In view of the uncertainty about the duration of immunity conferred by antityphoid inoculation and the occasional occurrence of typhoid fever among those recently vaccinated, it is highly desirable to have a test which will indicate the existence or absence of immunity and if possible also the degree of immunity. Gay and Force1 have discussed the heretofore unsatisfactory efforts to utilize agglutination and other biologic reactions for this purpose, and have described promising experiments with a cutaneous typhoidin test.
The technic used in this investigation was described by Gay and Force1 and is similar to the Pirquet tuberculin test. It consists in making two circular abrasions without drawing blood by rotating a chisel with a 2.5 mm. blade. "Typhoidin" was applied to one spot and the control application to the other. The preparation of killed typhoid bacilli in liquid culture medium having been found by Gay
KILGORE ES. THE TYPHOIDIN QUOTIENTQUANTITATIVE STUDIES OF THE CUTANEOUS TEST OF TYPHOID IMMUNITY. Arch Intern Med (Chic). 1916;XVII(1):25–31. doi:10.1001/archinte.1916.00080070043003