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22 Cards in this Set
- Front
- Back
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Troph stage
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Within host
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Cyst stage
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In environment, withstand changes; activated by pH in stomach
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Trophozoite characteristics
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4 pairs of flagella
2 nuclei adhesive disc SHED IN ACTIVE CASE |
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Cyst characteristics
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-4 nuclei
-SHED by active and chronic (more of a problem, infectious) |
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Symptoms of giardiasis
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Watery diarrhea w/o blood or pus
-recurrent episodes common -inflammatory cells not in stool, but chronic submucosal inflammation -steatorrhea (fat in stool) -malabsorption, esp. of fat-soluble vitamins |
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Giardia Transmission
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-Contaminated water (cysts chlorine resistant)
-person to person, fomites -food contaminated with cysts -animals reservoirs -small infectious dose (hand-to-hand) |
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Giardia reproduction
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asexual
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Immunity to Giardia infections?
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Some acquired immunity, usually self-limiting;
can be worse in some forms of immunodeficiency |
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Entamoeba histolytica life stages
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-pathogenic multiplying stage
-single nucleus with central nucleolus, ingested erythrocytes -Actively shed, environmentally fragile |
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Transmission
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excreted in chronic case, endures in environment (E.histo survives wide range of climates)
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Damage from E.histolytica
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-degrades mucin layer, allowing access to epithelium
-direct amoeba-cell contact -contact dependent killing -ingestion of killed host cell by amoeba |
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3 possible outcomes of E.histolytica
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non-invasive (90%): trophs remain in lumen
Intestinal: trophozoites invade mucosa, cause ulcer Extra-intestinal: disseminates to liver, brain, lung |
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Dx of E. histolytica
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Exam of stool, esp. if mucus from ulcers
-trophs with ingested erythrocytes -morphologically same as E.dispar -Antigen detection or DNA works |
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What do ulcers in amebic dystentery look like?
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Flask-shaped, undermining
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Amebic liver abscesses present how?
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Enlarged on CT, can be asymptomatic in terms of jaundice, can lead to death after months-year or two.
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Immune response to E. histolytica
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Involves host factors, cell-mediated immunity
-Ameoba kill neutrophils and non-activated macrophages -HIgh titer of serum Ab may be present, but not protective |
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Tx for amebiasis and Amebic liver abscess
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Metronidazole (penetrates tissue well, good for invasive disease)
-others may be used in lumen |
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cryptosporidiosis origins
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drinking water, daycare, cattle, rec water
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cryptosporidium stain used
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acid fast stain
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Transmission of cyclospora
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Acquired during tropical travel/fruits/veggies
-Cyst must mature, so no person-to-person transmission -only human host |
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How is toxoplasma acquired?
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Ingestion, but doesn't cause intestinal disease
-areas of concern include congenital transmission and immunocompromised |
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2 ways to become infected with toxoplasma
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handling litter boxes and eating less cooked meat.
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