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Bat Killer Identified

10/31/2011
Rachelle Dragani

Researchers are working against the clock to stop a fungus that has already killed millions of North American bats, hoping that this Halloween won’t be the last for the little brown bat.

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US researchers have identified the newly discovered fungus Geomyces destructans as the sole suspect in the mass murder of more than one million North American bats since 2006.

In a study published in Nature, the team led by David S. Blehart from the University of Wisconsin reported that when healthy little brown bats are exposed to pure cultures of G. destructans, they develop white nose syndrome (1). The infection, named for the fuzzy white patch it leaves on infected bat’s noses, causes bats to wake from hibernation early. Because the insects that they eat are not readily available in cold weather or the daytime, this premature awakening forces bats use too much of their fat reserve and wither away.

White nose syndrome named for the fuzzy white patch it leaves on infected bat’s noses, causes bats to wake from hibernation early. Source: US Fish & Wildlife Serivce National Digital Library







Previously, researchers have been unable to determine the primary pathogen of the disease, since European bats that live with G. destructans do not develop white nose syndrome. White nose syndrome was first identified in 2006 in upstate New York, and has since been confirmed in 16 states. In some caves, 90-100% of the populations have been wiped out. Within 15 years, researcher believe some species — such as the little brown bat, which has been the most susceptible to the disease — could become extinct. Because bats eat insects that spread infectious diseases, their loss could be devastating to humans.

The next step is to develop a treatment to kill and stop the spread of the bat-killing fungus, which may prove to be a rather daunting task. “When efforts are aimed at having a mass population saved, then individual treatment is not going to work,” said researcher Vishnu Chaturvedi who was not involved with the Nature study.

At the University of Albany, Chaturvedi and colleagues have been working with New York State Department of Health to study the fungus using rapid PCR and sequencing techniques. Previously, by analyzing three years worth of DNA samples from bats in a 500-mile radius in New York, his group concluded the fungus originated from a single point source in a New York bat cave. In a study published in Mycopathologia, his team reported their work on a real-time PCR assay to improve the detection of G. destructans in bats (2).

When looking for a treatment, Chaturvedi was surprised to learn that the pathogen, which thrives at low temperatures, responded to commonly available anti-fungal drugs that typically work at 30-37°C.

“This is one of those rare opportunities for science to not only address the immediate problem of bat decline, but also to investigate and put resources to try to understand how fungal enzymes, fungal proteins, and fungal gene expression can be adapted to work at such a low temperature and to allow that particular adaptation to cause disease symptoms,” said Chaturvedi.

Although the drug has been effective in some rehabilitating bats, it’s too early to call it a cure. Furthermore, the practical application of implementing an effective drug in the wild is unprecedented.

“If at least in the laboratory the fungus can be killed, you can treat [bats] in captivity and release them to have a founding population, if it comes to that,” said Chaturvedi.

References

1. Lorch, J.M., C.U. Meteyer, M.J. Behr, J.G. Boyles, P.M. Cryan, A.C. Hicks, A.E. Ballmann, J.T. Coleman, D.N. Redell, et al. 2011. Experimental infection of bats with Geomyces destructans causes white-nose syndrome. Nature. [Published online October 26, 2011]

2. Chaturvedi, S., R.J. Rudd, A. Davis, T.R. Victor, X. Li, K.A. Appler, S.S. Rajkumar, and V. Chaturvedi. 2011. Rapid real-time PCR assay for culture and tissue identification of Geomyces destructans: the etiologic agent of bat geomycosis (white nose syndrome). Mycopathologia. 172:247–56.