436 VETERINARY BACTERIOLOGY 



into cattle. It resembles the rat trypanosome in being thus limited 

 to a single host. The organism was first described as the cause of 

 galziekte, but the recent investigations of Theiler seem to show it 

 to be a relatively harmless commensal. 



Bacteriological Diagnosis. The organisms are quite common in 

 the blood, but soon diasappear. 



Transmission. It has been found to be transmitted by the 

 bite of the fly, Hypobosca rufipes. 



Trypanosoma gambiensc 



Synonyms. Tr. ugandense; Tr. castellanl. 



Disease Produced. Human trypanosomiasis, or sleeping sick- 

 ness in man. 



The disease known as sleeping sickness has been known among 

 the negroes of the west coast of Africa for over a century. Button, 

 in 1901, had an opportunity to examine the blood of a European 

 infected with the disease, and found and described the causal 

 trypanosome. Other investigators have abundantly confirmed 

 and extended his observations. 



Distribution. The disease is endemic upon the western coast 

 of Africa and in certain of the central portions. 



Morphology. The organism is 17 to 28 by 1.4 to 2 [i. Forms 

 undergoing division are somewhat larger. The free flagellum may 

 be one-fourth to one-third the length of the body. Rarely no 

 free portion of the flagellum can be demonstrated. The undulating 

 membrane is narrow. The blepharoplast is near the posterior end. 

 Protoplasmic granules that stain like chromatin are commonly 

 observed. 



Pathogenesis. Experimental Evidence. The disease, with its 

 characteristic clinical symptoms, may be reproduced by the injec- 

 tion of blood containing the organisms into the monkey. Dogs, 

 jackals, cats, guinea-pigs, and rabbits are readily infected. Mice 

 frequently recover and are thereafter immune. Goats and sheep 

 are relatively refractory, but sometimes succumb. It may pro- 

 duce a mild chronic infection in the horse and in cattle. 



Character of Disease. The disease is insidious in its onset. 

 Two distinct stages may be recognized. These were for a long time 

 supposed to be different diseases. In the first stage the organisms 



