I normally don't post this type of report but 128 bison? That's BIG outbreak of something...
Date: 6 Jul 2012
Source: Department of Environment and Natural Resources Multimedia Advisory [edited]
A total of 128 bison carcasses have been found in an area near Mills Lake, north west of Fort Providence. The carcasses were found on 3 Jul 2012 during a routine anthrax surveillance flight.
Samples are being sent to the Canadian Food Inspection Agency lab in Lethbridge for testing.
As a precaution, the Department of Environment and Natural Resources (ENR) has activated the Anthrax Emergency Response Plan. An ENR Incident Command team will be stationed in Fort Providence to deal with the potential outbreak.
The area is about 30 kilometres [18.6 miles] north west of Fort Providence and is only accessible by boat at this time of year. There are cabins in the area. Environment and Natural Resources (ENR) staff have warned people in the area to avoid these carcass sites and any contact with dead bison.
Routine aerial surveillance flights over the Mackenzie Bison Sanctuary area will continue until late August .
Anyone who discovers a carcass is asked to notify ENR as soon as possible. People are advised not to approach or touch carcasses.
For more information, contact:
Manager, Public Affairs and Communications
Department of Environment and Natural Resources
Date: 6 Jul 2012
Source: CBC News [edited]
Anthrax likely killed 128 bison in the NWT lowlands
Carcasses found close to Mills Lake during a routine anthrax surveillance flight
Anthrax is believed to have killed 128 [wood] bison north west of Fort Providence, NWT. The territory's Department of Environment says the weather has contributed to past outbreaks in the same area. The carcasses were found close to Mills Lake during a routine anthrax surveillance flight this week.
The Department of Environment and Natural Resources has issued an anthrax emergency response plan to deal with the potential outbreak.
"A field test on a couple of carcasses did turn out positive," said Judy McLinton, the department's spokeswoman. "Given the number of carcasses and the chance when they looked at them that it was probably or potentially anthrax, we activated our emergency response plan."
On Thursday [5 Jul 2012], the department sent samples from the dead animals to a Canadian Food Inspection Agency lab in Lethbridge, Alberta, for testing, she said. They expect the results in a week's time. [This is standard Canadian practice with suspected anthrax cases in animals, whether livestock or wildlife. - Mod.MHJ]
McLinton said the department will start disposing of the carcasses. Typically they burn carcasses that have died of anthrax but given the number, she said that could take up to 6 weeks. "They'll treat the carcasses with formaldehyde, tarp them, because we want to keep the anthrax spores intact [sic], and then we'll burn as we move along."
McLinton said it's not possible to vaccinate bison for anthrax because the spores are in the soil. [See moderator comments.]
She said the weather -- wet, followed by a hot, dry stretch -- contributed to the outbreak. "What happens is if you get the right environmental conditions, which we have right now, in that area, the spores are in the ground, the bison go in, start rolling around, wallowing in the mud near the water and the spores come up and inhale it," she said. [Ditto]
McLinton said the last large outbreak in the Mackenzie Bison Sanctuary was in 1993 when 172 animals died. She said anthrax killed 9 bison in the Mills Lake area in 2009 [Actually, 2010].
People with cabins in the area have been warned to stay away from the dead bison and the department said anyone who sees bison carcasses should call ENR right away.
[Our accounts of the 2010 outbreak near Mills Lake had 10 dead bison found and disposed of. This was a 1st for this SW corner of the MacKenzie Bison Sanctuary. In 1993 there was a big epidemic about Lake Falaise in the western shore of the Great Slave Lake, some 100 Kms east of Mills Lake. So we might assume that this is a new nidus for this pathogen in the area. Latterly in spite of the absence of overt cases in the MacKenzie Sanctuary routine bleeding for tuberculosis (TB) and brucellar surveillance had found the occasional animal with a positive anthrax titre. This was a puzzle as regular flights over the sanctuary failed to find any bison carcasses. Obviously more was going on that was seen. But it is also clear that the bison population near Mills Lake is relatively new. If we go by previous experience of a 10 per cent incidence in an epidemic, this would indicate a population in that area of some 1400 head.
The Canadians have been aggressively fighting this disease with the tools to hand; -- that is, actively looking for fresh anthrax carcasses and promptly burning them. And this has kept outbreaks in manageable numbers. They use teams of "hotshot" forestry firemen to burn the carcasses, who manage to burn up to 3 in a day. This is no mean feat as wood bison bulls weigh around 2500 lbs/1200 Kgs; they are significantly bigger than plains bison.
Back in the 1960s vaccination was attempted in the Wood Bison National Park but it was very expensive and involved a worrying bison mortality from stress. Bison can be vaccinated, vide Dave Hunter/Ted Turner's positive experience with the bison on the Flying-D ranch in Montana, but this is with plains bison on a managed ranch with extensive meadows, not woodland, and with an owner willing to carry the steep cost.
Bison bulls, which form the majority of cases, display by rolling in their wallows and generate a high column of dust to impress other bulls. Though theoretically the disease could be spread in this dust, it is a rare bull that dies in his wallow; usually the fevered animal heads for the shade of the nearby aspens and dies there or out on the grass meadows. If not found soon the ground contamination around a bison carcass can be extensive and very severe thanks to foxes, wolves, bears, and other scavengers. It is clear that this epidemic, like the 1993 one, was aided by a good hatch of tabanid biting flies; in 1993 the bison were noted to be "black" with flies.
The "field test" quoted is the US Navy HHA test, which works very well with wood bison. It has been deployed in the WBNP for some years now with success. - Mod.MHJ