Parasitology Exam 1 study guide.docx - Parasitology Exam 1...

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Parasitology Exam 1 study guideE ProtozoaGeneral Characteristics of ProtozoaoSingle celled Eukaryotic organismso1 nucleusomotileoOnly a small fraction are parasitic in manoGain entry to hosts 3 ways: Orally VectorSexual transmissionReproduction in ProtozoaoGeneral rule: asexual in hostoAsexual: Binary fission: one becomes twoMultiple fission: one becomes manySchizogonoyMerogonyGematogony formation of gametsoSexual: fusion of gametes (Syngamy) zygoteSeverity of Parasitic Disease: oSize of infective doseoImmune status of hostAmoebas + CiliatesMorphologyoTrophozoite – single cell, feeding + reproducing form oCyst – infective stage for new host, environmentally resistant formTransmission oDirect life cycle oCyst ingested by host Reproduction – binary fission Entamoeba (genus)E. histolytica - pathogenE. dispar – commensal E. coli – commensal E. hartmanni – commensal E. gingivalis – commensal E. histolytica Worldwide, trophozoite (motile, feeds on host cell), cyst (4 nuclei, infective stage)Host niche: large intestine and rectum
Transmission: ingestion of cyst Clinical classification – amoebas oIntestinal amoebas Asymptomatic carrier DiarrheaDysentery Chronic Asymptomatic carriers oNo clinical signs (trophozoites rapidly form cysts)oA source of infection for others (carriers shed infective cysts) Intestinal amebiasis – amebic colitis oDiarrhea – clinical sign oAcute amebic colitis (one or more days of diarrhea)oPathogenesis 1.amoeba attaches to surface of mucosal cells of large intestine 2.lyses cell3.invades 4.ulcerates5.ulcers amebic dysentery odysentery (bloody, mucoid diarrhea)otender abdomen otrophozoites only seen on fecesosevere bleeding into the gut lumen + sloughing of gut mucosa chronic amebic colitis orecurrent bouts of diarrhea (no dysentery)oabdominal pain otrophs + cysts in stool omucosal ulcerations ocomplications – gut perforation, ameboma (mass in large intestine composed oftrophozoites, WBC, and cellular debris)extraintestinal amebiasis odead end journey for parasiteotrophozoites only, no cysts ohepatic: liver abscesses (most common site)opulmonary: lung abscesses ocutaneous: skin abscessesocerebral: brain abscessesdifferential diseases – diseases with similar symptoms cutaneous amebiasis – perforation of amebic ulcer which adhere to abdominal wall Dx
intestinal omicroscopy stained fecal smear tissue biopsies stool antigen detection – rapid + reliable extra intestinal oserological test – ELISA oscans (CT, rads) – fine needle biopsy of large liver abscess or any abscess resistedto antibiotics Rxasymptomatic o

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Term
Spring
Professor
Farrar

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