A group of biologists and local residents gathered outside the Mark Twain Cave Complex in Missouri on May 19 to watch the release of 150 special bats. The bats were some of the first to be successfully treated for white-nose syndrome, a fatal disease that has wiped out millions of bats in the eastern half of the United States and Canada since it first appeared about a decade ago.
The treatment, based on the common bacterium Rhodococcus rhodochrous, was developed by Dr. Christopher Cornelison and several fellow researchers and students at Georgia State University.
“It was great to be there and more-so to see the locals who came out,” Cornelison said. “Those people who have been going to that cave for decades, spending their lives around these animals. A couple of years ago, when the mass mortality of the bats began, they were heartbroken.
“For me, seeing the hope that they had and how much they care for this resource was very powerful and reinvigorates me and motivates me and reminds me why I’m doing this work.”
White-nose syndrome was first discovered in the U.S. in 2006 in a cave in New York. Since then, it has spread rapidly, killing more than 5.7 million bats. The disease was given its name because of the white fungus that grows on noses, wings, ears and tails of infected bats while they hibernate. The fungus — which thrives in cold, damp environments, such as bat caves — eats away the bat’s skin, disturbs its hibernation and causes it to expend energy until it starves. Most bats infected with the disease don’t live through the winter.
How the treatment works
In 2012, Cornelison and a team of researchers at Georgia State University began looking at Rhodococcus rhodochrous, a common soil bacterium, as a solution for managing white-nose syndrome.
“It doesn’t have the inherent ability to inhibit fungi in a manner to make it effective for treatment,” Cornelison explained, “so what we do is a process called induction, which just means we’re growing it on very specific substrates … to increase the prevalence of certain enzymes.”
“What ends up happening is the cells produce chemical compounds that disperse through the air, and those compounds are capable of permanently inhibiting the fungus and slowing growth of mycelium [the vegetative part of a fungus],” Cornelison said.
Bats hibernating in four caves — two in Kentucky and two in Missouri — were captured for the trial treatment last fall. Numbered bands were placed on the bats forearms, and they were placed in an enclosure with the induced bacterium.
After 48 hours, the bats were released into mesh enclosures in their natural hibernacula and monitored all winter. When the bats rose in this spring, they were collected for inspection. Not only had they survived the winter, the bats appeared to be free of white-nose syndrome.
“There were no detectable signs of disease,” Cornelison said. “You could see scarring from the fungus that had healed. You could tell that they used to be sick, but there were no visible signs of disease.”
The seemingly healthy bats were set free.
“In a lot of animal studies, you’re obligated to euthanize the animals after the research,” Cornelison said. “It’s standard protocol. But in this case, both ourselves as researchers and state and federal conservationists recognized that the last thing we wanted to do was euthanize these animals at the end of the study when they’re doing so poorly on the natural landscape.”
White-nose syndrome in Maine
Maine appeared to be insulated from white-nose syndrome until spring 2011, when biologists found white fungus growing on bats in two caves in Oxford County, according to a previous BDN story.
An effort to stop the disease had long been underway. A large group of state and federal agencies, wildlife organizations, laboratories and universities were collaborating in research to better understand the white-nose syndrome, slow its spread and save the bats being infected.
In 2012, a batch of infected bats were sent to Limestone, Maine, for an experiment led by the U.S. Fish and Wildlife Service. The plan was to test whether sterilized, artificial hibernacula could be effective in reducing the impact of the disease.
The bats were placed in old military bunkers at the former Loring Air Force Base, now a part of the Aroostook National Wildlife Refuge. Fixtures had been secured to the bunker walls for bats to roost upon, and pools of water were installed on the floor. Throughout the winter, they were monitored by video camera.
The outcome was grim. Just nine of the 30 bats survived the winter. The bats that died were covered with white fungus.
By 2013, three bat species in Maine — little brown bats, northern long-eared bats and eastern small-footed bats — had seen somewhere between 80 and 100 percent declines in their populations.
“We’ve documented catastrophic declines in their populations,” Cory Mosby, small mammal biologist with the Maine Department of Inland Fisheries and Wildlife, said. “[White-nose syndrome] has affected all of our known hibernacula in Maine.”
What’s next?
The success of the new bacterium-based treatment in Missouri and Kentucky has given people hope that there may be a way to control the bat-killing disease, but the battle isn’t over yet.
Cornelison and his team plan to engage new states in the research and increase their number of trials for the upcoming winter. They also are focusing on how to optimize their treatment regime. And they need to know how this treatment could affect cave ecosystems.
“There’s a tremendous amount of work to be done,” Cornelison said. “We’re a long way from getting an upper hand on this disease.”
As far as Maine goes, Mosby isn’t sure whether the state’s bat caves would be candidates for the trials.
“I think one limitation in Maine would be the fact, of our current known hibernaculum, our populations have gone from hundreds of bats to single digits,” Mosby said. “If you were still in research phase and field testing, you’d want a larger sample size.”
“We really hope something has developed in terms of something to battle white-nose syndrome,” he added. “When it comes to finding treatments, there’s an amazing amount of effort and money going toward addressing this nationwide problem.”
To learn about white-nose syndrome, visit whitenosesyndrome.org.