124 DISEASES DUE TO PROTOZOA 



Nyanza and in Uganda. There is little doubt that men of Stanley's 

 expedition and Emin Pasha's followers carried the disease with them 

 across Africa into Busoga and Uganda. The former place was known 

 to be infected in 1896, and the latter extensively infected by 1900. The 

 western shores of Victoria Nyanza were found infected in 1901 ; the 

 eastern shores and German East -Africa in 1902 ; Button and Todd found 

 ii widelv disseminated in the Congo Stale 1904-1905, spreading along 

 trade routes. These writers stated that the disease would spread into 

 Eastern Rhodesia, which has since come true. It has spread upwards 

 from Uganda to Wadelai on the Victoria Xile since 1904, and had 

 invaded the Lado before 1908. It was recognized in the Sudan, 

 Bahr-el-Ghazal province, in 1909. 



Its present boundaries (1919) are : — 



On the West Coast from St. Louis in Senegal to Mossamedes in 

 Angola, up to Timbuctoo on the Niger, throughout the Congo into 

 Uganda, Rhodesia, Southern Nyasaland and Portuguese East Africa. 



From Uganda and Busera southwards to German East Africa and 

 Lake Tanganyika, and northwards to the Bahr-el-Ghazal province. 



It may spread to Arabia as tsetse flies exist there. 



Of course it may also spread to co-existing lands wherever tsetse 

 flies prevail. 



AETIOLOGY. 



The known causative organisms are T. gambiense, 1902, and 

 T. rhodesiense, 1910. The L'^ganda strains may differ from the others, 

 an hypothesis suggested by the difiference of its virulence. 



The trypanosomes of animal trypanosomiasis may cause it. Pro- 

 fessor Lanfranchi, who has never left Europe, was accidentally infected 

 with a supposed laboratory strain of T. brucei, causing irregular febrile 

 attacks, general debility, and large patches of cutaneous tvdema over 

 a period of two years. 



T. gambiense probably lives in antelopes chiefly. 



T. rhodesiense in hartebeest, waterhogs and domestic pigs. 



These animals and man form the reservoir from which man is 

 infected. 



It is not known if Glossinae infect their eggs. 



Trypanosomes are known to develop more rapidly at high tem- 

 peratures. 



The trvpanosomes are injected at the same time as the Glossina 

 palpalis and morsitans suck blood. 



Koch has suggested that it may be also transmitted by sexual 

 intercourse. 



Some authorities blame mosquitoes also. 



