Transmission
Scientists believe CWD proteins (prions) likely spread between animals through body fluids like feces, saliva, blood, or urine, either through direct contact or indirectly through environmental contamination of soil, food or water. Once introduced into an area or farm, the CWD protein is contagious within deer and elk populations and can spread quickly. Experts believe CWD prions can remain in the environment for a long time, so other animals can contract CWD from the environment even after an infected deer or elk has died.

The CWD prion has been shown to experimentally infect squirrel monkeys, and also laboratory mice that carry some human genes. An additional study begun in 2009 by Canadian and German scientists, which has not yet been published in the scientific literature, is evaluating whether CWD can be transmitted to macaques—a type of monkey that is genetically closer to people than any other animal that has been infected with CWD previously. On July 10, 2017, the scientists presented a summary of the study’s progress (access the recorded presentationExternalExternal
This study showed different results than a previous study published in the Journal of VirologyExternal
Additional studies are under way to identify if any prion diseases could be occurring at a higher rate in people who are at increased risk for contact with potentially CWD-infected deer or elk meat. Because of the long time it takes before any symptoms of disease appear, scientists expect the study to take many years before they will determine what the risk, if any, of CWD is to people.