52 TUBERCULIN DIAGNOSIS. 



Apropos this latter, v. Pirquet makes some very interesting observations. 

 Out of 747 children in Escherich's clinic in Vienna upon whom the reac- 

 tion was tried, there were: 



clinically tuberculous 130, out of which 113 (87%) showed a positive reaction; 



clinically non-tuberculous 512, " " " 104 (20%) " " " 

 doubtful 115, " " " 56(48.6%) " " " 



Almost all of the tuberculous children who did not react were cachectic. 



As for the positive reaction in non-tuberculous cases, the age of the child 

 in large part explains the great differences found. 



Whereas healthy infants up to the sixth month almost never give a posi- 

 tive reaction, healthy children of 



1 to 2 years react in 2 per cent, of cases. 



2 to 4 years react in 13 per cent, of cases. 

 4 to 6 years react in 17 per cent, of cases. 

 6 to 10 years react in 35 per cent, of cases. 

 10 to 14 years react in 55 per cent, of cases. 



In adults one meets with a positive v. Pirquet's reaction in more than 

 70 per cent, of all cases. V. Pirquet explains this by the presence of latent 

 tuberculosis. 



// therefore becomes self evident, that the cutaneous reaction in adults is void 

 of any diagnostic value. A negative reaction only, can be fully relied on, 

 and that, if no cachexia exists. 



In young children on the other hand, v. Pirquet's method should be the 

 choice. In addition to its being entirely harmless, and easily applied, it 

 possesses a high diagnostic value. 



As for Koch's subcutaneous reaction, it is specific, inasmuch as it is a rare 

 exception to get a negative reaction in an active tuberculous process. This 

 occurs only in cases either with very severe cachexia or those with freely 

 circulating anti-tuberculin in the blood. If the latter two possibilities are 

 excluded, the absence of a positive reaction speaks decidedly in favor of the 

 absence of tuberculosis. 



The interpretation of a positive reaction as to the existence of clinically 

 active tuberculosis cannot be so definitely answered. From the work of 

 most of recent authorities, however, it seems to be taken for granted that a 

 positive reaction does mean an active tuberculosis; still, this statement 

 requires a great deal of consideration and limitation as well. 



In this connection the statistics of Franz are of great interest. Out of 

 400 apparently healthy soldiers in one of the Austrian regiments who in 1901 

 their first year of service, received an inoculation of 0.003 c - c - f tuberculin, 

 a positive result was found in 61 per cent, of the cases. In the following 

 year (1902) 100 of the soldiers were re-inoculated and all of those who re- 

 acted positively the first time, did so a second time, in some instances even 

 though the second dosage was smaller. Moreover, fourteen others who 



