ARTICULAR RHEUMATISM. 331 



one and five years of age are most susceptible to whooping- 

 cough ; the disease is less common after the tenth year of 

 life, although it occurs also in adults, and not altogether 

 rarely in the first year of life. Whooping-cough has been 

 observed repeatedly in new-born children whose mothers 

 have suffered from the disease toward the end of gravidity. 

 The disease is especially common in spring and autumn. 

 As a rule, it attacks human beings but once. A large num- 

 ber of bacteria have been cultivated from the sputum of 

 patients suffering from whooping-cough, and animal para- 

 sites also have been found therein ; the demonstration of 

 any etiologic significance for any of these is yet lacking. 



ARTICULAR RHEUMATISM. 



Although the exciting agent of articular rheumatism is 

 entirely unknown, there is, however, no doubt that this 

 disease is infectious. The febrile course, with the general 

 manifestations, the frequent complicating inflammations of 

 serous membranes and the endocardium, and the secondary 

 nephritis, point forcibly to the infectious nature of poly- 

 arthritis. The disease is well known to be dependent in a 

 high degree upon meteorologic influences, but the necessity 

 for certain influences increasing the predisposition also in 

 the etiology of other infectious diseases has already been 

 demonstrated. Acute articular rheumatism is in no wise 

 contagious. Rheumatic polyarthritis is one of those infec- 

 tions after whose termination immunity lasts for only a 

 short time, if it occur at all, to be replaced soon by 

 heightened predisposition. Frequently the same individual 

 suffers from repeated attacks of this disease. It is doubtful 

 if all cases that are grouped clinically under the designation 

 of acute articular rheumatism are associated etiologically. 

 The fact that one-quarter of the cases are refractory to the 

 influence of the known specifics (salicylic acid, antipyrin) 

 appears indicative of etiologic multiplicity. In any event it 

 is to be borne in mind that the clinical picture of poly- 

 arthritis may also be produced by the exciting agents of 

 other diseases (gonorrhea, scarlet fever). 



