Transcript Detecting Mad Cow Disease

Detecting Mad Cow Disease
Current Issues in Biology, Volume 2
Scientific American
PowerPoint® Lectures
Lectures by April Lynch
Copyright © 2006 Pearson Education, Inc. publishing as Benjamin Cummings
Detecting Mad Cow Disease
Concept Review
• “Mad cow” disease is a neurological illness found in cattle.
• It is formally known as bovine spongiform encephalopathy
(BSE).
• BSE causes serious brain damage and death. It is triggered
by abnormal proteins called prions, which are not stopped
by most disinfection methods.
Copyright © 2006 Pearson Education, Inc. publishing as Benjamin Cummings
Detecting Mad Cow Disease
Concept Review
• Other creatures can also contract prion diseases that cause
fatal brain damage similar to BSE. These conditions include:
• Scrapie in sheep
• Creutzfeldt-Jakob disease (CJD) in humans
Copyright © 2006 Pearson Education, Inc. publishing as Benjamin Cummings
Detecting Mad Cow Disease
Concept Review
• Prion
disease spreads when normal prion proteins fold into
abnormal ones, sometimes after being “converted” by
abnormal prions.
Copyright © 2006 Pearson Education, Inc. publishing as Benjamin Cummings
Detecting Mad Cow Disease
Concept Review
• Abnormal prions can also spread from animal to animal.
• After a BSE outbreak in the United Kingdom in the 1980s,
scientists learned that cattle were sickened after eating feed
made from infected cattle and other livestock.
• People acquired a human form of the disease, a variant
of Creutzfeldt-Jakob disease (vCJD), after eating infected
cattle tissues. In the U.K., more than 140 have died.
Copyright © 2006 Pearson Education, Inc. publishing as Benjamin Cummings
Detecting Mad Cow Disease
Concept Review
• BSE has been found in more than 20 other countries,
including the United States and Canada.
• Two confirmed cases and one possible case had been
found in the United States as of mid-2005.
• BSE causes widespread economic harm, as meat sales
and exports drop after the disease is found.
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Detecting Mad Cow Disease
Concept Review
• The spread of BSE highlights the need for safe livestock
practices and better, faster tests for cattle and meat.
Copyright © 2006 Pearson Education, Inc. publishing as Benjamin Cummings
Detecting Mad Cow Disease
Concept Review
• For many years, BSE tests have only been possible to do
once an animal is dead.
• Early tests took a relatively long time – anywhere from
seven days to three years. Newer tests can deliver results
within hours, but are not always widely available.
• So far, no cure has been found for prion diseases.
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Detecting Mad Cow Disease
Testing Your Comprehension
A prion is an infectious agent consisting of
a)
b)
c)
d)
a membrane-bound nucleus.
a protein capsule containing RNA.
a protein.
DNA in a carbohydrate case.
Copyright © 2006 Pearson Education, Inc. publishing as Benjamin Cummings
Detecting Mad Cow Disease
Testing Your Comprehension
A prion is an infectious agent consisting of
c) a protein.
Copyright © 2006 Pearson Education, Inc. publishing as Benjamin Cummings
Detecting Mad Cow Disease
Testing Your Comprehension
Prions are known to cause which of these diseases?
a)
b)
c)
d)
scrapie
Creutzfeldt-Jakob disease (CJD)
bovine spongiform encephalopathy (BSE)
all of the above
Copyright © 2006 Pearson Education, Inc. publishing as Benjamin Cummings
Detecting Mad Cow Disease
Testing Your Comprehension
Prions are known to cause which of these diseases?
d) all of the above
Copyright © 2006 Pearson Education, Inc. publishing as Benjamin Cummings
Detecting Mad Cow Disease
Testing Your Comprehension
The BSE outbreak in the United Kingdom has been
attributed to
a)
b)
c)
d)
infected vitamin samples given to the cows.
cannibalistic feeding of cows.
contaminated milking machines.
straw and hay harboring prions from wild animals.
Copyright © 2006 Pearson Education, Inc. publishing as Benjamin Cummings
Detecting Mad Cow Disease
Testing Your Comprehension
The BSE outbreak in the United Kingdom has been
attributed to
b) cannibalistic feeding of cows.
Copyright © 2006 Pearson Education, Inc. publishing as Benjamin Cummings
Detecting Mad Cow Disease
Testing Your Comprehension
Currently, how does the cattle industry diagnose BSE
infection?
a)
b)
c)
d)
scanning the cow’s brain for damage
BSE is diagnosed only after an animal is dead
analyzing blood samples for nerve tissue wastes
sampling urine for signs of prion infection
Copyright © 2006 Pearson Education, Inc. publishing as Benjamin Cummings
Detecting Mad Cow Disease
Testing Your Comprehension
Currently, how does the cattle industry diagnose BSE
infection?
b) BSE is diagnosed only after an animal is dead
Copyright © 2006 Pearson Education, Inc. publishing as Benjamin Cummings
Detecting Mad Cow Disease
Biology and Society
After learning more about BSE, I am confident in the safety of
the beef I eat.
Strongly
Agree
A.
B.
C.
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D.
E.
Strongly
Disagree
Detecting Mad Cow Disease
Thinking About Science
Given what you’ve learned about prions’ resistance to current
disinfection methods, what would be effective ways to
eliminate them from the animal and human food supply?
Copyright © 2006 Pearson Education, Inc. publishing as Benjamin Cummings
Detecting Mad Cow Disease
Interpreting Data and Graphs
Has the presence of BSE in a country always resulted in vCJD?
If not, what are some possible reasons why?
Copyright © 2006 Pearson Education, Inc. publishing as Benjamin Cummings