MTPR

Chronic Wasting Disease Unlikely To Spread To Humans, Researchers Say

Apr 12, 2019

People around the world, especially those who eat venison, are worried Chronic Wasting Disease (CWD) might one day spread from animals to humans. But researchers at Rocky Mountain Laboratories in Hamilton say evidence suggests that’s not going to happen.

On Thursday night, roughly 150 concerned citizens filled an auditorium in Hamilton to learn about CWD, a brain-rotting disease spreading through North America.

CWD causes holes and swelling in the brains of cervids like deer, elk, and moose and is always fatal. It was confirmed to be present in deer in south-central Montana in 2017 and along parts of Montana’s northern border in 2018.

Many of the people in the audience said they regularly eat deer and elk meat.

One of the biggest questions surrounding CWD is if it will someday spread to humans who hunt and eat venison. Brent Race is a researcher at Rocky Mountain Labs, a federally-funded infectious disease research center. He’s studied CWD there for decades.

"I think what we know now is transmission to humans is unlikely. The research combined with the epidemiology suggests there’s a strong species barrier, but it’s still better to err cautiously and don’t consume CWD positive deer," Race says.

CWD is one of a few known prion diseases. Prions are proteins that don’t fold normally.

Other known prion diseases include bovine spongiform encephalopathy, commonly known as Mad Cow Disease, and Creutzfeldt-Jakob disease. Both have been found in humans. But another prion disease, scrapie, which infects sheep and has been around for centuries has never been shown to be transmitted to humans.

Race told the audience about three Rocky Mountain Lab studies where researchers tried to infect animals similar to humans with CWD. He says the animals exposed to high volumes of CWD didn’t show any signs of it throughout their lives. Brain scans taken after they died also revealed no signs of CWD infection.

Race says that because CWD has now been present for decades in Wyoming and Colorado and there have still been no observed cases in humans. That’s also a good sign.

"Every five to 10 year period that passes where we don’t see CWD in humans, I think we can become more and more confident that its an even stronger species barrier than we may think now."

Still, Race says it’s better to be cautious until more is known. He urged all hunters to get their animals tested for CWD before consuming them.

Emily Almberg, a disease ecologist with Montana Fish Wildlife and Parks echoed Race’s comments about testing. She said CWD infected animals can take years to show symptoms.

"All our positives to date have been great looking animals," Almberg says.

Over two dozen confirmed cases of CWD have been found in deer in Montana since 2017.

Learn more about how the state is managing CWD, and about new hunting restrictions related to the disease.