UCSF

Prion disease transmissionChronic wasting disease (CWD) is a highly contagious prion disease that causes neurodegeneration in several species in the deer family, including the elk and moose. The precise mechanisms of natural CWD transmission are unresolved. It is known that once an animal shows signs of the disease, its excretions can contain contagious prions. Stanley Prusiner and colleagues show that mule deer infected with CWD begin to excrete infectious prions in faeces long before they develop visible signs of the disease. This suggests a plausible, natural mechanism that could explain the high incidence and efficient horizontal transmission of CWD among deer — and may also be relevant for the similarly contagious scrapie in sheep.