Laboratory results confirmed Wednesday that anthrax was the cause of death in two bison near North Battleford.

The provincial government's Ministry of Agriculture said the infection is also believed to have killed seven more bison.

The ministry said anthrax is caused by naturally occurring bacteria Bacillus anthracis. A buildup of the bacteria on pastures is caused by changes in soil moisture such as flooding and drying. The spores concentrate in sloughs and potholes. It can survive for decades.

Affected livestock are usually found dead without showing any signs of illness. Carcasses should not be moved or disturbed and should be protected from scavengers to prevent spreading the infection to a wider area.

Animals who forage, such as bison, cattle, sheep and goats are highly susceptible especially during dry years. Swine, birds and carnivores are more resistant, but farm cats and dogs should be kept away from carcasses.

Anthrax can be prevented by immunizing livestock. Saskatchewan Agriculture suggests vaccinating animals if nearby farms have seen cases.

The bacteria only poses a minimal risk to humans, but people can become infected through direct contact with sick animals and carcasses.