290 



Antelope as a Reservoir for Trypanosoma gambiense. 



By H. L. Duke. 



(Communicated by Sir J. R. Bradford, K.C.M.G., Sec. R.S. Received 

 April 20 —Read June 6, 1912.) 



In considering the problem of the prolonged infectivity of Glossina palpahs 

 along the shore of Lake Victoria Nyanza, the subject must be approached 

 from three points of view : — 



Firstly. Some idea of the percentage of infected wild flies must be 

 obtained from time to time, in order to gauge the efficacy of the reservoir. 



Secondly. The wild animals frequenting the lake shore must be examined 

 for T. gambiense. 



Thirdly. The effect of T. gambiense on these animals should be studied in 

 the laboratory. 



With regard to the requirements (1) and (2), it has been pointed out in a 

 recent report covering the period from March, 1911, to January, 1912, that 

 the percentage of infected flies along the Chagwe coast line is still O014 per 

 cent., i.e., a very slight diminution from that reported in June, 1909. During 

 the interim no natives have been allowed in the neighbourhood of the fly, 

 except those in the employ of the laboratory, who are under constant 

 observation. 



On Damba Island in May, 1911, Carpenter obtained an infection of a 

 monkey with T. gambiense, using 880 wild fly, and two out of four situtunga 

 antelope shot on this island were found to harbour this trypanosome. For 

 Damba Island, therefore, it would appear that the role of the antelope in 

 keeping up the infectivity of the wild fly is conclusively established. The 

 conditions on this island are, however, in many ways exceptional, as the fly 

 and antelope are brought into very frequent contact. 



Under such conditions it would not be necessary for the antelope to remain 

 infected over a very protracted period of time in order to keep up the 

 infectivity of the fly. In other words, a single infected antelope let loose on 

 Damba Island would soon infect a large number of Glossince, which would in 

 turn have access to numerous situtunga. Nothing short of a very rapidly 

 acquired immunity to the disease in the antelope could prevent a relatively 

 large number of fly being infective at any given time. On the mainland the 

 opportunities for the fly to bite these animals probably occur much less 

 frequently ; and bearing in mind the small percentage of flies capable of 

 carrying T. gambiense, it becomes of great importance to know how long an 

 antelope can remain infective. 



x 2 



