TRYPANOSOMA RHODESIENSE 665 



Trypanosoma rhodesiense. In 1910, Stephens and Fantham 

 observed certain peculiarities in the trypanosomes derived from 

 a case of human trypanosomiasis occurring in an individual 

 who had returned to England from Rhodesia. The organisms 

 frequently presented a very blunt posterior extremity and the 

 trophonucleus tended to approach the kinetonucleus and in 

 certain cases to lie behind it. Another feature of the case was 

 that only Gl. morsitans, which up till then had not been sus- 

 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 redema, 

 especially of the face, is a marked characteristic. Some think 

 that Tr. rhodesiense may be a variant of Tr. brucei, and the 

 question must be looked on as at present sub judice. From the 

 morphological side, Bruce reports that in a strain of Tr. brucei 

 recently isolated in Zululand, posterior nuclear forms are very 

 abundant ; on the other hand, Laveran has found that animals 

 which have survived infection with Tr. brucei succumb to sub- 

 sequent inoculation with Tr. rhodesiense. The organism has 

 been cultivated on Novy and MacNeal's medium. 



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, the 

 application of which in the shape of atoxyl was first reconir 



