4 



SCIENCE 



[N. 8. Vol. XXXVI. No. 914 



gerous. Others there are who but tempo- 

 rarily carry the organism, which soon dis- 

 appears from the intestine if the source of 

 supply, such as contaminated milk or water, 

 is withdrawn. In these the natural resist- 

 ance, whatever that may be, is such as to 

 prevent the organism from gaining a foot- 

 hold and consequently it is soon got rid 

 of. The individual is and remains healthy, 

 and, because of the temporary presence of 

 the organism, is of relatively little danger 

 to others. On the other hand, the healthy 

 carrier may turn out to be in the incuba- 

 tional stage of the disease, the first symp- 

 tom of which may appear in several days, 

 <or two or three weeks after the detection 

 of the bacillus. 



During convalescence from typhoid fe- 

 ver, presumably because of persisting le- 

 sions, the specific organism continiies to be 

 eliminated for some time. In general, how- 

 ever, after the tenth day following the dis- 

 appearance of the fever, the typhoid bacil- 

 lus disappears from the excretions of the 

 convalescents, except from about 10 per 

 cent. Most of the latter clear up in from 

 three to four weeks, while others become 

 true chronic carriers. 



The chronic bacillus carrier is of especial 

 importance, since to such, more than any 

 other, must be ascribed the persistence of 

 the disease in sporadic form in communi- 

 ties where every precaution is taken to in- 

 sure a pure water-supply. This fact was 

 most clearly established by the investiga- 

 tions carried on in 1902 in Alsace and Lor- 

 raine, where typhoid fever was notoriously 

 in evidence in spite of the utmost effort to 

 control the disease by the ordinary sanitary 

 methods. The conclusions arrived at in 

 the course of those studies have been veri- 

 fied and extended by workers in all parts 

 of the world. The occurrence of typhoid 

 and para-typhoid bacilli in healthy and 

 chronic carriers can hardly be advanced as 



an argument against the accepted patho- 

 genic role of these organisms. The lesson 

 taught by the history of yellow fever and 

 hog cholera might lead us to believe that 

 the above-mentioned organisms were acci- 

 dental and not causative, and that the real 

 cause might be of an ultra-microscopic 

 character. No experimental evidence, how- 

 ever, has yet been presented in support of 

 this idea. On the contrary, all the known 

 facts, especially the serum reactions, and 

 above all, the remarkable results obtained 

 in the prevention of typhoid fever by in- 

 oculation of the dead bacillus point to the 

 etiologic significance of the typhoid germ. 

 The number of chronic typhoid carriers 

 is not large, being placed by various work- 

 ers at from 2 to 3 to 5 per cent. ; figures 

 which can not be considered as exact in 

 view of the known imperfections of the 

 methods employed. This low percentage, 

 however, is an encouraging and redeeming 

 feature when one considers that the excre- 

 tion of the typhoid bacillus by such car- 

 riers is not always limited to weeks or 

 months, but may continue for years and 

 perhaps till death. This remarkable per- 

 sistence of the germ is commonly consid- 

 ered to be due to its localization in, and 

 adaptation to the biliary passages. Its 

 presence in the bile and in biliary calculi is 

 an established fact. Usually, with the bile 

 the organism passes into the intestine to be 

 eliminated with the discharges; less often 

 it enters the circulation and appears in the 

 urine. The fact that the bile is a common 

 avenue of elimination when organisms are 

 introduced into the blood may lead one to 

 suppose that the bacillus is primarily local- 

 ized elsewhere than in the bile bladder, and 

 such a supposition is not without analogy. 

 A vegetative focus within an organ not 

 only explains the presence of the bacillus 

 in the bile and, at times, in the urine, but 

 also accounts for the fact that in others the 



