CWD one of several fatal prion diseases

Chronic wasting disease affects cervids, a family of animals that includes deer, elk, moose and caribou. Animals afflicted with the disease display excessive salivation, increased thirst, lack of co-ordination, paralysis and eventually, death.

It is caused by prions, which are proteins that can trigger normal proteins to fold the wrong way. When enough of these misfolded proteins build up, bad things happen.

Perhaps the most well-known prion disease is bovine spongiform encephalopathy (BSE). As its name implies, it causes holes in the brains of cattle it afflicts so they appear spongy in post-death examinations.

The BSE prion also causes similar effects in humans, known as variant Creutzfeldt-Jakob Disease. This is a version of a rare prion disease that occurs spontaneously in people. It is invariably fatal.

BSE caused immense disruption to the cattle industry when it appeared in Britain in the mid-1980s. While it resulted in fewer than 200 human deaths, beef consumption dropped like a stone. Public health measures included massive culling of herds and recommendations against eating parts of the carcass associated with the lymph system and central nervous system.

Economic echoes of BSE persist to this day. Borders slammed shut on Canadian beef when the first domestic case was detected in 2003 in northern Alberta. An aggressive surveillance and control program ensured the disease never got a foothold here. Nevertheless, it took until May 2021 for the World Organization for Animal Health to declare Canadian beef to be of “negligible risk” — its most favourable designation.

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