MICROBIAL DISEASES OF MaVt AND DOMESTIC ANIMALS 827 



sore be left untreated, it cures itself after some months. In countries 

 where it occurs, Delhi boil is particularly liable to form at the site of a 

 cut or abrasion. It is possible that, in some cases, the infection may 

 be carried to a wound by house flites. 



The condition may be treated by free excision although it runs a 

 seK-limited course. In places where it is endemic, care should be 

 taken to avoid the possibility of infection by carefully protecting all 

 wounds, no matter how small. 



Trypanosoma (Gruby, 1843) 



Trypanosomes aie parasitic in insects, fish, leptiles, birds, and mammals in 

 all parts of the world. Many of them seem to be harmless parasites; others cause 

 very serious diseases. 



Sleeping sickness since it affects human beings is regarded as the most im- 

 portant of the diseases due to trypanosomes. ' 



Sleeping Sickness 

 Trypanosoma gambiepse — Button, 1902 



Sleeping sickness is. a disease of man caused by Trypanosoma 

 gambiense; it is usually transmitted by the bites of Glossina palpalis, a, 

 tsetse fly. 



Sleeping sickness occurs only in ;those parts of Africa where this 

 species of fly is found. 



Fig. 174. — Trypanosoma granulosum. n, Tropho-nucleus; m, undulating 

 membrane; d, kinetonucleus; /, flagellum. X 2000 diam. {After Laveran arid 

 Mesnilfrom Doflein.) 



Trypanosoma gambiense (Fig. 174) is somewhat fusiform in shape and measures 

 about 17/* to 2Sm fto™ the posterior extremity to the tip of its flagellum. A large 



