I'm a Kentucky native, but on the question of whether BSE is related to a similar brain-wasting disease in humans known as variant Cruetzfeldt-Jakob Disease (vCJD), I'm from Missouri — show me.
A year and a half ago, following the detection of the first U.S. case of BSE, I expressed my doubts regarding a link between these two diseases. Almost two years later and despite the recent detection of a second U.S. case of BSE, I still harbor serious doubts. For that matter, so do a lot of other scientists in the U.S. and throughout the world.
The conventional view on BSE goes something like this: The huge spike in BSE cases that occurred in cattle in Britain in the 1990s corresponded with a modest increase in vCJD among young Britons. British medical authorities, anxious to craft a strategy for putting public fears to rest, began hammering out a consensus opinion based on the premise that there had to be some kind of connection between these two diseases. Otherwise, what accounted for the strange coincidence?
The culprit behind both of these diseases, they contend, is an aberrant protein, or prion, which could be ingested by cattle from tainted feed and passed along to humans who eat beef from infected animals. Even if, like “Drag Net's” Joe Friday, we ignore all of the extraneous noise from media and self-appointed consumer watchdogs and stick only with the facts, we still come up considerably empty-handed in the evidence department.
One of the first skeptics to weigh into this dubious evidence was George Venters, a British health consultant, whose controversial arguments in the British Medical Journal ignited a firestorm of debate. One factor that simply can't be ignored, Venters contended, is the “robust species barrier” between humans and other animals — underscored by the fact prions produced in ungulates, or hoofed mammals, have “different sequences of amino acids” than those associated with humans.
Besides, just because a rise in BSE cases among cattle occured about the same time as a rise in similar cases among humans doesn't necessarily mean the two are related. For a time, British health authorities even speculated the spike in BSE among cattle would be accompanied by a similar increase among humans who had been exposed to the diseases. That spike never occurred.
A number of other inconsistencies challenge the prevailing view. What, for example, accounts for the fact one victim was a vegetarian — or that similar cases have turned up in France where possible human exposure to the prions is much less likely?
Other experts have stepped forward with equally tantalizing clues. Danny Matthews, an internationally renowned BSE expert with the Veterinary Laboratories Agency in Weybridge, England, has speculated some BSE cases may occur spontaneously in cattle, much as a certain form of Cruetzfeldt-Jakob Disease, known as classic CJD, occurs in humans. Such a finding would constitute a major breakthrough in BSE research and seriously challenge the longstanding view that the disease is spread among cattle exclusively through tainted feed.
Granted, it remains little more than a hunch for now. Still, it's a compelling hunch shared by other internationally recognized BSE authorities. Among them is Bob Church, a Canadian beef expert working to help Canadian policymakers and producers better understand the risks associated with BSE.
Church, whose views were published in the March 2004 edition of Alberta Beef, concedes the almost 40,000 BSE cases in Britain can be traced to the now banned practice of feeding animal proteins, notably in the form of milk replacements, to dairy cattle. Nevertheless, he agrees with Venters that this link cannot be carried over to vCJD.
Church even believes the first and second cases of BSE detected in Canada occurred spontaneously in the animals and weren't caused from tainted feed.
Lots of questions remain. For now, BSE and its human counterpart to a great extent remain mystery diseases, much like yellow fever, pellagra and polio within the previous two centuries. It may be years, even decades, before science finally manages to cut through the dense web of confusion surrounding these diseases.
What we ultimately learn about them may surprise all of us.
Jean Weese is an Alabama Extension food scientist and Auburn University professor of nutrition and food science. Contact her at [email protected].