A study published June 16, 2026, in Science Advances by researchers at the University of Calgary and international collaborators has confirmed what wildlife scientists have long feared: chronic wasting disease prions can spread from deer showing absolutely no clinical symptoms of infection, meaning a deer that appears healthy, is behaving normally, and shows no signs of disease may still be actively shedding infectious prions in its saliva, feces, urine, and blood.
The finding has direct and immediate implications for hunters, wildlife managers, and the public health community. Chronic wasting disease (CWD) — nicknamed "zombie deer disease" for the late-stage symptoms of extreme weight loss, stumbling, and listlessness that infected animals develop — has now been confirmed in 36 U.S. states and five Canadian provinces, according to the CDC. It is the only transmissible spongiform encephalopathy known to affect free-ranging wildlife, and it is invariably fatal in infected animals. There are no vaccines and no treatments.
