hicks, the New York state wildlife biologist who discovered white-nose syndrome, says the evidence seems to line up in favor of the researchers' third, and more palatable, scenario: Geomyces is not as deadly to European bats as it is to those in North America.
He said that the bat's apparent good health, and that there have been no reports of massive die-offs attributed to the fungus among European bats, offers encouraging news.
Plus, the fungus may not be new to Europe. "Going as far back as the 1980s, there have been reports in the literature of bats in Europe with white powdery growths on their skin," Hicks said. While he says it is impossible after the fact to confirm the causal agent in the earlier sightings, it would be reasonable in light of recent findings to suspect the fungus.
David Blehert, the U.S. Geological Survey microbiologist who first isolated the fungus in 2008, agrees. He cited recent reports of bats with confirmed infestations of G. destructans captured in Germany, Hungary and Switzerland, along with photographic evidence of the fungus from the Czech Republic. Blehert said he is currently working with the Broad Institute at the Massachusetts Institute of Technology to sequence the fungus's entire genome, which will permit scientists to construct a history of its origin and travels.
Though Hicks concedes that the fungus might lead to some deaths in European bats, "It appears, in some way that European bats are resistant. They sure as heck are not dying like they are here."
"Definitively what's needed is microscopic analysis of skin from affected European bats," Blehert said. "In the U.S., the fungus causes an invasive skin infection; it would be very interesting to know if that occurs on European bats or if what we're seeing is just a superficial colonization of the fur."
Hicks suggested researchers will need to "look to see if anything being produced by the bats" is providing them with protection, or "whether there is another type of fungus or bacteria living on the bats affording them some protection."
While it is essential to answer these questions, Hicks said the discovery of white-nose in Europe highlights a broader issue. The finding "strengthens the probability that this is a European-born disease, and just the latest in the list of invasive species to arrive on our shores, threatening our ecosystems."
Once again, he said sadly, it shows how easily human activity can "overtax the system."
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