April 26, 1996

Mad Cow Disease

I never saw a crazy cow,

I never hope to see one;

But one thing that I'm certain of,

I'd rather see than be one.

The Brits are all panicked about mad cow disease and the rest of the world is also chewing the rug. The cattle markets are depressed, which means that some speculators will lose money and some will make money. I should explain that the word "mad" means crazy in English and angry in American.

There is a group of related diseases in animals and man which causes the brains of the victims to get spongy, resulting in death. One of these diseases is scrapie, which infects sheep and goats and gets its name from the habit of animals with the disease scraping themselves against fences until their sides were raw. Another is Aleutian disease of mink, which originally infected Aleutian-colored mink in mink ranches. Kuru is a similar disease that infected natives of New Guinea. Another is mad cow disease, which may be identical to scrapie and might have been transmitted to cows by feeding them sheep parts. A similar rare disease, that affects old people worldwide, is called Creutzfeld-Jacob disease(CJD).

What all of these diseases have in common is that they all attack the brain and produce similar changes. With the possible exception of CJD, where the cause and mode of transmission is unknown, all are transmitted by eating parts of infected animals. Kuru was spread among New Guinea natives by ritual feasts in which the brains of relatives were eaten -dead relatives, of course. The mink, sheep and cow diseases have also been spread by the habit of feeding animal parts to other animals: mink to mink, sheep to sheep and cow to cow. In people, it is called "cannibalism." Needless to say, once people found out what they were doing, and stopped doing it, the occurrence of the diseases decreased rapidly.

While the panic about mad cow disease just happened, it is surprising that it didn't happen much sooner. The disease was first identified in the eighties. Three years after the first infected cows were discovered, the British banned the practice of feeding animal parts, which dropped the incidence of the condition dramatically. However, a total of 162,000 cows have been infected to date. In 1992 the epidemic peaked at 37,000 cases of mad cow disease. By 1995, the incidence had dropped to just 7,000 cases per year. So far as we know, the disease seems to be restricted to the British Isles.

What seems to have trigger the panic was a recent report by Robert J. Will, a specialist in the human disease CJD. He had logged 207 cases of CJD in Great Britain since 1990; which is an indication of the rarity of the disease. Ten of those cases were unusual in that they hit relatively young people, with an average age of death of 27 years. CJD usually affects people over 60. Nothing to date indicates a relationship to mad cow disease, other than the fact that what happens to the brains of victims seems to be similar. None of the victims had a history of having eaten cows's brains. One victim had even been a vegetarian for the last five years. However, scientists believe that the incubation period, from the time of infection to the appearance of symptoms, may be a very long one, measured in years. If eating beef from an infected cow was all that it took to get CJD, we would expect a real epidemic; not just a few cases. At most, we are talking about 35 cases of CJD per year in Britain, of which only a few were in relatively young people.

In the U.S., CJD strikes 250 people per year. The Centers for Disease Control(CDC) has developed an interest in the disease, and now regularly gets reports of the disease in California, Connecticut, Minnesota and Oregon.

Where it has been investigated, all of these brain diseases are transmitted by a protein agent called a "prion." This agent is not a virus and has no DNA or RNA in it. Prions are very resistant to the heat that will kill any known virus. The diseases have been transmitted to laboratory animals. The most puzzling aspect of the case is that the prion protein seems to be produced by normal human genes, not an infectious agent. But the prions can be transmitted, much like a virus is, to other beings, including laboratory animals.

Hopefully, people will eat less beef and, as a consequence, be a bit healthier -that is, until the panic subsides. And it should subside, because there really isn't anything to panic about, unless you are in the habit of eating the brains of British cows, sheep or people.

I remember eating cow brains in my youth, as did many other people in that era. I didn't like either the taste or the consistency. However, maybe it did make my own brain spongy, which led to my becoming a columnist.

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