B5.007 Prework 2 Intestinal Protozoa Flashcards

1
Q

entamoeba histolytica

A

ameba

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2
Q

giardia intestinalis

A

flagellate

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3
Q

cryptosporidium parvum/hominis

A

gregarine

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4
Q

cyclospora cayeanensis

A

coccidia

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5
Q

trichomonas vaginalis

A

flagellate

not intestinal

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6
Q

microsporidia

A

fungus

not a protozoa

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7
Q

diagnosis of intestinal protozoa

A
eosinophilia absent (unlike helminths)
parasite in stool: O&P exam (trophozoites and cysts)
antigen detection (stool)
molecular testing
antibody detection (least useful)
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8
Q

trichomonas vaginalis life cycle

A

no cyst phase
infects squamous epithelium of urogenital tract
1. trophozoite in vaginal and prostatic secretions in urine
2. longitudinal binary fission
3. trophozoite in vagina or orifice of urethra

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9
Q

trichomonas trophozoite appearance

A
pear shaped/rounded
1 nucleus
5 flagella
undulating membrane
jerky motlity
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10
Q

trich transmission

A

sexual
2nd most common STI after HPV
3 million women acquire yearly
peak incidence 16-35

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11
Q

trich pathogenesis

A

parasites damage epithelial cells
increase risk of preterm birth
increases susceptibility to HIV

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12
Q

trich symptoms in women

A

persistent vaginitis
rarely asymptomatic
inflamed vaginal and cervical mucosa
petechial hemorrhage of vagina and cervix

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13
Q

trich symptoms in men

A

usually asymptomatic
dysuria
scant, nonpurulent discharge

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14
Q

diagnosis of trich

A

direct exam: wet mount, must view within 2 hr (20 min better), motile tichomonads
antigen detection
molecular detection (preferred)

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15
Q

trich treatment

A

metronidazole

treat sexual partner

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16
Q

entamoeba histolytica life cycle

A

cysts ingested
trophozoites excyst in small intestine
trophozoites adhere to colonic mucins
cysts and trophozoites present in feces

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17
Q

entamoeba cysts

A

1-4 nuclei

10-15 um

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18
Q

entamoeba trophozoites

A

directional motility
+/- ingested RBCs
1 nucleus
15-20 um

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19
Q

entamoeba transmission

A

fecal oral
endemic in regions with poor sanitation
mostly seen in travelers, immigrants, institutionalized

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20
Q

clinical manifestations of entamoeba

A
90% asymptomatic
incubation 2-4 weeks
4-5% dysentery (blood diarrhea w mucus)
1% ameboma
1% liver abscess
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21
Q

entamoeba path

A

mucosal ulceration with little inflammatory response

flask like large intestinal ulcers extend to submucosa

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22
Q

entamoeba extraintestinal disease

A

amoebic liver abscess: 1 or more, usually right lobe, filled with necrotic tissue, few amebae present
occasional dissemination to lungs, brain, spleen
occasional invasion of perianal skin

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23
Q

entamoeba treatment and prevention

A

metronidazole (even asymptomatic)

sanitary disposal of feces

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24
Q

giardia life cycle

A

cysts ingested
trophozoites excyst in small intestine
trophozoites remain in proximal small bowel lumen
encyst in colon; cysts and trophs shed

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25
giardia cyst
ovoid 2-4 nuclei 4 median bodies axonemes
26
giardia tophozoites
``` pear shaped 2 nuclei 2 median bodies 8 flagella ventral sucker falling leaf motility ```
27
giardia transmission
fecal oral | most common intestinal parasite in US
28
at risk for giardia
travelers (tropical), childcare, institutionalized, backpackers/campers, ski resorts, men who have sex w men
29
why is giardia easily acquired
``` low infection dose (10 cysts) environmentally hardy (resistant to chlorine, disinfectants, cold) animal reservoirs ```
30
incubations and durations of giardia
incubation 1-14 days | symptoms 1-4 weeks
31
symptoms of giardia
``` 90% asymptomatic 9% sudden onset explosive diarrhea foul smelling, greasy, floats ad pain bloating abundant gas nausea vomiting no fever ```
32
chronic giardiasis
1% have recurrent symptoms malabsorption weight loss lactose intolerance
33
pathogenesis of giardia
malabsorption of fat and carbs disaccharidase deficiency with lactose intolerance damage to microvilli, inflamm infiltrate
34
giardia diagnosis
antigen detection in stool O&P exam (min of 3 stool) jejunal biopsy
35
giardia treatment
metronizadole | test close contacts
36
giardia prevention
filter/treat water
37
life cycle of cryptosporidium
``` oocyst ingested excyst in small intestine sporozoites released sporozoites invade columnar epithelial cells mature into trophozoites oocysts shed in feces ```
38
crypto transmission
fecal oral worldwide distribution second most common intestinal parasite after giardia
39
at risk for crypto
HIV+, daycare, animal contact, sexual transmission, water
40
why is crypto easily acquired
low infectious dose (100 oocysts) | environmentally hardly- resistant to chlorine, disinfectants
41
incubation and symptoms periods of crypto
incubation- 2-10 days | symptoms 1-2 weeks
42
symptoms of crypto
``` sudden onset explosive diarrhea watery self limiting +/- dehydration, ab pain, nausea vomiting may be severe in immunocompromised ```
43
crypto histopath
intracellular extracytoplasmic trophozoites | tiny, spherical structures beneath surface of microvilli
44
direct exam of crypto
4-6 um visible in stool O&P acid fast
45
diagnosis of crypto
OK: O&P better: acid fast stain best: antigen testing
46
crypto treatment
nitazoxanide
47
crypto prevention
enteric precautions
48
cyclospora cayetanesis life cycle
oocyst ingested excyst and sporozoites invade epithelial cells excretion of unsporulated oocysts in stool
49
cyclo oocyst
8-10 um visible in stool O&P acid fast
50
cyclo transmission
``` fecal oral tropical environmental incubation associated with foodborne outbreak spring/ summer ```
51
cyclo incubation and symptoms
incubation 7 days | symptoms 10-12 weeks
52
cyclo symptoms
``` relapsing diarrhea watery self limiting +/- dehydration, ab pain, nausea, vomiting, fever worse in immunocompromised ```
53
cyclo histopath
parasite replicate within cytoplasm of enterocyte
54
cyclo direct exam
8-10 um unsporulated in stool sporulated in environment acid fast
55
cyclo diagnosis
O&P acid fast NO antigen testing
56
cyclo treatment and prevention
trimethoprim-sulfamethoxazole | food safety
57
microsporidia overview
ex parasite obligate intracellular parasitic fungi most common human pathogens: encephalitozoon, enterocytozoon
58
microsporidia life cycle
resistant spore with coiled polar tubule infective sporoplasm injected into cell via tubule mature spore ruptures cytoplasm, releasing spores
59
microsporidia opportunism
rarely infects immunocompetent significant in AIDS patients -chronic diarrhea and weight loss -dissemination to other organs
60
diagnosis of microsporidia
microscopy- trichrome stain, 1-4 um
61
microsporidia treatment
albendazole