White-nose syndrome (WNS) is caused by infection with a fungal agent, Pseudogymnoascus destructans (Pd). The fungus prefers cold, damp places, making caves during the winter an ideal place for it to grow. While bats are hibernating, the fungus will grow on their skin and wing membranes, causing damage. Bats wake frequently during hibernation because of Pd infection, depleting the energy stores they need for winter.
Currently, 12 bat species have been confirmed to have WNS in North America. Many of the bat species affected by WNS are state-protected in Alabama including, but not limited to, the tri-colored bat (Perimyotis subflavus), northern long-eared bat (Myotis septentrionalis)), Indiana bat (Myotis sodalis), and eastern small-footed bat (Myotis leibii). Nine additional species across North America have had positive detections of Pd without clinical signs of the disease.
The fungus is visibly white on the muzzle and wings of the bat, representative of the disease’s name. Infection with Pd often causes abnormal activity during the day, specifically during the winter and fall when cave-dwelling bat species should be hibernating. The fungus causes damage to the wing membranes, disrupting the metabolic and physiological processes during hibernation. Additionally, dead bats may be found near the entrance to caves or other hibernaculum.
The presence of fungus can be observed under ultraviolet light where it appears as an orange fluorescence, however, this is not Pd-specific. A diagnosis can be made from skin swabs or tissue samples of the muzzle and wing to test using a quantitative polymerase chain reaction (qPCR) or through a fungus culture.
Bats can transfer the fungus to each other, but it is often inadvertently spread by humans. In some areas, caves may be closed to the public. Strict decontamination procedures are also required to prevent the further spread of Pd. It has not been demonstrated that humans or other animals can be infected by Pd.
WNS is a serious disease for bat species. Since the first detection in North America in 2006, the disease has caused the death of over six million bats to date. Some caves have experienced mortality rates ranging from 90 to 100%. With several of the bat species infected being endangered or threatened, WNS is a significant threat to North American bats.
WNS has been detected in over 40 states in the U.S. and nine Canadian provinces and territories, as of March 2026. A full distribution map can be accessed at www.WhiteNoseSyndrome.org.
