Canada: Anthrax outbreaks in the Northwest Territories, Dozens of bison affected

July 19, 2023

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In a follow-up on the anthrax outbreak among bison in the Northwest Territories, the government now reports 28 confirmed cases in the Slave River Lowlands.

The outbreak was first reported on July 4.

Officials report incineration continued at three carcass sites – including 24 carcasses. These sites continue to be monitored. Burning will continue over the coming days.

Flights have been conducted and no new carcasses have been found. Mobilizing and onboarding disposal crews to be ready to safely treat carcasses and land.

In addition, anthrax has also been reported and confirmed along a 10-kilometre stretch of NWT Highway 5 in Wood Buffalo National Park. To date, nine carcasses have been observed and two cases were confirmed.

There was an anthrax outbreak most recently in Wood Buffalo National Park last year.

Officials say the risk to the public is very low.

The bacteria that causes anthrax occurs naturally in soil. But, its presence varies with soil types and climate conditions. It lies dormant in the ground, especially on low-lying or flood-prone land.

After wet weather, hot and dry conditions bring bacteria closer to the surface. Wallowing or pawing at the ground stirs it up, and animals like bison breathe it in and get infected.

Microbiology

The disease is fatal for bison. Though rare, it can also occur in other mammals, including humans.

While there have been no recent cases of human exposure or illness documented in the NWT, anthrax can cause an infection should a person come into direct contact with infected bison or bison parts. It is important to take appropriate precautions to prevent exposure.

Signs and Symptoms of Anthrax in Bison

Bison with anthrax may exhibit any of the following signs:

Found dead – often animals appear bloated and may be lying on their side in a sawhorse stance
White or bloody foam discharge from nostrils
Appearing depressed or unresponsive to stimuli
Stopping eating, or overfeeding and stop ruminating
Appearing lame or having a stiff-legged gait.
Swelling below the skin
Refusing to get up when people, aircraft, or vehicles approach

Signs and Symptoms of Anthrax in Humans

Anthrax occurrence in humans is extremely rare. You can only get anthrax by inhaling the spores, eating contaminated meat, or having the spores come in contact with your skin, particularly an open wound or mucosa. People with anthrax are not capable of infecting others.

Anyone who has been exposed to anthrax spores but is not yet sick should be treated with antibiotics and a few doses of the vaccine to prevent infection; please contact your local health centre

Signs and symptoms of anthrax can include the following;

Cutaneous (skin) anthrax which begins as a raised bump on the skin that becomes a blister, and then a painless ulcer with a black area in the center. Lymph nodes near the wound may become swollen. Skin anthrax is easily treated with antibiotics.
Intestinal anthrax is very rare. It begins with nausea, loss of appetite, vomiting, and fever. Those symptoms are followed by abdominal pain, vomiting of blood, and severe diarrhea. Early antibiotic treatment is important if you have intestinal anthrax.
Inhalation anthrax begins with flu-like symptoms (cough, fever, muscle aches). These symptoms may last two to three days, and then appear to go away for one or two days. Then the illness can come back, resulting in severe lung problems, difficulty breathing, and shock. Unless it’s treated, inhalation anthrax can be very dangerous – it’s fatal in up to 90 percent of cases.