Transmission 



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flies ? Sambon* and Brumpt f both suggested it, but it was 

 soon discovered that the geographic distribution of the tsetse- 

 fly, Glossina morsitans, that distributes nagana, does not co- 

 incide with the geographic distribution of sleeping sickness. 

 There are, however, different kinds of tsetse-flies, and Bruce 

 and NabarroJ first showed that it was not Glossina morsi- 

 tans, but a different tsetse-fly, Glossina palpalis, that is the 

 most important, if not the only source of the spread of human 

 trypanosomiasis. They submitted a black-faced monkey 

 (Cercopithicus) to the bites of numerous tsetse-flies caught 

 in Entebbe, Uganda, and found trypanosomes in its blood. 



Fig. 192. Glossina pal- 

 palis. A perfect insect just 

 escaped from the pupa. B, 

 pupa; a, b, valves; c, body 

 of the pupa (Brumpt) . 



Fig. 193. Glossina palpalis before 

 and after feeding (Brumpt). 



Bruce, Nabarro, and Greig allowed Glossina palpalis to suck 

 the blood of negroes affected with sleeping sickness and 

 afterward to bite five monkeys (Cercopithicus). At the end 

 of about two months trypanosomes appeared in the blood 

 of these monkeys. They also made maps showing the geo- 

 graphic distribution of African lethargy and of Glossina 

 palpalis, which were found perfectly to correspond. 



It is, of course, not impossible that other flies, especially 

 other species of tsetse-flies, may act as distributing hosts of 



c "Jour. Trop. Med.," July i, 1903. 

 t "C. R. Soc. de Biol.," Jan. 27, 1903. 



t ''Reports of the Sleeping Sickness Commission of the Royal Society," 

 1903, i, ii, ii. 



Ibid., 1903, No. 4, vin, 3. 

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