624 Relapsing Fever 



distribution of the micro-organisms in their bodies, and 

 found that they collected in large numbers in the ovaries, 

 so that the eggs were commonly infected and the embryo 

 hexapod ticks hatched from them were infective. Thus 

 in regard to Spirochaete duttoni we are able to say quite 

 definitely that the tick is the usual if not the only means of 

 dissemination. 



Pathogenesis. The spirochaetes of relapsing fever are 

 pathogenic for man and monkeys, some of them for smaller 

 animals. Novy and Knapp* found their organism and 

 S. duttoni to be infectious for mice and rats, and attribute 

 the failure of others to discover this to their failure to exam- 

 ine the blood during the first and second days. Fulleborn 

 and Meyer and Martin f were able successfully to transmit 

 the Spirochaete of Russian relapsing fever to mice after first 

 passing it through apes. Rabbits and guinea-pigs seem 

 to be refractory; white mice susceptible. Man, monkeys, 

 and mice suffer from infection characterized by relapses, 

 and in them the disease may be fatal. Rats never die and 

 rarely have relapses. 



The micro-organisms are free parasites of the blood in 

 which they swim with a varying rapidity according to the 

 stage of the disease. They are present during the febrile 

 paroxysms only, disappearing completely as soon as the 

 crisis is reached. 



Lesions. There are no lesions characteristic of relapsing 

 fever. 



Bacteriologic Diagnosis. This should be quite easily 

 made by an examination of either the fresh or stained 

 blood, provided the blood be secured during a febrile parox- 

 ysm. The readiness with which the organisms take the stain 

 leaves little to be desired. 



Novy and Knapp have found that the serum of recovered 

 cases can be used to assist in making diagnoses by its agglu- 

 tinating, germicidal, and immunizing powers. 



Immunity. The phenomena of immunity are vivid and 

 important. At the moment of decline of the fever a power- 

 ful bacteriolytic substance appears in the blood and dis- 

 solves the organisms. At the same time an immunizing 

 substance appears. The two do not appear to be the same. 



The immunizing body affords future protection of the 



* Loc. cit. 

 f Loc. cit. 



