David S. Blehert, PhD
National Wildlife Health Center, U.S. Geological Survey, Madison, WI, USA
White-nose syndrome (WNS) is a disease associated with unprecedented bat mortalities in the northeastern and mid-Atlantic United States. Since the winter of 2006–2007, bat population declines ranging from 80–97% have been documented at surveyed hibernacula. Estimated losses have exceeded one million bats over the past three years. Affected hibernating bats often present with visually striking white fungal growth on their muzzles, ears, and/or wing membranes. Histopathologic analyses confirmed that 90% (105 of 117) of necropsied bats submitted from WNS-positive sites exhibited an associated cutaneous fungal infection. Direct microscopy, culture, and PCR analyses demonstrated that the skin of WNS-affected bats is colonized by a new species of psychrophilic (cold-loving) fungus, Geomyces destructans. The fungal isolates were initially cultured at 3°C and grew optimally between 5°C and 14°C, temperatures consistent with the body temperatures of hibernating cave bat species within the WNS-affected region. Laboratory infection trials indicated that G. destructans is transmissible bat-to-bat, and the fungus has been identified in environmental samples collected from several bat hibernation caves within WNS-infested states. There is a growing body of evidence supporting an association between WNS and cutaneous fungal infection by G. destructans. Given the hundreds of thousands of hibernating bats found throughout the WNS-affected region, this disease represents an unprecedented threat to bats of the eastern United States and beyond.