Like most people, when I think of anthrax, I think of white powder, mail and terrorism plots. If I was the extremely paranoid type, the recent news reports of cattle dying of anthrax infection on farms in Saskatchewan and Manitoba might have me wondering whether our food-chain is now being targeted by terrorists.
The latest threat to Canada’s beef industry, following the mad-cow hysteria of the past few years, is anthrax. the Canadian Food Inspection Agency (CFIA) has reported 644 dead animals on 136 farms in Manitoba and Saskatchewan, most of these cattle. Why? Did terrorists tire of licking envelopes? Are they frustrated with the speed at which snail-mail is delivered? No. This recent outbreak of infection in cattle is naturally occurring, unrelated to any sort of conspiracy.
Anthrax is a zoonotic infection, primarily infecting grazing animals (herbivores) who ingest spores of the bacteria, Bacillus anthracis, found in soil. Bacillus anthracis in its spore form is extremely resistant to harsh environmental conditions such as drying, heat, cold and chemical exposure. This is the reason that anthrax spores have been popular throughout history as an agent of biowarfare and bioterror.
Not all bacteria have the ability to form spores, but for those that do, when environmental conditions become uninhabitable, the bacteria enters into a dormant or nonactive state. Once conditions improve, such as when the spore is inhaled into a nice warm moist nutritious body, animal or human, the spore changes back to its vegetative or active state and begins to grow and multiply. As Bacillus anthracis multiplies, it produces toxins that cause damage and are potentially life-threatening. Infected cattle die quickly once infected so that sick animals are not often seen.
The current outbreak is the largest recorded outbreak of zoonotic anthrax occurring over the largest area in Canada. The last largest outbreak reported by the CFIA was in 2000, involving 28 cattle – 24 in Manitoba, 3 in Ontario and 1 in Saskatchewan. There were also 10 deaths in other animals – 6 in bison (5 in Alberta and 1 in the North West Territories) and 4 in black bears, moose and wolves in Alberta. However, deaths are sporadically seen most years across the Prairie provinces. Why are we seeing so many deaths in livestock this year? The abundant rain and flooding in Saskatchewan and Manitoba this spring and early summer have been extremely favorable for bringing anthrax spores to the surface of fields and meadows where animals graze. Spores reportedly can live in the soil for 50 years or more. Once ingested by animals grazing in spore-rich areas, the bacteria causes a severe gastrointestinal infection, which very often leads to death.
What is the threat to humans? Check in next week to find out whether there is reason for concern.