882 MICROBIOLOGY OF DISEASES OF MAN AND DOMESTIC ANIMALS 



SLEEPING SICKNESS 



Trypanosoma gambiense Button, 1902 



Sleeping sickness is a disease of man caused by Trypanosoma 

 gambiense; it is usually transmitted by the bites of Glossina palpalis, a 

 tsetse fly. It is probably transmitted by all tsetse flies. 



In South Central Africa, a number of men have been infected with 

 trypanosomes which differ from Trypanosoma gambiense. The most 

 important of them is Trypanosoma rhodesiense; the others are identical 

 with trypanosomes usually found in animals. Trypanosoma rhodesiense 

 causes a rapidly fatal disease uninfluenced by any treatment. The 

 disease caused by Trypanosoma rhodesiense has not been observed in 

 epidemic form. Trypanosoma rhodesiense is usually transmitted by a 

 tsetse fly of another species, Glossina morsitans. In morphology it 

 differs from Trypanosoma gambiense in that, in the blood of experi- 

 mental animals, forms occur in which the trophonucleus is posterior 

 to the kinetonucleus. 



Sleeping sickness occurs only in those parts of Africa where tsetse 

 flies exist. 



m 



FIG. 185. Trypanosoma gramdosum. n, Tropho-nucleus3[w, undulating 

 membrane; c, kinetonucleus; /, flagellum. X 2000 diam. (After Laveran and 

 Mesnil from Doflein.) 



Trypanosoma gambiense (Fig. 186) is somewhat fusiform in shape and measures 

 about 17^1 to as/* from the posterior extremity to the tip of its flagellum. A large 

 tropho-nucleus is situated near the center of the trypanosome; a smaller, kineto- 

 nucleus lies near its posterior end. From this smaller nucleus a filament arises, 

 which runs the whole length of the parasite and extends from its anterior end as 

 a free flagellum. Where the filament runs along the body, the periplast extends 



