Miscellaneous Intestinal and Tissue Protozoa Flashcards
Life cycle: Oocyst exists the host. Contamination of water and food with oocysts. Oocyst ingested by the host
Route of infection: fecal oral route. Auto-infection
Geography: waterborne outbreaks
Specimen source: stool sample
Morphology: trophozoites are rarely seen. Cysts; oocysts are generally round, 4-6 mcm, each mature oocyst contains sporozoites
Lab tests: Concentrate or Sheather’s sugar flotation method- not used much anymore; immunoassay, direct and indirect florescent antibody tests, modified acid fast stain
Pathology: Asymptomatic, immunocompetent - self limiting. Symptomatic - water diarrhea, dehydration. Chronic infection in immunocompromised: extra intestinal infection, respiratory infection, death
Cryptosporidium hominis and Cryptosporidium parvum
Life cycle: Oocysts in feces. Immature oocysts transform with sporoblasts and sporocysts. Mature oocysts with sporozoites in intestine.
Route of infection: ingestion of oocysts
Geography: worldwide
Specimen source: stool sample
Morphology: oocysts; 20-33 by 10-19 mcm
Lab tests: Modified acid fast stain, (Sheather’s sugar flotation - old method)
Pathology: Asymptomatic, immunocompetent - self limiting. Symptomatic, immunocompromised patient - anorexia, nausea, abdominal pain, diarrhea, possibly malabsorption, eosinophilia
Isospora belli
Life cycle: two host life cycle
Route of infection: Contaminated meat - ingest sarcocyst and it goes to oocyst in our GI tract, we are adult host. Contaminated food or water - ingest sporocyst and it goes to sarcocyst in our tissue, we are intermediate host
Geography: worldwide
Specimen source: stool sample
Morphology: sporocyst- 9-16 mcm
Lab test: modified acid fast stain
Pathology: fever, diarrhea, abdominal pain
Sarcocystis species
Life cycle: Excretion of unsporulated oocysts in the stool. Environmental contamination. Sporulated oocysts in the environment. Oocyst sporulation enter the food chain. Ingestion of contaminated food/water
Route of infection: contaminated food or water:
Geography: worldwide
Specimen source: stool sample
Morphology: wet mounts- nonrefractile spheres - 8-10 mcm
Lab test: trichrome - ghost cells, modified acid fast - variable stain
Pathology: self limiting - explosive, watery diarrhea. immunocompromised host - anorexia, fatigue
Cyclospora cayetanensis
Life cycle: Spores enter the cells
Route of infection: Contaminated food/water
Geography: worldwide
Specimen source: stool sample
Morphology: spores 1.5-4 mcm (humans 1.5-2 mcm)
Lab tests: modified trichrome (chromotrope 2R), modified acid fast, silver stain, gold standard: electron microscopy and biopsy
Pathology: severe diarrhea, weight loss, cachexia - in immunocompromised
Microsporidia group
Life cycle: Cysts transform into trophs, then flagellated forms in water. Then enter through the olfactory neuroepithelium.
Route of infection: contaminated water via nasal passages
Geography: worldwide
Specimen source: cerebral spinal fluid
Morphology: 7-35 mcm
Lab test: CSF stained with Wright stain/Wright-Giemsa stain, or a wet prep. Growth on media: requires living cells (bacterial or cell culture; does not grow with >0.4% NaCl)
Pathology: primary amoebic meningitis (PAM)
Naegleria fowleri
Life cycle: Cysts transform into trophs through mitosis. Then enter through lower respiratory tract or through broken skin
Route of infection: contaminated water
Geography: worldwide
Specimen source: corneal scrapings
Morphology: cysts; 9-27 mcm, double walled, hexagonal. trophs; 15-25 mcm, large karyosome.
Lab test: CSF stains - similar to Naegleria testing, tissue stains - PAS, hematoxylin and eosin, calcofluor white. growth on media; may grow with out bacteria; not affected by 0.85% NaCl.
Pathology: blindness, chronic form of meningioencephalitis (granulomatous amebic meningitis (GAM)) - immunocompromised
Acanthamoeba sp.
Life cycle: Troph in vaginal and prostatic secretions and urine, Multiplies by longitudinal binary fission. Troph in vagina or office of urethra
Route of infection: sexual intercourse
Geography: worldwide
Specimen source: urine, vaginal swab
Morphology: 7-23 mcm, single large nucleus, undulating membrane, 4 anterior flagella, axostyle often projects terminally, cytostome very inconspicuous, no known cyst stage
Lab tests: wet prep, culture media, molecular tests
Pathology: female- itching, burning. male - asymptomatic. treat both partners
Trichomonas vaginalis
Life cycle: Fecal oocysts from cats contaminate food or water.
Route of infection: contaminated food/water
Geography: worldwide
Specimen source for antibody: serum sample - serology; immunology test. For tachyzoites/trophs: CSF
Morphology: crescent shape, 4-8 mcm.
Lab tests: Wright-Giemsa stain, bronchoalveolar lavage fluid, amniotic fluid - Molecular/PCR techniques
Pathology: children, adults - infections mononucleosis like syndrome. fetus - stillborn, mental disabilities, blindness. immunocompromised - CNS disease
Toxoplasma gondii
