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Chapter 20: Epidemiology

Chapter 20: Epidemiology. Important Point:. If you are having trouble understanding lecture material: Try reading your text before attending lectures. And take the time to read it well!. Common Terms. Common Terms. Fraction that get sick!.

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Chapter 20: Epidemiology

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  1. Chapter 20:Epidemiology

  2. Important Point: If you are having trouble understanding lecture material: Try reading your text before attending lectures. And take the time to read it well!

  3. Common Terms

  4. Common Terms Fraction that get sick!

  5. Humans are the most important reservoir of human infectious disease. Pathogen Reservoirs

  6. Pathogen Transmission

  7. Portals of Entry

  8. Portals of Exit

  9. The Broad Street Pump. Cholera! Common-Source Outbreak

  10. The Broad Street Pump. Common-Source Outbreak Individual cases of (deaths from) cholera.

  11. Common-Source Outbreak Sewage contamination of drinking water.

  12. Propagating Epidemic Epidemic spreads via multiple sources.

  13. Pandemic Index case.

  14. Pandemic

  15. Zoonoses are Human Diseases with Animal Reservoirs. Zoonoses

  16. Toxoplasmosis Zoonoses

  17. Modes of Transmission

  18. Contact Transmission Rhinovirus?

  19. Direct-Contact Transmission

  20. Direct Fecal-Oral Transmission Giardiasis in daycare centers.

  21. Indirect-Contact Transmission Methicillin-resistant Staphylococcus aurius (MRSA)? Beddings are an example of a Fomite, an inanimate object that can transmit pathogens between people.

  22. Indirect-Contact Transmission Influenza virus? Door knobs are another good example of a fomite.

  23. Droplet Transmission Less than one meter Measles?

  24. Airborne Transmission More than one meter Mycobacterium tuberculosis?

  25. Airborne Transmission Contact with air from small room containing 12 people. Contact with air from clean, empty room.

  26. Waterborne Transmission Cryptosporidium parvum?

  27. Waterborne Transmission Giardiasis from water.

  28. Foodborne Transmission Hepatitis A

  29. Foodborne Transmission Balantidium coli

  30. Modes of Transmission

  31. Portals of Entry “Many organisms that cause one disease if they enter one body site are harmless if they enter another, e.g., various enteric urinary-tract pathogens.

  32. ...is pretty crappy at dealing with cause and effect when associations are subtle. Epidemiology Do power lines really cause cancer? What about cell phones?

  33. ...is pretty crappy at dealing with cause and effect when associations are subtle. However... Epidemiology What about smoking, a crappy diet, and couch-potato tendencies?

  34. Types of Epidemiological Studies A.k.a. analytical

  35. Descriptive studies are simply those that describe the events and rates of disease. They tend to be the first sets of studies done.Quoted or paraphrased from http://dante.med.utoronto.ca/doch/Year1/EPIModule/Part6a.htm • Observational/Analytical studies then look towards finding out the causes of the observed rates. They are called "observational" since the epidemiologist does not intervene in the assignment of exposure. • Experimental studies are formal research experiments. The classic example is the randomized control trial where one group is randomly assigned a treatment and a control group gets the placebo or "usual" treatment. • Experimental studies are expensive and test a very specific question. Usually a great deal of descriptive and observational studies are done first. Types of Epidemiologcal Studies

  36. Just worry about top three and not about percentages. Relative Nosocomial Frequencies

  37. Nosocomial Infections 2 million acquire and 20,000 die, per-year in the U.S., from nosocomial Infections. Nosocomial Infections are, by definition, hospital or clinically acquired.

  38. Nosocomial Infections

  39. Compromised Hosts

  40. Compromised Hosts

  41. Compromised Hosts

  42. Compromised Hosts

  43. Compromised Hosts

  44. Nosocomial Infections

  45. Exogenous Infections

  46. Exogenous Infections

  47. Endogenous Infections

  48. Antibiotic Resistance

  49. Nosocomial Infections

  50. Chain of Transmission

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