Wolvesmay be best defense against deadly brain disease
Are the wolves of Yellowstone National Park the first line of defense against a terrible disease that preys on herds of wildlife?
That is the question for a research project underway in the park, and preliminary results suggest that the answer is yes. Researchers are studying what is known as the predator cleansing effect, which occurswhen a predator sustains the health of apreypopulation by killing the sickest animals. If the idea holds, it couldmean thatwolveshave a role to play in limiting the spreadof chronicwasting disease, which is infecting deer and similar animals across the country and around the world. Experts fear that it could one day jump to humans.
“There is no management tool that is effective” for controlling the disease, said Ellen Brandell, a doctoral student in wildlife ecology at Penn State University who is leading the project in collaboration with the U.S. Geological Survey and the National Park Service. “There isnovaccine. Can predators potentially be the solution?”
Many biologists and conservationists say that more research would strengthen the case that re introducing more wolves in certain parts of the United States could help manage wildlife diseases, although the idea is sure to face pushback fromhunters, ranchers and others concerned about competition from wolves.
Chronicwasting disease, a contagious neurological disease, is so unusual that some experts call it a “disease from outerspace.” Firstdiscovered among wild deer in 1981, it leads todeterioration of brain tissue in cervids, mostly deer but also elk, moose and caribou, with symptoms such as listlessness, drooling, stagger
ing, emaciation and death.
It is caused by an abnormal version of a cell protein called a prion, which functions very differently than bacteria or viruses. The disease has spread across wild c er v id populations andi snow foundin 26 statesandseveral Canadian provinces, as well as South Korea and Scandinavia.
The disease is part of a group called transmissible spongiform encephalopathies, the most famous of which is bovine spongiform encephalopathy, also known asmadcowdisease. Madcow inhumanscauses a variant of Creutzfeldt-Jakobdisease, and there was an outbreak among people in the 1990s in Britain fromeating taintedmeat.
Cooking does not kill the prions, and experts fear that chronic wasting disease could spread to humanswho hunt and consume infected deer or other animals.
The disease has infected many deer herd sin Wyoming, and it spread to Montana in 2017. Both states are adjacent toYellowstone, so experts are concerned that the deadly disease could soon make its way into the park’s vast herds of elk and deer.
Unless, perhaps, the park’s 10 packs of wolves, which altogether contain about 100
individuals, preyed on and consumed diseased animals that were easier to pick off because of their illness (the disease does not appear to infect wolves).
“Wolves have really been touted as the best type of animal to remove infected deer, because they are cursorial — they chase their prey and they look for theweak ones,” Brandell said. By this logic, diseased deer and other animals would be the most likely to be eliminated by wolves.
Preliminary results in Yellowstone have shown that wolves can delay outbreaks of chronic wasting disease in their prey species and can decreaseoutbreak size, Brandell said. There is little published research on “predator cleansing,” and this study aims to add support.
Aprime concernabout the disease in the Yellowstone region are the 22 state-sponsored feeding grounds in the area. Andjust south of Grand Teton National Park lies the National Elk Refuge, where thousands of animals, displaced by cattle ranches, are fed eachwinter to satisfy elk hunters and tourists. Many wildlife biologists say concentrating the animals in such small areas is a recipe for rapid spread.