January 8, 2004
by Dennis T. Avery
Despite the headlines, "mad cow disease" is unlikely to claim a single human victim in this country.
The reason is simple. The British have already paid the human price for learning about this apparently new and fatal disease, with nearly 140 deaths and years of lurking fear for millions of consumers. Thanks to the U.K.'s dearly-bought experience, America now knows what causes "mad cow," why it was epidemic in Britain—and how to keep it from attacking humans.
First, we know that "mad cow" is not very contagious. More than 180,000 British cattle have been officially diagnosed with "mad cow," and millions of British consumers may have eaten meat from affected animals. But the UK has less than 150 cases of the human disease thought to be caused by the cattle disease (a new variant of Cruetzfeldt-Jakob disease).
The rate of contagion is not much higher than a million to one.
Today, Britain, the U.S., and most other countries have banned the feeding of ruminant animals with meat and bone meal from other ruminant animals. That prevents spread of the disease among both animals—and humans.
Secondly, we know now that "mad cow" offers virtually no risk to humans unless we eat the brain or nerve tissue of affected animals. There has been no human transmission through the muscle meat or milk. Thankfully.
When the dairy cow in Washington State was reported ill at the slaughter house, the brain and nerve tissue were held out of the marketing chain. But throughout most of the epidemic, the British were routinely eating the brain and nerve tissue of their "mad cows," ground up in their cherished meat pies and sausages.
It all began in 1986, when the British found an epidemic was ravaging their cattle herds, making cows act drunk before they died. The disease was eventually named bovine spongiform encephalopathy (BSE).
At first, British authorities assured the public that "mad cow" presented no danger to beef consumers. Then came horrifying news that a few people had become infected with a new form of a brain-wasting ailment that could take years to incubate, and was always fatal.
One government science advisor estimated there might be as many as 800,000 human deaths. Everyone in Britain who'd eaten beef in the previous ten years feared the disease was already riddling their brain tissues.
The British eventually found that "mad cow" is caused by a previously unknown tiny "thing" called a prion, a sort of warped natural protein. Prions spread in Britain because the government had mandated a milder process for rendering dead animal carcasses into meat and bone meal. (They did it to lower energy costs and reduce solvent risks to rendering plant workers.) Every country renders livestock carcasses because they contain valuable nutrients—and because it would create a huge, expensive mess if we didn't.
But the Brits didn't know that the high rendering temperatures and harsh solvents had been protecting them and their animals from prions—which we didn't know existed.
A human prion disease in humans, Cruetzfeldt-Jakob Disease (CJD), occurs spontaneously in about one in a million humans. The BSE rate may be similar in cattle; we don't yet know. We don't know whether the Washington State cow and/or the Canadian animal diagnosed with "mad cow" earlier this year somehow got contaminated feed or were spontaneous cases. (They were born before the ban on feeding ruminant meat and bone meal to ruminants.)
The British now ban all ruminant nerve tissue, including spinal cords and brains—and even bone—in cuts of meat-from both human food and animal feed. That forces gourmets to give up eating brains as a delicacy, and would force a lot of Americans to give up T-bone steaks.
If we want to go that far, we could reduce the risk of new variant CJD from one in a million to perhaps one in 1.25 million. It's our choice.
But let's be thankful that science and the suffering of British consumers have already defused virtually all of the danger from the new disease. Or more likely, have nearly eliminated most of the risk from a very old disease that never threatened enough cows or humans to be noticed—until our well-meant effort to cut rendering energy costs gave "mad cow" its big chance to become an epidemic.
Dennis T. Avery is based in Churchville, VA, and is director of the Hudson Institute's Center for Global Food Issues.
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