CHAPTEE XX. 



DISEASES DUE TO SPIROCHETES— THE RELAPSING 

 FEVERS, SYPHILIS, AND FRAMBCESIA. 



The diseases produced by spirochsetes — spirilloses or spiro- 

 chetoses — 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. Infective jaundice, recently shown to be due to a 

 spirochsete, occupies a somewhat intermediate position, as the 

 organisms occur in the blood stream but tend to settle and 

 flourish in certain organs. As regards general morphology, 

 staining reactions, conditions of growth and culture, the various 

 spirochsetes 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 Fevees 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 spirochete obermeieri, or the spirillum of relapsing 

 fever. He described its microscopical characters, and found 



