Oh, the myths our ministers feed us - not to mention Japanese trade officials. "It was only one - OK, two - cows. Not to worry, Canadian sirloin is safe." But as the feds continue to dish out assurances, scientists are fretting over an ominous set of findings that suggest there's much more mad cow in our midst than we ever believed - and we don't mean in cattle.
Studies little known in North America but widely discussed in Europe raise the possibility that diseased beef has already killed off Canadians and may be responsible for a certain proportion of cases now thought to be Alzheimer's.
The spectre of a potentially hidden cache of human mad cow victims comes via the Institute of Neurology at University College in London. What researchers there discovered challenges one of the most fundamental assumptions about the human manifestation of mad cow disease.
Scientists have long known that gnawing on tainted beef products may lead to a new form of dementia, the human version of Bovine Spongiform Encephalopathy (BSE), or mad cow, called variant Creutzfeldt-Jakob disease (vCJD for short). And traditionally they have taken care to separate this "variant' strain from the more common "sporadic" form of the disease (sCJD), thought to be a totally random occurrence striking an unlucky one in a million.
But what the research team in London was shocked to discover was that the two strains may actually share the same source. Mad-cow-injected mice came down with both variant and sporadic CJD.
Despite repeated attempts to contact the British researchers over the last two weeks, NOW was unable to reach them. But team leader and prominent British CJD expert John Collinge told the London Times, "What took us completely by surprise was that some of these mice developed a different type of CJD, indistinguishable from sporadic CJD. The implication is that some cases of sporadic CJD are caused by BSE."
The findings rocked the UK when the study was released over a year ago. It was, after all, the second study to confirm these findings. (French scientists came to similar conclusions a year earlier.) Collinge pointed out that the UK, which first spotted mad cow in 1985, started to see sporadic CJD levels rise about 10 years later, adding, "The Swiss have recently reported a two to threefold increase in sporadic CJD. That may be linked to BSE, too."
Strangely, nary a word was uttered across the pond in North America, despite warnings by mad cow experts like Massachusetts-based physician Michael Greger.
"It's a scary surprise," says Greger, chief BSE investigator for U.S. based Farm Sanctuary, an animal protection group. "Because of this new evidence, we can no longer say that sporadic cases don't have anything to do with mad cow disease."
Translation: all the comfort the Canadian beef industry and government officials milked from the fact that we'd never had a homegrown case of vCJD suddenly vanished. And the 184 reported cases of sporadic CJD we've had in Canada to date? Well, perhaps they weren't so sporadic. "This may be a food safety issue after all," says Greger.
Still, some Canadian scientists are very cautious about extrapolating from the University College study. "(The findings) don't have any significance in the local context," says David Westaway, a molecular biologist and prion specialist at U of T's Centre for Research in Neurological Degenerative Diseases. How can he be so sure? The rate of sporadic CJD in Canada, he says, has been rock-steady at around 30 cases a year - in line with the predicted rate of one in a million.
Not that we would spot a rise right off the bat, concedes Westaway. "If there is a problem starting now, where animals are starting to get sick and there are some BSE prions in the Canadian food supply, one would expect a time lag before human cases appear." It takes up to 30 years before sCJD symptoms (like memory lapses and mood swings, and later blurred vision, jerky movements and limb stiffness) start to manifest themselves.
Health Canada says it's aware of the Brit's findings and not to worry. The department has had its thumb on CJD ever since 1999, when it created a mandatory CJD surveillance system. "It's one of the best CJD surveillance systems in the world," says HC spokesperson Emmanuel Chabot.
But critics say much CJD is still hovering below the radar, thanks to misdiagnosis. Some believe an unknown percentage of Alzheimer's cases are actually CJD, raising the possibility that, if the sporadic and variant forms are related, bad beef may be responsible for a number of CJD cases attributed to Alzheimer's.
"We have very good clinicians here at Yale, and yet they diagnosed people with Alzheimer's when they actually had CJD," says Dr. Laura Manuelidis. She and her late husband conducted one of the first studies revealing that mislabelled CJD is indeed slipping through the cracks. In her post-mortem sample of nearly 50 bodies, 13 per cent of Alzheimer's patients were actually found to have CJD. A similar study at University of Pittsburgh came up with 5 per cent.
Wondering if these studies were perhaps outdated (to be fair, they were conducted 15 years ago, and today's diagnostic procedures might be more refined), NOW contacted the Alzheimer Society of Canada to get its take on misdiagnosis. The society, which also counsels CJD sufferers, says that according to recent U of T stats, 12 per cent of CJD cases are indeed misdiagnosed.
But Westaway downplays the possibility. "I don't think it holds water, because Alzheimer's is a long, lingering disease, and sporadic CJD is a pretty short one," he says. "If a candidate Alzheimer's patient started going downhill really rapidly, this would immediately tip off the clinician that it might not be Alzheimer's disease."
But Michael Hanson, a senior research associate with New York-based Consumers Union and a prominent BSE expert, says he's heard that excuse before. "Usually the government says that CJD looks very different from Alzheimer's, that you wouldn't get confused," says Hanson. "But the fact of the matter is that this stuff ultimately has to be confirmed at autopsy, and there are so few autopsies done now."
From a public health perspective, says Greger, it's very important that sporadic CJD cases be hunted down. "We can't be missing these cases." If we do, say experts, it's possible people may unwittingly transmit the highly infectious disease to others by giving blood or going to the dentist. (CJD is so difficult to destroy that British doctors have started using disposable surgical instruments in some instances.)
At a time when all our knowledge on mad cow is shifting, one thing seems certain - the worst is yet to come.