When it comes to news and information, the internet can be a blessing or a curse. Stories go viral in an instant, regardless of whether they contain any modicum of truth. One reason a story goes viral quickly is that it plays on readers’ emotions, particularly when it’s presented as research-based content. For hunters, wildlife biologists or anyone who eats venison, few topics stoke anxiety and fear more than new research that suggests humans can contract chronic wasting disease from deer and other ungulates.
A story recently claimed two men had likely contracted a neurological disease after eating tainted meat.
“Two Hunters become first Americans to die from ZOMBIE DEER disease after eating infected venison”
The story immediately went viral, leading to a plethora of similar stories from other entertainment or news organizations, all purportedly reporting on an abstract from a study conducted by researchers from the University of Texas Health Science Center. Upon closer inspection, the investigation was actually a poster presentation by scientists at the 2024 American Academy of Neurology Annual Meeting and was reprinted in the peer-reviewed journal Neurology. Their abstract set the internet world ablaze:
This study presents a cluster of Creutzfeldt-Jakob disease (CJD) cases after exposure to chronic wasting disease (CWD)-infected deer, suggestive of potential prion transmission from CWD-infected deer to humans.
The authors state that two deer hunters likely contracted sporadic CJD, a degenerative brain disorder that leads to dementia and death, by consuming CWD-infected venison. Prior to this case study, there were no reported cases of CWD passing from animals to humans. In a nanosecond, the UT researchers called this belief among scientific AND hunting communities into question.
In 2022, a 72-year-old man with a history of consuming meat from a CWD-infected deer population presented with rapid-onset confusion and aggression. His friend, who had also eaten venison from the same deer population, recently died from CJD, raising concerns about a potential link between CWD and human prion disease.
Like a sudden snowstorm, the study – and stories it elicited – caused an avalanche of panic.
“One of the biggest problems with the case study presentation is the fear that it stoked in the community,” said Catherine Appling-Pooler, director of public policy for the National Deer Association. “Public safety is a huge issue for everyone. In conversations I had with hunters, it stoked a lot of controversy and fear.”
Before digging into the academic presentation and its shortcomings, let’s briefly review what we know about chronic wasting disease. Originally observed in a captive Colorado mule deer in 1967, CWD is a type of transmissible spongiform encephalopathy, or brain disease, affecting deer, elk and moose. It is similar to other TSEs like bovine spongiform encephalopathy, or mad cow disease, scrapie and CJD. The most popular explanation for CWD is that it’s caused by a misfolding prion, or protein, that first develops in the brain and spinal cord of infected animals. Although animals can live with CWD for years before displaying symptoms like emaciation, lack of muscle coordination, excessive thirst/urination and no fear of humans, the disease is always fatal.
A plethora of problems
Wildlife biologists and scientists who study CWD responded to the slew of stories by pointing out numerous flaws in the research project. For starters, despite the fact the authors indicate they’ll be presenting results of a study, no scientific investigation was conducted to examine a potential correlation between two humans contracting CJD and consuming meat from CWD-infected deer. Instead, researchers merely presented two cases of patients they think may have had CJD. Two case studies are a far cry from “a cluster of CJD cases” the scientists promised to deliver.
Brian Murphy, a renowned wildlife biologist and vice president of corporate relations and strategic partnerships for HuntStand (Huntstand.com) highlights other major flaws in the case studies.
“Only one of the men was diagnosed with Creutzfeldt-Jakob disease, and he had a friend who died of ‘similar circumstances,’” explained Murphy. “To our knowledge, the other man was not diagnosed with CJD. Two elderly men with brain disease isn’t news.”
Researchers also assume that living where CWD is found means both men must have eaten tainted meat.
“The researchers present no evidence that either man actually consumed CWD-infected venison,” Murphy added. “There are probably hundreds of thousands of elderly men who live in areas where there is CWD and eat venison. Even if both men ate infected venison and died of CJD, it still fails to prove they contracted the disease from the deer meat. CJD sporadically impacts roughly one in 1 million Americans, so sheer coincidence is just as likely a cause as consuming CWD-infected venison.”
Murphy’s last point is worth emphasizing. Scientists don’t know what causes sporadic CJD, so arguing that two hunters got the disease after eating CWD-infected venison is a stance no scientist should take. None of the venison the hunters ate was tested for CWD, yet researchers drew a clear connection between eating venison from a deer population where CWD is found and contracting deadly CJD.
“The glaring deficiencies and unsubstantiated assumptions in this study make its conclusions highly suspect, if not academically irresponsible,” said Murphy.
Numerous attempts were made to obtain a copy of the presentation the researchers made at the conference, and all interview requests with the researchers went unanswered. In email correspondence with Eileen Teves, public and media relations specialist with the University of Texas Health Science Center, Teves said:
After speaking with Dr. Sarah Horn [one of the researchers], she informed us that the information is not from a research study…. The conclusion from that presentation was there remain no proven cases of transmission to date.
Teves added that her message constitutes the only statement Horn would make. That’s little consolation for a presentation that caused grave concerns for anyone who eats and/or handles venison.
New research
New scientific evidence stands in stark contrast to the viral news. Scientists at Rocky Mountain Laboratories, a research facility of the National Institutes of Health, published a study in the June 2024 issue of the journal Emerging Infectious Diseases. Researchers used lab-grown human cerebral organoids, a close approximation to human brain tissue, to examine whether CWD-positive brain material could cross the species barrier and infect humans. Organoids tested represent two of the three most common human genotypes, or an organism’s unique set of genes, that humans possess. About 80-90% of all humans worldwide have one of the two genotypes. Researchers bathed each organoid in high concentrations of CWD prion strains from mule deer, white-tailed deer or elk for seven days and then monitored them for signs of infection for 180 days.
“After 180 days, we detected no prion disease in the organoids exposed to CWD prions,” said Dr. Bradley Groveman, one of the lead authors for the study. “This finding is in stark contrast to prior studies that have exposed organoids to human-derived prions and show signs of infection in as little as 35 days. This suggests a very strong species barrier that protects humans from contracting a prion disease from cervids.”
While Groveman and others don’t recommend it, the risk of humans contracting CWD from eating tainted venison would be much lower than the type of exposure used in the study. That doesn’t mean hunters should consume meat from a deer suspected of having CWD or any other disease.
“CWD is the most naturally transmissible prion disease we know about,” Groveman explained. “It can easily spread from deer to deer because CWD prions are shed in saliva, urine and feces and can exist in soil for decades. It’s important that hunters submit samples for testing to continue monitoring for new CWD strains that could develop or mutate and impact humans.”
In summary, be wary of viral news presenting ground-breaking “scientific” research.
“When you hear or read media reports on CWD like this case study, the NDA recommends doing your research by talking with experts in the field to find out what they think about the story,” said Appling-Pooler. “News can be quite loud, and you have to carefully sort through it to separate fact from fiction.”
As for health human health concerns, white-tailed deer expert Daniel Schmidt of D&DH explained it this way:
“U.S. health researchers have reviewed 30 years of data from over 2 million hunters in Colorado and Wyoming, including thousands who hunted in CWD outbreak areas. According to a recent, excellent article by Lindsay Thomas Jr., the researchers saw no patterns of prion diseases (namely Creutzfeld-Jakob) above the normal background level in all Americans — which inherently is one in a million.
“In short, your odds of getting CJD are already 1-in-a-million the day you’re born. But what are the odds if you eat venison from a CWD-endemic area for 30 years? Also 1-in-a-million.”