RELAPSING FEVER. 317 



Relapsing Fever. 



The exciting cause of relapsing fever is the spirochaete of 

 Obermeier, or the spirochsete of relapsing fever. This organ- 

 ism is seen usually as a very long, wavy thread varying in 

 length from 16 /JL to 40 //. It is flagellated and actively motile 

 (Figs. 141 and 142). Sporulation has not been observed. It 

 has not been cultivated as yet. 



The spirochsete is readily stained with the aqueous solutions 

 of the anilin dyes, but is decolorized by Gram's stain. Guen- 

 ther's method of staining is quite useful : The fixed cover- 



FIG. 141. 



Very large spirilla. (Park.) 



glass is immersed in 5 per cent, acetic acid for ten seconds, in 

 order to extract the haemoglobin from the red corpuscles ; it 

 is then stained with anilin gentian-violet or fuchsin. 



Pathogenesis : The organism is always found during the 

 paroxysm in the blood of patients sick with relapsing fever. 

 It disappears in the interval. It has also been found in leeches 

 that have gorged themselves with the blood of such fever 

 patients. 



These organisms appear in the blood just before the onset 

 of the paroxysm, during which they multiply rapidly, and 

 disappear just before the crisis. The spirochsete is strictly a 

 blood parasite. 



