The tuberculous organism will react in a threefold way on the injected tuberculin. There will be (1) a general reaction, (2) a focal reaction in all tuberctdously affected parts of the body and (3) a local reaction around the place of injection.
1. General Reaction.—Provided a minimal dose, suited to the indi vidual case, has been administered, the temperature will first slowly rise in about four to six hours after the injection, then rapidly rise after a further two to four hours. Then it \vill gradually decline and return to normal inside of twenty-four hours. In some cases the access of fever may last somewhat longer and exceed even twenty-four hours. It is said by some authors that the protracted reaction occurs oftener in children than in adults. In a third class of patients the rise in temper ature will occur considerably later, or the elevation take place slowly. The fever period is sometimes associated with headache, general malaise, possibly reduced appetite, and occasionally vomiting. Generally speaking these subjective manifestations are much less severe in children than in adults. The younger the child is, the less will be the manifestations, and in most cases an increased demand for sleep will tide them over the period of reaction. Of course, it is necessary for children to stay in bed all the time.
The reaction is considered positive, if the rectal temperature rises above 37.6° C. (99.5° F.), or if it exceeds by more than 0.5° C. (0.9° F.) the previous determinations. If is no reaction, or if the reaction leaves any doubt as to whether it is positive, the injections are repeated in slowly increasing doses and suitable intervals (twice or three times in twenty-four hours), until a close of 0.01 gram will decide the question. I have never known the subcutaneous tuberculin reaction to fail with this method of procedure. When it was positive and I had an opportunity to follow the case up, or to witness the autopsy, the presence of tuber culosis was always reliably demonstrated. When it was negative, we have never found tuberculosis at autopsy. Of course, the reaction merely indicates a tuberculous involvement, and not the presence of a tuber culous infection. I have never observed any injurious effect upon injected children and am, therefore, unable to agree with the contrary opinion of other authors, such as Neumann for instance.
2. The focal reaction finds expression in increased blood supply to all specifically affected tuberculous parts of the body. Even when apparently healed, they will swell under the influence of the injected tuberculin, become hyperxmic and proliferate more vigorously; in short, all parts which have ever undergone anatomical changes of a tuberculous origin, and where there are still specific changes, will demonstrate reactive processes. Ender certain circumstances the focal reaction may be of diagnostic importance inasmuch as it proves definite parts as tuberculously affected (articulations). Lastly, those parts of the skin where a cutaneous reaction had preceded the subcutaneous injection will again flare up.
3. Local Rcaction.—There are two kinds of local reaction: (a) Around the puncture of the needle which at the time of injec tion has penetrated through the epidermis into the tissues, there is often hypemmia and swelling six to eight hours after injection. This may persist for several days and vary in diameter between 1 mm. and 1 cm.
This is the "puncture reaction," and I wish it to be distinctly under stood that by puncture reaction I mean the manifestations just described, and no others.
ib) At the place where the point of the needle has introduced the tuberculin into the subcutaneous tissue there is another reaction, occur ring a few hours after injection, which consists in swelling of the sub cutaneous tissue, with possible tenderness on contact or pressure, and followed later by hyperaemia of the skin. It is opportune to thoroughly distinguish between the subcutaneous and puncture reactions. The places where they occur may be somewhat distant from each other if the needle has been pushed forward under the skin, driving the fluid for some distance into the subcutaneous tissue; in other cases the puncture reaction may, so to speak, form the centre of the subcutaneous reaction. The question whether a puncture reaction will occur or not depends upon the mere accident whether the epidermic layer has imbibed some of the tuberculin when the needle was inserted or withdrawn, whereas a dis tinctly visible subcutaneous reaction is rarely absent.