The Canadian province of British Columbia has released a strategy to combat the spread of chronic wasting disease (CWD) as the virus continues to move across North America.
Officials in the westernmost province this week ordered the testing of any road-killed deer, moose, elk and caribou after two cases were confirmed at the end of January. Both cases – in a mule deer and a white-tailed deer – were found in the Kootenay district. The province also placed restrictions on the movement and disposal of deer in the area.
The fatal disease is caused by misfolded proteins known as prions and affects species in the cervid family. It infects the host’s brain and nervous system, leaving deer drooling, stumbling, lethargic and with a blank stare, leading some to call it “zombie deer disease”. The province has asked residents to report any cervids that appear sick immediately.
In Canada, chronic wasting disease has previously been confirmed in farmed deer populations in Saskatchewan, Alberta and Quebec, as well as among wild deer in Manitoba. It has also been found in three wild moose, according to the Canadian Food Inspection Agency.
But a recent confirmed case in Yellowstone national park – the first at the famed nature reserve – has prompted fresh concerns about the potential risk posed by the disease.
Experts remain divided over whether CWD could make the leap to humans, as bovine spongiform encephalopathy – or mad cow disease – did nearly four decades ago.
“There is no direct evidence that the disease can be transmitted to humans and there have been no cases of the disease in humans,” the province said in its bulletin.
But Hermann Schätzl, the associate dean of research at the University of Calgary’s veterinary school, said previous research on macaques suggests transmission of CWD between primates is possible. Researchers fed the primates infected brain tissue to mimic the long-term consumption of CWD infected venison in humans.
“In our experimental models, it’s very likely that CWD can infect humans. Has it ever happened before? There is no positive evidence where you can say a human had this prion disease from the consumption of venison,” he told the Guardian.
“But will it happen in the future? Very likely, yes.”
Schätzl said the rapid spread of the virus across North America and Scandinavia – and the likelihood of the virus becoming more variable over time – should raise concerns.
“If chronic wasting disease goes into humans, can it go from human being to human being? That’s the worst case scenario: that you have transmission, a little bit like avian influenza [transmitting between] humans or like Covid making the leap to humans.”
He said research into macaques deliberately infected with CWD found more indicators of the virus in the spinal cord than in the central nervous system. “The thing is, nobody really looks there. And so that’s a question: if we were looking for it in the typical places, would we see it? I don’t think so. I suspect it would look more like an atypical disease.”
Schätzl says the long incubation period of prion diseases means that if a human were infected now, “you would see nothing, probably, and it would take many, many years to show up – and that’s a problem”.
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