Prophylaxis 563 



Dutton first found the parasites in the blood. As the para- 

 sites increase in number the somnolence begins to show itself. 

 The lymph-nodes enlarge at this time and become easily 

 palpable, and their enlargement is looked upon as one of the 

 most ready means for confirming the diagnosis in suspicious 

 cases. 



In the bodies of those that die there are few changes vis- 

 ible to the naked eye, but the microscope re veals that through- 

 out the body and especially in the nervous system there are 

 perivascular collections of lymphocytes and many trypano- 

 somes. 



Prophylaxis. This must be partly based upon measures 

 taken to prevent the infection of men by the flies, and partly 

 upon those preventing the infection of the flies by the men. 

 Its success must depend upon the probability that there is 

 no other host wild animals in which the parasites are kept 

 alive where there are no men. 



The tsetse-fly Glossina palpalis is a fairly large brown- 

 ish insect, easily recognized when once pointed out. It makes 

 a loud humming sound and thus attracts attention to itself. 

 In the larval and pupal stages it lives in the soft mud along 

 the banks of the streams and rivers, and its natural prey is 

 thought to be the crocodile, though it readily turns to other 

 animals and to human beings. In the adult state it still 

 remains more or less confined to the streams, though it has 

 been found to fly as far as a mile. 



To prevent the infection of men by the flies is extremely 

 difficult where naked or half -naked savages are to be dealt 

 with. For Europeans, the customary dress, the avoidance of 

 exposure in bathing, the use of mosquito guards, etc., are to 

 be recommended, as well as the erection of habitations and the 

 building of roads, etc., as far as possible from the fly districts. 

 The destruction of the grass and reeds along the river banks, 

 the use of drainage, and the introduction of chickens, to pick 

 up the larvae and pupae, have been recommended. 



To prevent infection of the flies is impossible where, as in 

 some sections of Africa, 50 per cent, of the population of 

 some of the villages already harbor the parasites. A means 

 to this end is, however, being tried, and the entire population 

 of a district has been removed from the fly country and the 

 land abandoned, in the hope that when, after the lapse of 

 some time, only healthy persons are permitted to return, the 

 absence of infected flies in the country, and the absence of 



