BACILLUS TYPHOSUS 211 



lesions. In the early stage of the disease there is acute inflamma- 

 tion ; leukocytes gather in great numbers in the invaded area and 

 suppuration and necrosis result. In the severest cases the lesions 

 may involve the muscular and peritoneal coats of the intestinal 

 wall and perforation may occur; peritonitis and death usually 

 follow. Passing through the injured mucous membrane into the 

 blood stream the bacilli are carried to all parts of the body and 

 become localized in groups or foci in the various organs. Of these 

 the spleen usually contains the greatest number of bacteria; it 

 becomes enlarged and congested and in tissue sections the bacilli 

 appear as clumps between the cells. A similar but less marked 

 invasion may take place in the liver and kidneys. In the gall 

 bladder they may occur in enormous numbers, and even after re- 

 covery they may persist there for years. 



In addition to the local changes in the various organs toxic poi- 

 soning is manifested in typhoid fever as in other infectious diseases 

 by disturbances in the circulatory, respiratory, and heat regulat- 

 ing centers. 



Occasionally complications occur, such as pneumonia, osteo- 

 myelitis, and other inflammatory conditions, in which the typhoid 

 bacillus seems to be the exciting cause. Usually, however, such 

 complications are due to a secondary or mixed infection with 

 staphylococci, streptococci, pneumococci, or the colon bacilli. 



The bacilli are eliminated mainly in the feces. About the second 

 week they are apt to appear also in large numbers in the urine. 

 Frequently they persist until several weeks or months after con- 

 valescence. Occasionally they are found in the secretions; or- 

 ganisms have been found in the roseolar spots which occur in ty- 

 phoid. It cannot be concluded, however, that their presence is 

 the cause of such spots. In cases of pneumonia due to the typhoid 

 bacilli they are abundantly present in the sputum. There is 

 strong evidence that the bacilli may persist in the gall bladder 

 for many years and from thence find their way into the intestines. 

 It is probable that the catarrhal inflammation they produce there 

 causes a deposit of the bile in a solid form, resulting in gallstones. 

 In operations on the gall bladder years after recovery from the 



