BSE (Mad Cow) Disease

[Guest guest]

BSE ( " Mad Cow " Disease) JoAnn Guest Jul 29, 2003 10:14 PDT

BSE ( " Mad Cow " Disease)

 

http://www.laurasleanbeef.com/science/BSE.html

 

As part of our commitment to producing healthy, all-natural beef,

Laura's Lean Beef does not allow any animal protein to be fed to our

cattle.

 

All reprocessed animal tissue and by-products are prohibited in our

feeding program, as are fecal materials of any kind, chemically altered

feeds, garbage and food waste.

 

While there have been no confirmed cases of mad cow disease among cattle

in the United States to date, nor have there been any human cases of new

variant Creutzfeldt-Jakob disease in the U.S., we present this

information because of recent media attention that has focused on mad

cow disease in Canada.

 

Bovine Spongiform Encephalopathy (BSE), commonly known as mad cow

disease, is one of a group of diseases called transmissible spongiform

encephalopathies (TSEs).

 

TSEs are found in a variety of mammalian species including mink, elk,

sheep, goats, cats, and humans. TSEs cause intellectual and motor

impairment and eventually death.

 

Upon autopsy, the brains of infected individuals appear to be riddled

with sponge-like holes.

 

BSE, or mad cow disease, was first identified in cattle in England in

1986.

 

An epidemiological study at the time linked the disease to a protein

supplement that included sheep parts infected with scrapie (the sheep

version of mad cow disease).

 

As a result of this study, the U.K. banned the use of mammalian protein

in ruminant animal feeds. In 1988, researchers first hypothesized that

the infectious agent for BSE came from animal by-products (such as bone

and blood meal) which were included in supplemental feeds given to

ruminant animals.

 

The human form of mad cow disease, called new variant Creutzfeldt-Jakob

disease, was first identified in Britain in 1996. As of February 2,

2001, a total of 94 cases of nvCJD have been confirmed or suspected in

the UK, according to the UK Department of Health.

 

Three cases in France and one in Ireland were reported by the European

Commission's Health and Consumer Protection Directorate.

 

New variant Creutzfeldt-Jakob disease is a new disease that differs from

Creutzfeldt-Jakob disease, which is a progressive neurological disorder

characterized by dementia and loss of motor control.

 

While CJD appears to occur spontaneously and is not believed to be

related to cows, similarly-named variant CJD is contracted from eating

mad-cow-tainted beef products.

 

In 1996, the British government ordered that cattle infected with, or

even exposed to, mad cow disease be killed. In the United States, the

USDA has, since 1989, banned the import of beef from countries where mad

cow disease is known to exist. Since 1997, the FDA has prohibited the

use of most mammalian protein in cattle and other ruminant animal feeds

(while permitting mammalian blood, milk, and gelatin products.)

 

" Whatever is causing this disease is unique; it falls out of the realm

of all other disease agents, " states Richard Rubenstein, head of the

molecular and biochemical neurovirology lab of the New York State

Institute for Basic Research.

 

Since research has shown that infected individuals show no antibody

reaction to the disease agent, Rubenstein believes TSEs are caused by a

virino, " a nucleic acid protected by a host protein that camouflages it

so that the immune system doesn't pick it up. "

 

Laura Manuelidis, head of neuropathology at Yale Medical School believes

that a " TSE shares all the signs of a slow viral disease. " She cites the

fact that many slow viruses hide in the central nervous system and

argues that since there are several strains of TSEs, each strain may be

tailored to the genetic makeup of the animal it infects. This would be

consistent with the way viruses work.

 

Stanley Prusiner at the University of California at San Francisco,

winner of the 1997 Nobel Prize in medicine, believes TSEs are " prion

diseases, " diseases transmitted by infectious proteins rather than by

bacteria or viruses.

 

Prions ( " proteinaceous infectious particles " ) do not contain any genetic

material (nucleic acids), and are unaffected by antibiotics, radiation,

chemicals, and extreme heat or cold.

 

Dr. Prusiner believes that infectious prions, an " entirely new genre of

disease-causing agents, " cause disease by impacting a gene called PrP,

which is present in all healthy and infected mammals and passed to their

offspring. It is not known whether normal PrP genes can be affected by

infectious prions, or if the genes of infected individuals are abnormal

or mutated.

 

When the infectious prions attack the (possibly mutated) PrP genes, it

may cause them to begin to produce an abnormal protein that eventually

causes disease symptoms. Those scientists who argue that an infectious

agent must contain nucleic acid do not accept the prion concept.

Research into TSE diseases is still in the early stages.

 

On March 23, 2001, the USDA removed a flock of approximately 126

quarantined sheep from a private farm in Vermont, after earlier having

removed 234 quarantined sheep from a nearby farm. The sheep, which had

been imported from Belgium and the Netherlands in 1996, were placed

under federal restrictions when they entered the country as part of the

USDA's scrapie control efforts. In 1998, the state of Vermont imposed a

quarantine on these flocks at the request of the USDA, prohibiting

slaughter or sale for breeding purposes. In July 2000, several sheep

from the flock tested positive for a TSE.

 

Because current live testing methodology makes it impossible to tell if

the sheep have scrapie, which has not been shown to pose a risk to human

health, or BSE, the USDA seized the sheep with plans to euthanize them

and perform diagnostic testing.

 

 

Another recent news story, in January 2001, focused on a herd of cattle

in Texas that had accidentally been fed bone meal and meat derived from

US cattle.

 

The feed had been manufactured by Purina Mills, Inc., which voluntarily

purchased all 1,222 of the animals in the herd in order to ensure that

meat from those animals would not enter the human food supply. The USDA

stated that the potential risk of BSE to these cattle was exceedingly

low, since any bone meal or meat in the feed would have come from other

US cattle, and no cases of mad cow disease have been found among US

cattle.

 

On May 20, 2003, one case of mad cow was confirmed in Alberta, Canada.

The United States has discontinued importing cattle and beef from Canada

and the situation is currently being investigated by the USDA.

 

References

 

Blakeslee, S. 2001. On Watch for Any Hint of Mad Cow Disease. The New

York Times (January 30).

 

Borman, S. 1998. Prion Research Accelerates. Chemical & Engineering News

(Feb. 9).

 

Bren, L. 2001. Trying to Keep " Mad Cow Disease " Out of U.S. Herds. FDA

Consumer magazine. (March-April).

 

 

FDA News Release, 2001. FDA Announces Test Results from Texas Feed Lot.

(January 30).

 

 

Green, E. 1999. Britain Details the Start of Its " Mad Cow " Outbreak. The

New York Times SCIENCE TIMES (Jan. 26).

 

Prusiner, S. 1995. The Prion Diseases. Scientific American (Jan.).

 

Reuters, 2001. U.S. Quarantines Texas Cattle Over Mad Cow Rules (January

25)

 

Reuters, 2000. Human 'mad cow' cases rising. (August 4).

 

Shell, E. 1998. Could Mad Cow Disease Happen Here? Atlantic Monthly

(Sep.):92.

 

USDA, 2000. News Release: USDA To Destroy Three Vermont Sheep Flocks

Quarantined for TSE. (July 14).

 

 

USDA, 2003. Backgrounder: Bovine Spongiform Encephalopathy (BSE) from

the US Department of Agriculture and Food and Drug Administration. (June

 

 

 

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