Across North America, a horrifying illness is taking hold of deer and elk populations, causing them to stumble, drool, and show severe weight loss. These animals exhibit a startling lack of fear toward humans, often gazing vacantly as if in a trance. Known ominously as “zombie deer disease,” this affliction is officially identified as chronic wasting disease (CWD), and it poses serious concerns not just for wildlife but potentially for human health as well.

CWD, unlike common diseases caused by viruses or bacteria, is a prion disease. Prions are misfolded proteins that induce normal proteins in the brain to also misfold, leading to devastating neurological damage and death. The severity of prion diseases, also referred to as transmissible spongiform encephalopathies (TSEs), is underscored by the fact that many remain untreatable and clinically fatal.

A Spreading Epidemic

First discovered in mule deer in Colorado 1967, CWD has gradually infiltrated populations of deer, elk, and moose across North America. Alarmingly, by early 2025, it had been reported in wild and domestic herds in 36 U.S. states as well as Canadian provinces, with its ominous reach extending to Europe and even farmed animals in South Korea. In areas like southern Saskatchewan, nearly 80% of male mule deer are now infected.

One of the fundamental reasons for this concerning spread is the durability of prions, which can persist in the environment for years. They are shed through bodily fluids such as saliva and urine, contaminating soil and vegetation, rendering it increasingly difficult for wildlife officials to manage. The risk is compounded as deer congregate at artificial feeding sites established by humans, facilitating the rapid transmission of the disease.

In states like Wyoming, the ongoing practice of winter feedgrounds has sparked warnings from conservationists, who assert that these practices are helping propagate the disease. Experts believe that state actions have created the perfect conditions for CWD to thrive and further spread.

Hunters at Risk

As infected deer wander further from their original habitats, hunters unknowingly capture these sick animals, potentially introducing contaminated venison into their communities. The Centers for Disease Control and Prevention (CDC) has been urging hunters to test deer from infected regions, but compliance remains alarmingly low. In recent years, funding cuts to critical CDC programs have raised further concerns about our capacity to monitor this health threat effectively.

Is Human Infection Imminent?

Although no confirmed cases of CWD transmission to humans have been reported, experts warn that the danger is rising. A significant report from the Center for Infectious Disease Research and Policy (CIDRAP), compiled by a team of 67 esteemed scientists and health professionals in January 2025, cautions of a looming global health crisis should CWD ever transfer to humans. Currently, there are no national plans to mitigate such an outbreak.

The report highlights the fact that prion diseases can spill over between species, as seen in the UK decades ago when mad cow disease (BSE) was transmitted to humans, resulting in variant Creutzfeldt-Jakob Disease (vCJD). As researchers continue to study prion spillover risks, it remains vital that we develop effective strategies for surveillance and detection.

Recent incidents have heightened concerns: two hunters in Texas who consumed venison from CWD-infected areas succumbed to Creutzfeldt-Jakob Disease, raising questions about a potential link.

Precautionary Measures Needed

Epidemiologist Amira Roess emphasizes caution, especially for hunters. While the immediate threat to human health appears low if proper precautions are taken, it is imperative to remain vigilant, particularly regarding contact with deer blood and tissues.

There is still time to prevent a human outbreak, but it demands swift action. Experts are calling for better cooperation from wildlife management, public health organizations, and scientists to initiate comprehensive surveillance programs, enhance awareness among medical professionals, and create clear public health guidelines for those exposed to deer.

As chronic wasting disease becomes endemic in more regions, the specter of a public health crisis looms over us. Urgent action is required to avert what could become a catastrophic situation for both wildlife and human populations.