Spreading. Apparently, CWD can be passed through multiple ways. Direct contact is one way the prions are transmitted, and another way is through plants and soil, either from live infected animals or deceased ones.
Mad Cow Disease and CWD. Mad Cow Disease is spread through prions as well. It evolved from attacking a different type of livestock to attacking cows and caused international concern.
Gestation. The infectious prions can be covered in layers of deformed proteins, keeping them viable in the soil and plants. On average, an animal can live with the disease for two years before displaying any symptoms.