300 IMMUNOLOGICAL METHODS OF DIAGNOSIS 



Intermittence of the reaction, moreover, is quite common and 

 emphasizes the necessity of frequent examinations still further. 



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 antecedent 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 dilution 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 formation 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 stand-point. 



