Canada had previously been considered free of BSE, although there had been one earlier reported case of a cow in Canada testing positive for BSE, in December of 1993. That cow, however, had been imported from Britain, and was immediately destroyed along with the rest of its five-member herd.
Officials are currently unsure if the recently-infected cow was born and raised in Canada or had been imported. It has been destroyed, as will be all 150 members of its herd. For additional details on this story, read the coverage by CNN or The New York Times (free registration required).
BSE is a degenerative neurological disease affecting adult cattle. It is believed by many to cause variant Creutzfeldt-Jakob disease or vCJD, in humans, although this is widely disputed. For more details on BSE and vCJD, and the possible link between them, see this earlier SFT/SciScoop story from February.
Can BSE easily be passed from one cow to another? Perhaps I misunderstand, but I thought an animal generally had to eat something containing the BSE-causing protein to be infected?
Cows don’t commonly eat other cows, AFAIK, so perhaps the critical question is ‘how did this Canadian cow get BSE, and are other cows in danger of picking it up in the same way?’
Think I’ll be eating more chicken and fish in the future. For more info straight from Edmonton, Alberta, see:
http://www.canada.com/health/madcowdisease/
They believe that BSE cannot spread from one cow to another, but only from contaminated feed. Right now, nobody knows how the cow got BSE, but it may have come from another country (they’re trying to track that down). If not, that spells trouble because it means it contracted it from feed and other cows may be affected. Since they only test for BSE does not work for living cows, all the cows from the 2 herds are being slaughtered and will be tested. I’m sure everyone has their fingers crossed that none of the other cows are infected.
From:
http://www.globeandmail.com/servlet/ArticleNews/TPStory/LAC/20030521/UBSEEN//?query=mad+cow+disease
“The brain-wasting disease was first identified in Britain in 1986. BSE is believed to have jumped to cattle from sheep infected with a similar disease called scrapie. The remains of sheep were ground up to create a product that was fed to cattle. BSE has been identified in 24 countries.”
“The principal source of BSE is from contaminated feed. Theoretically, it may be passed on from a cow to a calf in milk. Some scientists also believe that BSE can, in rare instances, occur spontaneously. BSE is not an infectious disease; it does not spread from animal to animal.”
BSE does not spread from cow to cow. It is spread through infected feed. Feed is infected by the use of ruminate animal protein being used in feed. Many cattle feeds contain meat meal, bone meal, and or blood meal. While this has been outlawed in the USA it is still common practice in many countries.
The restrictions on US feed are not nearly comprehensive. So far we’ve been lucky in that no cow has tested positive, but the U.S. isn’t 100% safe from BSE.
There is some speculation that US cows don’t live long enough to manifest symptoms of BSE, so only the limited testing will show us if we ever get a problem.