Flagellates​

Giardia

Cyst of Giardia sp. in a fecal preparation stained with iodine. Cysts of Giardia sp. are 9-13 x 7-9 µm and typically ovoid. Note the 4 nuclei, 2 median bodies, and axostyles within the cyst shown.

Trophozoite of Giardia sp. in a direct fecal smear from an infected dog. Trophozoites are 12-17 X 7-10 µm and are tear drop shaped with 8 flagella, 2 nuclei, and 2 median bodies.

Cysts of Giardia duodenalis recovered on fecal float from a dog. This image was taken with the 40X objective allowing more details to be seen. Giardia sp. cysts are 9-13 x 7-9 µm and typically ovoid. When intact, each cyst can be seen to contain axostyles, median bodies, and 2 to 4 nuclei.

Cysts of Giardia duodenalis recovered on fecal float from a dog. This image was taken with the 20X objective and shows numerous collapsed cysts and a few that have not yet collapsed.

Histomonas meleagridis

Histologic preparation showing amoeboid stage of Histomonas meleagridis, causative agent of blackhead disease in turkeys.

Lesions on turkey liver due to histomoniasis and secondary bacterial infection. Characteristic multifocal white pinpoint lesions can be seen around multiple dark, slightly depressed areas on a generally enlarged liver. Without secondary bacterial infection, Histomonas infections are only mildly pathogenic. In turkey flocks not on prophylactic antibiotics, histomoniasis mortality rates may reach 100%.

Leishmania infantum

Amastigotes of Leishmania infantum within macrophages in a Romanowsky stained spleen impression smear from a dog. Note darkly staining kinetoplasts and nuclei within the ovoid amastigote bodies.

Cutaneous leishmaniasis lesion in a brown rat. ​

Trypanosoma cruzi

Trypomastigotes of Trypanosoma cruzi in a Romanowsky stained blood smear. Note the darkly staining kinetoplasts and nuclei and the undulating membranes.

A collection of Trypanosoma cruzi amastigotes seen within a cardiac muscle cell. Replication of Trypanosoma cruzi takes place as intracellular binary fission of amastigotes, within the cells of the reticuloendothelial system and striated muscle.

Trypanosoma equiperdum

Trypomastigote of Trypanosoma equiperdum, causative agent of dourine in horses, in a Romanowsky stained blood film. This trypanosome is unique in that it is sexually transmitted and is not known to require an arthropod host for development.

Trypanosoma lewisi

Trypanosoma lewisi trypomastigotes in a blood smear from a rat. Transmitted by the rat flea Nosopsyllus fasciatus, Trypanosoma lewisi is generally non-pathogenic.

Trypanosoma theileria

Trypanosoma theileri trypomastigote, a hemoflagellate of cattle, transmitted and hosted by tabanid flies. Trypanosoma theileri trypamastigotes are among the largest, ranging from 60 - 120 μm in length, with a well developed undulating membrane and a well defined free flagellum.

Tritrichomonas foetus

​Trichrome stained Tritrichomonas foetus trophozoites. Note the undulating membrane indicated by arrow.

Trichomonas gallinae

Lesions of trichomoniasis, commonly referred to as 'canker' in pigeons or 'frounce' in raptors, consisting of diffuse multifocal areas of caseous necrosis in the esophagus and oropharynx of a dove. Lesions of trichomoniasis are usually found in the mouth, pharynx, esophagus, and crop, and are rarely seen posterior to the proventriculus.