Since 2007 White-nose Syndrome (WNS) has been associated with deaths of hundreds of thousands of cave 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 south-western Quebec and central and north-eastern Ontario in early 2010. In 2011, it was detected in New Brunswick and Nova Scotia. White-nose syndrome was not detected in any new provinces in 2012 although it continued to spread to new areas within provinces and move much farther south and west in the United States. In 2013 the disease was detected for the first time in Prince Edward Island. It has currently been confirmed in a total of 22 states and 5 provinces.
WNS is believed to be caused by Pseudogymnoascus destructans (formerly 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. It is believed that more than 5.5 million bats have died from the disease. 90-100% mortality has been observed in many hibernacula. The severity of the epidemic is such that the formerly very common Little Brown Bat, Northern Myotis and Tri-colored Bat have been recommended by the Committee on the Status of Endangered Wildlife in Canada to be listed as Endangered under the Species at Risk Act.
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. If you see bats flying during the daytime in winter or if you see any dead bats, please contact the Canadian Cooperative Wildlife Health Centre or your local Fish and Wildlife office.