A Tale of Two Maps
By Mark McCollough

In September of this year, a farm north of Montreal, Quebec was placed in quarantine because a captive deer tested for chronic wasting disease. Weeks later Maine Department of Inland Fisheries and Wildlife enacted emergency rules that affect the import of deer, moose, and caribou carcasses. All hunters returning with deer from afar must bring only boned out meat, hardened antlers, skulls cleaned free of brain and other tissues or finished taxidermy mounts.

Are these measures enough to prevent the dreaded prion disease from spreading? Probably not, and here is why.

Chronic wasting disease threatens deer populations and hunting in North America as we know it. “CWD” is a fatal neurologic disease that infects members of the deer family. It is caused by a non-living, protein that causes the natural prion proteins in our body to fold. It eventually leads to lesions in the brain; a brain that looks like Swiss cheese. All deer that contract the disease eventually die from it. There is now a growing body of scientific evidence to suggest that other neurodegenerative diseases such as Alzheimer’s and Parkinson’s disease are also caused by proteins that act in a similar fashion. Prion disease is known as scrapie in sheep, “mad cow disease” in bovines, and Jakob-Creutzfeldt Disease in humans. So far, no one has documented CWD jumping from deer to humans, but we know very little about these strange protein-based diseases.

Now, about the two maps accompanying this article and why they should scare the heck out of you and me. No one knows where CWD came from. Was it always here in North America? It was first recognized as a syndrome in captive mule deer in Colorado in 1967, but was not identified as a prion-related disease until a decade later. Shortly thereafter, it was detected in elk in Rocky Mountain National Park and spread geographically and increased in prevalence locally.

The genie apparently escaped the bottle. Prior to 2000, CWD was documented in just a few counties in southeastern Wyoming and adjacent northeastern Colorado. Because of significant increases in surveillance efforts, since 2000 CWD has been detected in many additional locations and is spreading. Currently, CWD has been documented in free-ranging cervid populations in 11 states, Alberta and Saskatchewan, and in over 80 individual captive cervid facilities in 9 states. First deer farms and zoos and now hunters seem to be spreading CWD across the continent.

The first map accompanying this article is from the U. S. Geologic Survey (who does much of the Federal wildlife research in Maine and the U.S.). The gray, shaded areas show where CWD is currently found in wild deer, elk, and moose populations. The yellow and red dots show deer farms where it has been documented. Note that, until now, the Northeast, Southeast, and eastern Canada have been CWD-free. Hunters here have not had to contend with the disease and the associated turmoil in cervid management.

The second map, also prepared by USGS, was published by Lindsay Thomas in April, 2018. Lindsay is the editor of Quality Whitetails magazine, the journal of the Quality Deer Management Association.

One “hotbed” for CWD is a 4-county area of southern Wisconsin where up to half the deer are infected with CWD. Tens of thousands of hunters from all over the United States travel to Wisconsin and other CWD hotspots, Colorado and Saskatchewan, to hunt deer and elk. In just one hunting season (2016-2017), over 32,000 deer were harvested in the 4-county CWD hot zone in Wisconsin!  The red dots on the map locate the home zip codes for every hunter who harvested at least one of those deer. 

Hunters from 49 states took home deer from the Wisconsin CWD hot zones. Only 7% of the harvested deer are tested for CWD. The remainder travel to home freezers across the country. Expect half of these Wisconsin deer carcasses to be infected with CWD. How many were butchered at home and bones discarded into the woods?

This happens every hunting season. This also happens with deer and elk carcasses transported out of Colorado and Wyoming and from the fabled deer hunting areas of Saskatchewan and Manitoba.

Why do we allow cervids to be transported out of known infection areas? You and I can probably guess…

The magnitude, complexity, and consequences of this wildlife disease boggles the imagination. The cost to state fish and wildlife agencies is and will be staggering. Imagine the cost of testing carcasses, identifying infected area, disposing of diseased animals, and difficult decisions on whether to reduce or eliminate deer populations in some areas. Infectious CWD prions can remain in the soil for at least 15 years so CWD is not eliminated even if all deer are.

Just as important, which game farms are trading deer with each other? How often are their animals tested? How often do captive deer escape? Why do we even allow deer farms given the risk to our native deer and moose?

Will Maine’s (or any other state) emergency regulations make a difference and prevent the spread of CWD? Such efforts probably have an educational effect. But can warden effectively monitor the Maine borders and airports for incoming and outgoing deer carcasses? Increasingly, hunters are traveling to out-of-state hunting destinations, and states and provinces welcome the non-resident license income and tourism dollars.

We need far more than emergency rules, which are difficult to enforce. Past management strategies of selective culling, herd reduction, and hunter surveillance in the infected areas have shown limited effectiveness. The initial strategy of disease eradication has been abandoned for disease control. Yet, the disease marches on. We need a continent-wide strategy for dealing with CWD, and we need it now.

Mark McCollough is a wildlife biologist who lives in Hampden, Maine. He can be contacted at ellmcc25@yahoo.com.


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