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41 Cards in this Set
- Front
- Back
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entamoeba histolytica
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lyses cells in colon and feeds on contents=colonic ulcerations and dysentery; ameba; causes amebiasis
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chronic persistent giardiasis may result in
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loss of intestinal villi, malabsorption syndrome, and weight loss
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trichomoniasis causes
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sexually transmitted vaginitis and urethritis
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sporozoans
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intracellular parasites that resproduce by alternating sexual and asexual cycles
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cause large waterborne outbreaks
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giardia and cryptosporidium
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colonic ulcer shape in entamoeba histolytica
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flask-shaped that undermine mucosal epithelium
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avirulent entamoeba
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entamoeba dispar-morphologically indistinguishable from virulent strains
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transmission of entamoeba histolytica
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person to person via fecal-oral route
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2 forms of entamoeba histolytica
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trophozoite=actively growing, vegetative; cyst=sormant and highly resistant
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who tends to transmit entamoeba histolytica infection
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asymptomatic carriers who excrete durable cyst form; active diarrhea with trophozoite easily dry and are destroyed
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adherence of entamoeba histolytica
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critical surface protein or lectin to specific receptors on host cells containing digalactose residues
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damage to host cells by entamoeba histolytica
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1) receptor-mediated attachement 2) contact-dependent killing (insertion of pore-forming proteins) 3) ingestion of killed host cell
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immune host defense against entamoeba histolytica
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cell-mediated
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amebas and antibodies
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known to produce cysteine proteinase that digests secretory IgA, IgG, and other proteins involved in humoral response
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sensitive test for entamoeba histolytica
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stool immunoassay for entamoeba histolytica antigen-also distinguishes virulent vs avirulent; doesn't distinguish past vs present
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entamoeba histolytica treatment
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metronidazole (anaerobic metabolism)-not as effective to eradicate luminal forms
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what is used to treat luminal entamoeba histolytica along with metronidazole
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diloxanide, paromomycin, and diiodohydroxyquin; also treat asymptomatic patients with
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giardiasis generally infects
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other animals and infects humans accidentally; resistant to Cl-
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symptoms of giardiasis
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often localized to duodenum and jejunum with mild/persistent diarrhea; chronic can cause malabsorption
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transmission of giardiasis
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cysts in contaminated water (due to animal feces)
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how do giardia attach to epithelium
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ventral sucking disk
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appearance of giardia
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face adorned with mustachlike flagella
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how does host respond to giardia infection
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submucosal infiltrate of chronic inflammatory cells (lymphocytes mostly) and effacement of normal intestinal villi
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fat-soluble vitamins
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A, K, D, and E
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cysts of giardia
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small, ovoid, nonmotile bodies with four nuclei
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stool sample and giardia
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trophozoites rarely seen in direct stool exam and make take 3-4 exams to find a cyst
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treatment of giardia
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metronidazole-relapses occur; tinidazole and nitazoxanide alternatives
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cryptosporidium transmission
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rural areas due to greater contact with animals; spread person to person in crowded urban areas/day care centers; surface waters
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life cycle in humans with cryptosporidium
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do not invade intestinal epithelial cells, nor disseminate; life cycle in microvilli of small intestine-immunocompetent patients, only 1 or 2 life cycles
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diagnosis of cryptosporidium
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acid-fast cysts in stool
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treatment of cryptosporidium
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nitazoxanide in immunocompetent hosts
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cyclospora cayetanensis specs
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protozoal parasite resembling cryptosporidium in producing acid-fast cysts, although about 2X size
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cyclospora cayetanensis spread
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oocysts not infectious when excreted in human feces, infectious only after days/weeks incubation in environmental sites that are warm and humid
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cyclospora cayetanensis symptoms
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watery diarrhea that may be associated with loss of appetite, bloating, cramps, nausea and vomiting, fatigue, muscle aches, and low-grade fever; few days to month or longer; relapses common
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treatment of cyclospora cayetanensis
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trimethoprim-sulfamethoxazole
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Isospora belli
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protozoan that causes transient watery diarrhea in healthy pl; tropical
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microsporidia
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obligate intracellular parasites, small relative to other parasites in this chapter; lack mitochondria; prokaryotic origin
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symptomatic intestinal infection associated with what species of microsporidia
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Enterocytozoon bieneusi-transient diarrhea in immunocompenet and protracted watery diarrhea in AIDS-dissemination
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treatment of microsporidia
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common agents not effective; possibly albenazole or fumagillin
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trichomonas vaginalis vaginitis
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frothy creamy discharge; men asymptomatic
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treatment of trichomonas vaginalis
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single-dose metronidazole or tinidazole; douching with vinegar for pregnant women
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