Prion disease exists in a whole swath of species. Mad cow, chronic wasting disease, they are practically the same as Alz and wilson's diseases. They produce amyloid plaques and are both linked to metal metabolism. It may be that these diseases are simply functions of an imbalance of nutrient metal homeostasis.

One of the things that can cause this reaction is exposure to heavy metals. Arsensic, as an example, can displace a nutrient ion such as copper, and cause conformational change, that is misfolding proteins into amyloid plaques, as well as cause mutation and epigenetic damage. Mutation to PRNP and an interaction with a yet unknown metal, or mixture of metals has been theorized as the driver of CWD, and by extension, prion disease as a whole.

The 'strains' of the disease and variations of its expressed symptoms could result of different metal intakes. Soil characteristics, for example, can increase the phyto-availability of metals to plants. CWD distribution has shown correlation with soils of high Ph and low clay contents- factors which increase plant uptake of metal ions. Much of the infected areas are on Mollisol, or Chernozem, a type of soil with the two prior factors and a high organic matter content. OM can increase the charge of the soil to trap metal ions, but it can also form hydroxl complexes at higher pH which can be uptaken by plants. I believe I also read that many of these same areas are Copper deficient, a necessary ion in brain homeostasis.

Explaining a source for toxic metal exposure to these populations, and my personal theory, is that the toxic metals are result of pesticide use. Glyphosate Based herbicides have been shown to contain cocktails of heavy metals as their true active ingredients. These formulations are amphiphilic (part polar, part non polar; dissolving in fat and water) which could help circumvent the buffer of the surface charge of the soil, and deliver the chemicals via water uptake by the plant. As CWD is concentrated around agriculture, and mono crops are common forage for ungulates, it follows that these populations would have fifty plus years of exposure to these ingredients which bio-accumulate and spread to offspring. Ungulates would be in the proximity of these toxins at application in the air, in their water sources, on the leaves, and in the leaves of their food. They would be among the first exposed and to the highest concentrations as these plants make their way to cattle and human feed. The round up ready crops, engineered to interact with GBH, are wheat, soy, alfalfa, corn, canola. I can't help but wonder if the divergent increase of neurodenegerative diseases is all result of chemical interference.