1. Chapter 13 Topics - Human Host - Progress of an Infection
- Epidemiology

2. Human Host
Acquire resident flora
New born exposure

3. Acquire resident flora
The human body supports a wide range of habitats
temperature, pH, nutrient, oxygen tension
Wide range of microbes can inhabit
Resident flora or microflora
Microbes that inhabit but do not harm the host

4. Acquire resident flora
Beneficial outcome
Removed by immune system
Microbial antagonism
Adverse effects
Escape immune system
Multiply and disrupt tissue

5. The benefits and adverse effects of microbial contact.
Fig Association between microbes and humans.

6. Locations on the host that harbor normal flora.
Table 13.1 Sites that harbor a normal flora

7. Types of microbes and the anatomic sites they occupy.
Table 13.3 Life on Humans: sites containing well-established
flora and representative examples.

8. Invasion of normally sterile regions of the body can result in infection and disease.
Table 13.2 Sterile (Microbe-free) anatomical sites and fluids

9. The absence of normal flora can have harmful effects.
Table 13.A Effects of the Germ-free state

10. New born exposure Mother’s birth canal Mother’s breast milk
Bottle-feeding
People

11. Newborns will be exposed to different types of microbes depending on the source as well as their stage of development.
Fig The origins of flora in newborns

12. Progress of an Infection
Pathogenicity
Portals of entry
Attachment
Surviving host defenses
Causing disease
Process of infections and disease
Portals of exit

13. Pathogenicity
True pathogens
Opportunistic pathogens
Virulence

14. True pathogen Cause disease in healthy individuals
Associated with a specific and recognizable disease

15. Opportunistic pathogen
Cause disease in immune compromised host
Gain access (injury) to sterile regions

16. Factors that predispose a person to infections.
Table 13.4 Factors that weaken host defenses and
increase susceptibility to infections

17. Virulence Virulence factors Ability to establish itself in the host
Cause damage

18. Portals of entry Most pathogens have specific portals on entry Skin
Gastrointestinal tract
Respiratory tract
Urogenital
Placenta
Inoculum size

19. Skin
Staphylococcus aureus
Boils
Haemophilus aegyptius
Pinkeye

20. Gastrointestinal tract
Salmonella, Shigella, Vibrio
Viruses – polio, hepatitis A
Protozoan – Giardia lamblia
Enter via ingestion or the anal route

21. Respiratory tract Streptococcus pneumoniae Fungi – Cryptococcus
Sore throat, meningitis
Fungi – Cryptococcus
pneumonia

22. Urogenital Numerous sexual transmitted diseases (STDs)
Virus – human papillomavirus
Genital wartsCan lead to Cervical Cancer
Go to
Protozoan – Trichomonas
trichomoniasis
Bacteria – Neisseriagonorrhoeae
Gonorrhea
Acquire by intercourse or intimate contact

23. Common STDs which include viruses, protozoan, fungi, and bacteria.

24. Placenta Some bacteria can penetrate the placenta barrier Birth canal
Syphilis spirochete
Birth canal
Herpes simplex virus

25. A fetus can acquire an infection from the mother via transplacental infections.
Fig Transplacental infection of the fetus.

26. Inoculum size Infectious dose (ID)
minimum number of bacteria required to cause disease
Low ID = high virulence

27. Attachment Adhesion Structures
Binding between specific molecules on both the host and pathogen
Structures
Capsules
Pili or fimbriae
Hooks

28. Example of how fimbriae and capsules are used to adhere to the host cell.
Fig Mechanisms of adhesion by pathogens

29. Examples of different microbes, the disease they cause, and the structures used for adhesion.
Table 13.6 Adhesion properties of microbes.

30. Surviving host defenses
Antiphagocytic factors
Capsule
Prevent phagocytosis
Leukocidins
Toxic to phagocytes
Some microbes survive inside phagocytes

31. Causing disease Virulence factors Occurrence of infection
Exoenzymes
Toxins
Capsule
Occurrence of infection
Signs and symptoms

32. Virulence factors such as enzymes, toxins, and capsules contribute to host tissue damage.
Fig Three ways microbes damage the host.

33. Exoenzymes Mucinase – digest protective coating on mucous membranes
Keratinase – digest the principal component of skin and hair
Collagenase – digest the principal fiber of connective tissue
Hyaluronidase – digest the substance that cements cells together

34. Bacterial toxins Exotoxins Endotoxins
Gram positive and Gram negative cells
Excreted (ex. Hemolysins)
Highly toxic in small amounts
Endotoxins
Gram negative cells
Membrane associated
Lipopolysaccharide (LPS)
Fever associated

35. Exotoxins are released by the bacterium and directly affect different host organs, while endotoxins are released after the bacterium is lysed.
Fig The origins and effects of circulating exotoxins and
endotoxins.

36. Summary of the different characteristics associated with bacterial exotoxins and endotoxins.
Table 13.7 Differential characteristics of bacterial
exotoxins and endotoxins

37. Process of infections and disease
Establishment
Signs and symptoms

38. Establishment Localized Systemic Focal Mixed Primary and secondary
Acute and chronic

39. Establishment of infections vary depending on location, type of microbe, and length of time.
Fig The occurrence of infections with regard to location,
type of microbe and length of time.

40. Signs and symptoms
Signs - objective evidence of disease based on observation
Inflammation – edema, granulomas, abscesses
Symptoms – subjective evidence of disease based on the patient
Inflammation – fever, pain, soreness, swelling
Syndrome – sign and symptoms

41. Some commons signs and symptoms associated with infectious diseases.
Table 13.8 Common signs and symptoms of infectious diseases

42. Portal of exit Enables pathogen to spread to other hosts Persistence
Respiratory
Salivary
Skin
Fecal
Urogenital
Blood
Persistence

43. Representation of the different portals of exit.
Fig Major portals of exit of infectious diseases.

44. Persistence Latency Sequelae – long-term damage to tissues or organs
Viral
Herpes virus
Bacterial
Tuberculosis
Sequelae – long-term damage to tissues or organs

45. Epidemiology The study of disease in populations
Frequency data
Distribution data
Center for Disease Control and Prevention (CDC)

46. Epidemiology Statistics Strategies Reservoir Carriers Vectors
Acquisition and transmission
Nosocomial
Koch’s postulates

47. Statistical data can be represented graphically, and can be used to predict trends.
Fig Graphical representation o epidemiological data.

48. The frequency of a disease in a population can be used to defined endemic, epidemic, sporadic, and pandemic diseases.
Fig Patterns of infectious disease occurrence

49. Commonly reported diseases that are tracked in the United States.
Table 13.9 Reportable disease in the U.S.

50. Reservoirs
Carriers
Vectors
Nonliving

51. Carriers
Asymptomatic
Incubation
Convalescent
Chronic
Passive

52. Examples of different types of carriers.
Fig Carriers

53. Vectors Biological Mechanical
Participates in the pathogen’s life cycle
Infected with the pathogen
Transmit by bites, defecation
Mechanical
Not part of pathogen’s life cycle
Not infected with the pathogen

54. Zoonotic infections are caused by vectors and animal reservoirs spreading their own infections to humans.
Table Common zoonotic infections

55. A mosquito is a biological vector and the common house fly is a mechanical vector.
Fig Two types of vectors.

56. Nonliving Reservoirs Soil Water – similar to soil
Transmit bacteria, protozoa, helminths, fungi
Transmit spores, cysts, ova, larvae
Water – similar to soil

57. Acquisition and transmission
Communicable
Non-communicable
Patterns of transmission

58. Communicable
Infected host transmits an infectious agent to another host
Receiving host must become infected

59. Non-communicable Host acquires infectious agent
From self (compromised individual)- microflora
Nonliving reservoir - soil

60. Patterns of transmission
Horizontal
Vertical
Direct (contact)
Indirect

61. Horizontal
Disease is spread through a population from one infected person to another
Kissing, sneezing

62. Vertical The disease is transmitted from parent to offspring
Ovum, sperm, placenta, milk

63. Direct (contact)
Kissing, sex
Droplets
Vertical
Vector

64. Indirect Contaminated materials Air
Food, water, biological products (blood, serum, tissue), fomite (door knobs, toilet seats, etc.)
Oral-fecal
Air
Droplet nuclei (dried microscopic residue)
Aerosols (dust or moisture particles)

65. Communicable diseases are acquired by contact and indirect transfer.
Fig Summary of how communicable infectious diseases
are acquired.

66. A sneeze can release enormous amounts of moist droplets, and the dry droplets form droplet nuclei.

67. Nosocomial infections
Infectious diseases that are acquired or developed from a hospital stay
Urinary tract infections
Respiratory infections
Surgical incisions

68. The most common nosocomial infections.
Fig Most common nosocomial infections.

69. To reduce nosocomial infections, different isolation procedures are used in hospitals.
Table Levels of isolation used in clinical settings.

70. Koch’s postulates Method used to determine the etiologic agent
Ex. Toxic shock syndrome, AIDS, Lyme disease, Legionnaires

71. Steps associated with Koch’s postulates.
Fig Koch’s postulates: Is this the etiologic agent?