Alberta uses hunters to reduce deer numbers in effort to slow spread of debilitating disease

CALGARY -

The province will issue more hunting licenses for female deer this fall in an effort to reduce their numbers and slow the spread of chronic wasting disease.

CWD is a fatal prion infection, similar to BSE or Mad Cow Disease, that was first identified in Western Canada in the late 1990s. It now affects members of the deer family throughout southern and central Alberta and continues to spread northward.

There is some hope that a vaccine can be developed to prevent the spread and work is currently being conducted at the University of Calgary's faculty of veterinary medicine.

"There is now really a lot of momentum to come up with a vaccine in a few years," said Hermann Schaetzl, who heads the research team. "We cannot guarantee this, but it looks promising."

Mule deer, especially older males, are most affected, followed by whitetail deer. It can also affect elk, moose and caribou. Pronghorn appear to be unaffected.

The majority of research suggests population can fall by 20 per cent a year once 20 to 25 per cent of a herd becomes infected.

"Antlered mule deer are up around 50 per cent," said Matt Besko, director of wildlife health and licensing for Alberta. "The entire population prevalence rates are somewhere between 12 and 14 per cent."

The recent jump in deer population leaves policy makers with a challenging choice: continue to do nothing and the disease becomes more common and deer die off, or greatly reduce some deer herds and slow the spread.

"We looked at a number of different modelled outcomes by harvesting different age classes and different sex classes and which wildlife management units to do so," explained Besko.

A recent report from the Canadian Agri-Food Policy Institute warned the disease poses a risk to the agriculture industry and human health.

The prions, a misshapen protein that triggers infection, can stay intact in the environment for 10 years or more. They're also very heat resistant and not destroyed by grassfire or standard medical autoclaves.

They've been discovered in plants, which the Institute cautions could potentially trigger trading partners to block shipments of some Canadian agriculture products.

There is also an emerging body of evidence to show it is possible for the prions to trigger infection in humans.

"I would say it's very likely this will happen," said Schaetzl. "The more CWD you have out there over a long time period, the more people consume infected materials, the higher the risk there will be an infection in humans."

One study showed feeding macaque monkeys infected meat over a prolonged period triggered the infection. Another similar study did not replicate those findings.

A separate study from the U of C, which is awaiting peer review, suggests genetically altered mice began producing human prions following infection with CWD. The researchers hope to publish their findings later this year.

Not everyone approves of the province's plan.

The Alberta Professional Outfitters Society says it's not clear herd reduction will work and reducing herds could damage deer populations long term.

"We want mature deer to continue to exist on the landscape and that's not possible with this type of program," said Corey Jarvis, APOS president and a mule deer hunting guide. "So our objectives are a little bit at odds with the government."

The Alberta Fish and Game Association says it mostly supports the province's decision, but would prefer to see fewer hunting licenses given out for female deer which have lower infection rates. Instead, they say, mule deer buck licenses should be increased to target the bulk of infections.

The province recommends all deer be tested for the disease before being eaten.

Long wait times for test results - often around three months - have been a growing problem. The province is now trying a pilot program to speed up lab times and reduce storage requirements. 

Instead of submitting a whole head and having provincial testers remove the samples, new videos are being prepared to teach hunters how to extract the lymph nodes and brain stems for testing.

The first deer hunting seasons in Alberta open Sept.1 and run until the end of November.