SLEEPIXa SICKNESS. 325 



draw your attention — a subject which has excited considerable 

 controversy already, and one which will, I expect, excite still 

 more in the near future. I refer to the connection between big 

 game on the one hand and trypanosomiasis of man and domestic 

 stock on the other. 



Since the beginning of last year, when Dr. Kinghorn and I 

 published our paper announcing the fact that a large proportion 

 of the wild fauna of Africa harboured the trypanosomes of man 

 and domestic stock, a considerable polemic has arisen over the 

 question of the advisability of attempting to exterminate the big 

 game in the vicinity of human habitations. 



In discussing this subject, it appears to me that I could not do 

 better than attempt to answer some of the objections which have 

 been raised against any prophylactic measure being adopted which 

 involves interference with the African fauna. 



It has been suggested that if the big game be destroyed in 

 any district, the fly, being deprived of its natural source of food, 

 might turn its attention solely to man and his flocks and herds. 

 It appears to me that but little importance should be attached to 

 this hypothesis. In the first place, cattle do not as a rule live in 

 the presence of Glossina morsitans. It was suggested that cattle 

 and other domestic stock might harbour the human trypan osome 

 for considerable periods without detriment to health. This, how- 

 ever, is not true in the case of the human trypanosome of Nyasa- 

 land and Rhodesia, which we jDroved rapidly killed horses, cattle, 

 donkeys, goats, and dogs. Moreover, even if the human parasite 

 did not kill domestic stock, these would still die from the ordinary 

 cattle trypanosomes such as T: pecorum, T. namwi, and 7'. vivax, 

 with which we found the wild Glossina moisitans to be heavily 

 infected ; so that it is quite obvious that domestic stock cannot 

 have the same significance as a reservoir of the virus as the 

 antelope, which are tolei'ant of the trypanosomes pathogenic for 

 man and domestic stock. Secondly, the tsetse fly does not invade 

 the clearings in and around villages to any great extent, and 

 therefore man is only attacked when for any reason he goes forth 

 into the bush, and it is hard to believe that he would suffer to 

 any much greater extent in the absence of game. Thirdl}^, a.nd 

 this is the most important point : if the game were removed the 

 reservoir of the virus is desti'oyed, and therefore in a short time 

 the fly would tend to become non-infective. The bite of a non- 

 infective Glossina morsitans hurts nobodv. Finally, there is 

 absolutely no evidence indicating that if the big game in any 

 particular district were slaughtered, the tsetse fly, unable to obtain 

 blood from these animals, would attack man and the domestic 

 animals to a greater extent than at present. It might equally 

 well be argued that if the food-supply of the fly be removed the 

 fly would disappear. There is, moreover, a considerable amount 

 of evidence that the tsetse fly spreads with the game. For 

 example, since the rinderpest swept through Central and South 

 Africa sixteen or seventeen years ago the big game have increased 



