Mad deer disease is here. Chronic wasting disease (CWD) is the official name for our latest wildlife plague. CWD is not spread by bacteria or viruses but by deformed proteins. Like other prion diseases, such as mad cow disease and scrapie, CWD kills by deteriorating the brain and nervous system. Prion diseases don’t jump from one species to another. At least, that’s what government agencies insisted when mad cow became epidemic in Britain in the 1990s. Then a not-so-funny thing happened: 140 humans died from a fatal dementia they developed after eating beef from infected cows.
We may well be repeating that mistake. If so, Albertans who eat venison should be worried, because CWD is spreading across our province. Since first appearing in captive deer and elk in Colorado, CWD has spread across North America because of a public-policy disaster—the decision to allow captive farming of native deer and elk. Actively promoted by state and provincial governments, including our own, game farming was seen as a way to diversify agriculture.
But native animals haven’t had centuries of captive breeding to help them build tolerances to diseases perpetuated when animals are crowded together, sharing troughs and water tanks. And trucking infected animals from one crowded facility to another over long distances is a sure-fire way to spread diseases. That’s how CWD came to Canada—in an infected elk shipped to a Saskatchewan game farm from one in South Dakota. From that first infected Canadian game farm the disease spread to others. Inevitably it soon appeared in wild deer near those farms.
In 2005 an Alberta hunter killed our first brain-wasted deer. It was far from being the last. Other early cases were along the Saskatchewan boundary south of Lloydminster. Infected deer are now being found along the Battle and South Saskatchewan rivers, the Red Deer River and, as of 2013, the Milk River. The disease is gradually spreading towards Calgary and Edmonton.
Hunters can contribute deer heads to a monitoring program. Out of 47,000 heads given since the government program began a decade ago, 164 were infected. Biologists found another 47 when wildlife officers culled deer in key areas. That’s a low infection rate, but it’s increasing. CWD showed up in about 1.4 per cent of mule deer tested in 2012 but in almost 2 per cent in 2013. Mule deer bucks have the highest rate of infection, and doe whitetails have the lowest. The disease has been found in at least one Alberta moose, though mule deer are its main victims.
The Alberta government continues to actively subsidize and promote game farming even though the industry has proven economically marginal. That awkward policy conflict may help account for why the government’s hunting website assures hunters that “…there is no evidence that CWD infects livestock or humans.” The World Health Organization has no conflict of interest. Its advice is unequivocal: “All products from animals known to be infected with any prion disease (including BSE in cattle, scrapie in sheep and CWD in deer and elk) should be excluded from the human food chain.”
Our government’s public backgrounder on the public health risks of CWD appears carefully crafted in light of the lessons of Britain’s mad cow deaths, with an eye to lawsuits: “Alberta accepts the current advice from local and international public health officials that there is no known health concern associated with CWD; however, persons should not knowingly consume meat of animals known to be infected with the disease.” In other words, we think it’s safe—but don’t eat it.
Our government makes no reference to antler velvet or urine—products sold by game farms—even though researchers have found that infectious prions concentrate in antlers and that urine helps spread the disease. All over Alberta, hunters douse their boots and hunting stands with “doe urine” bought at hunting stores, in the hope of attracting a big buck. That urine comes from game farms. Hunters may unknowingly be contributing to the spread of their biggest nightmare.
Some of those same hunters are working against a solution too. The hunter-based Wild Sheep Foundation, and until recently some local fish and game clubs, quietly subsidize trappers to kill wolves. Wolves are coursing predators; they are on the job 12 months of the year looking for vulnerable prey. CWD turns deer into just the kind of prey that wolves are quick to find and kill. Dead wolves, however, can’t kill sick deer.
The earlier a CWD-infected animal dies, the fewer prions it spreads. But hunter prejudice virtually guarantees wolves won’t help clean up our growing mad deer disaster. Instead, our government hopes hunters will do it—the same hunters the government reluctantly advises not to eat infected animals.
This has not been Alberta’s best example of intelligent wildlife policy.
Kevin Van Tighem spent over three decades studying, interpreting and managing nature in western Canada’s national parks.
Photo: Forest Ethics