888 PATHOGENIC MICROORGANISMS 



organisms in wild rats in the United States. From these and other 

 experiments, it appears probable that the disease is primarily one 

 of rats, and is transmitted secondarily to man. It may be trans- 

 mitted by contact with the urine of the rats and, according to the 

 Japanese investigators, the infected soil may play an important part. 

 Damp, cold mines in which rats abound seem to be particularly 

 favorable. Infection from man to man may occur, since, as we have 

 seen, the spirochaetes pass into the urine, but this is relatively rare. 

 According to Inada and his coworkers, 29 the spirochaetes enter the- 

 human body chiefly through the alimentary canal, but they may also 

 come in through abrasions of the skin. Among fifty-five cases ad- 

 mitted to Inada 's clinic, only a few indicated cutaneous origin, but 

 there were certain of these in which cutaneous origin could not 

 be denied. 



Serum Treatment. Inada and Ido 29 first attempted to treat the 

 disease with the blood of convalescent cases and observed astonish- 

 ingly favorable results. Later, they actively immunized horses with 

 pure cultures and finally obtained horses into whom they could 

 inject 800 c.c. of a pure culture containing thirty spirochaetes per 

 field. 0.01 c.c. of this serum injected into the peritoneal cavity of 

 guinea-pigs protected them against 1 c.c. of pure culture. In human 

 cases they injected as much as 60 c.c. of this horse serum in twenty- 

 four hours. Of thirty-five patients who received serum, seven died, 

 showing a mortality of 11.4 per cent as against 17.3 per cent of 

 cases dead at the same time, without serum. The serum completely 

 destroyed spirochaetes contained in the circulating blood. Further 

 work on specific treatment is in progress. 



Prevention. The prevention of the fever seems from the above 

 facts to rest primarily upon the destruction of rats and the preven- 

 tion of contact of rats with food, the prevention of the pollution of 

 soil, and isolation and care in regard to transmission in the case of 

 patients suffering from the disease. 



"Inada and Ido, Jour. Exper. Med., 24, 1916, 465. 



