ifihadmypickofwishes:

drferox:

Ah, prions. The number one argument against cannibalism, in all species.

Prions are super wicked cool but also unreasonably terrifying.

They are an infectious protein. They’re not alive. They contain no genetic material. They’re just a little protein, but they’re built wrong, bent into the wrong shape.

And they happen to be built wrong in just the right way to have become an enzyme that causes other proteins of the same components to bend into more of these wrong shapes, thus spreading through the affected organisms.

Perfectly ordinary, normal proteins that are just rearranged wrong. One analogy would be coming across a ‘human’ that has legs for arms and arms for legs. All the normal bits are there, but it’s rearranged. And when it hugs you, you become rearranged in the same way.

Add this to the list of horrifying things we don’t have in Australia. ^-^

Currently all the prion diseases we know infect the brain, including Scrapie (sheep) Mad Cow Disease of Bovine Spongiform Encephalopathy (BSE), Kuru and
Creutzfeldt–Jakob disease (CJD). Collectively these conditions are often called Transmissible Spongiform Encephalopathies (TSEs)

By the way, the ‘Spongiform Encephalopathy’ bit means ‘putting holes in the brain to make it look like a sponge’. That is about as bad as it sounds.

Scrapie is probably the oldest TSE, and existed exclusively in sheep. It causes neurological symptoms including the sheep scraping themselves on objects incessantly, hence the name. It seems to be transmitted by sheep consuming placenta, a natural reaction in reducing the smell of blood which might attract predators, rather than cracking open the brains of fellow sheep. So it’s potentially transmitted through any tissue, though neural tissue like the brain and spinal cord is increased risk.

One possible theory for the existence of Mad Cow Disease, BSE, is from feeding sheep to cattle.

Pellets fed to dairy cattle are high protein to encourage mild production, and those pellets are not vegan. They contain otherwise unwanted animal protein, including bits of sheep that are hard to sell like brains. Only shortly before BSE became a thing, the regulations were loosened at processing plants, so these proteins didn’t need to be heated to as high temperatures, which was probably deactivating the protein, as thorough cooking does.

Oh, there are bits of cows potentially in that cow feed too. This is where the cannibalism comes in.

While cattle will certainly share a placenta between the two of them, some clever humans decided that it was a perfectly fine and cool thing to do to send unhealthy dead cows to the rendering plant to be fed to other cows. And then deregulate that process.

We’re a clever species, aren’t we.

Cattle and sheep, being ruminants, don’t have lots of acid and proteases in their rumen, so may be a little more vulnerable to a prion infection, but enforcing cannibalism on an industrial scale probably didn’t help.

But it is quite likely that some transmission occurs across the mucus membranes of the mouth, and can be transmitted with any meat from an infected animal, including placenta, even though brains have the highest concentration of the protein.

You could theoretically also transmit prions with a blood or organ transplant, though that’s not really a veterinary medicine topic.

Yep, it’s transmissable via infected blood transfusions and other medical screwups. My high school German teacher was in the UK in the ‘80s when they had their vCJD crisis, and he’s not allowed to donate blood. Infected pituitary hormone transfusions (?) have caused over a hundred cases of TSEs. Infected medical tools can also transmit prion diseases. The scary part is current medical sterilization doesn’t kill the proteins on surgical tools very well, so anything used for a brain surgery on a suspected prion disease patient should be thrown away. A hospital in the US got in huge trouble a few years ago for re-using tools they’d used on a CJD patient.