Chapter 7 

 Protozoa parasitic in the circulatory system 



Flagellata 

 Trypanosoma 



TRYPANOSOMES are slender flagellates with tapering ex- 

 tremities. There is a vesicular nucleus located usually 

 near the middle of the body. The posterior end is less attenu- 

 ated than the anterior end. Near the posterior end is pres- 

 ent a small refractile body, the blepharoplast, which stains 

 deep red with Giemsa's stain. Originating in this or a 

 small granule located near it, there is a flagellum which 

 follows the outer border of an undulating membrane to 

 the opposite end and projects beyond freely. The organism 

 nourishes itself by absorption of liquid nourishment 

 through its body surface. It multiplies bv binary fission in 

 the human blood and gives rise to polymorphic individuals. 

 When a blood-sucking insect (Glossina, Triatoma, etc.) 

 sucks the blood of a person infected with Trypanosoma, the 

 latter undergoes a series of change and multiplication in its 

 digestive tract. During this development, the blepharo- 

 plast may shift its position toward the anterior end, and 

 the body may assume crithidia form. Finally in Glossina 

 engorged with the blood containing Trypanosoma gam- 

 biense or T. rhodesiense, the flagellates enter into and 

 continue to multiply in the salivary gland. These flies are 

 now infectious and when they feed on a human victim, the 

 trypanosomes enter the blood. In Triatoma infected by 



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