Host Parasite Interactions

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  1. A small organism which lives within or upon a larger organism of a different species at whose expense it obtains some advantage
  2. The larger organism that is parasitized
  3. Entrance, mulitplication, and colonization of a host--need not cause disease and may be "normal flora"
  4. The agent that causes disease
    Etiological Agent
  5. The disease producing organism
  6. A parasite that ordinarily does not cause disease. Occurs in compromised host
    Opportunist (Opportunistic Infection)
  7. Sequence of Infection (4)
    • Exposure
    • Multiplication
    • Recovery/Death
    • Convalescence
  8. Period prior to the development of symptoms (days to weeks)
    Incubation Period
  9. The very first symptoms of an infection
  10. Symptoms when disease is fully manifest
  11. Shortly after eradication of an infection
  12. The method for entry of the pathogen into the body
  13. First and most important step in infection. Involves contact with a mucosal cell surface molecule (receptor). Involves specificity, antagonism, and synergy
  14. Study of how a disease is transmitted (geographical distribution, animal reservoirs, season occurence)
  15. Routes of Transmission (5)
    • Direct contact
    • Aerosol droplets
    • Fomites
    • Ingestion
    • Arthropod vectors
  16. True or False:
    Adherence molecules extend from bacterial surface as lipoteichoic acid, proteins, and carbohydrates
  17. Degree of virulence is measured by (3)
    • Minimal Lethal Dose (MLD)
    • Lethal Dose50 (LD50)
    • Infectious Dose50 (ID50)
  18. Smallest dose that will result in death of the host
    minimal lethal dose (MLD)
  19. Dose that kills 50% of infected hosts
    Lethal Dose50
  20. Dose that infects 50% of treated hosts
    Infectious Dose50
  21. Ability to cause disease
  22. Ability to invade tissues and multiply
  23. Antibody with phagocytosis and killing of pathogen
    Extracellular Pathogen
  24. Cell-mediated immunity
    Intracellular pathogen
  25. Mechanisms to avoid host defenses by extracellular bacterial pathogens
    • Capsules (anti-phagocytic)
    • Fimbriae (adherence)
    • M-protein (anti-phagocytic)
  26. B cells produce specific antibodies (with Th2 cells) that _____ bacteria
  27. ______ can also opsonize bacteria
  28. Phagocytosis can happen via (3)
    • Chemotaxis
    • Engulfment
    • Intracellular killing
  29. These parasites require an intracellular environment. Examples include rickettsia, chlamydia, and viruses
    Obligate intracellular parasites
  30. These parasites grow intracellularly or on artificial media. Examples include mycobacteria, salmonella, brucella, legionnaire's disease, & listeria
    Faculatative Intracellular Parasites
  31. How do intracellular pathogens avoid host defenses?
    by preventing intracellular killing
  32. Secreted from bacterial cells into the surrounding medium
  33. Neurotoxin producing flaccid paralysis
  34. Neurotoxin producing spastic paralysis
  35. Causes cells of the body to produce large amounts of cytokines
    Toxic Shock Syndrome Toxin
  36. Enterotoxin--activates adenyl cyclase
    Cholera Toxin
  37. Part of the cell wall of Gram-negative bacteria. Activates macrophages causing them to make IL-1, TNF-alpha, and IL-6. Fever, hypotension, DIC. Lethal shock can occur
  38. The number of cases or incidence of a specific notifiable disease per unit population
    Morbidity Rate
  39. The number of deaths due to a specific notifiable disease per unit population
    Mortality Rate
Card Set
Host Parasite Interactions
Host Parasite Interactions
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