500 DISTIUBUTION OF NAGANA. 



APPENDIX E. 



The Geographical Distribution of Nagana, and the Possible 

 Transmission of the Parasite of the Disease by Species of 

 Glossina other than Gl. morsitans, and by Blood-Sucking 

 Flies other than Tsetse.* 



In spite of the apparently over-hasty conclusions of Koch and 

 other German investigators, the question as to the identity of 

 Nagana with the disease known in India as Surra is not yet by 

 any means finally decided. This, however, is beyond the scope 

 of the present work, which is confined to Africa. 



Apart from the region to the south of Lakes Tanganyika 

 and Nyasa, the chief foci of Tsetse-fly disease at present definitely 

 known ai-e situated in Gei'man East Africa, British East Africa, 

 and Somaliland on the east, and in the German Protectorate of 

 Togo on the west. In the opinion of MM. Laveran and Mesnil 

 [XXI.], Nagana probably occurs wherever Glossina morsitans or 

 one of its congeners exists, but information at present available 

 does not altogether warrant such a conclusion. Thus Stuhl- 

 mann [174] records the captuie in January, 1902, of specimens 

 of " Glossina tahaniformis, Westw." (Gl. fusca, Walk.), near 

 Dar-es-Salam, at a place where the same cattle and goats had 

 grazed for a long time without the disease having appeared 

 among them. On this account, and — " Reasoning from general 

 conclusions derived from analogy in connection with the diseases 

 due to infection of the blood, in which each parasite has its own 

 particular host and intermediate host " — Dr. Stuhlmann thinks 

 that it may be assumed that Tsetse-fly disease " is not conveyed 

 by Glossina tahaniformis." In this case we are given no informa- 

 tion as to the presence or absence of game in the vicinity, but 

 what appears to have been the same species of Tsetse was met 

 with in December, 1895, by Mr. A. H. Neumann [152], on the 

 eastern shore of Lake Rudolph, where game was abundant. 

 Mr. Neumann writes : " Whether this kind is poisonous or not I 

 am not sure. My donkeys never sufiered from having passed 

 here ; but then they can stand a few ' fly,' though where the 

 * Tetse ' is numerous they soon succumb." Turning to another 

 species of Tsetse-fly, in September, 1899, at Lumley, a few miles 

 from Free Town, Sierra Leone, I myself saw a hei-d of cattle 

 being pastured on grass-land in close proximity to a mangrove 

 swamp where Glossina palpalis, Rob.-Desv., was present in some 



* The statements in this section are by no means to be taken as 

 constituting the last word on the subjects referred to ; they are intended 

 rather to suggest lines for future investigation, by drawing attention to 

 the paucity of our present knowledge. 



