Bat Populations across North America have been dwindling over the past decade due to the introduction of Pseudogymnoascus destructans, also known as White-Nose Syndrome (WNS).  This pathogen is a fungal disease that originated in Eurasia before it was introduced to the United States.  The first confirmed case of White-Nose Syndrome was in 2007, when scientists discovered many dead bats in a cave in Albany, New York. However, there were earlier suspected cases from 2005 to 2006.  The exact cause of the fungal disease’s introduction to North America is still unknown, though most scientists agree that its origin was likely linked to humans indirectly (Hoyt et al., 2021).

The disease has spread all over North America at a rate of 200 km/year to 900 km/year in the first eight years.  This is now in 39 states in the US and 7 Canadian provinces. WNS is typically spread to bats through direct contact with infected individuals or environments.  Figure 1 below shows the cycle of how the disease spreads.  The graph in Figure 1 indicates that the disease infections begin in August/September and begin to peak in November/December.  WNS will persist through winter and decrease around May when spring approaches.  This coincides with bats’ hibernation, as depicted in Figure 1.  The disease infects bats in the winter months when the bats are hibernating and in close contact with each other.  Some bats will survive the disease, while others will die of the infection.  The bats will begin to recover during summer since they are outdoors more.  When they return the following winter for hibernation, they risk infection again (Hoyt et al., 2021).

Figure 1: How Whtie-Nose Syndrome Spreads

(Hoyt et al., 2021)

            The disease affects bats the most during the winter when they are in their hibernation state.  They are vulnerable during hibernation because it makes them active while attempting to conserve energy (White-nose Syndrome Response Team, What Is White-nose Syndrome?). Figure 2 depicts the disease’s physiological effects on bats. The disease starts by causing damage to the bat’s tissue, increasing the bat’s metabolic rates.  An accelerated metabolic rate can cause the temperature of the bats to rise, leading to dehydration and loss of vital electrolytes. Additionally, the metabolic rate increase leads to energy reserve loss and fat reduction.  These factors combined have led to the increased mortality of multiple bat species (Hoyt et al., 2021).

Figure 2: Physiological Effects of White-Nose Syndrome on Bat Populations

(Hoyt et al., 2021)

Many different efforts are being made to help slow down the spread of the disease.  One such team, the White-Nose Syndrome Response Team, implements these conservation efforts to save multiple species of bats.  One such method is biological, which involves applying a bacterium to the bats known as Rhodococcus rhodochrous. This bacterium has features that help kill the disease.  The team uses different chemicals to kill the disease and prevent its spread. An example of this is Polyethylene glycol (PEG) 8000.  Progress is being made to create a vaccine for the bats.  Scientists are also changing habitat conditions, such as the temperature, to make it less ideal for the disease to grow (White-nose Syndrome Response Team. Helping Bats Survive).

Citations

Hoyt JR, Kilpatrick AM, Langwig KE (2021) Ecology and Impacts of White-Nose Syndrome on Bats. Nature Reviews Microbiology. 19: 196–210.

White-nose Syndrome Response Team. What Is White-nose Syndrome? https://www.whitenosesyndrome.org/static-page/what-is-white-nose-syndrome ((date last accessed 2 April 2024)

White-nose Syndrome Response Team. Helping Bats Survive. https://www.whitenosesyndrome.org/static-page/helping-bats-survive ((date last accessed 2 April 2024)