. RACHEL'S ENVIRONMENT & HEALTH WEEKLY #606 .
. ---July 9, 1998--- .
. HEADLINES: .
. MAD COW DISEASE, PART 1 .
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MAD COW DISEASE, PART 1
In 1985, cows in Britain began to die of a mysterious ailment
that no one had ever seen before. The symptoms were strange. At
first the cows staggered and drooled, their ears twitching. Then
they began to show signs of fear, grinding their teeth, acting
aggressively toward other animals. Soon they died. Farmers named
the condition "mad cow disease" and the name stuck.
The disease is now known formally as "bovine spongiform
encephalopathy" or BSE for short. BSE is one of a small family of
diseases called transmissible spongiform encephalopathies, or
TSEs. TSEs destroy neurons, the main nerve cells in the brain,
creating holes that leave the brain resembling a sponge (thus
"spongiform"). BSE, like the other TSEs, is an infectious
disease, meaning that it can be transmitted from one cow to
During the 13 years since it first appeared, mad cow disease
has killed more than 167,000 cows in Britain and many more
became infected but were slaughtered for food before symptoms
appeared. Symptoms take an average of 5 years to show up after a
cow is infected. Until the late 1990s, there was no test that
could detect whether a cow was infected -- only the appearance of
symptoms and microscopic examination of the brain could provide a
definitive diagnosis. (Even today, tests require brain tissue, so
they cannot be conducted on live animals.) British-type BSE has
now been observed in cows in Switzerland, the Netherlands,
Ireland, Portugal, France, Oman and the Falkland Islands. To
date, the disease has not been observed in cows in the U.S.
When the disease first struck in Britain in 1985, health
authorities insisted that British beef was safe to eat. For 10
years they defended that position aggressively, despite mounting
evidence to the contrary. Then in 1996, the official story
changed suddenly and the public was stunned. A panel of
government scientists told Parliament in 1996 that the "most
likely explanation" for 10 cases of a new TSE disease in humans
was that BSE had moved from cows into people. That explanation is
now widely accepted by most scientists, though airtight evidence
By the time of the stunning announcement in 1996, some
British experts calculated that more than a million infected cows
had already been consumed in Britain.
In humans, the BSE-like disease is called "new variant
Creutzfeld-Jacob disease," or nvCJD for short. Creutzfeld-Jacob
disease (CJD) is a member of the TSE family, a brain-destroyer.
CJD has been recognized for a long time as a rare disease of the
elderly -- very similar to Alzheimer's disease -- but nvCJD is
different. It has somewhat different symptoms, a different
pattern of disintegration in the brain, and it strikes young
people, even teenagers. Between 1995 and early 1998, at least 23
people died of nvCJD in Britain and at least one in France, the
oldest of them age 42 and the youngest 15.
In January 1997, British epidemiologists tried to estimate
how large the outbreak of nvCJD might become. They concluded that
the data were not sufficient to allow a precise estimate:
somewhere between 75 people and 80,000 people would eventually
die of the new disease, they estimated. Only time will tell.
More precise estimates of the size of the problem are not
possible because no one knows for sure how long nvCJD
"incubates," how much time elapses between infection and the
appearance of symptoms.
An excellent recent book by Sheldon Rampton and John Stauber,
MAD COW U.S.A.--CAN THE NIGHTMARE HAPPEN HERE? tells the story of
the emergence of mad cow disease in Britain, and the scientific
and political battles that have ensued. Despite the evocative
title, the book is thoroughly-documented and carefully-written.
Without oversimplifying the details, the book recounts a
complicated story of medical discoveries, strongarm tactics by
the beef industry, and waffling and coverup by governments on
both sides of the Atlantic -- yet it reads as easily as a
detective story. As a piece of science writing -- a description
of science as it plays out in the real world -- the book is an
impressive accomplishment. By the end, the reader has absorbed
several important lessons about public health policies distorted
by big money, and about very serious threats to our first
amendment right of free speech. Rampton and Stauber show that the
U.S. beef industry will go to almost any lengths to try to
prevent a public discussion of "mad cow" and the steps that the
U.S. government still needs to take to prevent this disease from
becoming an American problem.
In a nutshell: Mad cow disease developed because of a
little-known but very-widespread modern agricultural practice --
farmers feeding dead cows to their cows, thus turning a
vegetarian species into meat-eaters.
In Britain and the U.S., when a cow is slaughtered, about
half of the animal cannot be sold for human uses -- the hide,
bones, entrails, hooves, horns, fat, gristle and tough membranes
are, by law, not permitted to be used in food. Obviously
something else has to be done with these parts, to avoid creating
a public health hazard.
Then there are "downer cows" that must be dealt with. Cows
that cannot stand up, cows that collapse, and cows that die
mysteriously are called "downers." Every year in the U.S. about
100,000 cows die of unknown causes. One day they are alive and
the next day they are dead, and no one knows why. Something must
be done with their carcasses.
In addition to downer cows there are thousands of pigs,
horses, chickens, and sheep that die of unknown causes each year.
To prevent public health problems, they must be disposed of. Then
there is road kill -- deer, elk and other large mammals killed by
In the U.S. all of these animals and animal parts end up at
280 "rendering" plants where they are ground up and boiled down.
(The British call such plants "abbatoirs.") Up until the 1960s,
the fat from rendering plants was generally used to make soap.
But the invention of detergents, derived from petroleum, greatly
reduced the demand for soap. As a result, the rendering industry
had to develop new markets for its products. They hit on animal
feed, and it became a great commercial success.
From the 1960s through the mid-1990s, rendering plants dried
their rendered products, ground them into the consistency of
brown sugar, and sold them for animal feed. Feed mills then mixed
these animal by-products into various feed formulations -- about
one-third for cattle, one-third for pigs and chickens, and
one-third for pets.
Unfortunately, some of the animals sent to rendering plants
(or abbatoirs) are sheep killed by a disease called "scrapie."
Scrapie is another TSE, a member of the same family as BSE, CJD,
and nvCJD -- one of those diseases that eats holes in the brain
and invariably kills its victims. Scrapie takes its name from the
way sheep act once they get the disease -- they rub up against a
fence or a barn until they scrape away their wool, leaving raw
wounds. Then they die.
Scrapie has been a well-known, though mysterious, disease of
sheep for at least 200 years, but only recently have
scrapie-infected sheep been fed to cows. Scientists who study mad
cow disease believe that the illness crossed the species barrier
from sheep to cows through contaminated feed. Indeed, the British
in 1988 banned the practice of feeding animal carcasses to other
animals and within seven years new cases of mad cow disease
diminished quite dramatically from 900 to 1000 per week to 280 to
300 per week.
The U.S., however, has been slow to act. Scrapie is
well-established among sheep in this country. From October, 1988,
to June, 1989, scrapie was diagnosed in 52 flocks of sheep in 20
states.[5,pg.104] Clearly, there was ample reason to ban the
feeding of animal carcasses to animals in this country when the
British took that action in 1988. However, the beef industry, and
the rendering and feed industries, have generally opposed such
TSEs have a very long incubation period. In cows, BSE takes
three to eight years (average, five years) from the time of first
infection to the appearance of symptoms shortly before death. CJD
in humans has an incubation period of 10 to 40 years. Thus, by
the time symptoms of BSE appear, many cows are likely to be
carrying the infection silently. This was confirmed earlier this
year in Switzerland when tests of brain tissues from 1761 cows
revealed 8 infected animals without any symptoms, for a "silent"
infection rate of 4.5 per 1000. This is 100 times as high as the
rate of Swiss cows showing symptoms. If this rate holds for
Britain, it means that today there are about 460,000 British cows
infected -- but symptom-free -- in a total herd of roughly 11
TSE diseases are characterized by a long incubation period,
and they are always fatal. Furthermore, the infectious agent is
incredibly resistant to deactivation. Cooking infected meat, or
even rendering it at high temperature, does not completely
eliminate its infectivity. Animals get TSEs by eating infected
animals or parts of infected animals, especially nerve tissues.
TSE diseases have now been identified in sheep, pigs, goats,
cattle, deer, elk, mink, mice, hamsters, guinea pigs, domestic
cats, puma, cheetah, eland, kudu, Arabian oryx, myland,
marmosets, macaques, chimpanzees and humans. In addition, a TSE
has been reported in ostriches in a German zoo.
Thus one might think the U.S. Food and Drug Administration
(FDA) would prohibit the feeding of any animals to any other
animals, as the British did in 1988. But that is not what the FDA
has done. Under pressure from the beef, rendering, and feed
industries, in 1997 FDA only prohibited the feeding of ruminants
and mink to ruminants.[1,8] Ruminants are animals that chew their
cuds, including cattle, sheep, goats, deer and elk. Mink are
included in the ban because they can get a TSE similar to mad cow
FDA is still allowing the feeding of pigs to other animals,
and the feeding of blood and gelatin from rendering plants to all
animals. For example, many calves in the U.S. are being raised on
a diet of dried blood taken straight from rendering plants. Pigs
and chickens are still being fed rendered animal products. There
are sound scientific arguments why this policy represents a form
of Russian roulette being played with the health of the American
public. Given that we are dealing with infectious diseases that
invariably kill, the precautionary principle (see REHW #586)
seems the only appropriate policy.
More next week.
(National Writers Union, UAW Local 1981/AFL-CIO)
 Michael Hansen, "The Reasons Why FDA's Feed Rule Won't
Protect Us from BSE," GENETIC ENGINEERING NEWS (July, 1997), pgs.
4, 40. See also Lawrence K. Altman, "F.D.A. Proposal Would Ban
Using Animal Tissue in Feed," NEW YORK TIMES January 3, 1997, pg.
A14, which says BSE has affected 165,000 British cows.
 John Darnton, "Britain Ties Deadly Brain Disease to Cow
Ailment," NEW YORK TIMES March 21, 1996, pgs. A1, A7.
 Associated Press, "Clues Found in Brain-Killing Process," NEW
YORK TIMES February 10, 1998, pg. F7.
 S.N. Cousens and others, "Predicting the CJD Epidemic in
Humans," NATURE Vol. 385 (January 16, 1997), pgs. 197-198. See
also, David C.G. Skegg, "Epidemic or false alarm?" NATURE Vol.
385 (January 16, 1997), pg. 200.
 Sheldon Rampton and John Stauber, MAD COW U.S.A. COULD THE
NIGHTMARE HAPPEN HERE? (Monroe, Maine: Common Courage Press,
1997). ISBN 1-56751-111-2. Available from Common Courage Press,
Box 702 Monroe, Maine 04951. Telephone (207) 525-0900; fax: (207)
 John Darnton, "Fear of Mad-Cow Disease Spoils Britain's
Appetite," NEW YORK TIMES January 12, 1996, pgs. A1, A8.
 Debora MacKenzie, "BSE's hidden horror," NEW SCIENTIST (June
13, 1998), pg. 4.
 [Michael Hansen], "Consumers Union's Comments on Docket No.
96N-0135, Sustances Prohibited for Use in Animal Food or Feed;
Animal Proteins Prohibited from Ruminant Feed, Draft Rule," April
28, 1997. Available from Michael Hansen, Consumer Policy
Institute, Consumers Union, 101 Truman Avenue, Yonkers, NY
10703-1057; telephone (914) 378-2000.
Descriptor terms: mad cow disease; emerging diseases;
creutzfeld-jacob disease; new variant creutzfeld-jacob disease;
nvcjd; cjd; great britain; consumers union; bse; tse;
transmissible spongiform encephalopathies; sheldon rampton; john
stauber; scrapie; britain; michael hansen;
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