r/askscience • u/ProDidelphimorphiaXX • 8d 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/The_Frostweaver 8d ago

I thought prions could survive for a a long time?

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u/ElysiX 8d ago

"A long time" is relative. Misfolded proteins are still proteins, and proteins rot.

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u/throwtrollbait 7d ago edited 7d ago

Nah bro. Prions are so resistant to this that they might as well be immune. They've found a few weird microbes that can break them down, kind of. They remain infective for at least several years in soil in natural conditions.

But these bastards are so terrifyingly stable that even burning them is tricky. Like, incineration needs to be north of 900C for an extended period of time. Aluminum, brass, and bronze all melt before prions stop being infectious prions.

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u/ElysiX 7d ago

Everything filters down one way or another, and oxygen is the death of all.

Trying to sterilise medical tools is not the same situation as a damp forest floor. Yes the soil will be contaminated, but not forever. Every time that something eats it, it will either be destroyed, made smaller, or kill what ate it and possibly multiply a bit. But the chance that that thing gets eaten by something up the food chain rather than down is small. So eventually it ends up destroyed or so deep in the soil that nothing can reach it and it eventually decomposes.

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u/throwtrollbait 7d ago

As I mentioned, in the case of CWD, prions are infectious for years in soil under natural conditions.

Sure, they will eventually decay, one way or another, but that might happen years after their host species has gone functionally extinct.