Hemoflagellates

HEMOFLAGELLATES
 characterized by the presence of a large mitochondrion known as a kinetoplast.

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the kinetoplastida assume different morphologic forms depending on their presence in vertebrate hosts, including humans, or their insect vectors .

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2 genera important in human disease: Trypanosoma Leishmania

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transmitted by arthropod vectors and have animal hosts that serve as reservoirs.

Amastigote stage    spherical, 2–5 μm in dm and displays a nucleus and kinetoplast. no external flagellum, although an axoneme (the intracellular portion of the flagellum) is apparent at the ultrastructural level. may be found in human or animal hosts infected with either T. cruzi or Leishmania spp., where they multiply exclusively within cells.

PARASITOLOGY

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Promastigote stage   is an elongated and slender organism with a central nucleus, an anteriorly located kinetoplast and axoneme, and a free flagellum extending from the anterior end. this stage occurs in the insect vectors of Leishmania and is the stage detected in culture.

Epimastigote   similar to the promastigote, but the kinetoplast is found closer to the nucleus and has a small undulating membrane that becomes a free flagellum. all species of Trypanosoma that infect humans assume an epimastigote stage in the insect vector or in culture.

Trypomastigote    kinetoplast is found at the posterior end and the flagellum forms an undulating membrane that extends the length of the cell. occurs predominantly in the blood stream of mammalian hosts infected with the various Trypanosoma spp. the infectious stage found in appropriate insect vectors following transformation from the epimastigote form are known as metacyclic trypomastigotes.

TRYPANOSOMA
a. Trypanosoma brucei (African or Old World trypanosomiasis) b. T. cruzi (American or New World trypanosomiasis, or Chagas' disease). c. T. rangeli (has been described in humans in America but does not cause