Transmission & Development

Transmission of the fungus associated with WNS is believed to occur in one of two ways: 1) through bat-to-bat contact or 2) by humans visiting caves and mines. Bat-to-bat contact occurs during pre-hibernation movements, while in hibernacula and in maternal colonies. Conditions in hibernacula make it an ideal place for the spread of the fungus as temperature and humidity are optimal and high densities of bats are gathered in one location.

Group of bats likely infected with WNS, Virginia 2009

There is also evidence that the fungus is inadvertently spread by humans. Cavers (spelunkers) may transfer the causative agent on their clothing, shoes and gear between caves. Evidence of WNS has been documented in caves absent of bats and many states have restricted access to caves to prevent further spread by humans.

More than one million bats have died from WNS and in some hibernacula, more than 90% of the bats have died.