Virulence and pathogenicity-parasites Flashcards Preview

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Flashcards in Virulence and pathogenicity-parasites Deck (10):
1

ectoparasite vs. endoparasite

 

Ectoparasite: lives on host and causes infestations

Endoparasite: lives in host and causes infections

 

*** Arachnids= ectoparasites

***Helminths= endoparasites

2

Definitive vs. Intermediate vs. Incidental hosts

Host Specificity: parasites need specific hosts for certain stages of life cycle!

 

Definitive host: harbors adult stage of parasite.

Intermediate host: harbors larval stage of parasite

Incidental host: unusual host/unnecessary for survival of parasite

3

Factors influencing parasite virulence (5)

Factors influencing parasite virulence

-type of parasite/host

-host stage

-severity of infection

-duration of infection

-route of exposure

4

Parasite Pathenogenesis (6)

Parasite Pathenogenesis= pregression of disease

*** these arent really sequential steps, more so just stuff that is all part of the infection/infestation

1. exposure (infective dose)

2. attachment

3. cell and tissue damage

4. loss of nutirents

5. disruption, evasion and inactivation of host defenses

5

Routes of parasite exposure (6)

Routes of parasite exposure

-Ingestion

-Skin/mucosal penetration

-Transplacental (parental)

-Transmammary(milk)

-Arthropod bite (vector)

-Sexual contact

6

Infective dose

infective dose= how many/much parasite was host exposed to

Fun Fact: adult helmuths do not multiply in host.  Thus infective dose=severity of disease

protozoa do multiply in host, so severity of infection changes with legnth of exposure.

7

Parasite attachment (2)

Step 2 of parasite pathenogenesis= attachment

Mechanical attachment- biting, suction disks, attachment organs, ect. (ex. hookworm)

Molecular interaction- some parasites use molecular interactions to target cell.

8

Cell and tissue damage (2)

Step 3 parasite pathenogenesis= tissue damage

Mechanical tissue damage due to:

  • blockage of internal organs
  • pressure atrophy
  • migration through tissues

Toxic parasite products damage tissue with:

  •  destructive enzymes
  • endotoxins
  • toxic secretions

9

Loss of nutrients (3)

Step 4ish parasite pathenogenesis= loss of nutrients

Nutrient loss can be due to:

1. parasite competition with host for nutrients

2. interference with host nutrient absorption

3. direct nutrient loss- hookworm causes iron loss

10

Concomitant vs. Premonition Immunity

Aquired immunity

Concomitant Immunity: immunity defends against all stages of a parasite, even if parasite is eradicated from host. 

 

Premonition Immunity: immunity develeoped to current parasites.  when parasited are gone, immunity is lost.