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 intracytoplasmic flagella 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.
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 lesions of the disease termed "Black head", multi-focal 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%.
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.
Trypomastigotes of Trypanosoma cruzi in a Romanowsky stained blood smear. Note the darkly staining kinetoplasts and nuclei, as well as evident undulating membranes.
A collection of Trypanosoma cruzi amastigotes seen within a cardiac muscle cell. Replication of T. cruzi takes place as intracellular binary fission of the amastigotes, within the cells of the reticuloendothelial system and striated muscle.
Trypomastigate 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 trypamastigote in a blood smear from a rat. Transmitted by the rat flea Ceratophyllus fasciatus, T. lewisi is generally non-pathogenic.
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.
Trichrome stained Tritrichomonas foetus trophozoites. Note the undulating membrane indicated by arrow.
Lesions of trichomonaisis, commonly referred to as 'canker' or 'frounce', consisting of diffuse multifocal areas of caseous necrosis in the esophagus and oropharynx of a columbiformes. Lesions are found in the mouth, pharynx, esophagus, and crop, rarely posterior to the proventriculus.