Chronic wasting disease is spreading in parts of North America. Should you worry? What a Canadian expert says

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A fatal neurological illness called chronic wasting disease (CWD) is silently spreading across parts of North America, posing a risk for deer and other cervids — and potentially for humans.

The most recent cases of the disease were confirmed in southeast British Columbia last month, where two infections south of Cranbrook, B.C. marked the province's first illnesses. Testing by a Canadian Food Inspection Agency lab confirmed the diagnosis from a mule deer harvested by a hunter and a white-tailed deer that was hit by a vehicle on the road.

Those two cases spurred the provincial government to create new rules in hopes of preventing CWD's spread in B.C. In the Kootenay region, the province noted any roadkill cervids — including deer, moose, elk and caribou — will be subject to mandatory testing for the disease. There are also new restrictions transporting and disposing those bodies.

Over the past few years, other provinces and parts of the United States have confirmed CWD cases. Alberta announced last year the disease was spreading, with some populations seeing a 23 per cent positivity rate. A couple of years prior, parts of Saskatchewan also saw as many as 70 per cent of male deer populations testing positive. Cases have also been found in Manitoba and Quebec, as well as several states like Wyoming, Idaho and Montana.

It's a 100 per cent fatal disease that some scientists fear could mutate to infect humans, with many places being unprepared for a spillover. It's also threatening food security for some hunters and First Nations, according to The Narwhal. But should you be worried about this illness if it's only affecting deer and other animals? Read on to learn more about chronic wasting disease.

What is chronic wasting disease?

"Chronic wasting disease is an infectious disease that's a member of a group of neurodegenerative diseases called prion diseases," University of Alberta professor Debbie McKenzie explained to Yahoo Canada.

Prion diseases — which belong to a general category of brain diseases that include those such as Alzheimer's and Parkinson's diseases — differ from viruses and bacteria in terms of their form. "It's just a mis-folded form of a normal protein," McKenzie noted, adding most mammals — including humans — have a prion protein. But if the prion takes on a different shape and gets into the brain, it can lead to the death of neurons and, eventually, the animal's death.

However, McKenzie added the prion diseases we know about have long incubation periods. For CWD, it would take at least two years for a deer to become infected and then die from it. Moreover, the majority of that time, around 85 to 90 per cent, she notes, the deer looks perfectly healthy. "You would not be able to identify it as an infected animal."

What are the symptoms of chronic wasting disease?

While a large portion of an CWD-infected animal's life goes asymptomatic, McKenzie said it's still "actively replicating this mis-folded protein."

"As the disease progresses, the animals gain a really hunched posture," she shared. "You know how you always think of deer with their heads up looking around, looking perky, it sort of flattens out and they get a hunchback. They have issues with swallowing, so they end up drooling a lot, and they can't eat as well so they get that very wasted appearance."

How does chronic wasting disease spread?

If a cervid has CWD, their infected prions are being shed into their saliva, urine and feces. This means they eventually end up in the environment, potentially infecting other animals and possibly lasting for many years, according to BC Centre for Disease Control. CWD can also likely be transmitted between live animals, as well as if an animal comes into contact with a carcass of an animal that had the disease.

"The concern I have in all of this, is that the number of animals that are infected with CWD continue to increase," McKenzie noted. "Early on, less than one per cent of the deer were positive for CWD. There are now areas where 85 per cent of the animals are positive."

McKenzie added there still isn't a good form of testing yet to diagnose live animals, where "most of the testing is done after they're dead." Since symptoms mostly don't appear until very late in the infection, she said many animals that were unknowingly infected might've been moved to new locations, thus accidentally spreading the disease.

Should people worry about being infected by chronic wasting disease?

Prion diseases are always fatal. While it's potentially possible CWD could be transmitted to humans, McKenzie said she believes the likelihood is very low and probably wouldn't happen for more than a decade. There's also no direct evidence the disease can be transmitted to humans and there have been no reports of cases in humans, according to the BC Centre for Disease Control.

There also doesn't appear to be a natural infection to cattle or other domesticated animals, according to the Centers for Disease Control. But for people who are hunting animals, especially those who are consuming them, they should take caution.

How can people stay safe from chronic wasting disease?

For hunters who are field dressing animals (removing organs), McKenzie warns people to be careful with sharp knives. For instance, if you cut yourself, you may expose yourself to the infected prions.

When it comes to consumption, cooking temperatures are not able to destroy the abnormal prions of an infected animal. Moreover, Health Canada urges people to avoid animals that are infected, as well as to avoid handling or eating the animal's brain, spinal cord, eyes, spleen, tonsils or lymph nodes.

"The real take-home message in all of this is that if people hunt and eat deer, elk, moose, that they should get those animals tested," McKenzie added. "Most states will do the testing, most provinces will do the testing. If your animal tests positive, I would strongly, strongly suggest you not eat it."

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