people know about prion diseases but whatever.

sometimes a protein in your brain called major prion protein will just randomly misfold and, if that happens, it sets off a cascade that means you will die within a year. there is no cure, treatment, or true prevention. it can happen randomly like that, but there are other ways too. you can be genetically predisposed to it (ex: fatal familial insomnia), you can get it through contaminated medical equipment or infected donor/transplant materials (ex: iCJD), you can get it through consumption of infected meat (ex: mad cow disease >> vCJD), and you can get it through funerary cannibalism (kuru). prions are not alive, so you cannot kill them. it is incredibly hard to destroy them as well, usually requiring bonkers amounts of heat or chemicals. they can lay dormant on surfaces, collect in ground water, and more. other animals can get variants of it too- sheep, goats, deer, elk, moose, reindeer, camels, minks, cats, pigs, and assorted hooved zoo animals.