SCHICK REACTION

Abstract

Systematic observations by numerous workers, notably among them Schick¹of Vienna and Park²of New York, indicate that the blood serum of about 80 per cent, of the new-born, from 50 to 60 per cent. of children and 90 per cent. of adults contains sufficient diphtheria antitoxin to make them insusceptible to diphtheria, and hence makes it unnecessary for them to receive a prophylactic injection of diphtheria antitoxin. Experience bears out this statement.³ A practical method for determining whether or not a person is susceptible to diphtheria has recently been devised by Schick¹while working in von Pirquet's clinic in Vienna. The reaction⁴depends on the local irritant action of minute quantities of diphtheria toxin when injected intracutaneously, in the absence of antitoxin. Schick's results are in accord with those obtained by the more elaborate method of Römer⁵which makes it possible to titrate