Canada's deer are dying of 'Zombie disease'; What is it and can it infect humans?

As the world continues to reiterate that "COVID-19 is not over" in the third year of the pandemic, another strange and rather highly communicable disease is spreading among the deer population in Canada West. Vice World News has reported that the disease impacting deer in Canada is named chronic wasting disease (CWD) which is an alarming phenomenon also known as 'zombie disease'. It is to note that experts have flagged CWD’s repercussions in the near future on ecological and conservation impacts. 

Margo Pybus, a wildlife disease specialist with the Alberta government’s fish and wildlife division and a researcher at the University of Alberta, told the media outlet, “There’s an epidemic of CWD in Alberta and Saskatchewan—and it’s already underway.” Pybus also said that the “epidemic” among deer is raging through the species in prairies and parklands. 

Where was CWD first detected among deer?

As per the report, the highly communicable disease, CWD, was originally detected in captive deer at a research facility in the late 1960s. Later, the same illness was detected in wild populations in Colorado in 1981. Since then, chronic wasting disease has been found in at least 26 states and is now considered endemic to Colorado, Oklahoma, Kansas, Nebraska, Minnesota, Wisconsin, South Dakota, and Montana.

However, in Canada, CWD first emerged in 1996 on an elk farm in Saskatchewan before spreading into the wild populations. Alberta, where the disease is now spreading rapidly among deer, confirmed the first case of the illness back in December 2005 in wild deer. Pybus told the media outlet that it was a game animal that was taken near the Saskatchewan border. 

Pybus was further quoted by Vice World News as saying, “We’ve been doing steady surveillance since 2005…And now we’re looking at CWD encroaching on the eastern edges of Edmonton, Red Deer, and Calgary.” CWD was first detected in Canada through a sample submitted under the hunter surveillance program in which hunters provide samples of harvested animals to check for the disease. 

Even though the majority of CWD cases in Canada were observed in Alberta and Saskatchewan, Manitoba reported its first documented wild case in late 2021, as per the report. 

More about CWD

CWD belongs to a peculiar class of pathogens called prions which is also the same class of diseases to which bovine spongiform encephalopathy (BSE) belongs. BSE is commonly called mad cow disease. Scrapie which infects sheep and goats and Creutzfeldt-Jakob disease (vCJD) which impacts humans also belong to the same category as CWD. 

While viruses and bacteria hijack the host cells before the symptoms are observed, no such genetic information is involved in a disease caused by prions. What makes prion disease infections more strange is that prions do not have genes and are instead composed of amino acids just like any other protein, stated the report citing  Dr. David Westaway, the Canada research chair in prion diseases and director of the Centre for Prion and Protein Folding Diseases. 

The long-term impact of chronic waste disease is a broader effect it has on deer populations. Pybus told the media outlet, "The really concerning thing about the chronic wasting disease is the long-term effect it has on deer populations". The expert further noted that deer that are born in areas where the disease is already established are more likely to be infected, and therefore die early, further shortening the population's reproductive capacity. It implies that deer are dying before they have time to make more deer. 

Can CWD infect other animals? Why is it called ‘zombie disease’?

Deer are considered to be the most common host for CWD disease, the disease is capable of impacting any cervid such as elk, moose, and caribou. The sickened animals grow thin and weak. Additionally, as per the report, CWD-infected animals lose their fear of humans and other predators, and exhibit drooling, stumbling, poor coordination, depression, behaviour changes, and paralysis. It is these outward symptoms among animals that led to some people calling CWD infection ‘zombie disease’. Linking the infection to zombies is even more appropriate because deer can transmit the illness through animal-to-animal contact, especially in urine and saliva. 

Pybus said CWD is a particularly “insidious” disease mainly because infected animals can take up to two to three years to show outward symptoms which appear “in the later stages, maybe the last month or so” of contracting prion. 

Can the ‘zombie disease’ infect humans?

CWD infection or ‘Zombie disease' has not yet been detected in humans. However, the United States Centre for Diseases Control, and Prevention “strongly recommends” having deer harvested from areas where the communicable disease is known to be present before consuming the animal, and not eating if it tests positive. These concerns are budded in the previous animal-borne pathogens jumping to humans, such as COVID-19.  

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