452 THE TUBERCLE BACILLUS GROUP 



were all free from tuberculosis, except one which had subsequently 

 developed miliary tuberculosis. His general conclusion is that the 

 unreliability of this reaction increases with age. 



Von Ruck 1 has collected a large series of cases from the literature 

 with the following results : 



Subcutaneous reaction, 8108 cases in all. 



4803 tuberculous patients (clinical) .... 4318 positive reaction 



485 suspected cases (clinical) . . . . . . 318 positive reaction 



2820 clinically non-tuberculous 1444 positive reaction 



Cutaneous reaction, 6571 cases. 



2192 tuberculous patients (clinical) . . . . 1851 positive reaction 



865 suspected cases (clinical) 563 positive reaction 



3514 clinically non-tuberculous 1047 positive reaction 



Conjunctival reaction, 6788 cases. 



2834 tuberculous patients (clinical) .... 2370 positive reaction 



1188 suspected cases (clinical) 685 positive reaction 



2766 clinically non-tuberculous 407 positive reaction 



SUMMARY. 



Tuberculosis Suspicious Non-tuberculosis 



Subcutaneous reaction . . 89.2%+ 65.5%+ 51.2% + 



Conjunctival reaction . . . 83. 6%+ 56. 6%+ 14.7 % + 



Cutaneous reaction . . . 84.4 % + 65.0 % + 29.8 % + 

 Cutaneous reaction (excluding 



children) 33.9 % + 



The tuberculin test, therefore, when positive gives no absolutely 

 definite distinction between healed, latent, or active foci of infection 

 with the tubercle bacillus. Furthermore, no quantitative evidence 

 of the nature of the reaction or extent of the lesions is elicited by a 

 positive reaction. A negative reaction properly performed, however, 

 in non-cachectic subjects or those who have not had progressive 

 treatment with tuberculin is fairly conclusive. The subcutaneous 

 test of Koch is moderately reliable in adults provided the dosage is 

 correctly selected a matter requiring unusual skill and experience. 

 The von Pirquet reaction is quite unreliable as an index of an active 

 focus in adults, because from 30 to 60 per cent, of all persons over 

 five years of age react positively in varying degrees. It is a fairly con- 

 clusive test in children under five years of age. Similar fallacies are 

 to be expected in the ophthalmo and Moro reactions. 2 



B. Serological Diagnosis. 1. Opsonic Index. Wright and his pupils 

 have followed the opsonic index in tuberculous patients and they 



1 Beitr. z. Klinik d. Tuberkulose, 1909, xiii, Heft 1. 



2 For a detailed summary of the Koch, Wassermann, von Pirquet, and Wolff-Eisner 

 theories of the tuberculin reaction and its importance for therapy, see Kuthy and Wolff- 

 Eisner, Die Prognosenstellung bei den Lungentuberkulose, Berlin and Vienna, 1914, 

 393-399. Also, Wolff-Eisner, Die Tuberkulinbehandlung, 1913. 



