causing Disease in Man in Nyasaland. 



27 



between S. lat. 13° 20' and 13° 50', and extending some twenty miles inland. 

 Through the centre of this area a road runs from Domira Bay on the Lake 

 into North-East Ehodesia. This road, until lately, was a principal highway 

 between the coast and Central Africa. Dr. Aylmer May, the Principal 

 Medical Officer of North-East Ehodesia, who lately visited Kasu, informed 

 the Commission that it was along this trade-route that all the North-East 

 Ehodesian cases of Human trypanosome disease have occurred. It is said 

 that some 25,000 native porters passed along this road every year, and as 

 they entered a Glossina palpalis area at the Congo end of their journey, 

 it seemed at first natural to suspect that the disease was true Sleeping 

 Sickness, and had spread from west to east along this trade-route. This 

 suspicion was shown to be groundless by the discovery that the parasite 

 causing the disease in North-East Ehodesia and Nyasaland is not Trypano- 

 soma gambimse, but a distinct and separate species giving rise to a totally 

 different disease. The cpaestion then arose as to whether this was an 

 imported or indigenous disease. It has, therefore, been one of the objects of 

 this Commission to determine whether the trypanosome causing Human 

 trypanosome disease in Nyasaland is restricted to the game and " fly " of the 

 Proclaimed Area, or if it extends to the north and south along the " fly-belt." 

 If it is found to extend over all the " fly-area " in Nyasaland, then the 

 disease is probably native to the soil and not an importation from Tanganyika 

 or the Congo. 



But it will be well at this point to lay down definitely the various opinions 

 or theories at issue. These are three in number. 



First, that the Human trypanosome disease of North-East Ehodesia and 

 Nyasaland is caused by a specific trypanosome, T. rlwdesiense, that the 

 wild game and " fly " are heavily infected with it, and that T. brucei, or 

 Nagana, is absent altogether. This is the theory held by one school. 



Second, that the wild game and " fly " are heavily infected throughout 

 these " fly-areas " by T. brucei, but that at certain places or foci another 

 trypanosome, T. rlwdesiense, occurs, which is pathogenic to man as well as 

 the other animals. That these two species of trypanosomes are indis- 

 tinguishable morphologically or by their action on animals, except that one 

 is capable of infecting man and the other not. That the only way to 

 separate them is by inoculating man : if the man reacts it is T. rlwdesiense, 

 if not, T. brucei. 



Third, that T. brucei — a common trypanosome of wild game, whose 

 distribution extends from Zululand to the Sudan — and T. rlwdesiense are one 

 and the same species of trypanosome, and that wherever wild game and 

 G. morsitans are found there also will be found cases of trypanosome 



