Anthrax outbreak in Canada kills more than 400 bison

The number of bison dead from an anthrax outbreak in Canada's Northwest Territories has increased to 429.

Todd Vermillion, the manager of wildlife and environment for the South Slave region for Canada's Department of Environment and Natural Resources, said that the increase in dead bison stems from newly found carcasses and not an increase in the number of infections, according to

"The way it worked out is we found such a large number right off the bat," Vermillion said, reports. "We had to start dealing with those and did more reconnaissance flights and flew more in the area with rotary helicopters coming up on more carcasses and dealing with those as we went along."

As of last week, the number of dead bison was estimated at 340, already making it the largest outbreak of the illness among bison ever recorded in the territory.

More than 150 carcasses were initially found in one large group near the town of Fort Providence. They are currently being incinerated to ensure the anthrax spores will not contaminate the area's soil, reports.

A large anthrax outbreak among bison occurred in 1994, infecting approximately 172 animals. Anthrax bacteria are found naturally in soil. During and after prolonged dry periods, bison are more likely to inhale anthrax spores and acquire the infection.