The prions are in the soil and even taken up by plants. Deer pass it through their saliva, grooming, feces, urine, food, scrapes. There isn’t anything like a gold standard scientific study on modes of transmission and percent of occurrence because it is a study impossible to do in a wildlife setting.
Game agencies set up rules trying to contain it just because they have to appear to be doing something. But they don’t have any true science that can be cited.
Heck, all the scientists and epidemiologists couldn’t tell accurately how COVID was transmitted. They put yellow caution tape all over our park benches to keep from picking it up, I guess.