PATHOGENICITY 73 



the condition is not known. The disease is pecuhar in being 

 very refractory to treatment by any of the usual methods of 

 cauterization or apphcation of drugs. Recently, however, it 

 has been found to succumb to X-ray treatment, and this method 

 is now extensively employed. Aragao and Vianna in Brazil 

 and Breinl and Priestley in Australia have obtained excellent 

 results from intravenous injections of tartar emetic. 



Spirochetes have been found in connection with still other 

 human afflictions, and it is possible that they may be the cause 

 of them. In most cases, however, it is more probable that spiro- 

 chsetes which are normally harmless and live only on dead matter 

 find congenial surroundings in tissues diseased by some other 

 cause, and that this accounts for their presence. Often, however, 

 such ordinarily harmless spirochaetes may change their habits 

 under suitable conditions and become pathogenic, thus aggra- 

 vating the diseased condition. The pathogenic propensities of 

 spirochaetes have been demonstrated in so many cases, however, 

 that they may rightly be looked upon as one of the most destruc- 

 tive groups of human parasites. 



Since this book has gone to press Futaki has found a spirochaete, which he 

 has named spirochwta exanthemotyphi, in the kidneys of seven out of eight 

 typhus victims in Japan, and in the urine of six out of seven other typhus 

 patients. The spirochaete was also found in a monkey inoculated with blood 

 from a typhus patient. It is possible that the minute coccoid bodies found in 

 tjTJhus-infected lice by Rocha-Lima, and named by him Rickettsia prowdzeki 

 (see p. 169), are really the granule stage of this spirochaete. 



