CHAPTER XX. 



DISEASES DUE TO SPIROCHAETES THE RELAPSING 

 FEVERS, SYPHILIS, AND FRAMBCESIA. 



THE diseases produced by spirochaetes 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 spirochaetes found in ulcerative and gangrenous con- 

 ditions 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 infection 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. 



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