CHAPTER XX. 



DISEASES DUE TO SPIROCH^ETES THE RELAPSING 

 FEVERS, SYPHILIS, AND FRAMBCESIA. 



THE diseases produced by spirochsetes spirilloses or spiro- 

 chaetoses fall into two main groups, one represented by the 

 human spirillar fevers and the corresponding affections of various 

 animals, and the second having as its two chief members 

 syphilis and yaws, though to the organisms of these diseases 

 various spirochsetes found in ulcerative and gangrenous condi- 

 tions seem to be closely related. The members of the first 

 group are essentially blood infections, and the organisms are in 

 most, if not in all cases, transmitted by blood-sucking ecto- 

 parasites; in the second group the organisms are primarily 

 tissue-parasites, blood invasion when it occurs being a later 

 phenomenon, and infection would appear to occur by direct 

 contact. As regards general morphology, staining reactions, 

 conditions of growth and culture, the various spirochaetes present 

 certain common characters, and, as already stated, it is still 

 uncertain whether they are to be regarded as bacteria or as 

 protozoa, though the balance of opinion is now distinctly in 

 favour of the latter. 



RELAPSING FEVER AND AFRICAN TICK FEVER. 



At a comparatively early date, namely in 1873, when prac- 

 tically nothing was known with regard to the production of 

 disease by bacteria, a highly characteristic organism was dis- 

 covered by Obermeier in the blood of patients suffering from 

 relapsing fever. This organism is usually known as the 

 spirillum or spirochcete Obermeieri, or the spirillum of relapsing 

 fever. He described its microscopical characters, and found 

 that its presence in the blood had a definite relation to the time 

 of the fever, as the organism rapidly disappeared about the time 

 of the crisis, and reappeared when a relapse occurred. His 



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