EDMONTON – The number of bison killed by anthrax in Wood Buffalo National Park continues to rise, says a senior park warden.
So far, 94 bison and two black bears have died from anthrax since mid-June. Park officials believe the deaths will taper off with the arrival of cooler weather.
“It seems with the cooler weather and the rain, it affects the spores somehow,” said Jonah Mitchell.
The anthrax deaths occurred in two areas of the 45,000 sq. kilometre park.
The first group of animals were found in the Trident Creek area where four creeks drain. Sixty-four carcasses were found there in mid-June.
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The second outbreak occurred in the Sweetgrass area along the Peace Ð Athabasca delta in mid-July.
The deaths are similar to those recorded in other anthrax outbreaks, said Cormack Gates, chair of the National Wood Bison Recovery Team at the University of Calgary.
Deaths usually follow years of flooding where anthrax spores are washed out of the ground and carried down river to low-lying areas.
When the ground dries, the bison wallow and make dust baths in the spore-infested area.
Infected bison get a high fever after inhaling the spores and usually die within 48 hours. Most of the dead bison at the park were found within one km of water. The majority of deaths involved mature males.
Gates was involved in developing an anthrax-reduction policy in the Northwest Territories after 172 bison died in the Mackenzie Bison Sanctuary in 1993. In that case, more than $1 million was spent bringing in coal, fuel and wood to burn the carcasses.
Brett Elkin, wildlife disease specialist with the territorial government, said it’s important to monitor bison herds frequently and destroy carcasses quickly. The anthrax spores are spread if the carcasses are ripped open by animals.
The second stage of the prevention program is to cover the carcass with formaldehyde or a similar solution to prevent scavenging.
After that, the carcass is burned.
“We don’t have the final scientific answer. But we think this is the best way to go,” said Elkin.
Dan Dragon, who has worked on anthrax in bison for his PhD thesis for the past eight years, said burning seems to minimize the number of anthrax spores.
Spores remain
Dragon took soil samples from the Mackenzie Bison Sanctuary where the animals were burned. Where the fire was hot and only ashes
remained, he found no anthrax spores. Where bits of bison hair and bone escaped the burn, he found 500 spores per gram of soil.
In Africa, soil samples taken around elephant carcasses that haven’t been burned contained millions of anthrax spores per gram of soil.
Park officials in Wood Buffalo National Park decided not to burn the infected bison carcasses.
Mitchell said government rules, park regulations, the cost of destroying the carcasses and the fact they are located in a heavily wooded area are hampering cleanup efforts.
Most of the bison carcasses were already ripped open when park officials found them, said Mitchell.
Seven carcasses located within 15 km of the community of Garden Creek were covered with lime.
In the heavily wooded areas, workers would have to hike more than two km carrying heavy equipment and wearing full protective gear.
Lack of manpower is also a consideration. After a 1962 outbreak when two people contracted anthrax, the government established a policy that a minimum number of people handle and investigate anthrax deaths. Both people in the 1962 outbreak were treated with antibiotics and recovered.
