70 SPIROCHiETES 



chaste in the saliva of infected rats or of other rodents, but only 

 in their blood. From this the conclusion has been drawn that 

 the source of infection in a rat bite is blood from hemorrhages 

 of the gums or tongue which contaminates the teeth. 



Both mercury and salvarsan are effective in the treatment of 

 this disease as of most other spirochaete diseases. 



Attention should be called to the fact that rat bites may often 

 give rise to diseases which may be of quite different nature from 

 the " rat-bite fever " described above. It is well known that 

 many different infective organisms live in the mouth and around 

 the teeth of such animals as rats, and it is not surprising that 

 infections of divers kinds may result from rat bites, and that 

 these infections should have been confused with typical rat-bite 

 fever. Several investigators have described a vegetable organ- 

 ism, Streptothrix, as the cause of rat-bite fever. Recently Ruth 

 Tunnicliff has shown that a form of pneumonia in rats is pro- 

 duced by a Streptothrix very similar to, if not identical with, that 

 described in some cases of rat-bite fever. It is very probable 

 that these cases were really infections with the pneumonia-caus- 

 ing organism, and quite distinct from the Japanese disease. 



Other Spirochaete Diseases 



Spirochsetes, often in association with bacteria of various kinds, 

 have been found in a number of other human diseases, and are 

 in all probability at least partially the cause of them. 



The common spirochaete, Sp. huccalis, which lives about the 

 gums and roots of the teeth in almost all human mouths is 

 thought by some investigators to be entirely harmless, living 

 only on waste matter. By others it is thought to become 

 pathogenic under some circumstances, and, in partnership with 

 certain cigar-shaped bacteria, to be the cause of Vincent's angina, 

 a diphtheria-like ulceration of the tonsils and throat; of noma, 

 an ulceration of the mouth cavity and cheeks; of ulcerations of 

 the nose, teeth and lungs; and of balanitis, an ulceration of the 

 genital organs which may occur after unnatural sexual relations. 

 In central America there is a common disease " mal de boca " 

 (disease of the mouth) which is marked by sw(jllen, spongy and 

 tender gums over which a whitish pellicle forms. It is infectious 

 and is probably caused by a delicate spirochaete found on the 



