Christopher Deck: White Nose Syndrome in Bats

White-Nose Syndrome: A North American Epidemic
By: Christopher Deck

In the northeastern United States, bat populations are currently dying off at an increasingly alarming rate. Their mortality has been linked to a disease known as White-nose syndrome (WNS), and infected populations have since been found to be dying at a rate of up to 90-100%. WNS has claimed over one million lives since its discovery. WNS was first discovered in a cave system outside of Albany, New York during January of 2007, and the disease has since spread rapidly to southeastern Canada and throughout the northeast United States. As of October 2010, WNS has already been identified as far west as Oklahoma and it is widely feared it could spread globally (United States Fish and Wildlife Service). Scientists and researchers around the country are desperately searching for a way to slow or stop the devastation that WNS is inflicting. Unfortunately, science has yet to find any definitive answers or solutions to this devastating puzzle.

Bats are often feared and misunderstood creatures that we think of as rabid, creepy, flying mice. However, bats are not rodents at all: they are actually closely related to humans and primates and only 0.5% have been found with rabies. Their wings are actually quite similar to our hands, containing four fingers and a thumb. The females, like primates and humans, nurse and care for their young until they are able to hunt on their own. Bats are an important member of their ecosystems, providing crucial insect population control. 70% of bats in the world eat flying insects, while some species eat fruit, small lizards, frogs, etc (New York State Department of Environmental Conservation). In New York State, all of the bat species are insect consumers, feasting on bugs such as moths, beetles, and mosquitoes every night (Kannan, Yun, Rudd & Behr). A single little brown bat will consume 4-8 grams of insects every night (Boyles and Willis). A colony of 20 million bats outside of Austin, Texas will consume an estimated 250 million tons of insects each night (Bodin). As the bat populations continue to decline, the insect populations are rising rapidly. Uncontrolled insect populations will spread disease and cause devastating damage to crops. Finding a solution to White-nose syndrome is important to not only bats, but the ecosystems that they participate in. If allowed to disappear, the loss of hibernating bats could have a chain reaction throughout their entire ecosystems, killing off various other crucial species.

The cause of white-nose syndrome has been linked to a recently indentified fungus named Geomyces destructans. This fungus can be found on the muzzle and flight membranes of infected bats (Boyles and Willis). This fungus has been the focus of numerous scientists and research teams throughout northeastern North America. Its source has only been hypothesized, and it remains a mystery. It is believed to spread when roosting bats rub against each other during hibernation (United States Fish and Wildlife Service). During hibernation, bats roost in clusters of up to 300 bats per square foot. In New York State, the majority of bats can be found hibernating in only five caves. The high concentrations of bats packed into only several locations are believed to have aided in the rapid spread of this fungus. Scientists are still speculating exactly how geomyces destructans is affecting the bats, but do believe it interferes with their hibernation cycles (New York State Department of Environmental Conservation). It is believed by some scientists that the geomyces destructans fungus is not actually directly killing the bats. Instead, it is thought to be more of an irritant, somewhat like athlete’s foot in humans (Bodin).

Although scientists believe the fungus is being spread between bats during hibernation, human-induced spreading is also a likely cause. According to an article published in High Country News in June of 2010, bats in Europe have exhibited a similar white fungus for decades. This ailment found in European bats remains non-lethal, but may be affecting American bats differently. The fungus is hypothesized to have been unknowingly brought to the United States from human contact with the bats via clothing or scientific equipment. WNS is now prevalent throughout northeastern North America and is spreading westward. As a precautionary measure, many parks and caves in the western part of the United States are currently implementing new rules and regulations for cave spelunkers and biologists alike. Some caves require every person to use decontamination stations, provided near the cave entrance, before they may enter. Other western caves are not allowing gear or clothing which was used in any eastern cave during the last five years. Some western states have even added decontamination stipulations to the permit process for biologists who wish to study the bats. Some states, such as Arizona, are surveying up to 30 caves per day for traces of WNS. So far, there has been no conclusive evidence of white-nose syndrome past the western Oklahoma state line. Since WNS has yet to be identified in the west, and because the decontamination process is time-consuming, sanitation rules are being relaxed for the cave surveyors in some areas. They must, however, remain in western caves to prevent contamination (Bodin).

The map below indicates areas affected by White-nose syndrome and how it has spread during the years spanning 2007 to 2010.

(http://www.fws.gov/WhiteNoseSyndrome/pdf/White-noseNatlPlanFSOct2010.pdf)

Currently, nine species of bats in North America are infected with WNS, 2 of which are on the Endangered Species list. According the United States Fish and Wildlife Service (USFWS), the 9 species are: the Big brown bat (Eptesicus fuscus), Eastern small-footed bat (Myotis leibii), Indiana bat (Myotis sodalis), little brown bat (Myotis lucifugus), Northern long-eared bat (Myotis septentrionalis), Tricolored bat (Perimyotis subflavus), Cave bat (Myotis velifer), Gray bat (Myotis grisescens), and the Southeastern bat (Myotis austroriparius) (United States Fish and Wildlife Service). The little brown bat (Myotis lucifugus) is New York State’s most prevalent bat species, and is also the number one affected species of WNS. When full grown, they have a wingspan of 8 to 9 inches and a body length of 3 to 4½ inches, which is roughly the size of a human thumb. The little brown bats fly at speeds up to 21 miles per hour while flapping their wings 15 times per second. (New York State Department of Environmental Conservation)

A recent study on the little brown bat has shown they exhibit high concentrations of persistent organic pollutants (POPs), which could be lowering their immune systems, allowing the geomyces destructans fungus to move in. The POPs found in the bats include: PCBs, PBBs, PBDEs, DDT, Chiordanes, HCHs, and HCB. The highest concentrations of toxins found were PCBs with DDT and PBDEs following. The toxins are stored in the vital fat reserves used to survive hibernation. When bats arouse during hibernation, they draw energy from these fat stores, which mobilizes the POPs into the brain and liver via their bloodstream. The presence of these POPs can be linked to abnormal behavior and increased metabolic rates in addition to lowered immune capabilities. A controlled laboratory study showed bats with these toxins lost weight at an increased rate of 24% (Kannan, Yun, Rudd & Behr). Because these POPs, which are stored in their fat, speed up their metabolic rates, the body fat the bats normally depend on for winter survival is now lost, contributing to their death. All bats found dead with WNS have little to no body fat.

On average, a healthy little brown bat will store 2 grams of fat for the winter, and a single arousal during hibernation can spend up to a month’s worth of these fat reserves (Quammen). During hibernation, healthy bats typically awaken for short periods of time, but infected bats are thought to exhibit altered behavior. During an arousal, they need to bring their body temperature back up to normal levels, as it drops significantly during torpor (inactivity). The raising of their body temperature uses vital fat reserves that were stored before hibernation. In addition to toxins in body fat, there are some other theories about WNS that would also contribute to problems with their vital fat stores. These theories include: first, the bats are not storing enough fat before entering hibernation; second, the bats are showing altered behavior during hibernation (more frequent arousals, longer arousal periods, and possibly, higher arousal body temperatures); or third, they may not be able to arouse from torpor at all due to low body-fat stores (Britzke, Sewell, Hohmann, Smith, & Darling). So far, nothing has been proven as a direct cause of the high mortality rate. However, the introduction of the geomyces destructans fungus is a likely candidate for causing these theorized symptoms, and the evidence suggests they are dying from starvation from one or more of the contributing factors.

It is believed by some scientists that the geomyces destructans fungus is acting as an irritant, and not directly killing the bats. The irritation would cause the bats to arouse from torpor more often during hibernation, thus spending their fat stores prematurely (Bodin). This, if proven, would give some insight on the above-mentioned theories as to why the bats are rousing more frequently and possible longer durations. The irritation from the fungus could also be the reason the bats may not be eating enough before hibernation. Perhaps it interferes with successful hunting. If the bats are unable to gather enough fat in their bodies before hibernation begins, they will not have enough energy to survive the winter months, which could be a contributing factor in the theory that they are unable to awaken.
A team of WNS researchers, in 2009, hypothesized that if the bats did not have to change their body temperature so drastically during the arousals, they would not spend as much fat energy, thus increasing the likelihood of their survival (Boyles and Willis). They propose to warm small sections of caves with known populations of WNS infected bats. This could be accomplished with small heating units, tailored specifically to each hibernaculum. The goal would be to raise the temperature in selected domes or crevices in the cave ceilings. Hibernating bats are typically found in the warmest part of the cave, so it is believed they would seek out a warmer section if one was provided by scientists. This would give them a warmer hibernation temperature which would allow them to spend less of their fat reserves when they rouse. Their models show mortality levels dropped from an average of 81.9% to 63% when the ambient model cave temperature was brought up to 12 degrees Celsius. When they increased the temperature to 20 degrees Celsius, the mortality level dropped further to 43.6%. The third model was tested with temperatures of 28 degrees Celsius and resulted with a mortality rate of only 25.2%. The researchers are proposing this plan not as a cure, but as a way to extend the amount of time for other research to find a cure (Boyles and Willis).

This temperature-alteration plan, however, would likely not be put into practice. While not definitive, some researchers suggest that cooler temperatures are vital to proper hibernation for the bats. Also, the extent and intricacy of white-nose syndrome is still unknown. Altering the temperature of the bats hibernacula could potentially increase or alter the effects of the geomyces destructans fungus, causing further complications. The researchers also caution: “increasing survival rates [of infected bats] could be disastrous if it increases the rate of spread of the disease” (Boyles and Willis).

Other projects are frantically being undertaken to further understand white-nose syndrome and to search for a cure. On October 6, 2010, the United States Fish and Wildlife Service (USFWS) announced they will be granting approximately $1.6 million for white-nose syndrome research projects. The USFWS’s white-nose syndrome coordinator, Jeremy Coleman, says, “These projects will help us answer critical questions about how to manage this devastating disease.” The funded projects will include:
Detailed studies of geomyces destructans, the fungus associated with WNS; improving WNS detection techniques; developing a better understanding of how WNS is transmitted; determining the mechanics of G. destructans infections in bats, including the susceptibility and resistance of bats to the infection; and determining how persistent the fungus is in the environment.

The Fish and Wildlife Service hopes these projects will result in answers and solutions to slow this rapidly growing epidemic (United States Fish and Wildlife Service).

Several research teams have tested the geomyces destructans fungus against commercially available azole-based fungicides. These types of fungicides are common “active ingredients found in over-the-counter jock itch, yeast infection, and athlete’s foot creams and dandruff shampoos.” The test results proved to be highly effective against the geomyces destructans fungus (Laboratory Equipment). The solution, however, is not as simple as spraying the bats with an athlete’s foot medicine. Direct application of over-the-counter fungicides has proven to be fatal during lab studies. A viable cure would have to take many other factors into consideration. The medicine would have to be dissolved into a solution that would not harm the bats further and be able to be applied without direct human contact. A single application would also be a desirable attribute so that scientists can avoid any further disturbances to the hibernating bats. The proper treatment must also work well at the cool temperatures in which the bats hibernate while not causing any other impacts to the cave ecosystem (Laboratory Equipment).

The use of commercially available fungicides, such as athlete’s foot treatment, is only approved for human use, not environmental health concerns. The Environmental Protection Agency (EPA) would need to approve these alternate uses before scientists could use them in the field. To avoid this problem, researchers have also been looking toward natural substances which are not restricted by the EPA. Spearmint oil has been found to be capable of killing the geomyces destructans fungus and the spores which spread it. The oil can be administered in vapor form, which solves the problem of human contact. The spearmint oil works well in laboratory settings, but is not likely to be used in the field because there are too many other non-target species inside cave ecosystems. Jeremy Coleman suggests if white-nose syndrome continues to progress, they may begin to capture the bats and relocate them to man-made structures where they can be treated without endangering other species (Laboratory Equipment).

For their December 2010 issue, National Geographic Magazine published an article titled “Crash”. It is one of the most up to date articles on white-nose syndrome at the time this paper was written. The author, David Quammen, does an excellent job conveying the seriousness and urgency surrounding this issue. He also provides the reader with helpful yet interesting background information on the geomyces destructans fungus and hibernation patterns along with the bats themselves. What he doesn’t provide are possible or proposed solutions to WNS. While estimates and models about solutions and hope would give his readers an insight as to what is being done, he speaks louder without so many words. He ends the article by describing the cluster of hibernating bats he saw during his visit to Hubbard’s Cave in Tennessee: “This single patch, I’m told, might encompass 300,000 bats. It resembles a buffalo robe. It resembles a huge, dark amoeba. It puts me in a mind of a giant Rorschach blot, testing our visions of the future” (Quammen). By leaving the reader guessing what is being done, David Quammen is putting his reader into the researchers’ proverbial shoes, showing just how little is known about WNS.

Scientists and researchers are faced with an important yet deceptive puzzle. Hopefully as they continue to study this puzzle of uncertainty, this Rorschach test, the answers will be realized.

As of December 2010, there are no known solutions or answers as to why WNS is happening, where it came from, how far it will spread, what the complete effects will be, or even how to viably and safely slow it down. If something is not done soon, hibernating bat species may be added to the history books for North America, and perhaps the globe. It is widely accepted in the scientific community that Planet Earth is undergoing its 6th mass extinction, with species currently dying off at up to thousand times the historic rate since the last mass extinction. Because of their importance, the disappearance of bats could initiate a domino effect in their ecosystems, feeding the mass extinction.

Works Cited
Boyles, J., & Willis, C. (2010). Could localized warm areas inside cold caves reduce mortality of hibernating bats affected by white-nose syndrome?. Frontiers in Ecology & the Environment, 8(2), 92-98. doi:10.1890/080187.

(2010). Bracing for white nose syndrome. High Country News, 42(10), 8-19. Retrieved from Environment Complete database.

Britzke, E., Sewell, P., Hohmann, M., Smith, R., & Darling, S. (2010). Use of Temperature-sensitive Transmitters to Monitor the Temperature Profiles of Hibernating Bats Affected with White-Nose Syndrome. Northeastern Naturalist, 17(2), 239-246. Retrieved from Academic Search Complete database.

Castle, K., & Cryan, P. (2010). White-nose syndrome in bats: A primer for resource managers. Park Science, 27(1), 20-25. Retrieved from Environment Complete database.


Kannan, K., Yun, S., Rudd, R., & Behr, M. (2010). High concentrations of persistent organic pollutants including PCBs, DDT, PBDEs and PFOS in little brown bats with white-nose syndrome in New York, USA. Chemosphere, 80(6), 613-618. doi:10.1016/j.chemosphere.2010.04.060.

Laboratory Equipment. (2010). Scientists Hope Genome Will Stop Bat Disease. Retrieved from http://www.laboratoryequipment.com/News-scientists-hope-bat-genome-will-stop-disease-111810.aspx?xmlmenuid=51.

New York State Department of Environmental Conservation. (2010). Little Brown Bat. Retrieved from http://www.dec.ny.gov/animals/59376.html.

New York State Department of Environmental Conservation. (2010). White-Nose Syndrome Threatens New York Bats. Retrieved from http://www.dec.ny.gov/animals/45088.html.

Quammen, David. (2010 December).Crash. National Geographic Magazine. 126-137.

United States Fish and Wildlife Service. (2010). A National Plan for Managing White-Nose Syndrome in Bats. Retrieved from http://www.fws.gov/WhiteNoseSyndrome/pdf/White-noseNatlPlanFSOct2010.pdf.

United States Fish and Wildlife Service. (2010). Fish and Wildlife Service Awards $1.6 Million in Grants to Research and Manage the Spread of White-Nose Syndrome. Retrieved fromhttp://www.fws.gov/WhiteNoseSyndrome/10062010.html.