Chronic wasting disease isn’t yet widespread in Utah, but officials urge caution
The iconic deer, elk and moose of North America are under threat, and scientists are only beginning to understand how.
Chronic Wasting Disease (CWD) hasn’t yet taken hold in Utah, but as spring life begins to return to the mountains, experts in Utah and Colorado say residents should be aware of the illness and its signs in native species.
The illness fatal to mammals of the deer family has spread across several states, including bordering Colorado and Wyoming, and across international borders. And in some places, like Colorado, it has reached a crisis point with government task forces being formed to plan a response. In some parts of that state, it is estimated that one in 10 individuals in a herd could be infected, and in some hunting areas, it is mandatory to take in felled deer for testing during rifle season.
Though studies have not shown what some call “zombie deer disease” to be transmissible to humans, authorities recommend against coming in contact with animals suspected to carry it.
That recommendation illustrates the primary challenge facing scientists and officials in Utah and in other states when it comes to mitigating the spread of CWD: In comparison to other diseases like influenza or even cancer, there isn’t as much of an understanding of the cause, said Annette Roug, a veterinarian with the Utah Division of Wildlife Resources.
The consequence to humans and the ecosystem of CWD’s spread are yet unclear, though on the margins, infected animals are preyed upon at higher rates and they’re at a higher risk to cause traffic accidents. (Mountain lions eating infected deer have not been observed to contract the disease.) A connection to climate change hasn’t been theorized yet, either, Roug said.
Unlike most diseases, CWD isn’t genetic, fungal, bacterial or viral. It’s the product of a protein gone bad — called a prion — that was already present in the bodies of those affected and can be spread to other animals, and as a result it doesn’t trip the body’s immune system.
The most infamous case of a prion outbreak is that of bovine spongiform encephalopathy — more commonly known as mad cow disease. The outbreak of mad cow in British beef products peaked in the 1990s, and that disease is believed to have spread to humans in the form of variant Creutzfeldt-Jakob disease.
The problem with containing prions in wildlife populations, according to Roug, is that because they aren’t living organisms like a fungus or a bacteria, they can’t be killed, much like viruses. They can lie inert in the soil for years before finding a host.
“The environmental persistence is a big problem with free-ranging animals,” Roug said.
Unlike with a virus, there is no vaccine — the prion “infects” normal proteins in the body with bad information, much as a cancerous cell does to its surroundings. It can take years for symptoms of transmissible spongiform encephalopathy to show up, as lesions in the brain reduce it to a sponge-like, porous state and eventually kill the individual.
But when they do, they’re unmistakable.
Signs of CWD in deer, elk and moose include an emaciated appearance, fearlessness, drooling from the mouth, difficulty standing and patchy fur.
“They don’t function like normal deer, or elk or moose,” Roug said.
Roug cautioned that as the mountain ranges of Utah continue to thaw out from a brutal winter, some animals may just appear lean simply because meals have been hard to come by in the past few months. But the Division of Natural Resources still recommends people exercise caution when interacting with roadkill and the spoils of a hunt, and DNR officials also test roadkill and live populations in the state. An action plan from the office is forthcoming.
The few cases recorded in Utah have mainly appeared in the northeast and southeast regions bordering Colorado, according to the DNR.
Across that border, the situation is much worse.
“The feeling is that it’s spreading, and we really don’t know how to stop it,” Travis Duncan, a spokesman for the Colorado Department of Parks and Wildlife, said.
Researchers near Fort Collins first observed CWD in the 1960s, and it’s unclear how long the disease had been present before that point. The Colorado Department of Parks and Widlife estimates a tenfold increase in infected herds in the state over the past two decades, and a task force has drafted a plan to address the issue including mandatory game testing, population control and minimizing infection sources.
Duncan hopes increased public awareness will help scientists and officials to better respond to the problem, as well as agencies working across state and national lines to compare notes on the disease.
“It’s getting more on peoples’ radar, but I personally wish people understood it better,” Duncan said. “We’ve got some of the leading scientists in the country who have been working on it for years.”
As more attention begins to focus on CWD, collaboration across those borders will likely become crucial, and there isn’t a guarantee Utah’s wildlife will remain safe forever. It’s not like the deer know where the borders are.
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