206 SPIRILLA. 



lire of the many attempts to grow many of these organisms. 

 Schaudinn, working principally with the " Spirochseta " pal- 

 lida, seems inclined to classify them as protozoa. 



RELAPSING FEVER. 

 Spirillum Obermeieri. 



History. As early as 1873 Obermeier discovered in the blood 

 of patients suffering from relapsing fever a long, spirillum-like 

 microorganism, measuring from 20 to 30 mikrons, having the 

 power of active motion. His observations have since been 

 confirmed by a number of other investigators. 



This spirillum, which has not been cultivated artificially, is 

 found in the blood and spleen, but never in the secretions of 

 patients affected with relapsing fever. 



Morphology and Biology. It stains readily by all the anilin 

 dyes, but does not stain by Gram's method. It is actively 

 motile and contains no spores. 



In the blood it is found in two forms: (1) during the pyrexia 

 as long twisted filaments ; (2) after the crisis of the fever is 

 reached it is seen in the leucocytes as short degenerated curved 

 rods. 



Pathogenesis. This spirillum is not pathogenic to the lower 

 animals, with the exception of the monkey, rat, or mouse. 



Blood taken from patients during the paroxysm when inoc- 

 ulated in other individuals may give rise to relapsing fever. 



One attack of the disease seems to confer immunity from 

 future attacks in a greater or less degree. Agglutinins have 

 been demonstrated in immune sera. 



Dulton and Todd have demonstrated that many of the 

 native African fevers are due to spirochaetee which they con- 

 sider identical with those of Obermeier, although the former 

 are somewhat smaller and the clinical symptoms produced by 

 them milder. They have shown that the African disease is 

 transmitted by a tick (the Ornithodorus moubata). 



