TYPHOID FEVER. 177 



of Widal, and in no instance has this dilution yielded the 

 reaction with serum not from a case of typhoid fever. It is 

 possible, however, that the agglutinating activity in cases 

 of typhoid fever may be below these figures ; with dilu- 

 tions between I : 50 and I : 10 Widal and Sicard rec- 

 ommend that the case be considered as suspicious with 

 regard to typhoid fever, and that the observation be re- 

 peated in the course of a few days. The serum of typhoid 

 patients, even when not sterile, retains its agglutinating 

 power unchanged for several months. It may, therefore, be 

 preserved and sent from one place to another. The time 

 when the agglutinating property appears in the serum is of 

 importance in diagnosis. As a rule, it is demonstrable 

 after the seventh day, although it may appear later or 

 earlier. The earliest that it has been observed was on the 

 second day by C. Frankel, and the latest in the first days of 

 convalescence by Achard. 



The Widal-Gruber reaction grows feebler in the first 

 weeks or months of convalescence, finally to disappear 

 completely in some cases. Frequently, however, it per- 

 sists, and it may be demonstrable after the lapse of years, 

 or even of decades, and it can thus be utilized as an evi- 

 dence that the individual in question has previously suffered 

 from an attack of typhoid fever. On this account it is 

 absolutely necessary, in the application of serum-diagnosis, 

 to learn from the patient's history whether he has not 

 already at some time passed through an attack of typhoid 

 fever, however mild ; otherwise, there is danger that a re- 

 action of older date may be employed diagnostically in 

 relation to the disease under observation. Widal and Sicard 

 divide their cases of typhoid fever into five groups, accord- 

 ingly as the serum exhibits a greater or lesser agglutinating 

 activity. In the first group the agglutinating power is 

 very slight, below I to 100; in the second group it is 

 feeble, between i to 100 and I to 200 ; in the third group 

 it is moderately great, up to I to 500 ; in the fourth group 

 it is great, up to I to 2000 ; and, finally, in the fifth group 

 it is above I to 2000. Each of these five groups includes 

 both mild and severe cases. The agglutinating curve in 

 individual cases of typhoid fever, observed throughout the 

 whole course of the disease, likewise exhibits the widest 

 variations. Each case bears in this respect, as Widal and 

 Sicard believe, its individual impress. Its agglutinating 



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