How does nature deal with prion diseases?

[u/ProDidelphimorphiaXX]

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.

[u/EricTheNerd2]

There is a fundamental flaw with your assumptions: prions are not terribly infectious. Animals with prions die off pretty quickly and to catch the disease you must consume the misshapen protein directly. It isn't like Covid where someone coughs and spreads it.

And once the host dies, unless something consumes it pretty soon thereafter, the prions won't be spreading.

[u/The_Frostweaver → u/EricTheNerd2]

I thought prions could survive for a a long time?

[u/KeyofE → u/The_Frostweaver]

How often do you eat things that have been long dead? And if you do and get a prion disease, how likely is it that you will be eaten? It’s a pretty big barrier to propagate.

[u/xiaorobear → u/KeyofE]

This is not the full picture- chronic wasting disease for example is a prion disease in certain types of animals that can be spread through contaminated soil and water for years. They don't have to eat the animal directly, indirectly works too. Fortunately humans haven't been affected by it.

https://www.cdc.gov/chronic-wasting/animals/index.html

[u/The_Frostweaver → u/KeyofE]

I was thinking of scavengers eating the body, or maybe insects eat the body then jump to a nearby animal and bite that animal spreading it.

There must be some sort of vector spreading it from one deer to the next

[u/Vitztlampaehecatl → u/The_Frostweaver]

I don't think an insect would spread prion diseases very well. There are only like 1 or 2 prions that affect mammals, and insects don't use the affected proteins, so any prions they eat wouldn't be able to replicate inside the insect.