Intestinal Protozoa: Flagellates and Ciliates

Question 1

Life cycle: Trophs are passed in stool. Transformation into cysts.
Route of infection: contaminated food or water
Geography: worldwide
Specimen source: stool sample
Morphology: Cysts; 8-19 mcm, prominent axostyle, 4 nuclei. Trophs; 10-20 mcm, axostyle, 2 nuclei, paranasal body, 4 pairs of flagella, suctorial disc
Lab tests: Ova and parasite exam - direct, concentrate, and permanent stain. EIA/ELISA, Giardia antigen test, duodenal aspirate, Entero-Test, fluorescent antibody test
Pathology: diarrhea, eosinophilia

Answer 1

Giardia lamblia

Question 2

Life cycle: Trophs are passed in stool. Transformation into cysts.
Route of infection: contaminated food or water
Geography: worldwide
Specimen source: stool sample
Morphology: Cysts; 6-10 mcm, single nucleus, lemon shape with anterior knob. Trophs; 6-24 mcm, single nucleus, 3 anterior flagella, parabasal body
Lab tests: Ova and parasite exam - direct, concentrate, and permanent stain. EIA/ELISA, Giardia antigen test, duodenal aspirate, Entero-Test, fluorescent antibody test
Pathology: Nonpathogenic

Answer 2

Chilomastix mesnili

Question 3

Life cycle: Trophs in feces. Transmission via fecal-oral route. Trophozoites ingested. Binary fission in the intestines
Route of infection: contaminated food or water. Possibly via helminth ova
Geography: worldwide
Specimen source: stool sample
Morphology: 5-12 mcm, 2 nuclei, Large karyosome and chromatin ring not visible, broad flat pseudopods, no cyst stage
Lab tests: Ova and parasite exam - direct, concentrate, and permanent stain. EIA/ELISA, Giardia antigen test, duodenal aspirate, Entero-Test, fluorescent antibody test
Pathology: It is not well defined. Intermittent diarrhea, abdominal pain, nausea, anorexia, and unexplained eosinophilia, and Charcot-Leyden crystals have been associated with it.

Answer 3

Dientamoeba fragilis

Question 4

Life cycle: Trophs are passed in stool. Transformation into cysts.
Route of infection: contaminated food or water
Geography: worldwide
Specimen source: stool sample
Morphology: 5-15 mcm, undulating membrane, 5 anterior flagella, 1 posterior flagella, axostyle, single, large nucleus, no known cyst stage
Lab test: Ova and parasite exam - direct, concentrate, and permanent stain. EIA/ELISA, Giardia antigen test, duodenal aspirate, Entero-Test, fluorescent antibody test
Pathology: considered nonpathogenic, but often recovered from diarrheic stools

Answer 4

Trichomonas hominis

Question 5

Life cycle: Cyst is the infectious stage and transforms into trophozoites in the intestines
Route of infection: contaminated food or water
Geography: worldwide
Specimen source: stool sample
Morphology: trophs; 50-10 mcm, single, large macronucleus, cilia covers entire body. cysts; 50-70 mcm, single large macronucleus, contains food vacuoles
Lab test: Hematoxylin and Eosin may be better than trichrome or iron hematoxylin, wet prep, Ova and parasite exam - direct, concentrate, and permanent stain. EIA/ELISA, Giardia antigen test, duodenal aspirate, Entero-Test, fluorescent antibody test
Pathology: Asymptomatic. Symptomatic - diarrhea, hysentery, abscesses, extra intestinal rare - bronchioalveolar lavage, urinary tract infection, vaginitis

Answer 5

Balantidium coli