THE AGGLUTINATION REACTION 267 



quite common and emphasizes the necessity of frequent examina- 

 tions still farther. 



While in some instances the reaction disappears very soon after the 

 temperature has returned to normal, and even earlier, it generally 

 continues well into convalescence, and may, in some instances, be 

 obtained after months and even years following the attack. In a 

 series of 71 post-typhoid cases, Krause found the reaction in 36, 

 viz., in 16 of 26 cases examined within a year, in 12 of 21 examined 

 between the second and the fifth year, in 7 of 19 between the fifth 

 and the tenth, and in 1 case out of 5 between the tenth and twentieth 

 (twelfth) year. In three instances no reaction could be obtained 

 within a month of the disease. To what extent the continued 

 presence of typhoid agglutinins may be referable to the persistence 

 of the corresponding bacilli in the body has not been ascertained. It 

 is known that they may persist in the gall-bladder and in the urinary 

 bladder for a long time, and in several instances they have been found 

 where no history of an antecent typhoid fever could be obtained. 

 In a case of cholelithiasis, reported by Gushing, typhoid bacilli were 

 found in the gall-bladder, and distinct clumping obtained with a dilu- 

 tion of 1 to 30, although the individual gave no history of typhoid 

 whatsoever. Cases, further, are occasionally seen which clinically 

 resemble typhoid fever very closely, but which do not give the Widal 

 reaction at any time, with the usual dilution of 1 to 50. Some of 

 these cases are referable to infection with organisms which are closely 

 related to the typhoid bacillus and which also give rise to the forma- 

 tion of agglutinins. These, however, do not react with the typhoid 

 bacillus excepting in low dilution. 



Infection with related organisms may also be responsible for certain 

 cases of febrile jaundice (Weil's disease), in which agglutination 

 of the typhoid bacillus has been observed. In others the reaction 

 may be due to a localized infection with typhoid bacilli. The biliary 

 constituents in any event are not responsible for the reaction. This 

 is clear from the observation of Kammerer, who obtained agglutina- 

 tion in only 3 cases of jaundice out of 50 selected at random. 



In the diagnosis of paratyphoid, Malta fever, and meningococcus 

 infections a corresponding technique is employed, for a consideration 

 of which the reader is referred to special works dealing with diag- 

 nostic methods from the laboratory standpoint. 



