Wolves could hold the key to preventing ‘zombie’ disease threatening US deer populations

Yellowstone's wolf packs could provide a model for other areas threatened by CWD

Credit: JudiLen /Getty 

Wolves could play a crucial role in combating a "zombie" disease which is threatening America’s deer populations and could one day spread to humans, new research suggests.

Chronic wasting disease (CWD) is a fatal illness similar to mad cow disease and cases have been reported in deer and elk in at least 24 US states.

The disease has been nicknamed "zombie disease" because it makes deer drastically lose weight, struggle to walk and become more aggressive and less afraid of human contact. 

An outbreak of the infectious disease is extremely difficult to contain and there is no treatment. 

But a research project in Yellowstone National Park suggests that wolf packs may hold the key to keeping the disease out of the area by identifying and killing off sick animals.

White-tailed deer are susceptible to chronic wasting disease

Credit: Reuters

The "zombie" disease has already infected deer herds south of the park in Wyoming and to its north in Montana, posing a threat to the park’s vast herds of elk and deer.

The US Centers for Disease Control and Prevention has raised concerns that CWD may also pose a risk to humans who hunt and eat infected deer or elk.  

The disease is particularly hard to manage because a deer can be infected for a year and a half without displaying symptoms. 

An outbreak of CWD in a herd could ultimately be deadly to the entire group, as prions are shed in urine and faeces and can remain in the soil for years and infect other animals. 

But despite its abundant elk and deer populations, no cases of CWD have been detected in Yellowstone so far — and researchers believe the park’s 10 wolf packs may hold the key. 

Yellowstone provides a unique opportunity to monitor the effect of wolves on the disease spread

Credit: AP

A project by researchers from Penn State University, the US Geological Survey and the National Park Service, now hopes to support the idea that the predators can be used to effectively manage the disease.

"Yellowstone is the US is the only place we can see if this is working,» explained Dr Ellen Brandell, who is leading the project, because of the overlap between high elk and wolf populations and CWD cases nearby. 

The park is home to 10 wolf packs and Dr Brandell believes the predators may be able to target and kill sick deer before the illness is detected by humans.

"They are quite unsuccessful at hunting so they’ll take the weakest ones — that’s exactly the type of cue you want a predator to pick up on," she said.

Dr Brandell said researchers were sampling the carcasses of deer and elk which have been killed by wolves to detect CWD.

The preliminary research suggests that the absence of CWD cases in the park may be evidence that their theory is correct. 

Some conservationists have suggested that more research would support the argument for the reintroduction of more wolves to some parts of the US, although the idea is fiercely opposed by farmers and ranchers. 

Dr Brandell said she hopes her study will show that having predators on the landscape can be useful for managing the disease.

"Wolves are a top predator in the ecosystem, they help balance everything that comes before them in the food population," she said. 

"They help keep populations smaller and healthier, so  they have a cascade effect on everything."