Experts say it may not be possible to eliminate chronic wasting disease in deer and elk in Canada.
The fatal infectious disease is so well-established in Saskatchewan and Alberta that the federal government and some provinces are rethinking how to deal with what is commonly known as CWD.
In 2005, Ottawa announced a national strategy to control chronic wasting disease in the hope of finding ways to eradicate it. Now the emphasis is shifting to preventing CWD from spreading, especially in the wild.
"We have to realize that we may not be able to eradicate this disease currently from Canada, given that we don't have any effective tools, so we may be looking at switching from eradication to control," said Penny Greenwood, national manager of domestic disease control for the Canadian Food Inspection Agency.
The agency says it is working with the provinces and the game-ranching industry to come up with a better plan, perhaps by next spring.
"We feel that the current program that we have had in place for chronic wasting disease ... is not effective in achieving its goals," Ms. Greenwood said.
CWD is caused by abnormal proteins called prions and is similar to mad cow disease. There is no vaccine against it. Symptoms can take months or years to develop. They include weight loss, tremors, lack of co-ordination, paralysis and, ultimately, death.
Some scientists believe infected animals can pass the disease to other animals through saliva, blood, urine or droppings, or indirectly through prions in the environment. The prions can remain active in dirt for years.
There is no evidence that the disease can affect people, but the food inspection agency recommends against eating meat from infected animals.
The latest report from the CFIA shows the disease is active in herds of deer on Saskatchewan game farms.
Scientists say the more pressing challenge is the growing number of infected wild deer and elk in Saskatchewan and Alberta. The disease has also been found in a moose.
Researchers believe that in one area of Saskatchewan, up to 50 per cent of the deer have chronic wasting disease.
"This is a disease that is now established in wildlife, and when you have a disease that is established in a wildlife reservoir, it is always extremely difficult to eliminate it," Ms. Greenwood said.
British Columbia and Manitoba have had no confirmed cases, but have put up billboards on highways warning hunters not to bring in deer or elk that have been shot in other jurisdictions.
The caption on the signs that B.C. put up this spring in the Peace and Kootenay regions near the Alberta boundary read: "Stop Chronic Wasting Disease. Do Not Import Intact Deer Carcasses. Keep B.C. Wildlife Healthy."
Scientists say a big challenge in tracking the spread of CWD is a lack of research into the disease and surveillance programs to track its spread.
The federal government ended a program on March 31 that was established in 2005 called PrioNet Canada that was conducting research into CWD and mad cow disease.
Surveillance in the wild is difficult because there is no way to test live animals for the disease. Provincial governments rely on testing the heads of animals turned in by hunters. But in Saskatchewan and Alberta, the provinces where the disease is well-established, it is not mandatory for hunters to do that.
More needs to be done, said Trent Bollinger, a CWD expert with the Canadian Co-operative Wildlife Health Centre at the University of Saskatchewan.
"It is a long-term commitment to both research and management to see how to best approach this and those are difficult things for governments to buy into," Mr. Bollinger said from Saskatoon.
Last year, Manitoba ordered conservation officers to kill as many as nine elk that escaped from a Saskatchewan game farm into the province.
Mr. Bollinger predicted that with infected wild deer close to the provincial boundary, it is only a matter of time before wild animals with CWD wander into Manitoba.
Alberta is funding research into the disease through the Alberta Prion Research Institute.
Debbie McKenzie, a University of Alberta biologist, said there is concern that CWD could eventually infect other species, including caribou.
She said researchers hope to develop a vaccine to stop the spread of the disease, but coming up with an effective way of vaccinating animals in the wild will pose another challenge.
"It is one thing for a farmer to vaccinate his cows. It is another thing to come up with cost-effective ways of vaccinating all of the deer and elk in an area."