Is Chronic Wasting Disease in Zombie Deer Dangerous to Humans?

It’s like something out of a science fiction movie: A disease that can lay dormant in its host for years, then suddenly cause devastating and irreversible symptoms like dramatic weight loss, lack of coordination and listlessness.

The disease is known as chronic wasting disease — or sometimes “zombie disease” — and it’s very real. It exists in deer, elk and moose populations throughout the United States. In August 2024, the first case in Washington was confirmed in a Spokane deer. As of that date, the disease has been found in animals in 34 other states.

You aren’t alone if you hear about zombie deer and imagine a “Walking Dead”-like scenario where people are next. Thankfully, so far there haven’t been any cases in humans — but the idea that the disease could jump from Bambi to us isn’t unfounded.

“We have enough evidence to have concern that there is some potential risk,” says Peter Rabinowitz, MD, MPH, director of the Center for One Health Research and co-director of the Alliance for Pandemic Preparedness at the University of Washington and an associate professor of family medicine at the UW School of Medicine.

While catching a zombie disease from deer may not be in our immediate future, humans can — and do — catch many illnesses from other members of the animal kingdom. (COVID-19, anyone?)

The goal of Rabinowitz’s work and the work of others in the field of One Health — which involves the study of humans, animals and our shared environment — is to learn how to avoid and prevent zoonotic outbreaks from occurring and to best manage the ones that do. 

The problem with prions

Chronic wasting disease is one of several conditions known as prion diseases. All are neurological in nature and some can affect humans. All prion diseases are fatal in both humans and animals, and there are no treatments and no cures.

The most well-known prion disease in humans is variant Creutzfeldt-Jakob disease. This rare neurodegenerative disorder has been linked to exposure to cow meat contaminated during the outbreak of bovine spongiform encephalopathy, aka mad cow disease, in the United Kingdom in the 1990s. That outbreak was, in turn, related to another animal prion disease called scrapie, which affects sheep and goats.

But how, exactly, do prion diseases jump species? Prions are proteins and, like all proteins, are strings of amino acids. Whereas normal proteins fold into predictable patterns, which is critical to their functioning properly, prions fold abnormally. An abnormally folded protein can set off a chain reaction to other nearby proteins, inducing them to fold incorrectly as well.

Some prion diseases occur spontaneously, but many are spread from one being to another. Prions are unlike any other infectious agent (such as viruses or bacteria), which makes them puzzling to researchers. Prions can also persist in the environment where infected animals are, contaminating water and soil.

It is comforting that prion diseases, including transmissible ones, are rare in humans. However, research has shown that non-human primates can be infected by the prion that causes chronic wasting disease, either from an injection of prions or being exposed to contaminated meat. That is enough cause for researchers to constantly monitor prion diseases in animal populations and continue studying the abnormal proteins to hopefully learn their secrets.  

“We don’t want to wait for human cases,” Rabinowitz says. 

The human-animal connection

Prion diseases are attention-grabbing because of their odd nature and devastating outcome for those infected. Yet, they are far from the only condition researchers are worried could jump from animals to humans.

First, the most obvious example: The COVID-19 pandemic likely started in animals and spread to humans, which is common behavior for viruses. Much of that human spread could have been prevented or mitigated, according to a report commissioned by the World Health Organization.

We can’t change the past, but we can learn from the mistakes that were made in order to prevent another similar disaster.  

In fact, looking to the animal kingdom is a good place to start when attempting to identify what the next major infectious disease outbreak will be, Rabinowitz says. He estimates about two-thirds of emerging infections are zoonotic in origin. These include COVID-19 as well as other recent and ongoing outbreaks of Zika, Ebola, mpox and H1N1 flu. Likewise for many other outbreaks throughout history, including the 1918 flu pandemic. 

In Washington state, common zoonotic diseases include salmonella, which people can catch from chickens and exotic pets like turtles; and ringworm, which is transmissible from pet cats and dogs.

But animals don’t just transmit diseases. They often get sick as well and can help clue healthcare providers in on potential threats to humans. Since animals will often get infected with a pathogen before humans do, they can act as heralds or sentinels of what could be headed our way, Rabinowitz says.

For example, in addition to chronic wasting disease, the state health department is currently monitoring a fungal disease called coccidioidomycosis that can be acquired by breathing infected dust. There have been a few cases in Washington, and health experts are trying to learn about geographic hotspots for the disease by looking for cases in pet dogs, who can also be infected by the fungus.

“Dogs are outdoors more than people, so they may get this before people do. Paying more attention to the health of dogs in certain areas alerts us to the possibility of human exposure,” Rabinowitz says. 

This also applies to other environmental health hazards, not just infections. If there is lead or mercury in the environment, pets often show signs of poisoning before people in the house. 

“We have to realize that being in contact with animals has risks, but there are also many benefits,” Rabinowitz says. “Animals play such an important part in our lives and our health, and constantly are trying to tell us something about the health of the environments we share.” 

This article was originally published on April 16, 2018. It has been reviewed and updated with new info.