DISEASES CAUSED BY SPIROCH^TES 



865 



the original attack. Two, three, or even four attacks may occur, 

 but the disease is not very often fatal. When patients do succumb, 

 however, the autopsy findings are not particularly characteristic. 

 Apart from the marked enlargement of the spleen, which histologic- 

 ally shows the changes indicating simple hyperplasia, and a slight 

 enlargement of the liver, no lesions are found. The diagnosis is 

 easily made during the febrile stage by examination of a small quan- 

 tity of blood under a cover-slip or in the hanging-drop preparation. 



FIG. 95. SPIROCHAETE OF RELAPSING FEVER. (From preparation furnished by 



Dr. G. N. Calkins.) 



Several types of relapsing fever have been described. In Africa 

 the disease has long been prevalent in many regions and the in- 

 vestigations of Ross and Milne, 45 Koch, 46 Button and Todd, 47 and 

 others have brought to light that many conditions occurring among 

 the natives, formerly regarded as malarial, are caused by a species 

 of spirochaete. Whether or not the microorganisms observed in the 

 African disease are exactly identical with the spirochaete observed 

 by Obermeier is yet a question about which several opinions are 

 held. Dutton and Todd believe that the same microorganism is 

 responsible for both diseases. Koch, on the other hand, believes 

 that the slightly smaller size of the African spirochaete and the 

 milder course of the clinical symptoms indicate a definite difference 



"Ross and Milne, Brit. Med. Jour., 1904. 



44 Koch, Deut. mod. Woch., xxxi, 1905. 



"Dutton and Todd, Lancet, 1905, and Jour, of Trop. Med., 1905. 



