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Test EVERY Cow in the Food Chain

Test EVERY Cow in the Food Chain
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Saturday, June 26, 2010

Giving Blood, The G8, Nat'l Security & Mad Cow Disease

There won't be blood

By John Allemang From Saturday's Globe and Mail

A shortage during the G20 underscores the irrational restrictions Canadians still face around blood donation
I want to donate blood, I really do. But the only way I can give the gift of life is if I tell a lie - and I just can't bring myself to do that.

My altruistic urges were stirred by an appeal from the Toronto branch of Canadian Blood Services. Appointments at the agency's city-centre clinics were down by 50 per cent this week, apparently in anticipation of the disruptions caused by the G20 summit.

Some good should come out of the G20, I decided. When a billion-dollar exercise in hypersecurity compromises our blood supply, then the notion of public safety is completely out of whack. Giving blood to those who need it would be a much more satisfying gesture than chanting slogans at sullen peace officers.

But then I read the fine print on the donation form. In the distant past, it turns out, I did something so risky that Canadian Blood Services now refuses my donation: I spent time in Britain.

From 1980 to 1996, I was in England for a total of three and a half months. During that period, some cattle in Britain were foolishly fed sheep's brains, and some of those cattle developed bovine spongiform encephalopathy (BSE), better known as mad-cow disease.

"It is possible," says the Canadian Blood Services website, "that people were exposed to BSE through food in the mid-to-late 1980s."

According to the risk-assessment measures followed by the administrators of Canada's blood supply, my sojourns in Britain puts me at greater risk both of developing the neurogenerative disease known as vCJD - variant Creutzfeldt-Jakob disease, the human form of mad-cow - and of passing it on to you though my possibly tainted blood.

Unlike HIV, for example, there is currently no available test for vCJD in blood donors. And since the symptoms may take a considerable time to reveal themselves, the fact that I'm outwardly healthy and lucid after all these years is no proof that I haven't been infected by the delicious steak I ate at an Oxford bistro in 1992. Though it's not known whether vCJD can be transmitted by blood, I'm officially considered hazardous to Canadians - just like prostitutes, intravenous-drug users, people who have recently been in jail and, most controversially, men who have had sex with men.

Like the G20 security bosses, the people who watch over blood donations err on the side of caution. Given the consequences of getting it wrong (remembering especially the tainted-blood scandal of the 1980s), they follow what's called the precautionary principle: When there's a shortage of good scientific evidence, it's better to overreact.

But when it comes to determining safety risks at the donor level, the blood agency's assessments can look highly arbitrary. Why not ban everyone who travelled to Britain from 1980 to 1996, and not just those who stayed three months or more? Because that would severely limit blood donations - too many Canadians made that trip. Why not distinguish between vegetarians and meat-eaters, or follow other countries that have set the rate at six months rather than three? Of course, in Britain there is no exclusion based on long-term residence - when everyone is affected, you don't have the luxury.

But then, says Greta Bauer, an epidemiologist with the Schulich School of Medicine at the University of Western Ontario, "We don't really know if there's any association between having been in the U.K. for three months and developing vCJD. How can you test for that? There's isn't a clear criterion for shaping that policy. It seems to have developed more along the lines of, 'We should do something. But what should it be?' " Such bureaucratic hesitation can be defended when so little is known about vCJD. But the lifetime ban for male donors who have had sex with men at any time since 1977 is proving much harder to justify.


" It's all quite irrational "- Mark Wainberg, head of the McGill University AIDS Centre


Dr. Wainberg is also co-author of a recent paper in the Canadian Medical Association Journal that argued against the lifetime ban - which was devised in 1983, before the development of highly sensitive tests now used to screen donated blood and detect HIV.

A categorical deferral like this, based on elevated HIV rates among gay men, is easy to implement, unapologetically discriminatory and broadly unfair - the same principle is applied to men who engage in unprotected anal sex with multiple partners as to monogamous male couples who have tested HIV-negative.

But other groups with elevated rates of HIV, such as native people, are (rightly) not singled out for exclusion. Nor are heterosexuals whose behaviour shades into risky categories held to the same standards. Provided she can claim to know the sexual background of her partners over the past six months, a highly sexually active woman is still a respectable donor.

Other countries do it differently, which helps to prove that the policy-making is arbitrary: In New Zealand, the deferral period for gay male donors is five years after a sexual encounter classified as risky; in Australia, it's only one year. Dr. Wainberg wants Canada to move in the same direction, both for social reasons (discrimination is wrong, and leads to a loss of donors) and for scientific ones (the risks to blood recipients do not change significantly).

Canadian Blood Services knows all this: The agency commissioned an excellent study on risk management from the University of Ottawa and then shelved it when the authors recommended a shift to a five-year deferral period. Its hesitation to change the dubious status quo doesn't surprise Prof. Bauer in the least.

The agency was created in the wake of the tainted-blood scandal, "and they've had to do a lot of PR work to get Canadians to trust the blood supply. So they're put in a difficult place if they do something that's popularly perceived to jeopardize the blood supply."

Scientists know better: The risk of HIV-infected blood escaping detection in Canada is now as close to zero as is humanly possible. So why not change the policy, enlarge the donor base and do some good for a long-stigmatized group?

Because in the politics of blood, change is too high-risk.

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