It was more a thing with the mad-cow disease. That spread by cows eating bone-meal from their own species. Infected by fungus.
As far as I know mad cow disease is a prion disease. Fungus has nothing to do with it, though I do believe the prions mostly collect in nerve tissue so feeding cows the waste meat from cows is a risk factor.
True! Prions not fungus.
Wouldn't it get cooked to remove any bacteria/viruses first?