March 30, 2007

We’re only a few months into the New Year and The Canadian Food Inspection Agency (CFIA) has already announced that a new case of bovine spongiform encephalopathy (BSE), or mad-cow disease, was confirmed in the Alberta cattle population.

Scared? Well if anything, you’re probably at least starting to ask a few questions: Do I have to go veggie or can I still enjoy a burger with my friends? Will these cases ever stop popping up? What steps is our government taking to keep our meat safe?

Before answering these questions, let’s take a closer look at the tiny enemy behind the scare and why it’s so different from other infectious agents like bacteria and viruses.

Did You Know?
A prion, pronounced “pree-on”, is a protein that folds into an abnormal shape and causes disease. BSE is caused by a prion. This oddly-formed protein travels from the digestive tract to the brain where it causes other similar proteins to fold improperly. Instead of reproducing like bacteria and viruses, prions are like trendsetters—they tell others to look and behave like them, and those proteins that conform, influence others to imitate them as well.

Eventually the buildup of these molecules causes the strange behaviours and symptoms of this fatal disease. For example, the infected cow might act scared and anxious around people, drool, stagger, and will show aggression by bullying other herd members. So the term “mad cow” is quite literal.

True or False: You cannot catch BSE from infected cattle. False: Consumption of meat contaminated with the BSE-causing prion can trigger the neurodegenerative disease in humans known as variant Creutzfeldt-Jakob disease (vCJD). We can treat some viruses with vaccines, and many bacterial infections are cured with antibiotics. So why can’t we get rid of prions? The answer is quite simple. It’s not easy to make a drug that can tell the difference between normal proteins and prion proteins. Since proteins are one of the major building blocks of our body’s tissues, it is difficult to design treatments for prions without risk to our normal cell proteins.

Should I be worried?

The answer is no. Canada does an amazing job of controlling our meat safety. It was recently recommended by the World Organization for Animal Health that Canada be put in the “controlled risk category” which decision will be formally approved this May.

Here’s a timeline for some major steps our government has taken to make sure your meat is safe:

- 1990: Reporting— Anyone who suspects a cow has BSE needs to report it to a federal veterinarian.

- 1992: Screening— Brains of all high risk cattle must be tested for BSE.

- 1997: Feed ban— Parts of animals called ruminants (cattle, sheep,goats, bison, and deer) at risk for BSE cannot be fed to other ruminants.

- 2000: Import ban— Canada won’t accept rendered animal from any country not recognized as BSE-free by our standards.

- 2001: Tracking—the Canadian Cattle Identification Program was made in order to trace all movements of infected animals from birth to slaughter.

- 2003: Lowering risk to humans—Cattle parts that are at high risk for prion contamination (such as brain and spinal cord) must be removed before processing meat that will eventually be eaten by us,the general public.

Did You Know?
Since January 2006, only 6/64859 Canadian cattle tested positive for BSE. That’s less than 0.0001%! These cattle never entered our food supply, so you’re way more likely to get hit by lightning than eat a BSE-tainted burger. The Canadian Food Inspection Agency (CFIA) predicts it will take 10 years to totally eliminate BSE from our cattle herd. But until then you can keep the beef in your tacos and the meat in your spaghetti sauce, as according to Health Canada “BSE continues to pose an extremely low risk to human health”.

Learn More!


Health Canada

Terrestrial Animal Health Code

World Health Organization

Braun,U., Pusterla, N., and Schicker, E. (1998). Bovine spongiform encephalopathy: Diagnostic approach and clinical findings. Compendium on Continuing Education for the Practising Veterinarian. 20: S270-8.

Hoag, H. (2003). BSE case rattles Canadian officials. Nature. 423(6939):427.

Steinhart, C. (1996). Sick cows, protein geometry, and politics. Journal of Chemical Education. 73(10): A232-3.

Watts, J.C., Balachandran, A., and Westaway, D. (2006). The expanding universe of prion diseases. PLoS pathogens. 2(3):e26.

Carey Greco is a graduate student at the University of Ottawa and studies bacterial contamination of blood products as part of a Canadian Blood Services research team. Realizing the importance of the blood supply to the health of many Canadians, she also volunteers at local blood clinics by handing out juice and cookies to donors.

Article published March 30, 2007.


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