Canadian anthrax outbreak grows, felling 746 animals

August 10, 2006 (CIDRAP News) – An outbreak of anthrax that began in early July, the largest ever recorded in Saskatchewan, has now killed at least 746 farm animals in that province and neighboring Manitoba, according to Aug 9 statistics from the Canadian Food Inspection Agency (CFIA).

The outbreak, which has led to at least 146 farms being quarantined, is the largest on the prairies since record-keeping began in the 1950s, said CFIA veterinarian Dr. Sandra Stephens, according to a Canadian Press (CP) story yesterday.

The vast majority of dead animals have been in Saskatchewan, with 628 anthrax-infected animals dying on 129 farms, according to the CFIA. In Manitoba, 118 animals have died on 17 farms.

Canadian public health officials emphasize that the risk of anthrax infection to people is extremely low, according to yesterday's CP story. "It's more of an animal health issue than a human health issue," said Dr. Huiming Yang, Saskatchewan's deputy chief medical health officer, in the CP article.

"This is field anthrax," added Stephens in the CP story. "It's an environmental disease. This is something that civilization has been dealing with for centuries and we will continue to live with for years to come."

Anthrax spores are found in soil in many parts of the world and can remain viable for decades. Epidemics can come after heavy rains, which bring the spores to the surface, or during droughts when animals need to graze deeper into contaminated ground, according to a report in today's Toronto Globe and Mail. This summer has produced perfect conditions for an outbreak, the article said.

Anthrax cannot pass between live animals, according to the Globe and Mail story, but animals that come in contact with infected carcasses can likewise become infected. So farmers across the two provinces have been burning dead infected animals to decrease spread of the disease, the story said.

In addition, according to the article, more than 250,000 animals have been privately vaccinated and 18,000 vaccinated by the Canadian government. Among affected animals are cattle, horses, bison, sheep, and goats.

Anthrax also cannot pass between people. However, in mid July cutaneous, or skin, anthrax, developed in a Canadian farmer, presumably via contact with an infected animal. Cutaneous anthrax is much less serious than inhalational anthrax (see Jul 17 CIDRAP News story). The farmer has since fully recovered, according to yesterday's CP story.

Meanwhile, across Manitoba's southern border, northwestern Minnesota has seen the state's worst anthrax outbreak since 1919, according to the Minnesota Board of Animal Health (BAH).

Since mid June, 23 farms in four counties have experienced anthrax infection, resulting in 68 cattle, bison, and horse fatalities. In 1919, 42 farms were affected.

Minnesota officials are also recommending vaccination. "We see anthrax cases throughout the summer, so producers still have time to vaccinate their livestock," said BAH senior veterinarian Dr. Linda Glaser in a Jul 20 BAH press release.

See also:

CFIA update on Canadian outbreak
http://www.inspection.gc.ca/english/anima/heasan/disemala/anthchar/situatione.shtml

CIDRAP overview of anthrax
http://www.cidrap.umn.edu/cidrap/content/bt/anthrax/biofacts/anthraxfactsheet.html