When Disease Runs Wild - An Ever Lurking Threat

Edmonton Journal feature writer Ed Struzik spent four months this summer trekking through Canada's national parks, from the High Arctic to Point Pelee, Pacific Rim to Gros Morne. He found a parks system adored by Canadians, yet crumbling due to neglect. Over eight weeks in the Edmonton Sunday Reader, Struzik explores the mounting challenges the parks face.

When disease runs wild: AN EVER-LURKING THREAT
Fear is growing that Canada's beloved oases of wilderness are becoming reservoirs for disease and that Parks Canada can't afford to monitor or curb the risk to wildlife and livestock

Ed Struzik
The Edmonton Journal
Sunday, November 21, 2004

WOOD BUFFALO NATIONAL PARK - Half an hour into a flight around Wood Buffalo National Park, we spot the first of several bison herds grazing along the broad expanse of swampy prairie that radiates outward from the Peace-Athabasca delta in northeastern Alberta.

Chief park warden Ed Coulthard tells the helicopter pilot to move in for a closer look, then shades his eyes from the bright summer sun to count the calves that were born that spring.

This is turning out to be another good year for the world's largest herd of wild bison, especially considering that a significant number of the animals in Canada's biggest national park suffer from tuberculosis and brucellosis, which can cause pregnant females to abort.

But what really interests Coulthard on this June day is a rogue herd of some 40 animals, reported to be moving towards the park's south boundary.

The prospect of any one of them setting foot on provincial territory and transmitting disease to other wildlife or cattle is Coulthard's worst nightmare, and one bound to breathe new life into a 15-year-old plan to kill all 4,000 bison in the park.

"Mad cow and avian flu in southern Canada have put the disease issue up here on the back burner to some extent," says Coulthard.

"But I doubt that will last for much longer, especially if this herd keeps growing like it has over the past four years. The more animals there are down there, the harder it's going to be to keep them within the park boundaries. There's going to be a lot of pressure for us to do something about it."

Ever since the introduction of 6,673 plains bison from Buffalo National Park near Wainwright brought brucellosis and bovine tuberculosis to Wood Buffalo in the late 1920s, disease has cost Parks Canada a huge amount of time and money. But that investment is small change compared with what may lie ahead for the cash-strapped agency. Officials now believe it would cost at least $50 million to slaughter the entire Wood Buffalo herd and replace it with healthy animals from Elk Island National Park near Edmonton.

And with recent outbreaks of bovine TB in Manitoba's Riding Mountain National Park, chronic wasting disease and West Nile virus near Grasslands in southern Saskatchewan, leptospirosis among sea lions along Pacific Rim in B.C., and the potential for lungworm outbreaks among muskoxen in the far northern parks, the agency now realizes it is facing a much bigger challenge.

"I don't think it's a matter of 'if' when it comes to more diseases spreading in and out ofnational parks," says Todd Shury, a wildlife health specialist recently hired by Parks Canada to tackle the disease issue. "It's more a matter of 'when.'

"With the decline of wilderness in southern Canada, national parks are not as insulated as they once were from disease transmission. And with warming temperatures in the Arctic and other parts of the country, the situation is becoming more favourable for the spread of other diseases down the road."

Nowhere is this more evident than in Riding Mountain National Park in central Manitoba where a unique strain of tuberculosis was identified in five cattle herds bordering the park in 1991 and in one wild elk five kilometres outside the park the following year.

Bovine TB is a contagious disease caused by bacteria. It affects cattle, bison, deer, elk,goats and other species, as well as humans. No one knows exactly how it got into the park's elk, but it's believed to have been introduced by cattle.

Although the same disease had killed two wolf cubs in Riding Mountain many years earlier, Parks Canada officials initially assumed it was solely an agricultural issue. When a second outbreak six years later resulted in the slaughter of animals at two more farms near the park, officials were still fairly certain the outbreaks were isolated. They did, however, begin a surveillance program.

RANCHER HAD HIS DOUBTS AFTER TB DEVASTATED HIS HERD

But rancher Ray Armbruster was suspicious. After losing 120 head of cattle, three horses and five pets due to a TB outbreak in 1997, Armbruster was convinced that Riding Mountain was a reservoir for the disease.

"My cattle had been tested twice in 1991 when some of my neighbours' herds were depopulated," he recalls. "Nothing had changed since then. So I was pretty sure that I had a healthy herd. There was nothing that I did over those six years that could have resulted in the spread of tuberculosis to animals on my property."

He thought the disease came from wild elk lured out of the park by hay in farmers' fields and by baiting stations that hunters set up along park boundaries. TB can be easily spread through saliva left behind by infected elk or deer munching on hay.

"I knew there was something wrong with some of those elk," says Armbruster. "I could see it every time I went into the park as an outfitter. Every once in a while we'd come across these die-offs, and it was apparent to us that the age of the population was changing. We were seeing a lot fewer mature animals."

Armbruster says he had no luck convincing Parks Canada that Riding Mountain might have a problem until a third TB outbreak hit the area in 2001, raising the total slaughter count to 2,050 cattle in 11 herds.

Parks Canada had no choice but to start testing animals in the park.

So far, 433 elk in Riding Mountain have been captured and tested for the disease. Of those, 114 were identified as potentially having it. To further clarify whether the blood tests were accurate, 50 of those animals were killed.

Greg Fenton, superintendent of Riding Mountain, admits that when the test results were finally clarified, no one was more surprised than him to learn that as many as one in 10 elk in the park's northwest section had the disease.

"You can argue we were not on top of the situation," he says. "And looking back on it now, it perhaps should have been more obvious to us given how many farms there are around us. But up until 2001, we just didn't have enough evidence to justify acting in a more aggressive way."

There are 50,000 cattle on 700 ranches and farms around Riding Mountain National Park. Because up to 40,000 of them are shipped out of the region each year, the Canadian Food Inspection Agency stepped in to test all the cattle during 2002-03 and to closely regulate the movement of animals in and out of the area. Sources within the agency say they don't want to give the United States another reason to keep its border closed to Canadian cattle.

So Parks Canada has no choice but to keep testing and slaughtering and to consider other ways of containing and eradicating the disease.

It's been a demoralizing experience for parks staff in Riding Mountain, most of whom signed on with the agency because of their love of wildlife and nature. While there is a vaccine for bovine TB, the inoculation renders subsequent testing programs useless because vaccinated animals test positive.

With help from the Canadian Food Inspection Agency and other government departments, Parks Canada has devised a number of strategies. But none of them are guaranteed to solve the problem soon -- and none of them are cheap.

For example, Parks Canada is paying about $5,000 for each fence built to keep elk away from hay on farms and ranches within a kilometre of the park. Fenton says the agency plans to extend that offer to farms up to two kilometres away.

Armbruster and other ranchers, however, don't think that Parks Canada is doing enough.

"You know the only way of effectively getting rid of the disease is to either fence off the park or kill off the animals and re-introduce healthy ones," he says. "But the reality right now is that neither Parks Canada nor the Canadian public is ready for that kind of scorched-earth action. It's probably going to take a lot more TB outbreaks among cattle for them to really do something meaningful. Unfortunately, that's what I think is going to happen."

With the bills piling up in an agency already starving for money, Fenton says it's been a wake-up call.

"But you know," he adds, "many of our parks are situated in the middle of agricultural country. What we're experiencing here now may just be the beginning of a big wave that will sweep across the country."

A new focus of concern within the agency is Grasslands National Park in southern Saskatchewan, where several cases of chronic wasting disease in white-tailed and mule deer have been identified.

CWD, a transmissible spongiform encephalopathy found in deer and elk, belongs to the same family of diseases as mad cow. The disease is new to science and shrouded in uncertainty. Scientists believe that an infected elk from a South Dakota game farm brought CWD into Western Canada in the 1980s. Since then it has spread to 40 game farms in Saskatchewan and three in Alberta, as well as to wild deer and elk.

CHRONIC WASTING DISEASE COULD BE BIGGEST CHALLENGE

A recent report done for the Canadian Co-operative Wildlife Health Centre warns that chronic wasting disease may be the most important wildlife management issue in North America today. If studies done in Wisconsin and elsewhere hold true, CWD could wipe out deer and elk populations over a huge part of Western Canada.

Grasslands is also on high alert for sylvatic plague, which is embedded in the endangered prairie dog population, and for West Nile virus, which felled sage grouse near the Alberta-Saskatchewan border two summers ago.

Not to be confused with the prolific Richardson's ground squirrel, prairie dogs are highly social rodents that live in underground towns. The plague they carry is the same one that killed a quarter of the human population in Europe during the 13th century, though it is unlikely to spread to humans today.

Black-footed ferrets, which have disappeared from Canada, are particularly vulnerable to the disease. While prairie dogs are more resilient, many colonies in the U.S. have been devastated by outbreaks over the past decade.

Sage grouse populations had been in a free fall across the prairies long before West Nile hit. No one is sure why, but drought, power lines, energy developments, inbreeding and the decline of nesting cover and food sources could all be factors.

Although protected by a national park, the small population of sage grouse at Grasslands has not been spared. At last count, there were just four leks, or mating grounds, being visited by 32 males.

"West Nile could be a factor in the decline in Grasslands sage grouse though there is no proof positive that mortality has been demonstrated here," says Pat Fargey, the park's specialist on endangered species.

"Although we are on alert, there's nothing much we can do about it if it hits. I mean, we have monster mosquito explosions here. Given the fact that West Nile is spread by mosquitoes, I'm afraid it's really an issue of dying or adapting for the sage grouse. Unfortunately, there's just not that many of them left to adapt to this new threat."

The appearance of West Nile in Western Canada also raises serious concerns about the future of the world's last wild flock of whooping cranes in Wood Buffalo National Park. With only 200 whooping cranes in that flock, an outbreak of the disease on the Alberta/Northwest Territories border or on the wintering grounds in Texas could undo more than 40 years of conservation efforts.

Fortunately, research on sandhill cranes in Maryland suggests that cranes are not as vulnerable to West Nile as are other avian species.

Unfortunately, Parks Canada lacks the resources and staff to monitor or control wildlife diseases in the parks. And the challenges keep mounting.

A recent study by Susan Kutz at the Western College of Veterinary Medicine at the University of Saskatchewan, for example, suggests that a warming climate could result in a dramatic spread of lungworm among muskox throughout the Arctic.

This could have huge consequences for Aulavik National Park on Banks Island, home to more than 60,000 muskox, or half of the world's population. Like most other northern parks, Aulavik has neither the staff nor the expertise to check for sick animals or do anything meaningful to contain an outbreak if one occurred.

The situation is a little better for parks in Southern Canada, which have access to experts from universities and governments. Pacific Rim, for example, has gone to B.C.'s Animal Health Centre to deal with an outbreak of leptospirosis, a contagious bacterial disease that infects both animals and humans, and has killed 15 sea lions since September.

And Wood Buffalo has relied on Agriculture Canada and the University of Saskatchewan to provide it with technical advice on diseased bison.

Relying on outside agencies has pros and cons. On the positive side, it saves Parks Canada money. But relying on an agency like Agriculture Canada, which it could be argued is more interested in cattle than bison, can have its drawbacks.

Back in the early 1990s, for example, Agriculture Canada's director of animal health warned if nothing was done to eradicate disease in Wood Buffalo's bison, "all free-roaming bison in northwestern Canada will probably die in 10 years."

History has proven him terribly wrong. The park has more bison today -- at least 4,000 -- than it had when that official made his prediction.

The truth is, the science of wildlife disease is as tricky as forecasting the weather.

There is a lot of evidence that many species can adapt to disease. West Nile, for example, is a new pathogen for every avian species in North America, but many birds have already developed antibodies for it.

Whether that's the case with bison in Wood Buffalo is far from certain.

Mark Bradley, the park's biologist, suspects that declines in winter snow and wolf populations -- two of the most lethal factors in bison survival -- are the main reasons the Wood Buffalo population is doing so well.

While climate change is being implicated in reduced snowfall, no one knows why the wolves are disappearing.

"I have to admit that even I've been surprised at how well the bison have been doing up here," says Bradley. "The past four surveys are a pretty good indicator that they are not on their way out, at least not any time soon."

The fact that bison are doing so well in spite of disease creates a major dilemma for Parks Canada as its officials hold high-level meetings with other government departments to consider action plans for Wood Buffalo.

On one hand, it helps the agency ward off calls by Agriculture Canada and the Canadian cattle industry for the slaughter of the bison herd. On the down side, though, an expanding population increases the chances of one or more diseased animals moving outside the park where they could infect cattle or healthy bison.

"This is a very big park (44,800 square kilometres)," says Coulthard. "To do just one circuit around the park boundaries takes a little over four hours of helicopter time. And then you've got a lot of territory on the perimeters that you'd also have to cover.

"To be honest, we just don't have the resources to do those kinds of surveys on a regular basis."

As the only wildlife health expert for all of Canada's 41 national parks, Shury concedes he could use a lot more help.

He sees hope, however, in the fact that provincial, territorial and federal agencies that once worked at cross-purposes on some animal health issues have now joined forces.

The Canadian Co-operative Wildlife Health Centre is an organization made up of Canada's four veterinary colleges and dedicated to applying their considerable medical skills to conserving and managing wildlife. The centre is supported by Ducks Unlimited, the Canadian Wildlife Federation, the Max Bell Foundation and several government agencies, including Parks Canada.

But for Parks Canada to be an effective force, it needs more people on the ground to monitor wildlife diseases.

"I think it was a big step forward for Parks Canada to hire a veterinarian like me," says Shury. "It really was long overdue. Parks people on the ground have been pushing for this for years.

"But the reality is Canada on the whole has been slow in responding to the threats posed by wildlife disease. Right off the top of my head, I can think of maybe 30 or 40 animal health experts in the United States. That's just a fraction of the expertise they have down there. But up here in Canada, I can count what we have on the fingers of my hand.

"The country as a whole, not just Parks Canada, really needs to do more to catch up with the rest of the world on this issue."

estruzik@thejournal.canwest.com