News about CWD—Mostly Bad, Some Good

The Pennsylvania Veterinary Laboratory tests for animal diseases. This machine cuts paraffin-embedded tissue specimens into microscopically thin slices for staining and viewing under magnification, to test for the presence of CWD prions. Photo by Steve Sorensen.

Contributing Writer
Steve Sorensen

Chronic Wasting Disease. At first it was just one more acronym—CWD. Even now most hunters know little about it except its initials, and that it’s bad. But people believe bad things pass, so what’s the big deal? It is bad, and, it’s time to learn, to understand, and to get serious about fighting it.

Last week I attended an educational meeting for outdoor writers about CWD in Harrisburg at the Pennsylvania Game Commission headquarters, the Pennsylvania Department of Agriculture building and the Pennsylvania Veterinary Laboratory.

CWD is what the scientists call a Transmissible Spongiform Encephalopathy. That $100 name needs to be looked at one word at a time, starting at the end. As an encephalopathy, it affects the brain. As a spongiform disease, it creates holes so that the brain or other nerve tissue becomes sponge-like. If that’s not enough to scare you, it’s also transmissible—it spreads.

Can it spread to humans? No, at least not yet, although there is a human type of TSE called Creutzfeldt–Jakob disease. You’ve heard of the type of TSE cows can get—Mad Cow Disease—which was epidemic in the 1990s in England where more than 4 million cattle were slaughtered to eradicate it. TSE in sheep is called Scrapie. One reason it’s less serious in sheep and cows is that we have almost absolute control over domesticated animals. Not so with deer. Since we cannot control the movements of wild deer, it’s very difficult to control the spread of CWD.

TSE diseases are caused by a prion. A prion is a protein. Every living thing has proteins, but a prion is a defective protein scientists describe as “misfolded.” Prions accumulate in glandular tissue such as the tonsils and in nervous tissue, and that’s where they do damage.

More bad news. Deer acquire the prion by being in contact with another deer that has it, or by being in contact with infected feces, saliva or other deer tissue. A deer can get it simply by feeding where diseased deer defecated. CWD-causing prions can remain viable in the soil indefinitely, so it’s possible a deer can be infected years after a prion has been deposited.

Another serious issue is that a deer can carry the prion for months and perhaps years before showing disease symptoms. All the while the prion is quietly doing its damage. And there is no way to detect CWD in a live animal. The animal must have tonsil and brain tissue extracted and tested, post-mortem.

Perhaps not every deer exposed to the prions will get CWD, but every deer with CWD will die.

Enough bad news. Is there any good news? Yes. First, the Center for Disease Control has statistics that show people do in fact consume meat from deer infected with CWD—somewhere between 7,000 to 15,000 people per year—and no human has thus far acquired any form of TSE from eating venison. That means the chance that the deer you kill this year will infect someone who eats it is virtually nil.

Hunter-killed deer are less likely to have CWD than road-killed deer, probably because deer that are disoriented from the disease are more apt to be hit by cars. Also, if you kill a deer in an area where CWD has not been detected, the chance of it having CWD is very remote. Where I hunt in New York and Pennsylvania, there have been no cases of CWD, so I will happily eat venison.

Every state game department monitors CWD. In areas where it exists, certain rules are in place to contain the disease. Hunters need to know and abide by those rules. Wayne Laroche, who leads the Pennsylvania Game Commission’s efforts to slow the spread of CWD and minimize its impact on whitetails and elk, says “CWD will be a long-term chronic problem, and it will have a long-term solution.”

Every state is taking CWD seriously, and hunters have the most to lose. Next time I’ll talk about what could happen if hunters don’t cooperate in fighting CWD.

When “The Everyday Hunter” isn’t hunting, he’s thinking about hunting, writing about hunting, talking about hunting, dreaming about hunting, or wishing he were hunting. Contact him at, and read more of his thoughts about hunting at