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BSE 141013.pdf

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1 10/13/14 Bovine Spongiform Encephalopathy Mad Cow Disease SS 10/13/14 ! Slowly Progressive, Degenerative, Fatal Disease affecting the CNS of adult cattle ! Behavior / temperament changes Tremors, incoordination, falling, and difficulty in rising Decreased milk production Apprehensive to aggression ! Small % “Mad Cow” ! Incubation period – 2 to 8 years SS Economic Impact ! Export Markets Closed ! Domestic Consumption Consumer Confidence Fast Food Chains Dem
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  1 10/13/14 Bovine Spongiform Encephalopathy Mad Cow Disease SS 10/13/14 ! Slowly Progressive, Degenerative, Fatal Disease affecting the CNS of adult cattle ! Behavior / temperament changes Tremors, incoordination, falling, and difficulty in rising Decreased milk production Apprehensive to aggression ! Small % “Mad Cow” ! Incubation period – 2 to 8 years SS Economic Impact ! Export Markets Closed ! Domestic Consumption Consumer Confidence Fast Food Chains Demand BSE Free ! BSE Cases - UK   Since 1986 – 180,000 Peaked 1993 – 1,000 cases per week 2000 - 1352 2003 - 154 ! Increased Demand for Grass/Grain Fed Beef ! Reduced trade in Beef by-product goods Make up Diet Supplements Health Products 10/13/14 SS 10/13/14 Etiology !   Not Yet Fully Characterized Protein only hypothesis !   Dr. Stanley Prusiner, Nobel 1997 Prion = Proteinaceous infectious particle Smaller than smallest known virus PrP C  PrP Sc (Normal cellular surface protein) (prion) conformational change SS  2 10/13/14 Normal protein !   Secondary structure dominated by !  helices !   Easily soluble !   Easily digested by proteases !   Encoded by PRNP gene (in humans) Located on human chromosome 20 SS Abnormal Protein !   Insoluble !   Highly resistant to proteases Survives in tissues post-mortem !   Extremely resistant Heat, normal sterilization processes, sunlight !   No detectable immune response 10/13/14 SS 10/13/14 Abnormal Protein !   PrP Sc  (Sc: scrapie) aa sequence & primary structure =normal protein Secondary structure dominated by  conformation !   When PrP Sc  contacts PrP C   Converts it to the abnormal form SS 10/13/14 PrP c PrP sc PrP c PrP c PrP c PrP c PrP c PrP c PrP c PrP c PrP c PrP c PrP c SS  3 10/13/14 PrP C PrP SC   PrP C SS10/13/14 PrP sc  fibrils SS 10/13/14 Plaque SS10/13/14 Epidemiology SS  4 10/13/14 Geographic Distribution SS 10/13/14 The spread of BSE SS 10/13/14 Geographic Distribution ! 95% of all BSE cases in U.K. Outside U.K. due to importation or contaminated feed ! No cases reported from Australia, New Zealand, Central America, South America ! 2003 Canada and U.S. reported single cow ! 2005 Additional Canadian cases U.S. reported single case - June SS 10/13/14 Animal Transmission ! Reasons for emergence under debate Feed contaminated with scrapie or unknown BSE Spontaneous Changes in feed processing ! Current thought Spread via ingestion of BSE contaminated feed ! High Risk Products Brain and spinal cord tissue Meat and Bone meal (MBM) ! Not in Muscle cuts, Steaks & Roast SS
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