- As panic over the spread of mad cow disease grips Western
Europe, American health officials say they have been taking stringent steps
to prevent the disease from taking hold in the United States.
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- The brains of sick cattle are routinely tested for the
disease. Imports of beef and certain beef products are banned. No one who
lived in Britain since the late 1980's, when the epidemic became known,
is allowed to donate blood.
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- "We are doing our best to not be complacent,"
said Dr. Linda Detiler, a veterinarian with the Animal and Plant Health
Inspection Service at the United States Department of Agriculture. Pointing
out that some European countries were sure they had no risk, but now find
themselves caught up in the epidemic, she said, "We have tried to
learn from their mistakes."
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- So far, they appear to succeeded. Mad cow disease and
its human analogue, the new variant Creutzfeldt-Jakob disease, have not
been found to have killed any cattle or been identified in people on this
side of the Atlantic. Given the small number of human cases in Europe and
that mad cow disease has never been proved to exist in American cattle,
most experts agree that the risk for most Americans remains extremely low.
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- Yet experts on mad cow disease say that there is cause
for concern. Despite a decade-long ban on British imports of meat and bone
meal - a form of animal feed rendered from cows that is blamed for spreading
the epidemic in Europe - the United States still imports tons of bovine
byproducts and manufactured goods containing bovine materials from Britain
and other European nations.
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- The disease formally called bovine spongiform encephalopathy
because of the spongelike holes that appear in the brain and other nervous
tissue, can also develop spontaneously. Although mad cow has not been detected
in cattle in the United States, a related malady called chronic wasting
disease is spreading rapidly among deer and elk herds, captive and wild,
in six Western states and in Canada. In laboratory dish experiments, chronic
wasting disease has been shown to infect human cells; in principle hunters
who ate infected deer or elk meat could have the disease and, if they donate
blood, could pass it on.
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- At 11 Midwestern farms, scores of captive mink developed
a form of mad cow disease after being fed meat from "downer cows"
- animals bred in America that died of unknown causes, possibly cases of
mad cow disease that were never diagnosed. At various times, 45 states
have had sheep that are infected with scrapie, another malady related to
mad cow disease.
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- It is not known whether eating infected sheep, deer or
elk causes any form of Creutzfeldt-Jakob disease in humans but the infectious
agent, misfolded proteins called prions, has been shown to cross barriers
between species.
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- Moreover, government officials acknowledge they are still
finding and filling gaps in the wall designed to protect the American food
supply from the disease. On Thursday, the Food and Drug Administration
reported that hundreds of feed manufacturers and rendering companies were
not complying with regulations intended to ensure the safety of domestically
produced fee.
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- The United States' ban on risky British meat products,
adopted in 1991 and extended to imports from other countries, contains
many loopholes and exceptions that could leave the door open to infected
products, says a report by a scientific advisory panel to the European
Union on the risk of mad cow disease in America.
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- Missteps by European governments, too, have made the
United States more vulnerable to the disease, said Dr. Maura Ricketts of
the World Health Organization's animal-and food-related health risks unit.
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- Even though Britain and the United States banned the
practice of feeding cows to cows in the early 1990's some British renderers
continued to make and ship contaminated meat and bone meal around the world
while some European farmers knowingly used such products until November
because the products were cheap, Dr. Ricketts said. Public health officials
suspect that infected meat was repackaged and resold as having come from
countries presumed free of mad cow disease.
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- "The murky movement of live cattle and rendered
animals around the world," Dr. Ricketts said, means mad cow disease
has gone global.
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- A few weeks ago, the United Nations estimated that at
the height of the mad cow epidemic in Britain at least 500,000 tons of
untrackable bovine byproducts were exported from Britain to Western Europe
and other nations around the world, including the United States.
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- British export statistics show that 20 tons of "meals
of meat or offal" that were "unfit for human consumption"
and probably intended for animals were sent to the United States in 1989.
And 37 tons were exported to the United States in 1997, well after the
government-banned imports of such risky meat. No one has tried to trace
this meat or to determine whether it was allowed into the United States.
In an exception to the import ban, many health supplements contain glandular
material from animals whose health status cannot be determined. While acknowledging
that the risk is very small, experts on mad cow disease note that glandular
material is more likely to be infected with prions, the disease's infectious
agent, than most other tissue. Products must have labels listing ingredients
like bovine pituitaries and adrenals, but manufacturers are not required
to list the country of origin.
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- Other beef byproducts that are still allowed in the country
include milk, blood, fat, gelatin, tallow, bone mineral extracts, collagen,
semen, amniotic fluid, serum albumin and other parts of European cattle
that are widely used in American products, including vaccines and medicines.
The federal Agriculture Department states that these tissues are not believed
to contain dangerous levels of prions, but acknowledges that not all have
been tested to prove that they pose no risk.
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- United States health officials are just now closing some
of these regulatory gaps documents posted on their Web sites say, One year
ago, the Agriculture Department told supplement manufacturers to avoid
neural and glandular material from domestic and foreign sheep flocks infected
with scrapie. Compliance is voluntary.
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- Although, cud-chewing animals, or ruminants, are the
known carriers of mad cow disease, the Agriculture Department last month
temporarily barred European feed supplements mad from nonruminant animals
like chickens or pigs. This is because through November, many European
farmers were still giving feed made from potentially infected cows to chickens
and pigs and were then feeding chickens and pigs back to cows. This practice
is now banned in Europe, and Agriculture Department officials are worried
that European feed manufacturers will slash prices and try to dump their
products on American farmers. In theory, prions could be spread in this
feed.
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- On Dec. 23, the Food and Drug Administration told American
drug manufacturers to stop using bovine serum from counties where mad cow
disease has been found for making vaccines against flu, hepatitis A and
diphtheria-pertussis-tetanus, but vaccines made from the materials are
still being used. The agency maintains these vaccines are safe. An F.D.A.
committee will meet this month to discuss extending restrictions on who
can donate blood to include people who lived in Europe for six or more
months in the 1990's. The committee is also expected to discuss whether
to ban donations from deer and elk hunters.
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- As potential weaknesses have emerged, the American beef
industry has become increasingly concerned, particularly about the safety
of animal feed. On Jan. 9, the F.D.A.'s Center for Veterinary Medicine
held a nationwide telephone conference with its field officers and 50 state
agencies responsible for inspecting feed producers. The agency told the
states that only about 2,700 of the estimated 9,500 feed manufacturers
had been inspected for compliance, the center's director, Dr. Stephen Sundlof,
said.
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- Among smaller companies that handle ruminant byproducts
and wastes, nearly half did not have a system for putting labels on their
products warning that they should not be fed to cattle or sheep, the F.D.A.
said. More than a quarter of large rendering companies that handle risky
material had no system to prevent the commingling of ruminent wastes with
that of other animals like chickens and fish.
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- Dr. Gary Weber, executive director of regulatory affairs
for the National Cattlemen's Beef Association said that enforcing the ban
must be a priority for President-elect George W. Bush.
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- Compounding officials' concerns is the baffling nature
of the infectious agent that is believed to cause these deadly diseases,
collectively known as transmissible spongiform encephalopathies. For unknown
reasons, a normal protein called a prion twists into an abnormal shape,
usually in the brain. These misfolded prions accumulate into toxic clumps
that eventually destroy normal brain tissue. Spongelike holes develop.
Animals and people are driven mad and then die. Apparently, these diseases
arise spontaneously in one out of every million humans, cows, sheep and
many other mammals. Since 36 million cattle are slaughtered annually in
the United States, about 36 cows spontaneously infected with mad cow disease
could be entering the nations food chain each year.
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- These abnormal prions can pass from one species to another,
including humans. Prions can survive outside the body for years and are
not easily killed by freezing or cooking. No on knows the incubation period
for humans. Nor does anyone know how much is required to transmit the disease,
although evidence suggests that people can be infected from even a few
bites of tainted beef.
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- Those infected share a genetic trait that appears to
have made them susceptible to the disease. Eighty-eight people have died
from or have been found to have the new variant, Creutzfeldt-Jakob disease,
in Britain. Three people from France and one from Ireland have also died.
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- This variant has not surfaced in the United States. Dr.
Pierluigi Gambetti, director of the National Prion Disease Pathology Surveillance
Center at Case Western Reserve University in Cleveland, said he has examined
tissues from 292 Americans known to have prion diseases but non have shown
the hallmarks of this variant.
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- But at the same time, chronic wasting disease is a growing
problem, said Hal Herring, a hunter and writer in Corvalis, Mont., who
is tracking that disease. Thirteen captive herds in the United States have
been infected and up to 18 percent of wild deer in parts of northern Colorado
and southern Wyoming are infected, Mr. Herring said. In December, a federal
agency in Canada slaughtered 1,700 domestic elk at six Saskatchewan farms
to contain an outbreak. The disease was traced to a single animal, which
never showed any signs of illness, exported to Canada form South Dakota.
No one knows how deer and elk in the wild or in captivity pass the disease
among themselves, Mr. Herring said.
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- An unknown number of American sheep are infected with
scrapie, which, like mad cow disease, is a spongiform encephalopathy. It
is not known if scrapie can harm humans who eat infected sheep tissue,
but last autumn the fear of such transmission led the Agriculture Department
to quarantine and order the destruction of a herd of sheep, exported to
Vermont from Belgium. A few of the animals had been found to have developed
a spongiform encephalopathy of unknown origin. The sheep's owners, who
make cheese from the sheep mild, fought back. Lawyers continue to argue
over the fate of the remaining animals, which show no sign of illness.
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- Dr. Tom Pringle, a biochemist in Eugene, Ore., and independent
researcher on transmissible spongiform encephalopathies, says American
officials have not done enough to battle the disease. He says the United
States should set up a system to track bovine material coming into this
country and increase testing. Out of 900 million cattle, the Agriculture
Department tested fewer than 12,000 sick cows for mad cow disease in the
last decade. None were found to have the disease. France, with 5.7 million
cattle, is now testing 20,000 animals each week and identified 153 infected
animals last year.
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- Dr. Pringle and other experts emphasize that Americans
should not panic over events in Europe. While prion diseases are frightening,
they say, the odds of coming into contact with them are extremely low for
most Americans.
- Comment
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- From Fred Houpt
1-23-01
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- Readers in Canada should ask whether it is wise of the
Government of Ontario to advertise on the Ministry of Agriculture web site
for farmers raising steer and cows to continue adding animal based protein
supplements to their food?
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- See: http://www.gov.on.ca/OMAFRA/english/livestock/dairy/facts/96-067.htm
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- This very same proceedure that has been linked to the
spread of TSE in the U.K. The issue can be summarized as a problem of feeding
herbivores to herbivores, regardless of whether TSE exists. What seems
to be clear from the results of the New Guinea studies of kuru is that
for mammals when we introduce cannibalism we end up, over time, with kuru
which is what TSE seems to be. So, if this is the case, why is the Government
of Ontario suggesting that farmers continue this ruinous course of action?
Even more amazing is the fact that European farmers are now banned from
doing so regardless of whether the food stocks have any TSE in the food.
They European Union simply did not want to take any more chances and taking
their lead from the U.K., they decided that the evidence was too strong
to allow any more mammals being fed to cows. What is going on here in Ontario?
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- Regards,
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- F. Houpt
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