U.S. Department of Agriculture: Animal and Plant Health Inspection Service


Date of this Version



North American Elk, May, 2016:69.


US government work


Chronic wasting disease (CWD) is an infectious, neurodegenerative disease of deer (white-tailed and mule), elk, moose, sika deer and muntjac caused by a misfolded version of a normally occurring protein. The notion that CWD could be spread indirectly via the environment has been documented and accepted in the scientific community for quite some time. Deer and elk consume soil, inhale dust and lick objects that have infectious material on them, resulting in chronic, low dose exposure. Surface contamination of plants with urine or feces is likely an additional source of exposure via ingestion and has been modeled in the laboratory by Pritzkow, et. al., (2015). In 2014 Dr. Christopher Johnson and his colleagues at the United States Geological Survey (USGS) and the University of Wisconsin, Madison proposed a novel mechanism for CWO infectivity associated with plants at the international Prion meeting. Dr. Johnson and his group hypothesized and presented data supporting the idea that plants could take up infectious prion proteins into their tissues by contact and absorption through their roots.