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Wk4 GI Parasites Flashcards

1
Q

Three unicellular eukaryotic parasites:

A

Protozoans
1. Entamoeba

  1. Giardia
  2. Cryptosporidium
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2
Q

Life stage of nematodes, Cestodes, and trematodes in mammal host:

A

Juvenile and adult worms

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3
Q

Giradia mechanism:

A

Presence of parasite decreases absorptive surface area

diahrrea 1-2 weeks, may resolve then return

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4
Q

Form of Giardia that gets ingested:

A

cysts

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5
Q

Form of Giardia present in fecal matter:

A

Trophozoites + cysts

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6
Q

FOUL smelling diarrhea

Flatulence

Greasy stools that float

A

Giardia

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7
Q

Failed sanitation system (water park, drinking water)

Diarrhea 1-2 weeks –> 30 days

A

Cryptosporidium parvum

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8
Q

Ingestion of SMALL oocysts

disrupts epithelial microvilli –> envelopes in host cell membrane

impaired absorption, enhanced secretion

watery, frequent, NON-bloody stools

Opportunistic (HIV)

A

Cryptosporidium parvaum

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9
Q

Cryptosporidium form found in feces:

A

oocysts

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10
Q

Infectious and damage causing forms of Cryptosporidium:

A

Sporulated oocysts

Sporozoites

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11
Q

Bloody-MUCUSEY loose stools

can invade liver –> abcess

Dx: cysts in stool

No fever, chills, or pus

A

Entamoeba histolytica

–> Amebic dysentery (differentiate from Bacillary which HAS fever, chills, and pus)

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12
Q

Location for Entamoeba histolytica:

USA at risk population:

A

tropics –> poverty areas

homosexual males

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13
Q

Life cycle for Entomoeba histolytica on host:

A

ingest cysts –> trophozoites in small intestine –> migrate to colon –> cysts and trophozoites in feces

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14
Q

Disease mech for E. histolytica:

hint: “Hitsto–lytica”

A

tissue lysis

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15
Q

tissue abcess in upper right liver lobe

RUQ pain

fever

weight loss

A

Amebic hepatitis

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16
Q

TISSUE antiparasitic (completely absorbed)

free-radical forming –> DNA strand breaks

A

TiniDAZOLE

MetroniDAZOLE

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17
Q

Antiparasitic

intersferes with pyruvate

moderatley absorbed – primarily luminal

less efficacy in immunocompromised with Crypto

A

Nitazoxanide

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18
Q

luminal antiparasitic (amebicide)

loss of visual acuity

careful with thyroid disease

A

Iodoquinol

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19
Q

Luminal antiparasitic

Aminoglycoside (30s subunit)

Side Fx: diarrhea

A

Paromomycin

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20
Q

Systemic side effects of aminoglycosides not a problem with paromomycin?

A

ototoxicity

nephrotoxicity

**not absorbed

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21
Q

Most common helminth (worm) infx in the US:

A

Enterobius vermicularis

*a round worm

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22
Q

perianal pruritis

A

Enterobius vermicularis

**a round worm

23
Q

Form of E. vermicularis ingested:

A

pinworm eggs

**can remain viable on surfaces for 2-3 weeks

24
Q

Life span from egg to adult Enterobius vermicularis:

A

1-2 months –> live for 2 months as adult

25
Where/when do Enterobius vermicularis lay their eggs?
perianal region at night **larva can crawl back up for retroinfection
26
Dx for Enterobius vermicularis:
Scotch tape of anal region looking for eggs in the morning **NOT likely in stool
27
Soil transmitted round worm 9-11 mm eggs in stool can be in skin and lungs blood suckers
Necator Necator americanus/Ancylostoma duodenale hookworms**
28
Iron deficiency anemia
Necator OR Trichuris trichuria
29
Recurrent raised red rash along thighs and buttocks Autoinfection in IC pts a few mm in size
Strongolides stercoralis **a round worm
30
barrel shaped eggs in feces adults 3-5 CM finger clubbing bloody, mucus, watery diarrhea (Fe deficiency anemia)
Trichuris trichiura **a round worm
31
Huge worm (15-35 cm) not common in US 1 BILLION in tropics infected per year
Ascaris
32
Charcot-Leyden crystals eggs with THICK shells
Ascaris
33
Binds parasite B-tubulin (different than host tubulin) inhibits motor activity and metabolism
Albendazole (better for tissue) Mebendazole
34
Cholinergic antihelminth drugs cause spastic muscle contraction so parasite can be swept away
Pyrantel pamoate Levamisole **N/V, diarrhea, poorly absorbed
35
Binds glutamate gated Cl- channels worm paralysis and death by starvation Spectrum: ?
Ivermectin Nematodes - Ascaris, Strongyloides, Onchocerca
36
Typical human tape worm:
Taenia 3-10 m length
37
tapeworm beef or pork
Taenia
38
Fish tapeworm size ?
Diphyllobothrium HUGE!! up to 30 ft
39
Tapeworm of liver, lungs, brain size?
Echinococcus tiny, a few mm
40
Morphological difference between round worms and tape worms:
tape worms are SEGMENTED
41
Competes for B12 in intestine **maybe after eating uncooked fish
Diphyllobothrium
42
Stage of Taenia ingested from beef or pork?
cysticerci --> grows to tapeworm in small intestine **can become cysticerosis if migrates to muscle, brain or other tissue
43
Dogs are definitive host not really GI illness at all sheep farming cysts in organs
Echinococcus
44
Tx for tapeworms that also targets GI roundworms: MOA?
Benzimidazoles -Albendazole, Mebendazole B-tubulin binder -inhibits motor function and metabolism
45
Tapeworm drug increased permiability of parasite --> divalent cations --> contraction of worm musculature
Praziquantel
46
Cestodes?
tapeworms
47
Liver involvement RUQ pain
Entamoeba histolytica
48
Second to malaria as most devastating parasitic disease:
schistosomiasis **a fluke
49
Mechanism of disease for schistosomiasis:
IMMUNE response to eggs
50
infection --> days --> rash, itching 1-2 months --> F/C, cough, muscle aches Chronic --> abd pain, HEPATOMEGALY, bloody stool/urine increased risk of bladder cancer
schistosomiasis
51
How does Schistosoma infect humans?
lives in snails in water (sporocysts--intermediate host) free swimming cercariae leave snail and penetrate human skin get into blood and go to lungs, heart, then liver (thats where they mature) migrate to bowel and bladder 300 eggs/day to blood, can live 20 years eggs leave in feces and urine --> back to water for round 2
52
Swimmers itch
Cercarial dermatitis
53
Tx for schistosomiasis:
praziquantel same as tapeworm drug, increases permiability low efficacy against immature worms

GI (46 decks)

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