202 ACTIVE IMMUNIZATION 



As initial dose, that amount is suggested which a preliminary 

 diagnostic examination has shown to produce a systemic reaction 

 (see tuberculin test). If this is for any reason omitted, it is best to 

 start the patient with 0.1 milligram, and to increase the dose progres- 

 sively at intervals which are determined according to the activity 

 of the reaction, and which accordingly vary from one to two weeks. 

 In the event of a marked reaction, it is best to repeat the last dose, 

 or to increase this only very slightly. A reversion to a smaller 

 dose is to be avoided, and it is better, if need be, to wait a week longer 

 before the next injection is given. In the light cases it is thus pos- 

 sible to run up to a dose of 1000 milligrams without much trouble, 

 while in the presence of more advanced lesions this is more difficult; 

 when the higher doses are reached the intervals between the injec- 

 tions may have to be lengthened to a month or even longer. The 

 treatment is virtually considered at an end when the patient can 

 stand a dose of 500 milligrams without marked systemic reaction. 



New Tuberculin. One c.c. of new tuberculin represents 5 milli- 

 grams of the dry powder. Koch recommends that the injections 

 be started with a dose of 0.0025 milligram. To this end the original 

 product is diluted with sterile water to the required degree, such that 

 the amount to be injected is less than 1 c.c. in bulk, as larger quan- 

 tities favor the development of local infiltration. For convenience 

 sake we can start with a dilution of the original product of 1 in 10 

 (A), 1 c.c. of which in turn is diluted 1 :10 (B), and of this again 1 c.c. 

 in the same proportion (C) ; 1 c.c. of A then contains 0.5 milligram, 

 1 c.c. of B 0.05, and 1 c.c. of C 0.005; one-half c.c. of the latter 

 dilution being thus the initial dose. 



The injections are at first given four days apart, and later when 

 reactions begin to appear (i. e., when amounts varying between 

 the tenth and one hundreth part of a milligram are injected) at 

 intervals of eight days, in gradually increasing amounts, such as 

 4-5-0 milligram; -^, y|-o, rfro> r!~o> TITO> TIT rfa* TTF f F> T 3 o" etc., 

 exactly as was customary with the old tuberculin. Koch advocates 

 that the immunization be continued until the patients can take 20 

 milligrams of the dry powder without any reaction. 



Point of Injection. As in the case of the other bacterial vaccines 

 the injections can be conveniently given into the loose subcutaneous 

 tissue in the district over the triceps, or in the back on a level with 

 the angle of the scapula. Lowenstein states that the injections 



