COURSE OF SLEEPING SICKNESS 103 



Under such circumstances they have a tendency to mass together 

 in large numbers, up to a hundred or more, hke sheep in a storm, 

 all with their flagellated ends projecting from a common center 

 (Fig. 23). Such " primary agglomerations " may adhere to form 

 " secondary agglomerations " comprising altogether many hun- 

 dreds of parasites. When the unfavorable conditions disappear, 

 the trypanosomes disentangle themselves without any apparent 

 ill effects, although a few of them remaining agglutinated may 

 die and disintegrate. Another peculiar habit described by some 

 investigators is the extrusion from their bodies of very minute 

 granules, really tiny buds from the nucleus, which ultimately 

 develop into new trypanosomes. This is said to occur just be- 

 fore the temporary disappearance of the trypanosomes from the 

 blood. 



The Disease. — The course of the disease caused by trypano- 

 some infection is insidious and irregular in the extreme. The 

 Gambian and Rhodesian diseases are essentially ahke in their 

 symptoms and in the course they run, except that the latter is 

 usually more rapid in development and more virulent in effect, 

 as a rule causing death within three or four months after in- 

 fection. The variety of the 

 Gambian disease found in 

 Nigeria is comparatively mild 

 and of long duration. 



The bite of an infected tsetse 

 fly is usually followed by itching 

 and irritation near the wound. 

 After a few days fever is felt 

 and a peculiar tenderness of the 

 muscles develops, so that strik- 

 ing against an object causes 

 undue pain. Usually the fever 

 comes and goes at irregular in- 

 tervals of days or weeks or even Fig. 24. Negro infected with trypano- 

 months, an infected person f™*^' f'™/"'?'-^''^ ''^'-^'f' ^1^°^^- 



' _ ^ (Alter Kolle and Wassermann.) 



sometimes carrying the para- 

 sites in his blood, as shown by its infectivity when injected into 

 susceptible animals, for months at a time without any appreciable 

 fever, and in insufficient numbers to be seen readily by microscopic 

 examination. When the attacks of typical trypanosome fever do 



