368 TYPHOID FEVER 



the b. typhosus constitutes a distinct species of bacterium, and 

 that it is the cause of typhoid fever. Evidence of an important 

 nature confirmatory of this view is, we think, found in the fact 

 that cases have occurred where bacteriologists have accidentally 

 infected themselves by the mouth with pure cultures of the 

 typhoid bacillus, and after the usual incubation period have 

 developed typhoid fever. Several cases of this kind have been 

 brought to our notice, and are not, we think, vitiated by the fact 

 that other similar instances have occurred without the subsequent 

 development of illness. These latter would be accounted for by 

 a low degree of susceptibility on the part of the individual or to 

 a want of pathogenicity in the cultures. 



As there is thus strong evidence of the etiological relationship 

 of the typhoid bacillus to typhoid fever, the view of the 

 development of the disease usually taken has been that the 

 bacilli, being ingested, multiply in the intestinal tract, cause 

 inflammation and necrosis of the lymphoid tissue, and, gaining 

 an entrance to the general circulation, produce the septicsemic 

 phenomena which we have described. 



Within recent years, considerable attention has been attracted to 

 another view of the course of infection put forward by Forster and 

 his co-workers in Strasburg. According to this, the process is primarily 

 a septicaemia, and the intestinal manifestations are looked on as 

 secondary. The bacilli are supposed to gain entrance to the circulation 

 possibly through the tonsils, sore throat being a not uncommon initial 

 symptom of typhoid fever. In the blood they multiply, and, passing 

 through the liver, gain access to the gall-bladder, set up a catarrhal 

 inflammation there on the products of which they flourish, and thence 

 pass out to infect the intestine. The intestinal lesions are either due 

 to an elective action of bacteria brought by the blood, or come from 

 infection by the bacilli which pass out from the gall-bladder, the 

 former being apparently the alternative to which Forster leans. The 

 evidence on which this view is based consists, firstly, in the results 

 of animal experiments in which bacilli introduced intravenously have 

 been subsequently found chiefly or solely in the gall-bladder, it may be, 

 persisting there for weeks. Further, it is stated that bacilli can be 

 isolated from the blood during the later parts of the incubation stage of 

 the disease, and before they can be demonstrated in the intestine, where 

 they are said not to appear until sometime during the first week of 

 active disease. And again it is stated that in the bodies of persons 

 dying from typhoid fever, while bacilli are always present in the gall- 

 badder and in the upper parts of the small intestine, they are frequently 

 absent from the lower part of the latter and from the colon. It cannot 

 be said that this view of the disease has been satisfactorily established. 

 Opinion differs as to the alleged late appearance of the bacilli in the 

 intestine, and the infectivity noticed during the incubation stage must be 

 explained. Further, there is strong reason for believing that multiplication 

 of the bacilli in the intestine can take place. The evidence of this rests 

 on the finding of bacilli, it may be in considerable numbers, in the faeces 



