88o 



THE ANIMAL CARRIERS OF DISEASES 



Rhodesiense Type of Sleeping St^'c^;^^s5.— Kinghorn and Yorke 

 have described short blood trypanosomes in man, and, judging 

 by Miss Robertson's Castellanii experiments, these must be the 

 transmission agents which infect Glossina morsitans, in the salivary 

 glands of -which short trypanosomes occur, which infect the verte- 

 brate, which is the intermediate host. 



We now come to the very important question of the intermediate 

 reservoir of this trypanosome. Bruce says that T. hrucei and T. 

 rhodesiense are one and the same parasite. Assuming this to be 

 true, the intermediate reservoir would be the African antelopes 

 — e.g., Catoblepas gnu, the wildebeest; Strepsiceros cap ensis, the 

 koodoo; Tragelaphus scriptus var. sylvaiicus, the bush-buck. But 

 there are doubts about this, because — 



Fig. 462. — Glossina morsitans Westwood, 1850: The Carrier of the 

 Trypanosome of the Stephens and Fantham Type of Sleeping 



Sickness. 



(From a photograph by J, J. Bell.) 



1. Stephens and Blacklock have shown that two distinct trypano- 

 somes have been called T. hrucei — viz. :— 



(a) Monomorphic. — This is the original strain of hrucei discovered 

 by Bruce in cattle suffering from nagana in Zululand. 



{h) Polymorphic. — This is a posterior nucleated form from Uganda, 

 where the Rhodesiense form of sleeping sickness is unknown. 



2. Chalmers and O'Farrell, working with a posterior nucleated 

 trypanosome, sent to them in dogs inoculated from a case of sleeping 

 sickness in the Bahr-el-Ghazal province of the Anglo-Egyptian 

 Sudan, found it to differ markedly in serological experiments and 

 animal inoculations from the original strain of T. rhodesiense. 

 This shows that merely obtaining a posterior nucleated trypanosome 

 in a sleeping sickness area does not prove that it is T. rhodesiense, 

 or, indeed, has anything to do with sleeping sickness. 



