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Comment by pash

14 hours ago

I’m not qualified to comment intelligently on what might be going on here, but I’d like to add some background color that the article lacks.

Creutzfeldt–Jakob Disease is a prion disease [0] for which there is no definitive diagnosis in vivo. A confident diagnosis can be made only after examining brain tissue under a microscope.

Prions are an unusual type of mis-folded protein that induce other proteins to take on a similar mis-folded shape when they come into contact with them. The mis-folded shape of the prion itself is what causes the mis-folding in adjacent proteins. It’s a chemical-bonding thing at the molecular level. It’s the shape of the prion that causes other proteins to take on a similar shape and become prions, etc.

Some prion diseases occur spontaneously (when a protein takes on a mis-folded configuration due to mis-transcription or random energetic impulses) and some are transmitted, typically by eating some part of an animal that contains prions, which then end up in your own body, inducing proteins in your body to take on prion configurations.

Prion diseases are the only known transmissible diseases that do not involve the replication of a pathogen’s genetic material in a host cell. The only known prion diseases affect nervous tissues, and in humans the only known prion diseases affect brain tissues.

I’m not an expert on prion diseases, but I’ve had a bit of a fascination with them since having to report on a bunch of USDA surveillance lectures on mad-cow disease (bovine spongiform encephalopathy, BSE) and to summarize a bunch of symposia on prion diseases in a previous life. The symptoms reported in the article sound very much like a prion disease, and the tests for CJD indicate that the doctors in the region suspect as much.

But we simply don’t have good tests for prion diseases in vivo. And prion diseases are not well understood in general, so it wouldn’t be surprising that a new one would present as something of a mystery.

It is also the case that I know very little about New Brunswick, but I will mention that prion diseases in humans are thought to be far more commonly acquired than spontaneous. The most common cause of acquisition is eating animals with endemic prion diseases; this is most often nervous tissue of venison, but rarely nervous tissue of cattle infected with BSE, which is present in Canada more than anywhere else (by a small margin).

It is also possible (but not likely) that a prion disease can arise de novo.

0. https://en.wikipedia.org/wiki/Prion_disease

8 comments

pash

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gucci-on-fleek  12 hours ago

> but rarely nervous tissue of cattle infected with BSE, which is present in Canada more than anywhere else (by a small margin).

I don't think that that's quite right. Over the past 15 years, only 3 cases have been reported in Canadian cattle [0], while Canada has over 12 million cattle at any given moment [1]. This organization claims that Taiwan, Greece, Ecuador, and Russia are all higher-risk [2].

You could certainly argue that cases in animals could be under-reported, but human cases are much harder to hide, and only a total of 2 cases have ever been reported [3]. Canadians eat a lot of beef, so this suggests that the reported numbers for cattle are probably accurate, otherwise the human numbers would be much larger.

However, a different neurological condition (Multiple sclerosis) is more common in Canada than anywhere else in the world [4], which might have some connection with the disease discussed in the article (but this is just a wild guess).

[0]: https://inspection.canada.ca/en/animal-health/terrestrial-an...

[1]: https://www150.statcan.gc.ca/t1/tbl1/en/tv.action?pid=321001...

[2]: https://www.woah.org/en/disease/bovine-spongiform-encephalop...

[3]: https://health-infobase.canada.ca/diseases/cjd/dashboard.htm...

[4]: https://globalnews.ca/news/4191203/multiple-sclerosis-canada...

wombatpm  12 hours ago

The first patient in this cluster to die should provide confirmation of CJD or other prion disease.

There is a theory that spontaneous CJD can be spread environmentally. Apparently particles of sufficiently small size (10 nm) can pass from the nasal cavity directly into the brain via the olfactory nerve. And there was a cluster of CJD victims who were rose gardeners. Rose gardening commonly use Bone and Blood meal to feed the roses, and is typically made from cattle unfit for consumption-ie downer cows/BSE. I may have read about it in The Coming Plague: Newly Emerging Diseases in a World Out of Balance Book by Laurie Garrett.

  • autoexec  11 hours ago

    They've done autopsies on 11 which pointed to various known conditions according to the article.

thelastgallon  13 hours ago

Thank you for the context.

> some are transmitted, typically by eating some part of an animal that contains prions, which then end up in your own body, inducing proteins in your body to take on prion configurations.

I wonder about this part. I thought consumed protein gets broken down into amino acids and new proteins are created later. Do prion proteins bypass this step?

  • pash  12 hours ago

    From what I understand, which is very incomplete, the leading hypothesis at the moment is that ingested prions are a bit hard to digest (because they’re malformed proteins), so they end up making it out of the gastrointestinal tract somehow, interacting with the nervous system via the intestinal lining or lymphatic system. Then they travel to the brain via nervous pathways, by-passing the usual blood–brain barrier.

    But transmission of prions by ingestion is thought to be quite rare, as that mechanism suggests. Transmission by any means seems to be quite rare, even heritable transmission (e.g., vCJD). So that’s why it seems unlikely that whatever is happening in New Brunswick is CVD.

    But if it’s not some minor mass hysteria, then maybe prions.