Mad Cow Disease

1
Mad Cow Disease

• ??? ??? ???

2
What is Mad Cow Disease ?

• A kind of transmissible spongiform
  encephalopathies (TSE)
• Occurs in many mammals, including human
• Cow
• -Bovine Spongiform Encephalopathy(BSE)
• -progressive neurological degeneration
• Human
• -Creutzfeldt-Jacob disease (CJD)
• -new variant of CJD (vCJD).

3

• When was BSE first reported ?
• November, 1986

• In which country ?
• United Kingdom (U.K)
• By what reason ?
• By feeding cattle with meat-and-bone
• meal from BSE-infected cattle.

4
Important facts about the history of BSE

• The vast majority of BSE cases have been reported
  in the U.K.
• The U.K. epidemic peaked in January 1993 at
  nearly 1,000 new cases per week.
• Among Britains 34000 herds of cattle, 176000
  cattle were infected in 2000.

5
What countries have had BSE ?

• Surveillance in Europe has also led to the
• identification of cases of BSE in Belgium,
• Denmark, France, Ireland, Switzerland,
• Germany, Spain, and Italy.

• A widespread outbreak infected more than 100,000
  cows across Europe in the mid-1990s.
• Recent cases are reported in Japan, Canada, and
  America.

6

• Whats the human form of TSE?
• -There are 6 kinds of TSE occur on humans.
• -Kuru (the earliest discoverd)
• -Creutzfeldt-Jacob disease (CJD)
• -variant Creutzfeldt-Jacob disease (vCJD)
• The origin of human TSE
• -1957
• -Kuru
• -In the Fore natives of the New Guinea
• highlands.
• -The Fores were cannibals.
• Scientific Research
• -Kuru was first diagnosed in 1920.
• -Dr. Prusiner found the cause of the disease.
• -He won a Nobel Prize in 1997.

7
Why do we fear BSE?

• In 1996, scientists found a possible link
  between BSE and a new variant of CJD (vCJD).
• Evidence indicates that humans may acquire vCJD
  after consuming BSE-contaminated cattle products.
• From 1995 through early December 2000, 88 human
  cases of vCJD were reported in the U.K.

8
Is this possible in the future?
9
This is a mad cow.
10
Why is BSE mad cow ?

• Irritable
• Violent
• Threatening fashion when approached by humans
• The most plausible cause of the disease is a
  prion, an abnormal form protein.

11
The pathogen of BSE

• The mechanism of prion--

prion
Normal protein
12
Explanations for the prion theory

• Two formsPrPc PrPsc
• The two kinds of protein are different in 3D
  structure.
• PrPsc can accumulate and leading to amyloid
  changes and giosis.

13
Routes of infection

• Acquired infection
• Diet
• Growth hormone injections
• Corneal transplants
• Heredity
• The human PrP-gene (PRNP) is localized on the
  short arm of chromosome 20.
• Mutations

14
Clinical symptom in vCJD

• The decline of memory
• The abnormal behaviors
• The inharmonious gait
• The fierce spasm
• The body incapable

15
Control and Prevention

• UK - banned using any ruminant (cattle, sheep,
  goats) or ruminant by-products in animal feed in
  1988.
• banned exports of
• cattle to other countries.

16

• destroyed BSE-infected cattle and monitored herds
  for signs of BSE.
• monitored the
• general population
• and reported any
• cases of nvCJD

17
The U.S. government has instituted the following
policies regarding BSE

• USDA has prohibited imports of live ruminants or
  ruminant products from Europe.
• The USDA inspects all cattle used for food for
  signs of neurological diseases..

18

• The U.S. Food Drug Administration (FDA) has
  prohibited using
• mammalian proteins in making animal feeds for
  ruminants.
• The FDA has recommended
• that pharmaceutical
• companies should not
• use animal tissues from
• countries with BSE in
• making drug products
• (vaccines).

19

• The FDA has asked blood centers to exclude
  potential blood donors who have spent six or more
  consecutive months in the UK between 1980 and
  1986.
• The Centers for Disease Control (CDC) regularly
  monitors the U.S. population for signs of nvCJD.

20

• The USDA has tested any cattle showing abnormal
  behavior for BSE.

21

• The CDC has issued guidelines to travelers in
  Europe
• 1.avoid beef and beef
• products altogether
• 2.if eating meat, then select beef or beef
  
• products that have less opportunity for
• contamination from nervous tissue (solid
  
• muscle cuts vs. processed sausages or
  
• hamburgers)

22

• 3. milk or milk products are not believed to pose
  any risk from the BSE agent
• The National Institutes of Health (NIH) conducts
  research on BSE, CJD, nvCJD and related nervous
  system diseases.
• Current news

23
conclusion

• If an evil force could devise an agent capable
  of damaging the human race, he would make it
  indestructible, distribute it as widely as
  possible in animal feed so that it would pass to
  man, and program it to cause disease slowly so
  that everyone would have been exposed to it
  before there was any awareness of its presence,
  British microbiologist, Richard Lacey.

24
Sorry, we give you troubles

• The End