RELAPSING FEVER 251 



recover from the disease, whereas if the spleen is removed, 

 the spirilla multiply enormously in their blood, and cause 

 the death of the animal. 



Pathogenesis. — The ages at which the chief number of 

 attacks occur are between fifteen and twenty. The incuba- 

 tion period is about twelve days, and an attack affords little 

 or no protection. In some respects relapsing fever exhibits 

 resemblances to typhus fever, but is admitted on all hands 

 to be a distinct specific disease, as the Spirillum Obermeieri 

 is found in all cases of relapsing fever, and in no other 

 cases of disease whatever. 



Eelapsing fever has not recently occurred in this country 

 to any appreciable extent, and is essentially a disease likely 

 to affect persons exposed to unhealthy surroundings and 

 want of food. 



Loeventhal, of Moscow {Deut. med. Woch., August 26, 

 1897), says that the presence of specific bacterial products 

 in the blood during the apyretic stage of relapsing fever, as 

 shown by Gabritschewsky, led this author to make use of a 

 serum test. The technique is easy, but as no cultivation of 

 the spirillum has yet been made, the test can only be 

 applied when there are cases available from which spirilla 

 containing blood can be obtained. The two sorts of blood 

 are intimately mixed together and placed in the warm 

 incubator, a control specimen being always made. The 

 spirilla gradually become motionless and collect together in 

 masses. The reaction is usually complete in half an hour. 

 If none occur within two to two hours and a half relapsing 

 fever as the cause of the preceding febrile attack may be 

 excluded. Gabritschewsky shows that the reaction is a 

 specific one. 



Practical Disinfection. — The excreta and secretions should 

 be disinfected in the same manner as recommended in 

 enteric fever. 



