You pick me apart every time I oversimplify to make a point Fred. I didn’t actually say it started with deer though....

I agree, the research facility is almost certainly where a sheep-borne prion disease jumped species to whitetails. Prion diseases have shown the ability to move somewhat fluidly between different mammal species. At some point in that mammal chain there was a prion mutation, that “one in a million” that became highly contagious. It either started with sheep or passed through sheep and then onto whitetails. Though technically you could of had that “one on a billion” arise at the exact same time deer were housed at Fort Collins with sheep carrying scrapies , that is extremely unlikely.