Research: CWD may pose risk to humans
Canadian researchers find other animals, including monkeys, can get disease
Chronic wasting disease, a fatal brain illness killing area deer, may have the potential to infect humans, according to warnings from North American governments.
And while there has not been a case of a human infection, local experts said they have been monitoring the illness with the same concerns.
“We’re absolutely discussing things like that,” said Wayne Laroche, the Pennsylvania Game Commission’s special assistant for chronic wasting disease response.
Last year, a branch of Health Canada — the Bureau of Microbial Hazards — issued a risk advisory opinion, warning that “the most prudent approach is to consider that CWD has the potential to infect humans.”
That warning followed a series of tests performed by Canadian researchers on animals, including human-like macaque monkeys, which became infected with the disease.
Officials at the U.S. Centers for Disease Control and Prevention also have referenced the tests, explaining macaques contracted the disease when they were fed muscle or brain tissue from infected deer and elk.
Some of that meat, according to the CDC, came from asymptomatic deer — deer infected with chronic wasting disease that appear healthy and have not yet begun to show symptoms.
“To date, there have been no cases of (chronic wasting disease) in people and no direct proof that people can get (the disease),” according to a CDC report. “Nevertheless, these experimental studies raise the concern that (the disease) may pose a risk to people and suggest that it is important to prevent human exposures to (it).”
Chronic wasting disease is a resilient prion — an infectious protein — which attacks deer brains, eventually leading to a loss of motor functions and death. It is similar to but not the same as mad cow disease.
In some cases, a deer doesn’t begin to show symptoms of chronic wasting disease until a year after contraction, according to the Game Commission. Symptoms include drastic weight loss, stumbling, listlessness and other neurologic symptoms.
The disease was first detected in Blair and Bedford counties after the 2012 hunting season.
A disease management area spanning more than 2,000 square miles has since been created, and it includes parts of Bedford, Blair, Cambria, Clearfield, Franklin, Fulton, Huntingdon and Somerset counties. The area is known as DMA 2.
The disease likely got its start sometime in the 1960s at a feed testing facility in Colorado and was transported to other areas through infected deer.
“They were trading deer,” Laroche said, hinting at a larger problem of humans spreading negative environmental factors from place to place.
“It all boils down to people,” he said. “We’re moving everything around.”
Chronic wasting disease has been detected outside of North America, including in Norway and South Korea.
Locally, 25 deer tested positive for chronic wasting disease in 2016, Laroche said. All of the deer were in or near DMA 2, “the only area of the state where (the disease) has been detected in the wild,” according to Game Commission data.
In 2017, 55 deer tested positive for the disease in Pennsylvania, Laroche said, revealing that the number could increase as 4,000-plus 2017 samples still have not been tested.
Chronic wasting disease can be spread through direct physical contact or through bodily fluids, meaning if a deer expels excrement onto a surface and another deer comes in contact with that surface, it can become infected.
That makes areas frequently populated by deer — bait piles, salt licks and deer pens — especially concerning, Laroche said.
“Those are likely places where we might have a high enough dose for infection,” he said.
And once an area is contaminated, it can remain that way for more than a decade, Laroche said.
“This stuff can be on the landscape for at least 15 years and be infectious,” he said.
To both study and eliminate the spread of chronic wasting disease in Pennsylvania, Game Commission officials have occasionally suggested culling deer.
In early 2017, officials addressed a crowd gathered at Central High School, revealing a consideration of using sharpshooters to kill targeted groups of deer in areas where the disease is abundant.
And just last month, officials announced a since-halted plan to kill about 40 deer in the Portage area to monitor the spread of chronic wasting disease.
In both of those cases, plans to eliminate deer were met with much criticism from local hunters who are concerned the killings could drastically decrease the chances of bagging a buck during the following hunting seasons.
“Of course everybody is worried about the deer (they’re) going to get next year,” Laroche said.
Laroche said he has spoken with a number of hunters who believe the problem will go away or “burn itself out” without human intervention.
“It may burn itself out, but there may be just smoke and ashes left,” Laroche said, explaining the disease has already decimated deer populations in Wyoming, where it is predicted that the animals “could be extinct in 40 to 50 years” if remedial action is not taken.
“We absolutely need the support of the public,” Laroche said. “We are doing it for them, for their kids and for the future of hunting.”
One thing is for sure: Now that chronic wasting disease is here, Pennsylvania hunting is going to change, said John Kasun — a longtime hunter, outdoors writer and columnist for the Mirror.
“I don’t want to take a doomsday approach, but we are going to see a change,” he said.
Kasun said he encourages hunters to strive to be part of the solution through engaging with officials, listening and responding with thoughtful feedback. He also said they should report any suspicious deer activity.
Kasun also acknowledged a culture of conflicting information and opinions surrounding chronic wasting disease, calling the illness “a cauldron of misunderstanding and misinformation.”
“I think we have to increase our communications about the issue,” he said. “We should be focusing on what we can do to help. … Unfortunately nobody has that answer yet.”
At least one Blair County deer meat processor, who asked not to be named, made sure to point out that there is no evidence that humans can surely contract the disease and said he is doubtful that they can.
It seems it will be some time before that question can be answered, as “scientists expect the study to take many years before they will determine what the risk, if any, of CWD is to people,” according to the CDC.
Mirror Staff Writer Sean Sauro is at 946-7535.