In the remote wilderness of Canada's Northwest Territories, high-tech infrared cameras and computers are being enlisted by wildlife managers to spot bison carcasses infected with anthrax, a lethal disease caused by a spore-forming bacterium called Bacillus anthracis.
"We're up to 44 dead bison," Troy Ellsworth told Discovery News yesterday.
Ellsworth is the Government of the Northwest Territories’ manager of wildlife, and so far, thanks to low forest fire activity this year, he's had enough people available to dispatch the carcasses.
But finding the dead bison in the first place is crucial to mitigating an outbreak. If left unchecked, scavenger including ravens, bears, wolves and foxes -- who appear to be immune to anthrax -- can tear apart the carcass, allowing the anthrax bacterium to reach the soil, where it produces spores. Spores can remain viable for years or even decades. And it's thought the bison wallowing in dusty areas (above) where spores exist may be inhaling the deadly disease. Or it's possible that they are ingesting the spores during grazing.
The wildlife managers started using infrared technology back in 1993, but the cameras were big, had to be specially mounted to helicopters and flown and operated by trained individuals.
Starting in 2006 -- when the last anthrax outbreak killed 28 bison -- the team switched to handheld devices, which they were using to spot the remnants of forest fires smoldering unseen under two to three feet of peatlike material.
The devices aren't cheap, Ellsworth says. A replacement lens alone can cost $10,000. But they're user-friendly and operators can be trained on the ground before ever getting onboard a helicopter.
Left: A herd of bison as seen with an infrared camera. Right: A dead bison found intact.
Not every summer brings with it an outbreak of anthrax. And the anthrax season itself seems to last between the end of the June and the middle of the August.
But once it strikes, death occurs within a couple of days. Often the ground around a dead animal shows no visible signs of thrashing. It's as if the bison fell where it stood and died instantly.
In the heat of fever, they often take shelter under the cool shade of dense brush, and that makes finding the carcass a challenge.
As a matter of routine, the wildlife crew uses a plane to perform about four visual surveys each summer of known bison habitats. If a dead animal is found to be infected with anthrax, the wildlife managers switch to conducting more frequent surveys using the infrared cameras.
"As soon as it dies, the microbial floral in the gut breaks out to decompose the carcass. That throws off a lot of heat," said Daniel Dragon, a biosafety officer at the University of Alberta, who has conducted research on anthrax and bison in the Northwest Territories.
The search typically begins early in the morning, starting between 4 a.m. and 5 a.m., when the ground has had time to cool off.
In the right conditions, "These guys light up like Christmas trees even under complete tree cover," said Dragon.
Once an animal is found, a specially trained crew wearing protective clothing is dispatched to dispose of the animal. The best method so far is burning. About 4,000 lbs of wood and coal are used per animal.
The approach used in the Northwest Territories is very well regarded in the anthrax community, said Dragon, because there are less frequent outbreaks and when one happens, fewer animals die.
Already Ellsworth thinks that the current outbreak is fading. On four different occasions in the last 10 days, his crew has been out scanning the area.
"We haven’t found any more carcasses. We are continuing to conduct aerial surveys," he said, "But if we don’t pick up any more through the weekend, we’ll be done.
Let's hope for the sake of the herd, that's true.
Tags: Animals, Aviation, Computer Peripherals, Infectious Diseases, Wildlife Conservation
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