504 Typhoid Fever 



animals. Stern * found in the blood of human convalescents 

 a substance thought to have a protective effect upon infected 

 guinea-pigs. His observation is in accordance with a pre- 

 vious one by Chantemesse and Widal, and has recently been 

 abundantly confirmed. 



The immunization of dogs and goats by the introduction 

 of increasing doses of virulent cultures has been achieved 

 by Pfeiffer and Kollef and by Loffler and Abel.J From 

 these animals immune serums were secured. 



The typhoid immune serum is specific, but its action 

 requires the presence of additional complementary sub- 

 stance, and by itself it is useless. Indeed, by itself it may 

 do harm by causing the formation of anti-immune bodies. 



So far, no serum has been produced that is of any value 

 in therapeutics. 



Serum Diagnosis. The specific action of the artificially 

 prepared serums can be used to differentiate cultures of 

 the colon, paracolon, typhoid, and paratyphoid bacilli, the 

 typhoid bacilli alone exhibiting the specific effect of the 

 typhoid serum. 



Richardson has found it very convenient to saturate filter paper 

 with typhoid serum, dry it, cut into 0.5 cm. squares, and keep it on 

 hand in the laboratory for the purpose of making this differentiation. 

 To make a test, one of these little squares is dropped in 0.5 c.c. of a 

 twenty-four-hour-old bouillon culture of the suspected bacillus and 

 allowed to stand for five minutes. A drop of the fluid placed upon 

 a slide and covered will then show typical agglutinations if the culture 

 be one of the typhoid fever bacillus. In a second mention of this 

 method || he has found its use satisfactory in practice and the paper 

 serviceable after fourteen months' keeping. 



Christophers ** found that the serum from typhoid patients 

 occasionally caused agglutination of the colon bacillus, but 

 concludes that this does not lessen the specificity of the 

 reaction, as there may be two combined specific actions of 

 the serums. Experiments on rabbits have shown that both 

 typhoid and colon immune serums can be produced, each 

 specific in its agglutinating power upon cultures of its 

 respective organisms. 



* "Zeitschrift fur Hygiene," 1894, xvi, p. 458. 



f ' Centralbl. f. Bakt. u. Parasitenk.," Jan. 23, 1896, Bd. xix, No. 

 23, p. 51. 



I Ibid., 1896. 



"Centralbl. f. Bakt. u. Parasitenk.," 1897, p. 445. 

 || "Journal of Experimental Medicine," May, 1898, p. 353, note. 

 ** "Brit. Med. Jour.," Jan. 8, 1898. 



