ALLERGIC REACTIONS 333 



limit, beyond which a reaction cannot be considered as specific. 

 Should elevation of temperature follow any one of the injections, 

 even though amounting to but three-tenths of a degree (C.), the 

 next dose should be of the same size, but it is not to be given until 

 the temperature has returned to normal. It will often be found, 

 then, that the second reaction is more marked than the first. Such 

 an occurrence Koch regards as particularly characteristic, and, 

 indeed, as an infallible indication of the existence of tuberculosis. 



Before beginning it is, of course, desirable to observe the tempera- 

 ture of the patient for a while, and not to inject until it has been 

 found below 37.3 C. for a day or two. 1 The reaction is regarded 

 as positive if the temperature reaches a point that is at least 0.5 C. 

 above the highest noted before the injection. 



If small doses have been used the rise usually begins after ten to 

 sixteen hours, while with the larger doses it may occur after six 

 to eight hours. There is usually a slight chill which is accompanied 

 by headache and pains in the muscles, nausea, palpitation of the 

 heart, etc. An hour or two after the injection there may also be 

 evidence of an inflammatory reaction at the point of inoculation 

 (redness and tenderness). At the expiration of about ten hours 

 there is marked infiltration at this point, which may persist for two 

 to six days before resorption has taken place. After reaching its 

 highest point the temperature usually drops within a few hours, 

 so that normal relations are again restored at the expiration of 

 twenty-four to forty-eight hours following the injection. The 

 patient may experience a certain degree of lassitude for two or 

 three days and possibly have an increased secretion of sputum, but 

 is then restored to the same condition as before the examination. 



A positive reaction, of course, only means that the patient has 

 a tubercular focus somewhere in his body, but does not in itself 

 indicate whether this is active or not. This point must be decided 

 by the history, the clinical findings, etc. 



Regarding the constancy of the reaction in cases of proved tuber- 

 culosis, in suspected cases and in supposedly non-tubercular individ- 

 uals the accompanying table will furnish the desired . information : 



Pulmonary tuberculosis 90.0 to 100.0 per cent. 



Suspected cases 92 . 1 per cent. 



Non-suspected cases . . . 56 . 1 per cent. 



1 The temperature should be taken every three hours. 



