INTESTINAL OR COLON-TYPHOID GROUP 281 



are usually found in the blood, though not commonly in large num- 

 bers, but are abundant in the spleen. Cystitis, cholecystitis, and 

 bone metastases are not uncommon sequelae to the infection. 



Immunity. Xo true toxin has been demonstrated for B. 

 typhosus, but an endotoxin is present. Agglutinins and pre- 

 cipitins specific for the organism are likewise produced. Bac- 

 teriolysins may be demonstrated in the blood of animals that have 

 been artificially immunized by injections of the typhoid bacillus. 

 There is developed in the body of an individual that has recovered 

 from typhoid a certain degree of immunity, but this disappears, 

 so that it is not unusual for a person to have several attacks of the 

 disease. This immunity is probably both bacteriolytic and 

 opsonic in nature. 



The use of antisera in passive immunization against typhoid 

 and in curing the disease has not proved successful. The injec- 

 tion of such sera has not been shown to have either an immunizing 

 or a curative effect in man. Active immunization by the injec- 

 tion of dead or living bacteria or their products has, on the con- 

 trary, been quite successful. Usually the organisms are scVaped 

 from the surface of agar cultures, suspended in physiologic salt 

 solution, and killed by heat, or a broth culture may be used. 

 Such injections are, of course, only prophylactic. 



Bacteriologic Diagnosis. The Widal or agglutination test is 

 commonly used in the diagnosis of typhoid. A dilution of 1 : 40 

 and higher is generally made to minimize the effect of the normal 

 agglutinins which may be present in the blood. Both microscopic 

 and macroscopic tests are used; the former is the more delicate, but 

 the latter somewhat more reliable. The agglutinins often appear 

 early in the course of the disease usually by the fifth day or rarely 

 later. Blood or serum for making the test may be either liquid 

 or dried. It is received in the latter condition by many of the 

 state and municipal bacteriological laboratories. The bacteria 

 may be cultivated directly from the blood of a patient. Fre- 

 quently the organisms can be found in the blood somewhat before 

 the serum exhibits a marked agglutinating power. Isolation of 

 the organisms directly from the feces is sometimes resorted to in 

 an effort to determine the occurrence of the so-called " bacillus 



