348 



PROTOZOOLOGY 



cell infiltration of the perivascular lymphatic tissue throughout the 

 central nervous system. 



T. rhodesiense Stephens and Fantham (Fig. 143, e-h). Morphologi- 

 cally similar to T. gambiense, but when inoculated into rats, the posi- 

 tion of the nucleus shifts in certain proportion (usually less than 5%) 

 of individuals toward the posterior end, near or behind the blepharo- 

 plast, together with the shortening of body. Some consider this 

 trypanosome as a virulent race of T. gambiense or one transmitted 

 by a different vector, others consider it a human strain of T. brucei. 



The disease caused by this trypanosome appears to be more 

 virulent and runs a course of only a few months. It is known as 

 Rhodesian or East African sleeping sickness. The organism is con- 

 fined to south-eastern coastal areas of Africa and transmitted by 

 Glossina morsitans. 



T. cruzi Chagas (Schizotrypanum cruzi C). (Fig. 144). A small 



Fig. 144. Trypanosoma cruzi in experimental rtas. a-c, flagellate forms 

 in blood; d, e, cytozoic forms, all X2300; f, a portion of infected cardiac 

 muscle, X900. 



curved (C or U) form about 20m long; nucleus central; blepharoplast 

 conspicuously large, located close to sharply pointed non-flagellate 

 end; multiplication takes place in the cells of nearly every organ of 

 the host body; upon entering a host cell, the trypanosome loses its 

 flagellum and undulating membrane, and assumes a leishmania form 

 which measures 2 to by. in diameter; this form undergoes repeated 

 binary fission, and a large number of daughter individuals are pro- 

 duced; they develop sooner or later into trypanosomes which, 

 through rupture of host cells, become liberated into blood stream. 

 Life cycle (Elkeles, 1951). 



This trypanosome is the causative organism of Chagas' disease or 

 South American trypanosomiasis which is mainly a children's dis- 

 ease, and is widely distributed in South and Central America and as 



