Anthrax striking bison in NWT

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Little can be done to contain a deadly outbreak of anthrax among bison in a northern sanctuary, say experts.

"All you can really do to control anthrax in wildlife populations is to burn and bury the carcasses to prevent spores from spreading," said veterinarian Brett Elkin.

Approximately 90 bison in the Mackenzie Bison Sanctuary have died from the highly contagious disease. Sanctuary officials have mobilized an emergency response team to locate and destroy carcasses to minimize the spread of anthrax among the 2,000 bison in the park.

While this is the first such outbreak reported in the sanctuary, at least 1,100 bison in nearWood Buffalo Park and the Slave River lowlands have died from anthrax since 1962. The first signs of an outbreak were discovered Aug. 1 when park staff reported a number of dead bison showing signs of having succumbed to anthrax.

"The signs were typical - blood coming from the nose, and the carcasses were in a sawhorse stance, said Elkin. In other words, very bloated, with all legs stiff and extended, signs of a quick death.

"We suspected it was anthrax and proceeded as if it was. We didn't want to wait for lab tests, which can take up to two weeks, to be sure," he said.

The first step was to fly over the 10,000 square kilometre range with a helicopter equipped with infra-red heat detectors. The equipment is normally used to detect hot spots fire fighters, and has proved invaluable in spotting carcasses hidden deep woods, said Elkin.

"There is enough bacterial activity in carcasses to show up as heat for several days after death occurs," he explained.

Six crews of four to five staff members are on the ground, disposing of carcasses, for a total of 33 men. As an extra precaution, the protective outfits worn the crews are also burnt before leaving the site.

While anthrax can affect humans, no cases have been reported, said Elkin. Humans can become infected if they come into contact with diseased animals, eat meat from infected animals, or handle hides from diseased animals. Therefore the public has been warned to stay away from the area of the outbreak and to report any sick or dead bison to the Department of Renewable Resources immediately.

But the disease is easily treated with antibiotics if caught early, Elkin said.

Anthrax is spread spores which can survive dormant for decades in soil. Bison usually contract the disease eating grass, drinking water or inhaling air contaminated with the spores.

Experience has proven that adult male bison are the most likely to be attacked the bacteria, partially due to their behavioral patterns. Those appear to be seasonally related to hot weather, insect harassment, and the rut.

Outbreaks usually occur in mid to late summer when the weather is hot and dry. An unseasonable cold spell with temperatures dropping to zero degrees Celsius may keep in check, but Elkin is uncertain how the outbreak will progress.

"It's quite unpredictable. We'll just have to play it day to day."