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BSE
- Questions and Answers Part 1
"Mad Cow Disease" - Bovine
Spongiform Encephalopathy
Are BSE and "mad cow disease" the same thing?
- Yes.
BSE stands for bovine spongiform encephalopathy, and it is widely
referred to as "mad cow disease." It is a chronic
degenerative disease that affects the central nervous system
of cattle. BSE is named because of the spongy appearance of
the brain tissue of infected cattle examined under a microscope.
Is
BSE related to any other diseases?
-
BSE belongs to a family of diseases known as the transmissible
spongiform encephalopathies (TSEs). TSE animal diseases found
in the United States include scrapie in sheep and goats, chronic
wasting disease in deer and elk, transmissible spongiform encephalopathy
in mink, feline spongiform encephalopathy in cats, and in humans:
kuru, both classic and variant Creutzfeldt-Jakob disease, Gerstmann-Straussler-Scheinker
syndrome, and fatal familial insomnia.
(Note:
The one case of variant Creutzfeldt-Jakob disease in the United
States is in a young woman who likely contracted the disease
while living in the United Kingdom. Symptoms appeared after
she moved to the United States. The Centers for Disease Control
and Prevention has not found additional cases in the United
States through its surveillance program.)
What
causes BSEs and other TSEs?
-
The agent that is responsible for BSE and other TSEs has not
been fully characterized. Although other types of agents have
been implicated, the theory that is most accepted in the scientific
community is that the agent is a prion, which is an abnormal
form of a normal protein known as a cellular prion protein.
The TSE agents are extremely resistant to heat, ultraviolet
light, ionizing radiation, normal sterilization processes, and
common disinfectants that normally inactivate viruses and bacteria.
What
about the possibility of BSE coming from other TSEs already in
the United States, such as deer and elk with chronic wasting disease,
or other sources such as the practice of feeding cattle parts
to pigs?
- As
mentioned before, there are several TSEs in the United States.
However, there is no evidence to date that BSE has emanated
from TSEs in other animals.
Regarding feeding practices, it is known that cattle can become
infected with BSE by eating feed contaminated with the infectious
BSE agent. This is why in 1997 the U.S. Food and Drug Administration
(FDA) prohibited the use of most mammalian protein in the manufacture
of animal feed intended for cattle and other ruminants
Where
is the BSE agent found in cattle?
-
Current scientific research confirms that BSE infectivity occurs
in the brain, trigeminal ganglia, tonsils, spinal cord, dorsal
root ganglion, and distal ileum of the small intestine of cattle
experimentally infected with the BSE agent. Research also confirms
that BSE infectivity is in the brain, spinal cord, and retina
of the eyes of cattle infected with the agent under field conditions.
Although bone marrow has demonstrated infectivity in experimentally
infected cattle, these findings are not conclusive.
Can
BSE be transmitted from one cow to another cow?
- No.
BSE is not a contagious disease. There is no evidence that the
disease is transmitted through direct contact or animal-to-animal
spread. The primary means by which animals become infected is
through consumption of feed contaminated with the infectious
BSE agent.
What
is FSIS doing to protect the public from BSE? While FSIS believes
that the food supply is safe, the Agency has taken a number
of steps to ensure that the public does not receive product
that could have the BSE infectious agent - however remote that
risk is to begin with.
On December 23, 2003, after the discovery of a presumptive positive
of BSE found in a Holstein dairy cow slaughtered at an establishment
in Moses Lake, Washington (see recall release FSIS-RC-067-2003)
, FSIS immediately issued a press release that announced the
firm's voluntary recall of 10,410 pounds of raw beef.
This
product might have been exposed to tissues containing the infectious
agent that causes BSE. The recall was made out of an abundance
of caution, since muscle meat does not contain the high risk
neural tissues such as brain and spinal cord, and is considered
safe.
In
addition, on December 30, 2003, Agriculture Secretary Ann Veneman
announced new policies that would further strengthen an existing
solid food safety system against BSE. On that date, an immediate
ban was enacted to prevent all non-ambulatory disabled cattle
from being used in the human food supply.
This
group contains the highest risk population of cattle that could
possibly have BSE. However, even before this ban, FSIS inspectors
at slaughterhouses were condemning all cattle they suspected
of showing central nervous system disorders.
The
four policies that Secretary Veneman announced on December 30,
2003 were made effective by FSIS on January 12, 2004. These
included:
Product
Holding - FSIS inspectors no longer mark cattle tested for BSE
as "inspected and passed" until confirmation is received
by FSIS and the plant that the cattle have, in fact, tested
negative for BSE.
Specified Risk Material - FSIS declared that skull, brain, trigeminal
ganglia, eyes, vertebral column, spinal cord and dorsal root
ganglia of cattle 30 months of age or older and the small intestine
of all cattle are specified risk materials that are prohibited
in the human food supply. Tonsils from all cattle are also not
allowed in the human food supply.
Advanced Meat Recovery - FSIS expanded a prior prohibition on
spinal cord from being allowed in product produced from a technology
called advanced meat recovery (AMR). This new regulation prohibits
dorsal root ganglia, clusters of nerve cells connected to the
spinal cord along the vertebral column, in addition to spinal
cord tissue from being in AMR product.
Air-Injection Stunning - FSIS banned the practice of air-injection
stunning to ensure that portions of the brain are not dislocated
into the tissues of the carcass as a consequence of humanely
stunning cattle during the slaughter process.
Is
there a BSE test for meat?
-
No. The only USDA approved testing for the agent is post-mortem
analyses of brain tissue. This is a laboratory screening test
for BSE.
How
does one test for BSE?
- Currently,
there is no test to detect the disease in a live animal or in
muscle meat. Veterinary pathologists confirm BSE by postmortem
microscopic examination of brain tissue using sophisticated
laboratory techniques, such as a histopathological examination
to detect sponge-like changes in the brain tissue and immunohistochemistry
to examine the BSE fibrils.
These
are "gold-standard" tests, and they take more than
a week to run. More rapid tests that provide results within
36 to 48 hours have been developed to detect the abnormal prion
in brain or spinal cord tissue of dead animals. Rapid tests
can be used to determine if BSE exists in a population and to
obtain an indication of its prevalence or detect animals with
the disease which are not yet showing clinical signs.
What
are the clinical signs that cattle have BSE?
- Cattle
affected by BSE experience progressive degeneration of the nervous
system. Affected animals might display changes in temperament,
such as nervousness or aggression, abnormal posture, incoordination
and difficulty in rising, decreased milk production, or loss
of body weight despite continued appetite.
Is
there any cure for BSE?
-
No. There is no treatment for BSE. The course of the disease
varies from two weeks to 14 months, usually resulting in death
or humane destruction within four months in countries where
the disease is present.
How
long can BSE be in an animal before it shows signs of the disease?
-
The incubation period (the time from when an animal becomes
infected until it first shows disease signs) is from 30 months
to eight years with only a few rare exceptions in younger animals.
Following the onset of clinical signs, the animal's condition
deteriorates rapidly. This process usually takes from two weeks
to six months. Most cases in Great Britain occurred in dairy
cows between three and six years of age.
Are
humans susceptible to BSE?
-
Although not scientifically proven, there is strong epidemiologic
and laboratory data linking a rare, degenerative, fatal brain
disorder in humans called variant Creutzfeldt-Jakob Disease
(vCJD) to the consumption of BSE-contaminated product. This
type of disease begins primarily with psychiatric symptoms and
affects younger patients (median age, 28 years).
How
many cases of vCJD have there been and have there been any in
the United States?
- As
of December 1, 2003, a total of 153 cases of vCJD had been reported
in the world: 143 from the United Kingdom, six from France,
and one each from Canada, Ireland, Italy, and the United States.
(Note:
The one case of variant Creutzfeldt-Jakob disease in the United
States is in a young woman who likely contracted the disease
while living in the United Kingdom. Symptoms appeared after
she moved to the United States. The Centers for Disease Control
and Prevention has not found additional cases in the United
States through its surveillance program.)
How
is variant Creutzfeldt-Jakob Disease different from classic Creutzfeldt-Jakob
Disease?
-
The classic form of Creutzfeldt-Jakob Disease is endemic throughout
the world, including the United States. The median age at death
of patients with classic CJD in the United States is 68 years,
and very few cases occur in persons under 30 years of age. In
contrast, the median age at death of patients with vCJD is 28
years.
The
vCJD can be confirmed only through examination of brain tissue
obtained by biopsy or at autopsy, but a "probable case"
of vCJD can be diagnosed on the basis of certain clinical criteria
developed in the United Kingdom. The incubation period for vCJD
is unknown because it is a relatively new disease.
However, it is likely that ultimately this incubation period
will be measured in terms of many years or decades. In other
words, if a person develops vCJD from consuming a BSE-contaminated
product (not yet scientifically proven), he or she likely would
have consumed that product a decade or more earlier.
In
contrast to classic CJD, vCJD predominantly affects younger
people, has atypical clinical features, with prominent psychiatric
or sensory symptoms at the time of clinical presentation. There
are delayed onset of neurological abnormalities, including ataxia
within weeks or months, dementia and myoclonus late in the illness.
Typically, the duration of illness is at least six months.
Can
BSE be transmitted to milk and other dairy products?
-
There is no scientific evidence to suggest that milk and dairy
products carry the agent that causes BSE.
What
do I do if I ate recalled meat associated with BSE?
- The
recalled meat (class II from December 23, 2003) is considered
safe by USDA, as the tissues that would carry the BSE agent
were completely removed at slaughter and not used in meat cuts
or products that might have been consumed by humans.
The recall from December 23, 2003 was made out of an abundance
of caution. If you have concerns that you might have contracted
a foodborne illness, then you should contact your health care
provider.
Will
cooking (including microwave cooking) kill the BSE agent?
-
Current scientific research indicates that cooking will not
kill the BSE agent.
Will
irradiation kill the BSE agent?
-
Current scientific research indicates that irradiation will
not kill the BSE agent.
Are
baby foods safe?
- Beef
products processed by mechanical separation may not be used
in the formulation or production of baby, junior, or toddler
foods.
Advanced
meat recovery (AMR) products, which are processed by removing
muscle tissue without breaking bones and do not include spinal
cord tissue, is allowable for these products (However, there
are further prohibitions of material allowed in AMR).
Are
meats used in the National School Lunch Program safe?
-
Yes. USDA's Agricultural Marketing Service (AMS), by specification,
does not allow beef that is mechanically separated from bone
with automatic deboning systems, advanced lean (meat) recovery
(AMR) systems, or powered knives for any commodity programs.
USDA procurement specifications for beef specifically prohibit
the use of meat from downer animals - animals too sick or injured
to walk.

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