Widal Reaction of Agglutination 505 



Loffler and Abel also prepared a colon immune serum that 

 exerted a specific action upon the colon bacillus, but was 

 without effect upon the typhoid bacillus. 



Widal Reaction of Agglutination. In 1896 Widal and 

 Grtinbaum,* working independently, discovered that when 

 blood-serum from typhoid fever patients is added to cultures 

 of the typhoid bacillus a definite reactive phenomenon 

 occurs identical with that already described by Charrin and 

 Roger and Gruber and Durham (see "Agglutination"). 

 The phenomenon, now familiarly known as the "Widal 

 reaction," consists of complete loss of the motion so char- 

 acteristic of the typhoid bacillus, and collection of the micro- 

 organisms into clusters or groups agglutination. The 

 bacteria frequently appear shrunken and partly dissolved. 



The previous work of Gruber and his associates merits 

 careful study (see chapter upon "Infection"), but so long 

 as the matter was in Gruber's hands it was an interesting 

 observation. Widal developed it into an accurate means 

 of diagnosticating typhoid fever and other diseases. 



The reaction usually appears by the seventh day of the disease, some- 

 times earlier. Johnston and McTaggart f usually found it quite well 

 marked by the fifth day, and sometimes observed it forty-eight hours 

 after the beginning of the fever. Widal and Sicard { state that the 

 reaction occurs on the first day of infection. Not infrequently it fails 

 to develop until later, but most cases react well in the second week, 

 and all show reaction in the third week. 



In between 4 and 6 per cent, of cases of clinical typhoid fever the 

 reaction fails to appear even though the case prove fatal. These are 

 probably cases of paratyphoid infection. 



In 1899 I made a large number of blood-examinations to deter- 

 mine the value of the serum test as an aid in diagnosis. The Widal 

 test was made day after day in 230 cases of typhoid fever affecting 

 soldiers of the United States army during the Spanish-American 

 War returned from the camps to be treated in the Medico-Chirurgi- 

 cal Hospital. Of these, 219 reacted positively, or 95.64 per cent, 

 of the total number examined. One of the fatal cases, which was 

 otherwise typical typhoid fever, failed to show a reaction so late as 

 the seventeenth day of the illness ; this was excluded, for the obvious 

 reason that had the patient survived for a longer period a positive 

 reaction might have been obtained. So in 10 cases no reaction was 

 present, although the blood was repeatedly tested until the return 

 of the temperature to normal. The percentage of cases, therefore, 

 in which the reaction failed was 4.36 per cent. 



Of the 219 cases giving a positive result, 128 showed the reaction 

 prior to the appearance of the rose-spots, or before the eighth day; 



* "La Semaine medicale," 1896, p. 295. 



t"Amer. Medico-Surgical Bulletin," Jan. 10, 1897, p. 12. 



$ "Ann. de 1'Inst. Pasteur," May, 1897. 



"Phila. Med. Jour.," April 8-15, 1899. 



