TRYPANOSOMA 



491 



Flo. 148 



Morphology. The organisms are long, slender, flexible, spiral or 

 wavy filaments with pointed ends, from 16/^ to 40/^ in length and 

 from one-quarter to one-third the thickness of the cholera spirillum 

 (Fig. 148). They stain somewhat faintly with watery solutions of the 

 basic aniline dyes, better with Loeffler's or Kiihne's methylene-blue 

 solutions, or with carbol fuchsin; best with the Romanowsky method 

 or its modifications. They do not stain by Gram's method. 



Biological Characters. In fresh preparations from the blood the 

 spirocheetes exhibit active progressive movements accompanied by 

 very rapid rotation in the long axis of the spiral filaments or by undu- 

 lating movements. They are found only in the blood or blood' organs, 

 never in the secretions, and only during the fever, not in the intermis- 

 sions, or at most singly at the begin- 

 ning of or for a short time after an 

 attack. 



When kept in blood serum or a 0.6 

 per cent, solution of sodium chloride 

 they continue to exhibit active move- 

 ments for a considerable time. They 

 may be preserved alive and active for 

 many days in sealed tubes. They are 

 killed quickly at 60 C., but they re- 

 main alive for some time at C. 

 Efforts to cultivate them in artificial 

 culture media have thus far been 

 unsuccessful, although Koch has ob- 

 served an increase in the length of the 

 spirilla and the formation of a tangled and 

 mass of filaments. But now with the 

 cultivation of trypanosomes in vitro by Novy and MacNeal successful, 

 one may hope for similar results with the spirochsete Obermeieri. 



Pathogenesis. In man, whether the disease is acquired naturally 

 or by artificial inoculation, the organism causes the following symp- 

 toms : After a short period of incubation the temperature rises rapidly, 

 remains high for five to seven days, and then returns to normal by 

 crisis. About seven days later there is another sudden rise of tem- 

 perature, but this time the crisis occurs sooner. A second or third 

 relapse may occur. The organisms increase in numbers rapidly in 

 the blood from the beginning of the fever, large numbers often being 

 found in every microscopic field. They begin to disappear a short 

 time before the crisis, and immediately after the crisis it is practically 

 impossible to find them in the circulating blood. The mortality varies 

 in different epidemics from 2 to 10 per cent. When monkeys are 

 inoculated with human blood containing the spirilla they become 

 sick about three and a half days later, but show only the initial febrile 

 attack, or, at the most, an occasional short relapse. The organisms 

 are found to have the same relation to the pyrexial period as in man. 

 Blood from one animal taken during the fever induces a similar febrile 

 paroxysm when inoculated into another animal. 



Spirochsete Obermeieri blood smear. 

 Fuchsin. x 1000 diam. (From Itzerott 



