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• Entamoeba histolytica
• Giardia sp.
• Trichomonas muris
• Trypanosoma brucei
• Leishmania donovani
• Babesia canis
• Haemoproteus columbae
• Leucocytozoon smithi
• Eimeria spp.
• Isospora spp.
• Sarcocystis sp.
• Toxoplasma gondii
• Cryptosporidium parvum
• Review Question

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Card 2:1

Entamoeba histolytica - trophozoite Note the single, spherical, vesicular nucleus (containing an endosome). The cyst is the diagnostic stage in monkeys and humans, but are almost never seen in infected dogs. In dogs the trophozoite is the diagnostic stage.

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Giardia - cysts Cysts measure about 10 to 12 um in length and each contains two to four nuclei, an axostyles and a median body.

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Giardia - trophozoites This trophozoite was found in the watery feces of an infected dog by a direct smear. Normally only cysts are found in the feces. Note the shape (pear shaped), and the size (10 to 18 um in length). The internal organelles are doubled (i.e. two nuclei, 2 median bodies, etc.) and there are 8 flagella.

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Trichomonas muris This flagellate is similar in appearance to T. foetus of cattle. Note the undulating membrane and free flagella.

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Trypansoma brucei Pathogenic trypanosome of domestic animals in tropical Africa. Note the nucleus, kinetoplast, undulating membrane and the free flagellum.

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Card 2:5a

Leishmania donovani This slide is a tissue impression of the spleen (stained with Giemsa) of an infected dog.  The spleen cells have ruptured during the making of the slide, leaving behind nuclear material (green arrows).  The Leishmania amastigotes however are too small to be effected by the forces that ruptured the spleen cells so they remain intact (yellow arrows).  Note the nucleus and kinetoplast that are present in each amastigote.

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Babesia canis The trophozoites are pyriform and 4 to 5 um long, or amoeboid 2 to 4 um in diameter. They generally contain a vacuole and multiple infection of the erythrocytes is common.

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Haemoproteus columbae This blood smear shows a gametocyte which is wrapped around the nucleus of an erythrocyte (which is not distorted). Remember that the schizonts are not found in the blood cells.

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Leucocytozoon smithi - gametocyte This slide shows a typical gametocyte which has distorted the white blood cell into an elongate, elliptical body. Little evidence of the white blood cell morphology remains. Note that no schizonts appear in the blood.

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Eimeria tenella These are sporulated oocysts, note that each contains 4 sporocysts each with 2 sporozoites.

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Eimeria tenella This slide shows the 2nd generation schizonts E. tenella. In this species the 2nd generation schizont is large and subepithial in position. Note the many merozoites within the mature schizonts.

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This illustration shows the lesion site of E. tenella in the chicken - the ceca. The top image shows the swollen, thickened ceca found in an affected chicken, and the bottom illustration shows the location of the caeca in the intestinal tract. Diagnosis of coccidiosis in poultry is done by showing the presence of oocysts in the feces or other stages in the intestinal epithelium. Species identification is made by determining the location and type of lesions in the intestine.

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Card 2:11

Eimeria sp. Unporulated oocyst from the feces of a goat. Note the thinning of the wall (arrows) at one pole of the oocyst - this is the micropyle.

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Eimeria sp. This is a cross section of the intestine of a goat infected with Eimeria sp. This section shows the gametes in the epithelial cells. The majority of these gametes are macrogametes (female). The small granules within the macrogametes are assumed to form the oocyst wall after fertilization has occured.

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  Card 2:12a

Isospora felis oocyst (blue arrow, unsporulated,   about 40 µm) and a sporulated Isospora rivolta oocyst (red arrow, about 20 µm).  The oocyst of I. canis (dog) looks like that of I. felis (cat) and the oocyst of I. ohioensis (dog) is similar to that of I. rivolta (cat).

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Sarcocystis sp. This is a sporocyst recovered from the feces of a dog.

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Sarcocystis sp. A mature cyst in the muscle of the intermediate host.

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Toxoplasma gondii Sporulated and unsporulated oocyst. Oocysts sporulate within 48 hours after being passed from the cat. Note the small size (9 to 14 um) and the round shape.

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Toxoplasma gondii The tachyzoites are elongate and crescent-shaped. They measure 4 to 6 um in length.

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Toxoplasma gondii Note that this cyst contains many bradyzoites.

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Toxoplasma gondii Schizonts in the intestinal cells of a cat. Note the tachyzoites radiating from the center of the schizont.

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Cryptosporidium parvum This is a fecal smear stained by the acid fast technique. The oocysts are acid-fast and therefore stain red. Yeasts (which are about the same size as the oocysts, 5 um) stain a light blue or green (depending on the counter-stain used).

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Card 2:20

Review Question This slide shows the result of a zinc sulfate flotation of a fecal sample from an asymptomatic kitten. The object shown is 14 X 9 um. A. Identify the parasite (Genus only). B. The client's dog ate some of the kittens's feces just before this sample was collected from the litter box. Is the stage seen on this slide (red arrow) infectious to dogs? Click here for answer

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