There are deer (and related animal, like elk) in 24 states that have tested positive for chronic wasting disease – sometimes referred to as the “zombie deer” disease, and scientists are worried that humans might not be immune to catching it, should we eat tainted meat.
The disease causes infected animals to stumble through the forest, drooling and becoming more aggressive toward humans. They’re listless, consistently lose weight, and will eventually die from the incurable infection.
It’s the result of a prion – a mis-folded brain protein that’s mysteriously able to infect other nearby proteins, talking them into re-folding wrong, too. A prion is not alive, so it cannot be killed, which means there are no treatments or cures for chronic wasting disease or any other prion diseases like it.
We’ve been aware of these types of infections, and how hard they are to fight, for years. Mad Cow Disease is the result of prions, as is Jakob Creutzfeldt Disease. In humans, prion disorders cause people to decline over the span of several months; they lose the ability to speak, move, and eventually control the muscle movements necessary for life.
CWD (Chronic Wasting Disease) currently seems limited to deer, moose, and elk, but researchers at the University of Minnesota are urging local lawmakers to consider funding further research into the matter.
Michael Osterholm, the university’s Center for Infectious Disease Research and Prevention director, is at the forefront of the effort.
“It is my best professional judgement based on my public health experience and the risk of BSE transmission to humans in the 1980s and1990s and my extensive review and evaluation of laboratory research studies …that is it probably that human cases of CWS associated with the consumption of contaminated meat will be documented in the years ahead. It is possible that the number of human cases will be substantial and will not be isolated events.”
Basically, even though as of yet there is no reason to panic, scientists are sounding the alarm.
Osterholm has reason to be concerned – he was involved with the British review panels that dealt with the mad cow disease scare, when it was found that it was rare, but possible, for humans to contract the disease by eating contaminated tissue.
That said, all evidence points to the consumption of brain tissue specifically as being the means for transmission, not other, more commonly-eaten portions of meat.
The existence of CWD in deer and the potential for contraction in humans is not news to the CDC – since the 1990s, they’ve kept an eye on hunters who come down with versions of the prion disease killing the deer. Many are diagnosed at surprisingly young ages, and some were known to eat deer meat regularly.
All of the patients died not long after their symptoms emerged, but in all cases, no known herds infected with CWD were in the area.
Basically, there was no way to confirm that they contracted anything at all from eating contaminated deer meat – some of the men weren’t even conclusively diagnosed with prion infections – so it could have been a simple coincidence.
Rates of prion disease in human aren’t any higher in areas rife with infected deer than anywhere else in the United States, but scientists are also quick to point out how little we know about the afflictions overall.
This CDC report states that “because CWD has occurred in a limited geographic area for decades, an adequate number of how people may not have been exposed to the CWD agent to result in a clinically recognizable human disease. The level and frequency of human exposure to the CWD agent may increase with the spread of CWD in the United States.”
The disease has been spreading through deer, elk, and moose populations since 1981 (at least), when it was first identified in wild deer. While most populations still have low infection rates, they have grown to 10% or even 25% in others.
The more deer infected, the bigger risk to humans, warns a 2012 review in Emerging Infectious Diseases.
“The potential for interspecies CWD transmission (by cohabitating mammals) will only increase as the disease spreads and CWD prions continue to be shed into the environment.”
The CDC and WHO agree that transmission between species is possible, or one day could be, even though we have no evidence that it has already happened. Researchers are hoping to develop a test that could be used in the field, one that would tell hunters whether or not the meat they’re butchering is contaminated before they eat it.
University of Minnesota scientists are working on that now, but in the meantime, if you hunt in an affected area, be aware of what the animals you kill looked and acted like prior to being shot. In all cases, you’re better off avoiding touching the internal organs as much as possible, particularly the brain and spinal cord.
If you’re worried, contact your local wildlife authority to get the animal tested before consuming it.
This is new territory, but as with most things that could cost you your life, better safe than sorry.