Grouping Chart for Parasite
Eggs and CystsTrichrome stain; the trophozoite stage is most often diagnosed in a saline smears of fresh feces and looking for organisms that exhibit characteristic movement or general appearance. Trophozoites are usually found in diarrheic and mucoid fecal samples.
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Unstained saline smear (leukocyte-sized oval with curved refractory structures inside). This is the most common for to find in feces and is most easily found in a thin saline smear. Feces will be formed.
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Yeast cells are often mistaken for Giardia cysts or other parasites while examining fecal saline smears. Pollen grains plant hairs, plant cell walls, and ingested free-living organisms can also be confused for parasites.
Other pseudoparasites:
Merozoites, bradyzoites, tachyzoites, and sporozoites hemosporidians and coccidial parasites are similar in form. This image shows a sporozoite exiting from a sporocyst.
This oocyst is typical of Eimeria spp found in ruminant feces. The micropyle cap would indicate that this specimen came from sheep or goats. Cattle coccidia usually don't have micropyle caps
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This sporulated oocyst, (probably from a dog or cat) has two sporocysts which is characteristic of the genera Isospora, Toxoplasma, Levinea, Besnoitia, Frenkelia, Hammondia, and Sarcocystis.
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Trichomonad trophozoites showing typical morphology. Diagnosis is most often made from a thin saline smear of fresh feces or vaginal washings. These protozoa do not have cysts stages, and flagellated trophozoites exhibit a jerky erratic movement. Closse examination will reveal the whipping action of the anterior flagella, and a waving undulating membrane runs down the back of the organism.
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Trypanosoma cruzi from dog blood
These organisms were found in the blood of a dog from Oklahoma. Raccoons, opposums, armadillos and other wild mammals serve as reservoir hosts. The disease produced is called Chagas' disease and is often overlooked in the differential diagnosis of cardiomyopathy cases. Pseudocysts containing amastigote forms localize in the cardiac muscle.
This buffy coat smear from blood of an infected dog contains epimastigotes. This form normally occurs in arthropod vectors or in cultures maintained at ambient room temperature. In this case the organisms transformed to epimastigotes because the blood sample was kept at room temperature for more than a week.
