[imgcontainer right] [img:DSC00775-crop.jpg]A Canadian cow has been diagnosed with BSE, raising fears that the contagion still exists despite measures to eliminate it. Labeling meat by its country of origin helps contain the spread of disease, the author says.[/imgcontainer]
Livestock born and reared over generations on the same farm seldom become ill. That’s because of natural immunity passed from mothers to their offspring, and because a major contributor to sickness in animals is stress caused by relocating them to new surroundings and different feed, especially during weaning. Also, many times illness is introduced by commingling animals from several different herds together under those conditions.
It’s sort of like a room full of public school kindergarteners during flu season.
One exception to that in ruminant livestock is the cattle disease, or epizootic (called that because it may be transmitted to humans) known as bovine spongy encephalopathy or BSE. You may have heard it referred to by another name, Mad Cow Disease. A similar disease called Scrapie is found in sheep, and one known as Chronic Wasting Disease (CWD) in deer populations.
BSE first came into the news in the 1980s when it was identified in cattle in the United Kingdom. That discovery led to massive culling of several million head and a change in feed rules that had previously allowed the feeding of animal offal.
(Offal is the ground and cooked remains of livestock not utilized for human food. In the past it was a valuable source of protein for farm animals. But new rules that allowed it to be cooked at lower temperatures may have contributed to the spread of BSE.)
Since then about 177 British citizens have been identified to have died from BSE’s human variant known as Creutzfeldt Jakob Disease. Authorities feel it’s possible many more fatalities due to CJD have never been identified, or have been attributed to other causes.
It is feared those people were infected by consuming meat containing BSE agents.
Now, BSE has again been diagnosed in a Canadian cow born two years after measures meant to control BSE were put into effect in Canada. That means whatever causes BSE may still be present in Canadian herds.
About 20 Canadian BSE cows have been identified since tracking began. That compares to over 180,000 in the United Kingdom, and thousands more across most of Europe. In the U.S. there have been four detections. One was in the state of Washington and traced to Canadian origin. One was a milk cow in California where Canadian cows have been known to be commingled. And two (an aged cow in Texas and one in Alabama) that were thought to have died from a similar but possibly genetically inherited trait known as atypical BSE.
The thing that sets BSE and its companion diseases apart is that it is not the result of bacterial or viral infection, but is instead caused by an infectious protein called a prion. The initial discovery and identification of prions was first questioned as radical but has since been widely accepted as the cause of brain and spinal cord wasting in humans and some animals.
All protein including prions is made up of individual molecules known as amino acids. There are many different types of amino acids our bodies rely on for virtually every biological function. Humans rely on nutrition to replace vital amino acid rich proteins. That’s why we eat meat from animals, because it is a source of protein used to renew our own supply.
Meat is certainly not the only source of protein in human diets, but it is one of the most common.
In the course of becoming protein, amino acids line themselves up a little like magnetic beads on a string. Some beads attract, others repel, something like magnets do based on polarity. That’s why protein strings aren’t straight, because amino acid “beads” cause the string to curl or fold into specific shapes complementing the work of the amino acids themselves.
Prions that cause BSE are dysfunctional proteins whose mis-folded amino acids are disruptive, behaving in a destructive manner. In most cases that is manifested by a degenerative condition of the brain resulting in lack of muscle coordination, dementia, and eventually death.
Unlike biological agents, prions aren’t easily destroyed by heating. It takes temperatures in excess of 600 degrees to do that, compared to about 150 degrees to destroy bacteria.
At 600 degrees, the best steak in the world becomes leather. But before you cook that prime cut of beef into an unrecognizable boot sole, new research says not all prions are BSE-bad because some may actually help improve long-term memory.
While BSE is virtually non-existent in New World countries of the U.S., South America and Australia, Canada’s higher incidence is traceable to closer trading ties with Great Britain when both animals and contaminated feed may have been imported.
Also, the U.S. was quicker than Canada in adopting and adhering to new feed rules that may have limited our exposure.
Young cattle seldom show signs of BSE because it takes time to develop. BSE is normally found in older animals, usually cows. Since younger slaughter animals are seldom much older than two years, there isn’t much chance of consuming beef with BSE from one of those.
Testing is usually only done on animals exhibiting symptoms.
Each confirmed BSE positive raises eyebrows, because it shows the disease is still around in cattle populations, especially in Canada–and even more prevalent in Europe. That’s one reason why traceability of foreign beef imported into America is so important, and one reason why Country of Origin Labeling for beef is more than just a marketing issue.
COOL, a law that requires meatpackers to label meat so consumers can tell where it comes from, is about food safety too.
Richard Oswald, a fifth generation farmer, lives in Langdon, Missouri, and is president of the Missouri Farmers Union.