666 TRYPANOSOMIASIS 



pected of being capable of transmitting trypanosomiasis to man, 

 prevailed in the regions through which the patient had travelled. 

 Shortly thereafter a serious outbreak of trypanosomiasis was 

 reported from the country west of Lake Nyassa, and it is now 

 known that the disease prevails on several of the northern 

 tributaries of the Zambesi, in the adjacent parts of the Belgian 

 Congo, and even in Portuguese East Africa in districts where 

 only Gl. morsitans and not Gl. palpalis prevails. It was, however, 

 shown by Kinghorn and Yorke, working on the Luangwa (a 

 tributary of the Zambesi), that Gl. morsitans could transmit 

 trypanosomes from human cases to rats, the cycle in the fly 

 being about eleven days, and that a definite percentage of wild 

 flies in this region harboured the human parasite. There is thus 

 no doubt that man, in widely extended regions of southern 

 Central Africa, is exposed to danger when bitten by Gl. morsitans. 

 Further, the opinion is generally accepted that Tr. rhodesiense 

 is a species distinct from Tr. gambiense. The disease in man 

 tends to be more acute ; there is frequently not a terminal 

 sleeping sickness stage, and there is less pronounced infection of 

 lymphatic glands. The organism is also more virulent for 

 animals, the duration of the illness being shorter and the 

 susceptibility of the sheep and goat is greater than towards 

 Tr. gambiense. In both of these animals widespread oedema, 

 especially of the face, is a marked characteristic. The organism 

 has been cultivated on Novy and MacNeaPs medium. There 

 has been considerable controversy regarding the relationship of 

 Tr. rhodesiense to Tr. brucei. While differences in the patho- 

 genic effects of the two organisms have been observed, the right 

 interpretation of the data constitutes a difficult question. Bruce 

 and his co-workers, founding largely on extended biometric 

 investigations, are of opinion that the Tr. rhodesiense is a strain of 

 Tr. brucei which has adapted itself to man, and this view is now 

 widely held. A number of other strains of trypanosomes have 

 been recognised in human cases, and the relationship of these to 

 the more fully determined forms has been the subject of much 

 investigation. 



Not much success has attended remedial efforts in those suffer- 

 ing from trypanosome infection. Here attention has been chiefly 

 concentrated on the action of organic arsenical compounds 

 (salvarsan, galyl, etc.), the application of which in the shape of 

 atoxyl was first recommended by Thomas. A great range of 

 such substances and also of aniline derivatives was investi- 

 gated by Ehrlieh and his co-workers, and under certain conditions 

 of artificial infection in animals a complete or partial destruction 



