130 DISEASES DUE TO PROTOZOA 



These trypanosomes will now be dealt with a little more in detail. 

 T. hrucci (rhodesiense). 



History. 



It causes nai^^ana in domestic animals. 



It causes Trypanosomiasis in man of a virulent type. 



It was the first pathogenic trypanosome discovered in Central' or 

 South .Africa. Jl was found by Sir David Bruce in North Zululand, 

 1895. 



Stephens, in 1909, was examining a supposed gambiense at Liver- 

 pool when he noticed different characters to those expected, hence he 

 called it T. rhodesiense. The parasite was obtained from a patient 

 who had been resident in Northern Rhodesia and was suffering from 

 Trypanosomiasis. In this way the Congo and the Rhodesian types 

 of the disease were differentiated for the first time. 



It lias been decided for the present that T. brucei and T. rhodesiense 

 are identical. 



Distribution. 



T. brucei and nagana are widely distributed from the Sudan on 

 the north to Zululand on the south, from Gambia on the west to 

 Zanzibar on the east. It may be that the T. togolense of Togoland 

 and the T. ugandas of Uganda are the same species. 



Morphology. 



In the T. brucei there is a greater diversity of shape than is found 

 among species of other groups; the short, stumpy forms have no free 

 flagellum, while the long forms are slender and have a well-marked 

 free flagellum. 



They are actively motile, but do not move far from one place. 



The protoplasm of many trypanosomes show granules, especially 

 at the anterior end. 



The nucleus is oval in the slender and round in the stumpy forms. 

 It is frequently placed far back in (he bod\' of the organism, more so 

 in the short forms. 



The kinetonucleus is small, round, and about 1*4 — 2 ^ from the 

 posterior extremity. 



The flagellum averages 5"8 jj,, bul is absent in stinnpy forms. 



Animal Susceptibility . 



It attacks man, horses, mules, donkeys, oxen, goats, sheep, 

 monkeys and dogs. Birds, crocodiles, lizards and frogs are not 

 affected by it. 



One trypanosome may begin the infection as well as a thousand. 



Infection can take place very easily through the skin; the slightest 

 puncture or scratch suffices. Infection probably takes place also 

 through the mucous membrane, l^ndoubtedh' infection is most 

 frequently by the tsetse bite. 



