Could the Environment Trigger Mad Cow?
May 29 -- What if it turns out that the human form of mad cow disease is triggered by environmental factors — and not by infectious beef products — as some ongoing British research at Cambridge University suggests?
What if much of the science to date, focusing on contaminated meat, has been overly simplistic or even dead wrong?
The immediate implication would be that we would have to rethink everything already done to fight the disease, both in Britain where it began, in Europe, where it has spread, and in other nations, including the United States, where concerns are mounting about its potential to be unleashed.
Last week, in order to prevent the disease from contaminating the blood supply, the American Red Cross, in accepting the view that infectious beef is to blame, barred donations from anyone who consecutively spent three months in Britain and six months in Europe since 1980.
Presumably, anyone in those countries for that long a period would have had the opportunity to contract an infection from eating contaminated beef and then possibly pass it on by donating blood.
But, of course, this prevention strategy presumed the prevailing scientific perspective on mad cow disease and its human form, variant Creutzfeldt-Jacob disease or vCJD, is correct.
Conventional View: Consumed Infectious Agent
The viewpoint held by most scientists is that an infectious agent likely moved from sheep to cows and gained enough strength in its cross-species jump to ravage the nervous system and cause the bovine brain to appear spongy and rife with holes like Swiss cheese. This brain-destroying "mad cow" infection was further transmitted, according to this interpretation, via the rendering of carcasses, to meat and bone meal in feed. That set off the epidemic in British cows in 1986.
The human form of the disease began to turn up in Britain in 1995 when, according to the conventional wisdom, the infectious agent in cows, thought to have been passed on to humans by contaminated cooked meat products, had sufficient time to incubate and become destructive to the nervous system.
So far, about 100 people have developed vCJD and died, the majority of them in Britain. Mind and body are usually destroyed within a year.
Paul Brown, a research scientist at the National Institutes of Health in Bethesda, Md., echoing the conventional view on mad cow disease and vCJD, wrote in the April 7 edition of the British Medical Journal that it is "uncontestable" that the disease in cows is the cause of vCJD.
But not according to David Brown, a biochemist at Cambridge University, who counters that "there is no conclusive proof that [mad cow disease] caused vCJD."
Next week at a scientific conference in Quebec City, he'll discuss some of his most recent research, pointing to a possible environmental explanation of both mad cow disease and vCJD.
