Jody Serrano
Editor in chiefEditor in Chief at Xataka On. Before joining Webedia, I was a tech reporter at Gizmodo and The Messenger. While I've covered all sorts of things related to technology, I'm specialized in writing about social media, Internet culture, Twitch, and streamers.
While using the word “zombie” to describe a disease might make some think about Halloween, there’s nothing sweet about Chronic Wasting Disease (CWD), which is also referred to as “zombie deer disease.”
The fatal disease affects cervids, including deer, elk, and moose, and has now been found in animals across 36 states and four Canadian provinces. While no human cases have been ever been reported, scientists say that the possible transmission from animals to humans would case a “national and global crisis.”
What is zombie deer disease? As explained by the Centers for Disease Control and Prevention, CWD is a prion disease, which are a type of disease that occurs when proteins in the body misfold. While the misfolding of proteins in rare, when it does happen, it can lead to brain damage and other symptoms. Prion diseases can affect animals and humans, though symptoms can sometimes take years to develop.
CWD is often called zombie deer disease in the media because of the symptoms it causes in animals. These include stumbling or lack of coordination, drooling, appearing “out of it,” drooping ears, and lack of fear of people. However, the CDC says that it’s difficult to diagnose animals with CWD based on symptoms alone. These symptoms can also appear in animals affected with other diseases or when they’re not eating enough.
CWD is almost always fatal to animals.
A potential disaster. Scientists have been worried about CWD and its potential spillover, or transmission, to humans for years. In January, the Center for Infectious Disease Research and Policy released a report on CWD preparedness and response.
The report stated that although the possibility of a spillover event to humans is increasing, there are no national or international contingency plans in place to address the situation. Some scientists point to the mad cow disease—officially known as Bovine Spongiform Encephalopathy, another prion disease—outbreak in Britain as an example of how bad things could get.
More than 180,000 cows were thought to be affected with the disease, and more than four millon were killed to prevent its spread. In the end, the disease also spilled over to humans, with positive cases linked to eating contaminated meat. The version of the disease affecting humans is called Variant Creutzfeldt-Jakob disease (vCJD). More than 177 people have died from vCJD since 1996.
“We’re talking about the potential of something similar occurring,” Cory Anderson, an epidemiologist specialized in CWD transmission, said in 2023. “No one is saying that it’s definitely going to happen, but it’s important for people to be prepared.”
Disease transmission. Unlike other diseases, CWD isn’t caused by a specific bacterium or a virus, but by prions. Infected animals shed prions through their urine, defecation, and saliva or via decomposition after they die. Importantly, these disease-causing agents have the ability to remain active in soils for years, The Guardian reported, and can affect animals that come into contact with those areas.
Relatedly, one of the biggest concerns about CWD transmission today centers around feedgrounds. These are spaces where thousands of deer and elk gather every winter in close confines and are fed artificial forage. Allowing so many cervids to remain in close quarters allows diseases, including CWD, to easily spread.
“It would be such a shame if we continued doing something as foolish as concentrating thousands of elk and deer, making them more vulnerable to catching and spreading this catastrophic disease, when we didn’t have to,” Lloyd Dorsey, a former professional conservationist for the Sierra Club, told the outlet.
The human question. Although there have been no confirmed CWD cases in humans, it’s a theoretical risk, according to the CDC. The agency points out that another prion disease, mad cow disease, has already been proven to infect people. Furthermore, some studies in monkeys have suggested that they can contract the disease by eating the meat and brain tissue of infected deer or elk.
Experts say that if CWD does spill over to humans, it would most likely be through eating meat from an infected animal. This is already happening. In 2017, the Alliance for Public Wildlife estimated that humans unknowingly ate between 7,000 and 15,000 CWD-infected animals per year. The organization added that the number was expected to increase 20% annually.
Image | Diana Parkhouse
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