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Diarrheagenic Protozoan Flashcards

1
Q

Acquiring Giardiasis

A

zoonosis - beaver, dogs, cats, and primates

drinking contaminated drinking water

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2
Q

At risk for giardia

A 
children
immoncompromised
day care workers
backpackers/campers
drink shallow well water
oral sex
travel
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3
Q

What causes giardiasis

A

G. Lamblia (G. intestinalis)

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4
Q

Most commonly identified intestinal parasite in the world

A

G. lamblia

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5
Q

G. lamblia description

A

flagellate protozoan; no intermediate hosts required

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6
Q

Morph stages of g. lamblia

A

Trophozoite, cyst (infective)

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7
Q

Trophozoite of g. lamblia

A

exists freely in small intestine; TEAR DROP W/ BILOBED VENTRAL DISCS, FLAGELLA AND 2 NUCLEI; does not invade tissue/RBC; feeds on mucous

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8
Q

Cyst of g. lamblia

A

form passed into environment;
oval, hyaline wall
4 nuclei when mature
1 cyst = 2 trophozoites

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9
Q

Giardia life cycle:

A

ingest cyst –> encystation in stomach (acid/enzymes) –> trophozoites (pathogenic) pass into small bowel where they divide quickly (9-12 hrs) –> trophozoites in large bowel encyst in neutral pH and bile –> cyst passed to environment

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10
Q

Epidemiology of Giardiasis

A

highly contagious
drinking water contaminated w/ feces
Children/developing countries (June-Oct)
Rocky Mountains

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11
Q

Infective dose of g. lmablia

A

10-25 cysts (>25% = 100% infection rate); 2 week incubation; can be STI

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12
Q

Sx of giardia

A 
Watery Diarrhea (NO BLOOD)
Stomach pain/anorexia
B12 Deficiency (malabsorption)
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13
Q

Virulence of G. lamblia

A

ventral disc imprints on intestinal mucosa – damages mucosa by flattening vili (leads to malabsorption)

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14
Q

Dx of g. lamblia

A

O&P exam/stool sample

ELISA - detects GSA65 (problem: antibodies carried >2 years in humans)

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15
Q

Prognosis of G. lamblia

A 
excellent
most pt. asymptomatic and self-limiting
weight loss, growth retardation
re-infection are possible 
Mortality rare = dehydration
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16
Q

Protozoan illness that can result in colitis and liver abscess

A

Amoebiasis

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17
Q

Cause of amoebiasis

A

E. hysitolytica

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18
Q

Species of entamoeba

A

many are nonpathogenic; E. histolytica is only one that causes disease; E. dispar is commensal (HIV positive patients)

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19
Q

Causes wide spectrum of illness

A

E. histolytica (intestinal and extraintestinal)

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20
Q

Morph of E. histolytica

A

Trophozoite (invasive, pathogenic), cyst (infective)

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21
Q

Trophozoite of E. histlytica

A 
1 nucleus
non-flagellated
feeds (invades tissue/RBC)
pseudopod-forming
invasive and pathogenic
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22
Q

Cyst of E. histolytica

A

round/oval; 4 nuclei

infectious stage

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23
Q

Life cycle of E.histolytica

A

ingest cyst –> excystation in colon –> forms highly motil trophozoites –> colonizes the mucosa of the colon (encyst and pass in feces OR invade intestinal mucosal barrier and go into bloodstream (dissemination))

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24
Q

Dissemination

A

E. histolytica invading and going into bloodstream

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25
Epidemiology of Amoebiasis
most prevalent in tropical/subtropical fecal contamination of watter and food causes more deaths that any parasite other than malaria and shistosomiasis reportable disease
26
High risk for amoebiasis
``` children pregnant long term steroids malnourished immoncompromised institutionalized oral-anal sex ```
27
Incubation period of amoebiasis
SHORT- 10 days (compared to 2 weeks for giardia)
28
S/sx of Amoebiasis
``` BLOODY STOOLS fever, vomiting, weight loss Extraintestinal- ulcers (RUQ pain) Death from peritonitis, cardiac failure and exhaution anemia (destroys RBC) ```
29
Virulence factors of amoebiasis
"lets form a PAC...LPAC) lectin - assist w/ adhesion phospholipases amoebapore- active peptide released to insert ion channel into host cell lipid struction (lysis host cell) cystein proteases (degrade mucus/immunity, antibody, complements, cellular matrix)
30
Dx of amoebiasis
trophozoites or cysts in stool radiology (extraintestinal)- CT/MRI ELISA- differentiates E. histolytica from E. dispar PCR
31
Tx of amoebiasis
metro/tinidazole + iodoquinol | may need surgical repair of abscesses
32
Non medical tx of amoebiasis
purified water (cysts resistant to Chlorine!!!!) - boiling, iodine, bottled
33
Resistant to chlorine
amoebiasis
34
non-bloody, watery stools
Giardia
35
Cryptosporidiosis cause
at least 15 species (hominis and parvum) hominis- humans only parvum- bovine and humans
36
Prognosis of cyrpto
self-limiting in healthy | serious in immunocompromised (aids)
37
Morph of Cryptosporidium
oocysts & sporozoites
38
Oocysts of crypto
contain 4 sporozoites; infectious stage; does not multiply outside of host; asexual and sexual reproduction in host (sexual = evolution)
39
Sporozoites
motile | bind receptors on surface of intestinal epithelial cells
40
life cycle of crypto
ingest oocytes --> activated to release 4 infective sporozoites --> bind receptors on intestinal epithelial cells --> ingested into parasitophorous vacuole --> inside epithelial cell, parasite undergoes sexual/asexual reproduction to form more oocysts (thin/thick walled oocysts) --> oocyst shedding
41
Thin walled oocysts
asexual; lead to reinfection of host
42
Thick walled oocysts
sexual; shed into environment
43
auto-infection possible
crypto (thin-walled)
44
Parasitophorous vacuole
produced by crypto; near surface of epithelial cell, separated from cytoplasm by dense layer; protects crypto
45
2 nuclei, flagella
giardia
46
parasitophorous vacuole
crypto
47
1 nuclei, no flagella
amoebiasis
48
Epidemiology of crypto
fecal-oral contamination sporadic cases from contaminated water/food -- cows, recreational water (prevalent in swimmers/pools) Associated with AIDS developing countries
49
People most likely to get crypto
AIDS, swimmers, work w/ cows
50
Pathophys of crypto
highly infectious (10 oocysts; infective immediatly after excretion) 5-10 incubation infection difficult to treat (vacuoles) Infection: due to increased intestinal permeability, chloride secretion and malabsorption
51
Sx of crypto
WATERY DIARRHEA patient severely wasted lasts ~2 weeks (self-limiting in immunocompetant) Immunocompromised: bad prognosis if CD4 low, pancreatitis, severe weight loss
52
Dx of crypto
oocysts in stool (zinc sulfate centrifugal flotation), IMMUNOFLUORESCENCE, acid fast oocysts are round, ELISA
53
small, oval and acid fast
Crypto
54
Linked to patients in latin america
cyclosporiasis
55
Cause of cyclosporiasis
cyclospora cayetanensis
56
Autofluorescent oocyst
Cyclosporiasis (much larger oocysts than crypto)
57
how do you get cyclospora?
ingest oocyst in contaminated water and imported foods (fresh fruit and veggies)
58
Life cycle of cyclospora
ingest oocyst --> similar progression; resistant to chlorine Oocysts shed in feces: MUST SPORULATE IN THE ENVIRONMENT (days-- reinfection rare)
59
Resistant to chlorine
Cryptosporidium, cyclospora
60
Presentation of cyclospora
EXPLOSIVE, non-blood watery diarrhea
61
Dx of cyclospora
Large oocyst in stool samle (difficult due to low #'s in stool, may have to repeat several days); ACID FAST POSITIVE, AUTOFLOURESCENT OOCYTE; PCR
62
Blastocystis hominis
polymorphic; ingest cyst from contaminated food/water (animal feces); LARGE CENTRAL VACUOLE, MULTIPLE NUECLEI AROUND RIM
63
Balantidium Coli
large intestine microbe (zoonotic: pigs); can result in GUT PERFORATION Tropho and cyst forms: contains MACRONUCLEUS; cilia evident on trophozoite

Micro (3 decks)

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