DIPHTHERIA IMMUNITY TEST 475 



becomes dark bluish red. The induration disappears within two weeks, 

 as a rule. 



In the pustular form, after the fourth or fifth day, the inflammatory 

 process increases in intensity and the papules become vesicular and later 

 purulent. The pustules rupture spontaneously and the defect caused by 

 the escape of the pustular content becomes quickly covered by a crust 

 that falls off within a few days. A small induration sometimes remains 

 for a few weeks or often months, leaving a small keloid after healing. 



In the torpid type of syphilis the site of injection fades to an almost 

 invisible point within three to four days, so that it may be erroneously 

 considered a negative reaction. After ten days or even longer, the spot 

 suddenly begins to enlarge and goes through the same stages as seen in 

 the pustular type. 



Luetin is employed for the diagnosis of syphilis. It is of use in the 

 examination of tertiary cases but rarely gives a positive reaction in the 

 primary cases or in untreated secondary cases. In patients who are under 

 treatment by mercury or salvarsan the reaction is frequently positive even 

 in cases which fail to give a positive Wassermann reaction. 



The amount of luetin to be injected for one test is 0.07 mil. The mate- 

 rial should be properly diluted and injected into, but not under, the skin. 

 A site should be selected on the skin of the upper arm, cleansed and steril- 

 ized and the injection made as described. 



DIPHTHERIA IMMUNITY TEST (Scmcx TEST). This test is intended to 

 determine those persons who have not in their blood an amount of diph- 

 theria antitoxin sufficient to render them immune. The test depends on 

 the phenomenon that when a small amount of diphtheria toxin is injected 

 intradermally into a person who has no free antitoxin in his blood, a cir- 

 cumscribed area of redness and infiltration from i to 2 cm. in diameter 

 develops at the site of injection. Should the patient have free antitoxin 

 in his blood no reaction occurs. The reaction occurs in twenty-four to 

 forty-eight hours and is at its height in forty-eight to seventy-two hours. 

 It remains for six to twelve days, is followed by slight scaling and leaves 

 a brownish pigmented spot. In some persons, pseudoreaction may occur, 

 which may be differentiated by its earlier appearance and disappear- 

 ance and the fact that it is less circumscribed and is not followed by 

 pigmentation. 



The test is of special value for use in institutions and among groups 

 of persons exposed to diphtheria, in order that it may be determined which 

 individual should be given an immunizing dose of diphtheria antitoxin. 

 It is also of value in the diagnosis of other conditions stimulating diphtheric 

 infection. 



Diphtheria toxin in dilute solution, such as is necessary for the tests, 

 soon loses in potency. 



