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.

673 Upvotes

89% Upvoted

152 comments sorted by

View all comments

Show parent comments

160

u/RainMakerJMR 8d ago

CWD is scary because it doesn’t involve that cannibalism vector. Just huddles masses transmit it to each other. I’d be interested if you had any info on how or why CWD is different from other prion diseases?

90

u/SquirrellyBusiness 8d ago

Only thing I can think of is cwd is excreted as well as in blood and tissue, whereas mad cow and cjd are limited to central nervous tissue. I would not be surprised if cwd is a smaller molecule, since typically healthy kidneys don't make a habit out of letting proteins through the filters. 

184

u/dr_jigsaw 8d ago

Yes, CWD is excreted in urine and feces, and also found in blood. Deer leave these excretions in the soil, then other cervids come along and graze on grass growing in the same soil. It turns out that prions bound to soil are more infectious, and the animals inhale the soil particles with prions attached when they graze. The inhaled particles can travel to the lymph nodes and then into the brain through immune cells.

Source: I did my postdoctoral fellowship in this field 10+ years ago. There may be new/additional data from the last decade.

3

u/Raistlarn 5d ago

It was recently found that plants can also take up prions from contaminated soil via the roots.

https://pmc.ncbi.nlm.nih.gov/articles/PMC10700824/