White-Nose Syndrome - Background

Since 2007 White-nose Syndrome (WNS) has been associated with deaths of hundreds of thousands of cave bats (especially Little Brown Bats), first in the north-eastern United States, but now extending down the Appalachian chain and into the lower mid-west. WNS was first confirmed in Ontario in early 2010 at a number of hibernacula in south-central, eastern and northeastern Ontario, and has again been identified in 2011 in bats at new locations near previously confirmed sites. WNS also was confirmed in south-western Quebec in 2010, and in 2011 surveillance is ongoing there and in the Maritimes, where it was not recognized in 2010.

WNS is believed to be caused by Geomyces destructans, a fungus that grows in the skin of the bat, producing a fuzzy, white appearance on the muzzle, wings and ears, giving the condition its name. Infection of the skin of the wings may have a detrimental effect on water metabolism, causing bats in cool hibernacula to emerge from torpor more frequently than normal during the winter, exhausting their energy reserves before food becomes available in spring.

WNS spread rapidly from the epicentre in Upper New York State, probably carried by infected bats, but how the infection originated or was introduced to North America is not understood. The severity of the epidemic is such that the formerly very common Little Brown Bat is projected to become endangered over a large part of its range within the next few decades.

There is no evidence that the fungus has any effect on humans or pets. However, members of the public are encouraged to avoid bats and bat hibernacula to prevent accidental translocation of the fungus by human activity. As well, caution should be taken in dealing with bats, since they may carry rabies.