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Microbio Exam 1 > Parasitology > Flashcards

Parasitology Flashcards

1
Q

Define parasite

A

-organisms that live on or within other living organisms (the host) for a significant period of its life and obtains nourishment from it

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2
Q

Give broad examples of parasite categories and be sure to name which 2 are the most common

A
  • All viruses, some bacteria, some fungi
  • protozoa**
  • helminths**
  • arthropods: biting insects (lice, mites); important as vectors for other diseases
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3
Q

Compare protozoa and helminths

A
  • P: unicellular, multiply in host, short life cycles, acute/chronic infections
  • H: multicellular, do not multiple (lay eggs), long life cycles, chronic infections
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4
Q

4 main parasite portals of entry

A
  1. ingestion
  2. arthopod bite
  3. transplacental penetration
  4. organism-directed penetration
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5
Q

Describe the structure and reproduction of protozoa

A
  • single celled, eukaryotic organisms with NO CELL WALL
  • usually reproduce by binary fission
  • often produce cysts to survive harsh conditions–aid transmission
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6
Q

How do protozoa obtain nutrients from the host?

A

-via diffusion or pinocytosis

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7
Q

4 types of protozoa

A
  1. amoeba
  2. Sporozoites
  3. Flagellates
  4. Coccidia: non-motile
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8
Q

We covered 7 protozoa in lecture, belonging to 3 categories based off of location. Name them.

A
  1. GI protozoa: entamoeba histolytica, Giardia lamblia, Cryptosporidium
  2. GU protozoa: trichomonas vaginalis
  3. Blood and tissue protozoa: toxoplasma gondii, falciparum (malaria), naegleria fowleri
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9
Q

How is Entamoeba histolytica spread?

A

-fecal oral route after ingestion of a cyst

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10
Q

What is the growing/active form of Entamoeba histolytica called?

A

-trophozoite

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11
Q

What about the Entamoeba histolytica cysts make them useful in diagnosis?

A

-they have multiple (4) nuclei

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12
Q

Where to Entamoeba histolytica invade?

A

-colonic epithelium

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13
Q

Both the Entamoeba histolytica cysts and trophozoites are excreted, but the _______ die quickly and it is the __________ that spread the infection.

A
  • trophozoites die quickly

- cysts spread infection

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14
Q

What is the characteristic pattern associated with Entamoeba histolytica?

A

-flask-shaped ulcers

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15
Q

Describe the life cycle of Entamoeba histolytica

A
  1. fecal oral transmission of cyst
  2. acid in stomach converts to trophozoite
  3. invasion and division in colon wall- lyses epithelial cells
  4. forms flask-shaped ulcerations
  5. division and excretion of cysts (and trophozoites) and spread of infection
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16
Q

Entamoeba histolytica epidemiology

A
  • found world-wide, especially in areas with poor sanitation where attach rates can be 10-50% of the population
  • many patients are asymptomatic and the infection is cleared
  • symptoms will depend on level of infectious dose
  • millions of cysts shed in stool per day
17
Q

3 outcomes of Entamoeba histolytica infections

A
  1. asymptomatic infection
  2. intestinal amebiasis (amebic dysentery)
  3. extraintestinal amebiasis
18
Q

If carriers of E. histolyticas, how long do their infections usually last?

A

-1-2 years

19
Q

Clinical manifestations of intestinal amebiasis

A
  • related to destruction of colonic epithelial cells

- cramping, diarrhea (not absorbing water well), pain, bloody stools with mucus

20
Q

Clinical manifestations of extraintestinal amebiasis

A
  • fever and rigors
  • liver is primary target and can lead to abscess formation in liver
  • immunosuppressed individuals are at greater risk of this
21
Q

What are the 3 general factors that determine severity of E. histolytica

A
  1. virulence of strain
  2. inoculum
  3. immune status
22
Q

How does one diagnose E. histolytica?

A
  • detection of trophozoites and cysts (multiple nuclei) in stool
  • serology can be useful, but not in endemic areas since most people will be seropositive
23
Q

What is the treatment of E. histolytica?

A

-Metronidazole (flagyl) followed by iodoquinol

24
Q

What is the ultimate effect of metronidazole? Is it active in its ingested form or must it be activated?

A
  • fragmentation of DNA

- must be reduced inside of bacterium (by ferrodoxin) to be active, and then it leads to fragmentation of DNA

Microbio Exam 1 (13 decks)

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