CHAPTER XLI 



SPIROCH^ETA OBERMEYERI 



(SPIROCHvETA, OF RELAPSING FEVER) 



Spirochaeta Obermeyeri occurs in the blood of those suffering with relapsing 

 fever and in certain lice, bugs and ticks that have fed upon infected persons. 



Morphology. Spirochaeta Obermeyeri show marked variations in length; 

 the average dimensions are 20 /j. long by i n wide. It is spiral, the curves being 

 of uneven lengths and depth. It is actively motile and progresses with a screw- 

 like motion. The ends are pointed and it is said to possess terminal flagella. 



Staining. Same as for treponema pallidum (see page 150). 



Growth. -Cultivation on artificial media is difficult; most attempts result 

 in failure and it is not necessary for diagnostic purposes. 



Pathogenesis. Inoculation with blood taken from relapsing fever patients 

 has produced the disease in monkeys and rats. Rabbits and guinea-pigs are 

 immune. Spirochaeta Obermeyeri has been found alive and infectious in ticks 

 and leeches several days after they fed upon infected persons. When the body 

 louse imbibes this spirillum it may pass it through heredity to the next 

 generation. 



Diagnosis. In suspected cases blood should be obtained from the finger 

 during the febrile period. Several thin films should be made on clean slides or 

 cover glasses; these should be dried at room temperature or placed in an incu- 

 bator, not flamed. At the same time a drop of blood should be examined in 

 the fresh state. Place it on a clean slide, gently drop a clean cover upon it and 

 immediately examine with an oil immersion lens. 



The organisms, most of them five or ten- times as long as the diameter of a 

 red blood cell, are observed moving about with great rapidity, by a screw-like 

 and also undulatory motion, often pushing red cells aside. 



During the febrile period of the disease spirochaeta Obermeyeri retreats from 

 the peripheral blood and examination at this time is not advisable. 



Differentiation of the closely related spirochaeta can be made only by 

 agglutination tests with the serum of immunized rats. 



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