A fatal disease is spreading amongst Alberta's deer population.
Chronic Wasting Disease (CWD) is a brain disease that affects deer, elk, and moose in North America, including right here in Southern Alberta.
"It's a strictly fatal disease, so it's always deadly," explains Dr. Sabine Gilch, who is a professor of Prion Diseases at the University of Calgary. "It is contagious, so it is transmissible from animal to animal within a population. And the very special thing about it is that it is caused by very unique pathogens that are called prions."
Prions are pathogens that only consist of a protein, which clumps together in the brain and other body parts of the animal.
Eventually, these leave holes in the brain, causing what is known as Spongiform Degeneration.
"A similar disease, for example, is Mad Cow Disease, or BSE, that people might remember from the epidemic in the 1990s in the U.K., and then when it swapped over to Canada, and what economic losses it caused. It's the same type of infectious agent."
However, CWD gets transmitted through the urine, saliva, and feces of the infected animal, which then contaminates the environment.
"The infectious particles are very sturdy, so they can last in the soil for, like, ten years and still remain infectious. And they won't go away. They cannot be destroyed."
This means that once the disease gets established in a certain area, it becomes almost impossible to get rid of the disease and will just keep transmitting from animal to animal.
While CWD was first detected in Colorado and Wyoming in the late 1960s at a research facility, no one knows how this disease started, and there is no agreement on the exact origin of CWD in North America.
Even though CWD is a contagious disease amongst deer, there is no evidence that CWD has been transmitted to non-cervid animals or humans.
But that doesn't mean that it will never happen.
There has been research done with mice and CWD, and they found that the barrier for transmission might not be absolute.
"What we basically say is, 'It might happen.' And the concerning part of our findings was that these mice, how they presented the disease, so the symptoms they showed and how we were able to detect or not detect the infectious agents in the brains of those mice, was completely untypical and not related or reflected in any other prion disease we know of."
What that means is if CWB were to be transmitted to humans, it might be difficult to diagnose the disease.
The current methods to detect prion diseases in humans do not work well to detect CWD.
Gilch says that while the time from when a deer gets infected with CWD to when it shows symptoms can take up to two or three years, that animal has already been shedding the infectious prions, transmitting the disease.
"Once the clinical signs start to show, then the animal will die within three months, six months, or so."
The symptoms include the animal looking emaciated, having problems walking straight, separating from the herd, salivating excessively, losing their fear of humans, and not moving.
In Alberta, testing for the animals largely depends on hunters.
In some areas of Alberta where the disease is more prevalent, hunters must provide the Alberta government with the head of the deer to be tested for these types of diseases.
Currently, it is estimated that roughly 18 per cent of the deer between Calgary and Edmonton are infected with Chronic Wasting Disease.
"To put that into perspective, I moved to Calgary ten years ago, and at that time, this number was below two per cent. So, it increased tenfold over the last ten years. Which is kind of crazy."
Not only that but according to Gilch, in the Southeastern corner of the province, the prevalence of CWD in Mule deer bucks is above 50 percent.
That means that hunters in that area of the province have about a 50/50 chance of shooting a deer with CWD.
Because of that, Health Canada recommends having the deer tested prior to throwing the meat onto the grill, and the deer must be tested if it was shot in an area where CWD is prevalent.
"The recommendation is if your animal tests positive, do not eat it," Gilch says.
That's because Mad Cow disease proved that prion diseases could possibly be transmitted to humans.
While not every hunter is required to provide the deer head to be tested for diseases in the province, Gilch strongly suggests all hunters get the animal tested before eating the meat.
To learn more about Chronic Wasting Disease and how to submit a deer head to be tested, click here.