PATHOGENICITY 73D 



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

 very refractory to treatment by any of the usual methods of 

 cauterization or application 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. 



Japanese Seven-Day Fever. A number of Japanese workers 

 have recently described this disease as resembling infectious 

 jaundice but usually without the occurrence of jaundice. It has 

 a fairly wide distribution in Japan among field workers. A 

 spirochsete morphologically indistinguishable from Leptospira ic- 

 terohcemorrhagice, but distinct in its immune reactions, has been 

 found in blood and urine of human cases, and in inoculated 

 animals. The organism was named Spirochceta hebdomadis, but 

 if related to the organism of infectious jaundice should be called 

 Leptospira hebdomadis. A spirochaete believed to be identical 

 with this was found in the field mouse, Microtus montebelli, 

 and the Japanese believe that this mouse acts as a reservoir for 

 the disease as does the rat for infectious jaundice. 



Other Spirochaetes. Spirochsetes have been found in con- 

 nection 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 spirochaetes 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 aggravating the diseased condition. The patho- 

 genic propensities of spirochsetes have been demonstrated in so 

 many cases, however, that they may rightly be looked upon as 

 one of the most destructive groups of human parasites. 



