UV Screening for Bat White-Nose Syndrome Surveillance

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Detailed Description

Long-wave ultraviolet (UV) light can be used to detect orange fluorescence associated with white-nose syndrome (https://www.usgs.gov/centers/nwhc/science/white-nose-syndrome-surveillance) on bat skin. White-nose syndrome (WNS) is a highly fatal disease affecting multiple species of North American bats that is caused by the fungus Pseudogymnoascus destructans. While UV screening does not definitively diagnose white-nose syndrome in bats, it can be used to guide further sampling for white-nose syndrome surveillance. More information on white-nose syndrome surveillance is available from the USGS National Wildlife Health Center (https://www.usgs.gov/centers/nwhc/science/white-nose-syndrome-surveillance). This video shows the proper technique for safely screening bats for white-nose syndrome with a hand-held UV light source and is intended to be performed by an authorized wildlife professional only. Bats may carry rabies and should never be directly handled without appropriate safety precautions.


Date Taken:

Length: 00:02:54

Location Taken: Madison, WI, US

Video Credits

Filming and narration by S. Grange. Technique demonstrated by A. Ballmann. Video editing by S. Grange and A. Ward. Audio description by A. Ward.


UV screening is required if collecting a skin biopsy. It is not a diagnostic tool, but rather a screening tool. Having a UV positive result is not definitive for White-Nose Syndrome. Nor does a negative UV result mean that there is no White-Nose Syndrome or Pd. It is thought that the fungus produces a fluorescent riboflavin when invading the tissue, but if the fungus has not yet invaded the tissue or the animal is healing, the UV screening might appear negative.


Always wear UV eye protection when using a UV light. In addition, although this video shows the technique in white light, UV screening needs to be performed in complete darkness.


UV screening can be done when the bat is roosting. A moderate infection can be seen on the muzzle, ears, and forearms, but a minimal infection may be overlooked.


Hold the UV flashlight at about a 45 degree angle and approximately 3-5 inches from the bats skin. Make sure to shine the light down and away from the bat’s eyes.


Digital pictures can enhance fluorescence, but it is difficult to get a clear image without the use of a camera tripod setup.


This is a UV negative bat, but as you can see other things fluoresce such as minerals, mites, and other body structures. This could lead to a false positive.


As you can see, White Nose Syndrome is a fungus that is rounded with fuzzy edges. They are pinpoint spots that can be grouped together into large clumps. However, when viewed under white light, fungus may not be visible.


When viewed under UV light with the naked eye, fluorescence is not as bright, and your eye must be trained to the right search image.