TRYPANOSOMA GAMBIENSE 



531 



Transmission. — T. gambiense is conveyed from man to man by the 

 tsetse fly, Glossina palpalis, which has a distribution in Africa corre- 

 sponding fairly closely with that of the trypanosome (Fig. 223). After 

 Bruce (1895) had demonstrated the carriage of T. brucei by G. 7norsitans, 

 many prophetic utterances as to the probable transmission of T. gatnbiense 

 by tsetse flies were made. The first of these was that of Brault (1898), who, 



Fig. 223. — Diagram of Trypanosoma gambiense in the Blood of Man and the 

 Tsetse Fly {Glossina palpalis). (After Wen yon, 1922.) 



A. Ordinary forms in the blood of man. T>. Dividing forms in the blood of man. 

 P. Trypanosomes passing through proboscis of fly. 



S. Trypanosomes in stomach of fly. I. Trypanosomes in salivary gland of fly. 



E. Long trj^anosomes which make their way from the stom.ach to the salivary glands via the 

 proboscis. 



B. Crithidia forms developed from the long trypanosome forms in the salivary glands. 



C Metacyclic trypanosomes developed from the crithidia forms in the salivary glands. These 

 forms produce infection when injected with the salivary secretion of the fly. 



before the actual discovery of T. gambiense, predicted that sleeping sickness 

 would probably be found to be a disease caused by trypanosomes and 

 transmitted by tsetse flies. Bruce, Nabarro, and Greig (1903), working 

 in Uganda with wild G. palpalis caught off animals, showed that batches 

 of flies fed on sleeping sickness cases were able to transmit infection to 

 monkeys up to forty-eight hours after feeding. Combined with the fact 



