Good news and bad news about BSE
Published in the Ottawa Citizen, April 8, 2006
Two cases of BSE in Alberta caused a $10-billion crisis in the Canadian cattle industry. Now British Columbia's burgeoning biotechnology sector is developing tests that have the potential to identify BSE and similar brain-wasting diseases that threaten human as well as animal populations.
In other words, it's good news and bad on the mad-cow file.
First the good. Bovine spongiform encephalopathy appears to be on the wane. Thanks to good science, the materials that spread the disease among previously infected animals have been removed from the feed. With the worldwide rate of BSE cattle deaths down by 50 per cent per year, the United Nations Food and Agriculture Organization reported only 474 cases in 2005.
This is good news for beef consumers who were at risk of contracting the always fatal brain-wasting human form of BSE called variant Creutzfeldt-Jacob disease (vCJD). The cattle industry, which in the U.K. was devastated by BSE and in North America closed the U.S. border to Canadian imports, will also be relieved.
Good news too because even if the disease isn't fully understood or eliminated, it is being controlled. For instance, though cattle may be infected from a very early age, if they are slaughtered before the disease becomes symptomatic and its risk materials removed, the beef is considered safe for consumption. Presumably, too, farm and meat processing facilities are monitored to prevent cross-contamination between infected and non-infected materials.
Now the bad news. While we have some idea of how many cattle are dying because of BSE, we don't know how many are infected. And despite widespread speculation, neither do we know what caused BSE in the first place.
Mostly, we don't know the full implications of BSE and other diseases that involve the misfolded proteins underlying such brain-wasting diseases in both animal and human populations.
And there's a slew of these, says University of British Columbia's Neil Cashman. According to the neurodegenerative disease expert, they can be divided into two groups: "those in which misfolded proteins, not thought to be infectious, may be only a marker but not necessarily the cause of diseases like Alzheimer's, Parkinson's and ALS and those highly infectious misfolded proteins called prions that are not only a marker but the bad actor. They cause BSE, vCJD, CJD and chronic wasting disease in wild and farmed elk and deer."
Worse, the highly infectious variety is impervious to normal sterilization techniques, including radiation, and none of these diseases can be identified definitively except through post-mortem testing.
According to a recent study, some 14,000 Britons may be infected with vCJD but because of its lengthy incubation period and no ante-mortem test, none are aware and many may even die of other causes first. In the meantime, their blood remains highly infectious and could spread the disease through blood donations or post-operative surgical instruments.
More worrying, at least a few (admittedly controversial) studies suggest some misfolded protein diseases are misdiagnosed as other misfolded protein diseases. Matters reached such a scientific pitch in the U.K. that the Nobel scientist who discovered the prions responsible for mad-cow disease, Stanley Prusiner, called for nation-wide post-mortem testing of human brain tissue even though the British Department of Health reported only 110 confirmed deaths from vCJD by March of this year.
Now more good news.
Diagnostic blood tests for protein misfolding diseases are now on stream at UBC and the University of Toronto spinoff biotech firm, Amorfix Life Sciences Ltd. Dr. Cashman is its director and co-founder.
New technology developed by Amorfix extracts misfolded proteins from the blood stream and identifies them. A test for vCJD will likely be developed within the year, Cashman says, while the Ontario Genomics Institute and Amorfix recently announced a partnership to accelerate development of a blood test for Alzheimer's -- a disease which now affects 10 per cent of those over 65. After Alzheimer's, Dr. Cashman expects a BSE test for cattle will be next.
Accurate testing means accurate statistics, better protection of the food and blood supply and earlier diagnosis of potentially treatable misfolded protein diseases.
In the meantime, calls for a National Autopsy Program in the U.K. continue. If enacted, the news could be very good or very bad.
MARGRET KOPALA’s column on western perspectives appears every other week.