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As illustrated, metacyclic
trypomastigotes (MT) in the saliva of the tsetse fly infect the bloodstream of the
mammalian host as long slender (LS) forms, exhibiting a trypomastigote morphology. In
addition to the LS forms, intermediate and short stumpy (SS) forms are also found in the
blood. The bloodstream trypomastigote differentiates into a procyclic trypomastigote (PT)
within the gut of the tsetse. After reaching the salivary glands, the procyclic
trypomastigotes transform into epimastigotes (E) and attach to epithelial cells via their
flagella. Metacyclic trypomastigotes (MT) in the salivary glands are transferred to the
bloodstream of the mammalian host and multiply by longitudinal binary fission (LSs). T. brucei rhodesiense lives in East Africa, and another
subspecies T. b. gambiense lives in West Africa. The organisms are long and
slender, 30 x 3.5 microns. Each has a nucleus (N), kinetoplast (K), undulating membrane
(UM) and long flagellum (F). |