What are prion diseases? Hunters died of fatal disorder after eating tainted deer meat, researchers say

(NEXSTAR) – A recent report published in the medical journal Neurology suggests that two hunters contracted Creutzfeldt-Jakob disease, a fatal neurological disorder, after eating venison obtained from deer infected with chronic wasting disease.

For years, researchers have thought cross-species transmission of chronic wasting disease (CWD) to be plausible. But this latest report, describing what researchers call a “cluster” of cases, presents some of the strongest evidence yet of possible animal-to-human transmission.

“Although causation remains unproven, this cluster emphasizes the need for further investigation into the potential risks of consuming CWD-infected deer and its implications for public health,” researchers at the University of Texas at San Antonio, who authored the report, said of their findings.

The two hunters described in report’s case studies had been from the same lodge, and were both known to consumer meat from deer belonging to a CWD-infected population.

Both of the hunters contracted fatal cases of Creutzfeldt-Jakob disease, with one presenting symptoms shortly after the other’s death, according to the researchers.

The incidents point to “a possible novel animal-to-human transmission of CWD,” the authors wrote.

What is chronic wasting disease?

Chronic wasting disease, or CWD, is a neurological disorder increasingly affecting deer populations, but also other cervid species in the same family. Symptoms usually present around 18 months after infection, and include weight loss, increased salivation, increased thirst, increased urination and loss of awareness, per the U.S. Geological Survey. Cases in deer are always fatal, the agency adds.

CWD can be spread by animals through contact, or through contaminated body fluids, the USGS says. The Centers for Disease Control and Prevention (CDC) adds that deer can also become infected via food, water or soil that has become contaminated.

CWD is also categorized as a prion disease, meaning it affects the brain’s prion proteins. When abnormal versions of these proteins infect the animal, they cause normal prion proteins to fold, leading to a host of nervous system issues.

Preventing infection and mitigation are the main courses of action to control the spread of CWD, as there is no known cure, according to the USDA’s Animal and Plant Health Inspection Service. Cases of CWD among animal populations in dozens of U.S. states have been reported, and officials warn against eating any meat suspected to be from an infected population.

What is Creutzfeldt-Jakob disease?

Creutzfeldt-Jakob disease, like CWD, is a prion disease, albeit one affecting humans. A neurodegenerative disorder, CJD is characterized by Alzheimer’s-like symptoms, though they get worse “much faster,” the Mayo Clinic writes. Specifically, symptoms can include memory loss, coordination issues, trouble speaking and personality changes, according to the Mayo Clinic.

The rate of CJD diagnoses in the U.S. is about one person per million, the CDC estimates.

The CDC further notes that CJD is not “related” to bovine springform encephalopathy (BSE), also known as “mad cow” disease, despite both being caused by a prion. It has been proven, however, that BSE can indeed be transmitted to humans via the consumption of tainted meat, leading to a disorder called Variant Creutzfeldt–Jakob disease, or vCJD. Both CJD and vCJD are fatal, and share similar symptoms, per Johns Hopkins Medicine.

Cases of CJD caused by tainted deer meat have not been confirmed like those of vCJD from tainted beef. But the possible link between CWD and CJW presented in the UTSA report should not be dismissed, the researchers suggest.

“Although no conclusive evidence of cross-species prion transmission exists, vigilance for such cases is crucial for public health," they wrote.