microbial diseases of man and domestic animals 847 

 Relapsing or Recurrent Fever 



Spirochmta recurrentis — ^Lebert, 1874 



This is still a common disease in some parts of Europe. Its symp- 

 toms are almost identical with those of tick fever; and the spirochaete 

 causing it, formerly called Spirochata obermeieri, can only be dis- 

 tinguished from Spirochata duttoni by the fact that an animal which 

 has recovered from an infection by one of these parasites is immune 

 to inoculation with it, but is susceptible to an inoculation with the other 

 spirochaete. The means by which relapsing fever is transmitted is not 

 known; it is probably carried by 'the bites of lice, or bedbugs. 



Treponema (Schaudinn, 1905) 

 Two species of this genus are very important parasites. 



Syphilis 

 Treponema pallidum — Schaudinn, 1905 



This disease, in all its diverse forms, is caused by Treponema 

 - pallidum. 



The treponema is an exceedingly slender, thread-like organism, with a waved 

 body which measures from 6/i to 14;^ in length (Fig. 183). It greatly resembles the 

 spirochsetes, but differs from them in having each end drawn out to resemble a 

 very slender flagellum. Very little is known of the life history of the treponema 

 except that it multiplies by transverse division. It is transmitted by the contact 

 of a lesion, containing the parasites, with the broken skin, or with a mucous mem- 

 brane of an uninfected person. The symptoms of syphilis are attributable to 

 continuous mild injury, and destruction of the tissues of the infected persons by 

 the treponema and by its toxic effects. It is a parasite of the connective tissue. 



Mercury and potassium iodide were formerly almost exclusively 

 employed in treating syphilis. The search for an efficient drug for 

 the treatment of trypanosomiasis has led to the discovery of other 

 drugs which are of value in the treatment of sj^hilis, such as atoxyl 

 (the sodium salt of para-amido-phenyl-arsenic acid) and its acetylated 

 derivative, and of dichlorhydrate-diamido-arseno-benzol. The last- 

 named drug has proved of great importance in the treatment of syphilis. 



