Mad Cow Disease

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Mad Cow Disease

• Are humans susceptible?

By Lacy D Lapio
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What is Mad Cow Disease?

• Mad Cow Disease is scientifically known as Bovine
  Spongiform Encephalopathy (BSE).
• BSE affects the central nervous system of cattle,
  destroying brain tissue and eventually causing
  dementia and death.
• The nature of the transmissible
• agent is unknown.
• There is no known cure.
• The disease is carried in nervous system tissue.

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What is Mad Cow Disease?

• The infectious agent that is widely thought to
  cause disease is the prion (although that is
  speculative there is a lack of evidence), a
  particle of clumped-up protein.
• In its normal form, the prion protein is found in
  a wide variety of tissues throughout the body,
  including the brain, immune system, blood, gut,
  and liver, and causes no disease. But mutations
  in the protein can cause it to fold abnormally
  and clump up to form infectious prions.
• Researchers also believe that new prions can form
  when a normal prion protein comes into physical
  contact with an abnormally shaped prion protein.
  For reasons that are still unknown, the bad
  protein makes the good protein turn bad.

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What causes Mad Cow Disease?

• Although the cause is unknown, Scientists
  speculate that the disease has spread among
  cattle primarily through "animal recycling" --
  the use of bone meal and other ground animal
  parts in feeds.
• Mad cow disease was first identified in Britian
  in 1985.
• BSE does not
• spread from
• cow-to-cow contact

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What is being done about it?

• The European Union implemented new rules Jan. 1,
  2001 requiring all cattle over 30 months old to
  be tested for the disease.
• The FDA prohibits all material from
  non-ambulatory cattle in human food, removing
  certain cattle tissues
• from the human food,
• and banning certain
• nervous system tissues
• in meat products.

Source FDA
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Source Rutgers Poll 2.2.04
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What is the human variant of Mad Cow Disease?

• The human form of Mad Cow disease,
  Creutzfeldt-Jakob disease (CJD) is a rare,
  degenerative, invariably fatal brain disorder.
• Typically, onset of symptoms occurs at about age
  60.
• There are three major categories of CJD sporadic
  CJD, hereditary CJD, and acquired CJD

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What causes CJD?

• In sporadic CJD, the disease appears even though
  the person has no known risk factors for the
  disease. This is by far the most common type of
  CJD and accounts for at least 85 percent of
  cases.
• In hereditary CJD, the person has a family
  history of the disease and/or tests positive for
  a genetic mutation associated with CJD. About 5
  to 10 percent of cases of CJD in the United
  States are hereditary. 
• In acquired CJD, the disease is transmitted by
  exposure to brain or nervous system tissue,
  usually through certain medical procedures. There
  is no evidence that CJD is contagious through
  casual contact with a CJD patient. Since CJD was
  first described in 1920, fewer than 1 percent of
  cases have been acquired CJD.

Source http//www.mydna.com/health/diseases/madco
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How is it detected?

• There is currently no one diagnostic test for
  CJD.
• First it is important to rule out treatable forms
  of dementia such as encephalitis or chronic
  meningitis.
• The only way to confirm a diagnosis of CJD is by
  brain biopsy or autopsy by removing a small piece
  of brain tissue to be examined by a neurologist.
• Early symptoms in humans
• include insomnia, memory
• loss, and depression.

                                     
Brain tissue infected with prions has a spongy appearance.Image courtesy NEJM.
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What is the treatment and prognosis?

• Due to the lack of knowledge of what causes it,
  there is no treatment that can cure or control
  CJD
• Around 90 percent of patients die within the
  first year. In the early stages of disease,
  patients may have failing memory, behavioral
  changes, lack of coordination and visual
  disturbances. As the illness progresses, mental
  deterioration becomes pronounced and involuntary
  movements, blindness, weakness of extremities,
  and coma may occur in the patient.

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What link is there between bse and cjd?

• We dont know much about how the disease is
  transmitted or why only certain people appear
  susceptible, says Richard Johnson of Johns
  Hopkins University in Baltimore, Maryland, who
  headed a recent Institute of Medicine panel to
  study mad cow and related diseases. There are
  too many questions and not enough answers.
• An experimental study reported in June 1996
  showed that three cynomologus macaque monkeys
  inoculated with brain tissue obtained from cattle
  with BSE had clinical and neuropathological
  features strikingly similar to those of variant
  CJD.
• A study published in 1996 indicated that a
  Western blot analysis of infecting prions
  obtained from 10 variant CJD patients and
  BSE-infected animals had similar molecular
  characteristics that were distinct from prions
  obtained from patients with other types of CJD
  (Nature 1996383685-90).

Source http//www.mydna.com/health/diseases/madco
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What do most americans believe?
Of those who had heard of the disease, 65 percent
believe the nations beef supply is safe, 24
percent believe it is unsafe and 10 percent are
unsure.
Source Rutgers Poll 2.2.04
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How does this affect the economy beef market?

• The EU has set aside about 1 billion for the
  tests, which cost about 100 per animal. The
  European Commission estimates the cost of
  incinerating slaughtered animals at 3.3 billion.

• Nearly 1 in 5 (19.5 percent) of those who knew
  about mad cow disease say they have since reduced
  their beef consumption. About 9 percent say they
  eat somewhat less beef, 5 percent say they eat
  much less and nearly 5 percent say they have
  stopped eating beef altogether. As such, about 4
  percent of the total population claims to have
  stopped eating beef.

Source Rutgers Poll 2.2.04
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How does this affect the economy beef market?

• Nearly a quarter (24 percent) of 19.5 percent
  of those who have claimed to have stopped eating
  beef say they will never resume eating it.

Source Rutgers Poll 2.2.04
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Should you avoid hamburgers?

• The average annual CJD death rate in the United
  States has remained relatively stable at about
  one case per million population per year. In
  addition, CJD deaths in persons aged lt30 years in
  the United States remain extremely rare (lt1 case
  per 100 million per year).

Source http//www.mydna.com/health/diseases/madco
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Questions about my research?

• Contact me at LLapio_at_smu.edu

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Where did I get this information?

• http//www.pbs.org/newshour/bb/health/mad_cow.html
  
• http//www.mad-cow-facts.com/News-Commentary/rutge
  rs_poll_2-2-04.htm
• www.genomenewsnetwork.org/. ../01/23/mad_cow.php
• http//www.fda.gov/fdac/features/2004/304_cow.html
  
• http//www.mydna.com/health/diseases/madcow
• http//www.ninds.nih.gov/disorders/cjd/detail_cjd.
  htm