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afebrile diarrhea caused by parasites Flashcards

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1
Q

definitive host

A

harbors sexual stage of parasite -where they produce eggs

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2
Q

intermediate host

A

harbors asexual stage

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3
Q

monoecious

A

both male and female organs: “hermaphrodite”

vs. diocious

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4
Q

protozoan parasites

A

unicellular, eukaryotic
at least 1 nucleus
motile: cilia, flagella, +/- pseudopodia, sexual/asexual repro

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5
Q

helminths

A

worms:
nematodes
cestodes
trematodes

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6
Q

nematodes

A

non-segmented roundworms

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7
Q

cestodes

A

flat, segmented bodies with head (scolex) and segments (proglattids)
also called tapeworms

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8
Q

trematodes

A

flukes, nonsegmented flatworms

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9
Q

arthropods

A

fleas ticks, lice, etc

important VECTORS of parasitic, viral, bac diseases

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10
Q

both Giardia and Cryptosporidium parvum are acq. via..

A

food and water contaminated w. human/animal feces

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11
Q

infective stage for Giardia ?

for Crypto?

A

cyst -G

oocyst -C

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12
Q

both Giardia cysts and *Crypto oocytes are resistant to..

A

Chlorine (typical levels)

*both assoc with swimming rel. GE outbreaks

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13
Q

reservoir for both G and C

A

humans and animals

worldwide

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14
Q

G and C seasonality

A

late summer, early fall

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15
Q

G and C infectious dose?

A

low!

person-person spread is important (1-1000!!!)

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16
Q

which one (G/C) is an EC pathogen and which is an obligate IC invasive parasite?

A

Giardia: EC
Crypto: IC

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17
Q

Crypto parvum may be found ?? in who ?? and produces ??

A

anywhere in GIT of immunocomps, causes cholera-like illness

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18
Q

Giardia and Cryptosporidium ddx

A

amebiasis, bac overgrowth, Crohn ileitis, Cryptosporidium enteritis?, IBS, sprue, celiac or topical sprue

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19
Q

Giardia lamblia

2 forms:

A

flagellated protozoan

2 forms: trophozoite and cyst

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20
Q

Giardia trophozoite

motility?
inhabits?

A 
pear/tear shape, "spook"
2 nuclei, 4 pairs of flagella
motile: "falling leaf" 
found in duodenum and upper jejunum
(what you will see in diarrhea)
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21
Q

Giardia cyst

A

infectious form
formed as trophozoite dehydrates with feces as it transits large bowel
oval w. tough hyaline wall and 4 nuclei

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22
Q

what form of Giardia is in environment and resistant?

A

cyst:

can survived in moderately moist cool environments

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23
Q

most common human intestinal parasite ID’d in US?

how ??

A

Giardia

community outbreaks when fecally contam. central water supplies are ineffectively treated or pre-filtered

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24
Q

Giardia reservior

transmission

A

animals: beavers, cototes, cattle, cats, dogs
humans
fecal contam of drinking water, sometimes food
infected ppl may poop out 10^8-10^9 cysts/day may for months

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25
Giardia associations
MALES* at higher risk no seasonality places: St. Petersburg, New Zealand (waterfalls)
26
ppl @ risk for Giardia
``` travelers to endemic areas child care kiddos close contacts drinking contam drinking/"outside" water outdoor activites: backpack/camp: unfiltered water contact with infected animas men sex w. men ```
27
Giardia lamblia life cycle: trophozoites are... grow/replicate where? then do what??
noninvasive small bowel attach to intestinal microvillus surface with sucking disks or move about free in lumen
28
Giardia: how transform from tropho to cysts
dehydrates with poop as it goes from small to large bowel (encystment)
29
Giardia cysts found ??? | trophozites in ??
hard, formed stools | diarrhea
30
host ingests this form of Giardia via ??
cysts | contaminated food, drink, high-risk sex (fecal-oral)
31
Giardia histo changes: if trophos adhere.. called what ???
cause villous atrophy, crypt hyperplasia, epi damage, extensive infiltration of LP by plasma cells, lymphos, PMNs "lawnmower effect"
32
Giardia-inf. pt symptoms are caused by....
mechanical blockage of absorption of fat and protein
33
asymptomatic Giardia carriers do not have bowel histo changes but ???
poop out cysts at constant level or intermittently | unknown mech, homeostasis btw host imm. sys and parasite
34
Giardia immunity
secretory IgA Abs | B cell-independent mechanism also: parasite eradication (poorly understood)
35
Giardia acute infection onset presentation? fever?
9-15 days incubation watery foul-smelling diarrhea w. nausea, abd distension, flatulence, mostly afebrile (uncommon low-grade) variable presentation in regard to other symptoms
36
how long does acute Giardia last? | additional effect?
3-4 days | lose 10 lbs (average)
37
Giardia chronic infection onset persist up to ? pt may not?? symptoms
follows acute 9 yrs remember initial episode greasy, foul-smelling stool w. wl and malabsorption
38
Giardia dx: lab
symptoms vary so lab findings 3 specimens 1/day or alt. days cysts or trophos depending on poop type organisms are shed periodically (>6 tests may have -)
39
if Giardia poop can't be sampled quickly
place in fixative: polyvinyl alcohol, sep container of 10% formalin then tested with EIA kit
40
other Giardia dx methods
-endoscopy: collect tissue/fluid specimens -enterotest: "duodenal string test" left 4 hrs, moves into intestine, pulled back up, expressed (addition not replacement of still sample) -DFA -PCR
41
Giardia tx
``` quniacrine (anti-protozoal) metronidazole furazolidone albendazole *all have some toxicity/side effects, monitor* *follow-up with stool samples* ```
42
furazolidone mech
cross-link DNA, tx diarrhea and enteritis from bac/protozoal inf.
43
albendazole
vermicidal, causes degen. alterations in tegument and intestinal cells of worm by binding to colchicine-sensitive site of tubulin-->inhibs its polymerization or assembly into microtubules-->impaired glucose uptake by larval and adult stages of susceptible parasites, depletes glycogen stores degen. changes in ER, mitochondria of germ layer, subsequent release of lysosomes-->dec. production of ATP-->diminished energy, dies
44
Giardia prev/ppx
proper disposal of feces good personal hygiene only drinking tx water
45
Cryptosporidiosis parvum characteristics stains with??
obligate IC protozoan parasite, minimally invasive small (4-6 micron) Giemsa, H&E, *acid-fast*
46
Crypto outbreaks occur from
contaminated central water supplies that are ineffectively tx or pre-filtered *most frequently recognized cause of recreational (outside) water-assoc. outbreaks of gastroenteritis* particularly in treated venues (not Giardia??)
47
Crypto reservoir? | transmitted via ??
zoonosis: mammals, birds, ruminants | fecal contamination of drinking water (sometimes food)
48
Crypto-infected ppl poop out how many?? oocysts in single poop, also excrete inf. oocytes up to ?? days after diarrhea stops
10^8-10^9
49
Crypto gender, season assoc.
none
50
Cryptosporidiosis risk factors
poor sanitation, poor water supply, poor personal hygiene | day care, inf. fam member, oral-anal sex
51
Crypto high risk groups
travelers to high endemic areas, hikers, campers (drinking streams) men sex w. men
52
pops at risk for severe disease from Crypto
AIDS pts, other sev. T cell comps Antiretroviral drugs correlate with dis. protection hypogammaglobulinemic, IgA deficient ppl *both T and B cell immunity involved*
53
Crypto oocyte are ?? than Giardia lamblia
MORE resistant to chlorine and removal by flocculation and filtration water sanitation methods hyperchlorination (9600 ppm) somewhat effective (640x Giardia-cidal concentration!!)
54
Crypto infective stage..
sporulated oocyst containing four motile sporozoites reaches upper small bowel-->sporozoites get out via proteases and bile salts-->attach and infect superficial surfaces of sm. intestine epi (brush border)
55
after infect sm. intestinal epi, Crypto divide asexually once (intracell.) to form ??
eight merozoites- in a unique vacuole IC but extracytoplasmic @ cell apex released from intestinal milieu to infect other epithelial cells
56
Crypto oocysts formed via | then ??
sexual reproduction: micro or macro: gametogenesis | "passed" and either autoinfect host or pooped out-resistant to outside environment
57
Crypto vs. immunocompetent host: infects where ?? | limited to ??
infects jejunum | replication restricted to epi cells of microvillous border of upper intestinal tract
58
Crypto vs. imm.compromised, esp. AIDs pt: org found where ??
virtually entire GIT, liver, pancreas | *greatly exacerbated disease*
59
Crypto histo changes
villous atropy, crypt enlargement, mononuclear infiltrates in LP
60
Crypto path suggests involvement of ?? bc org induces apoptosis in neighboring cells (cause of villous atrophy)
cholera-like toxin
61
Crypto immunity: ??? appear to control replication
TH1 and IgA
62
Crypto signs and symps: onset?? | presentation?
7-10 day incubation may be asymptomatic, acute self-limiting diarrhea, or persistent diarrhea most common: profuse *explosive* watery diarrhea +/- vomiting, flatulence, abd. pain, cramping
63
Crypto presentation: fever? stools/day ?? duration ?? self limiting??
1/3 with low grade fever 12 stools/day (median) 2 wk duration, is self limiting
64
Crypto presentation in AIDS pts: duration?
prolonged, chronic diarrhea lasting >2 mos | some: sev. cholera-like diarrhea with wl, 2L watery stools/day! (0.15 L/day normal)
65
Crypto dx
acid fast oocytes in stool (special order for AF on O&P) DFA *sn Ag-capture ELISA enterotest
66
Crypto tx abx? however....
mostly supportive: fluid and e-lyte replacement, nutrition, antidiarrheal agents??(usually contraindicated) nitazoxanide: only one approved in US (>1yo, not proven effected for immune compromised)
67
Isospora belli actual name... | clinically indistinguishable from ??
Cytoisospora belli | Crypto
68
Cytoisospora belli defining feature..
respond promptly to tx with TMP-SMX
69
pts who have AIDS + Cytoisospora belli have a ??? therefore ??
high release rate after complete remission | need to be maintained on suppressive therapy
70
Cytoisospora belli dx blood?
``` clinical, epi, dx tests *peripheral eosinophilia* stool specimens: large oocytes on modified AF stains Charcot Leyden crystals in poop PMS NOT observed in poop NO serology ```
71
Blastocystis hominid clinically indistinguishable from ??
Crypto | protozoan pathogen, can be carried asymptomatically
72
most common cause of chronic diarrhea in HIV+ pt?? | which are what?
microsporidia | fungal pathogens
73
most common microsporidia | also most common microsporidian causing enteritis in AIDS pts
Enterocytozoan bieneusi
74
Enterocytozoan bieneusi
zoonotic obligate IC pathogen (all microspor)
75
Enterocytozoan bieneusi infectious stage size comparison?? infectious mechanism??
spore smaller than cyclospora, crypto (protozoa>fungi) has a coiled polar tubule, extrustion mechanism for injecting contents of infective spore into host cells (dx for microsporidial infections)
76
Enterocytozoan bieneusi affects who...
about 50% of AIDS pts have microspor. inf-->dev. chronic diarrhea also traveler's diarrhea, kissods, org transplant recipients, oldies
77
Enterocytozoan bieneusi transmission | can survive??
directly human-human | can survived in water and food -found in surface water used for drinking
78
Enterocytozoan bieneusi associations
no gender, no seasonality assoc
79
Enterocytozoan bieneusi risk factors
AIDS, immunocompromis | *rarely* causes hyperacute diarrhea in immunocompetent ppl
80
Enterocytozoan bieneusi infection occurs when this happens to host cells
introduction of infective sporoplasm thru polar tubule-->microspor. multiply extensively within host cytoplasm
81
Enterocytozoan bieneusi immunity
T cells (CMI, why AIDS pts with low CD4+ are infected)
82
Enterocytozoan bieneusi s/s
diarrhea, acalculous cholecystitis
83
Enterocytozoan bieneusi dx
standard O&P concentration | recommended: modified trichrome stain
84
Enterocytozoan bieneusi tx
albendazole
85
Cyclospora spp. *disclaimer*
low grade fever is possible
86
Cyclospora is like Crypto how so??
causes similar diarrhea- normal in competent ppl, *esp. dangerous in AIDs pts* mildly AF+ and have EC as well as IC existence
87
Cyclospora occurs in who, where ?? | Chicago outbreaks linked to??
natives and traveler to Asia and S. america contam. drinking water, imported fruit (rasp/strawberries) Chicago hospital diarrhea >9 wks in half! (tap water)
88
Cyclospora age and gender assoc.
NONE
89
Cyclospora seasonality
warm and rainy seasons
90
Cyclospora risk factors
US outbreaks: imported fruit (berries)
91
Cyclospora oocyst is ?? when passed in stools | **different from Crypto**
NOT INFECTIVE | therefore, NO fecal-oral transmission
92
Cyclospora sporulation...
occurs in environment after days-wks @ 22-32 degrees-->division into 2 sporocysts (each have 2 elongate sporozoites)
93
?? can serve as a vehicle for transmission of Cyclospora oocytes
fresh produce and water | therefore can be ingested
94
Cyclospora oocyts ?? in the GIT
"excyst"-->freeing the sporozoites-->which invade epi cells of sm. intestine
95
once inside epi cells of sm. intestine, Cyclospora sporozoites do what ??
undergo axexula multiplication and sexual dev.-->mature into oocysts-->pooped out
96
Cyclospora immunity
unknown
97
Cyclospora onset? presenstation?? fever?
1 week incubation (infects sm. intestine) watery diarrhea, frequent, often explosive BMs may have loss of appetite, substantial wl, bloating, inc. gas, stomach cramps, N/V muscle aches, fatigue *may have low-grade fever*
98
some Cyclospora-inf. ppl are
asymptomatic
99
if Cyclospora not tx, may last how long ?
few days-->month or longer! | may relapse
100
Cyclospora dx | size comparison to Crypto??
oocytes LARGER than Crypto oocytes autofluoresce under UV *Crypto doesn't* modified AF stain (unstained (wrinkled)-light pink-deep red) -wrinkliness of oocyst wall helps distinguish from artifact
101
Cyclospora ddx
Cypto, Giardia
102
Cyclospora tx
TMP-SMX *unlike Crypto*
103
how TMP-SMX is effective
sulfamethoxazole: acts like substrate inhib of dihypropteroate synthetase via comp. inhib of p-aminobenzoic acid PABA (it's an analog) TMP: interferes with bac DHF reductase, inhib syn. of THF
104
how to prev. cyclospora
clean yo fruit!

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