r/askscience • u/ProDidelphimorphiaXX • 9d ago

Biology How does nature deal with prion diseases?

Wasn’t sure what to flair.

Prion diseases are terrifying, the prions can trigger other proteins around it to misfold, and are absurdly hard to render inert even when exposed to prolonged high temperatures and powerful disinfectant agents. I also don’t know if they decay naturally in a decent span of time.

So… Why is it that they are so rare…? Nigh indestructible, highly infectious and can happen to any animal without necessarily needing to be transmitted from anywhere… Yet for the most part ecosystems around the world do not struggle with a pandemic of prions.

To me this implies there’s something inherent about natural environments that makes transmission unlikely, I don’t know if prion diseases are actually difficult to cross the species barrier, or maybe they do decay quite fast when the infected animal dies.

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u/Randvek 9d ago edited 9d ago

It’s truly awful, but read about Kuru sometime.

Prions are rare because by far the easiest way to spread the diseases involve cannibalism. This isn’t common in nature and was quite uncommon in civilization as well until modern factory farming techniques started “recycling” animal parts. Mad Cow Disease spreads amongst cows via cannibalism, then humans eat the cannibal cows and get it. Humans don’t spread it to other humans (edit: without eating them).

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u/porgy_tirebiter 9d ago

Humans absolutely do spread it to other humans by the exact same route of cannibalism.

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u/AndreasDasos 9d ago

Has there been a single case of vCJD spread via human cannibalism…? That sounds doubtful.

Kuru yes.

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u/KaBar42 9d ago

VCJD? Not that I'm aware of, since vCJD is just the term for Bovine Spongiform Encephalopathy (Mad Cow) that has jumped that species barrier to infect a human. Since it was first discovered in 1996, only 233 people have been infected with it globally.

Considering how few civilizations practice cannibalism to begin with, there's been basically zero chances for vCJD to be spread via cannibalism.

However, it's believed that Kuru first developed from the Fore consuming the brain of a tribesman who died while infected with CJD.

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u/AndreasDasos 9d ago

Right that’s what I mean, they probably misunderstood what the previous commenter was referring to. Prion diseases in general have certainly spread through human cannibalism, but probably not vCJD, which is the ‘mad cow disease’ the other person referred to.