Mad Cow Disease: Frequently Asked Questions
How
does mad cow disease threaten human health?
Bovine
spongiform encephalopathy (BSE, also known as mad cow disease) has
surfaced in Great Britain, France, Switzerland, Canada, Spain, Germany,
Japan, Russia, and, as of December 22, 2003, in the United States.
Health authorities consider it to be the most likely cause of a
new variant of Creutzfeldt-Jakob disease (vCJD), a fatal brain disease
that has affected more than 130 people worldwide.
How
do humans become infected with vCJD?
It
is believed that vCJD results from contact with prions
in tissues of cattle with BSE. Prions are proteins that are normal
in their molecular makeup but abnormal in their shape, like springs
that have been bent out of configuration. These prions in turn distort
normal proteins in human brain and nerve cells. Only minuscule amounts
of prion-tainted tissues are required in order to transmit the disease.
Prions concentrate in the brain and spinal cord, but also have been
found in blood and muscle tissue.
What
are the effects of vCJD?
vCJD,
like other transmissible encephalopathies, robs an affected individual
of mental faculties and muscle coordination, eventually leading
to coma and death. There is no cure.
Can
consumers protect themselves from vCJD by cooking meat thoroughly?
No.
Prions, the misshapen proteins that cause vCJD, are very difficult
to destroy, even by the chemical or heat disinfectant methods used
in hospitals.
Hasn't
the federal government monitored cattle to ensure the safety of
the meat supply?
The
fact is that Department of Agriculture officials have not been seriously
looking for BSE cases. Data from the National Veterinary Sciences
Laboratories BSE Surveillance program from 1990 to 2000 show that,
of approximately 900 million cattle slaughtered, only 11,954 brains
(approximately 1 in 75,000) were examined for BSE. In fiscal year
2002, the USDA tested only slightly more—19,990—cattle for BSE.
Further,
brain examinations have generally been prompted by the presence
of neurological symptoms. However, the symptoms of BSE do not commonly
manifest in cattle until about five years of age, which is after
the usual age of slaughter. For example, most U.S. dairy cows are
slaughtered before four years of age, when even a prion-infected
cow is likely to appear healthy.
In
sharp contrast, Japan tests every slaughtered cow for the disease.
Aren't
consumers protected by legal restrictions on what can be fed to
cattle?
Unfortunately,
U.S. feed producers are blatantly violating restrictions
on feed production. Despite a 1997 Food and Drug Administration
(FDA) ban on the feeding of most mammalian remains to ruminants,
a January 2001 FDA report showed that, of 180 renderers, 16 percent
lacked warning labels on feeds designed to differentiate those intended
for ruminants from those for nonruminants and 28 percent had no
system to prevent the actual mixing of these feeds.
Does
the FDA feeding ban have other flaws?
There
are crucial loopholes in the FDA-mandated protections against mad
cow disease, including the following:
-
There
are no limits on the use of non-ruminant, such as pig or horse,
remains in feeds, due to an exemption in the 1997 ban. Because
prions are so difficult to destroy, if the remains of BSE infected
cow are fed to a pig or horse and then the pig or horse remains
are fed to cows, the cows may subsequently be infected. Similarly,
ruminant remains can be fed to poultry and, in turn, poultry
feces are routinely used in cattle feed.
-
There
are no limits on the “recycling” of beef or other meat products
in the form of garbage from restaurants or other institutions
for use in animal feeds.
-
There is no
restriction on the use of animal byproducts, including blood
and blood products, gelatin, milk, and milk products, in feeds
through which prions may be transmitted.
If
the regulatory system is so flawed, why hasn't anyone in the U.S.
been infected with vCJD?
There
is simply no way of knowing whether vCJD has begun in the United
States or not. Death certificates from 1979 to 1998 show that 4,751
people were identified with CJD in the United States. While the
presumption is that they had the “classical” form of the disease,
rather than the new variant form that is believed to come from animal
tissues, this remains uncertain. While most victims were older (a
sign of classical CJD), a small number were surprisingly young.
The reported cases are probably underestimates due to the problems
of misdiagnosis and underreporting.
Transmissible
encephalopathies are not yet reportable diseases for the Centers
for Disease Control and Prevention. Individuals showing signs of
dementia due to such a condition may be misdiagnosed as suffering
from Alzheimer's disease or stroke, and most dying with neurological
illnesses are never autopsied, so their brains are never examined.
How
could the government truly protect consumers?
The
following are PCRM's recommendations to the government for protecting
the public against vCJD:
- Ban the use of
animal-derived livestock feeds for any species, given the likelihood
that animal byproducts will, in turn, be recycled to ruminants
(that is, cows, sheep, and goats).
- Ban the slaughter
of downed animals, animals too sick to stand, for human food.
The Washington state cow that tested positive for mad cow disease
in December 2003 was a downed animal.
- Prohibit animal
byproducts in all medications, supplements, or cosmetics.
- Label all foods
containing animal byproducts (such as gelatin or “natural flavorings”),
indicating both the presence of animal byproducts and the species
of origin.
- Provide warning
labels on all foods that carry a risk of vCJD, using standards
similar to those for tobacco and alcohol products.
- Institute comprehensive
monitoring programs to check for diseased animals and humans in
the United States. Monitoring programs for BSE and other encephalopathies
in animals should include but not be limited to testing all suspect
animals (rather than a fraction of them) and holding back the
carcasses of tested animals from the food supply until the test
results are known. For humans, monitoring programs should be implemented
that require all states to report CJD cases and dementia of unknown
cause (especially in young individuals) to the Centers for Disease
Control so that any cases where vCJD is suspected can be confirmed
or dismissed by autopsy.
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