TPI test in treated syphilis.

The Treponema pallidum immobilization (TPI) test has received wide attention as a diagnostic test for syphilis, but few studies have appeared on the response of this test to adequate treatment for syphilis. The Blue Star study of the Public Health Service (Bauer, 1951 ; Shafer, Usilton, and Price, 1954) offered a group of patients who had had bonafide syphilis, who had been adequately treated, and who had been closely observed for many years after treatment. The purpose of the present study is to determine the TPI results in these patients and to compare them with results of the VDRL slide and Kahn quantitative tests. When the Blue Star study patients were seen for their latest evaluation (5 to 9 years after treatment) blood was drawn and sent to the Venereal Disease Research Laboratory for the performance of the TPI, VDRL slide, and Kahn quantitative tests. During the early years of the Blue Star study, which was initiated in 1945, patients with any syphilitic diagnosis were accepted for study. As the study progressed and it was found that patients with secondary syphilis were the most satisfactory group for evaluating schedules of treatment, selections were limited to this stage. Therefore, of the 366 Blue Star patients who had TPI tests as of August, 1955, 213 were in the secondary stage at time of original treatment, 91 in the primary, 36 in the early latent stage, and only 22 in the late stages (twelve were diagnosed as having late latent syphilis, and ten as having symptomatic or asymptomatic neurosyphilis). In four patients treated before admission to the Blue Star study, the diagnosis at time of first treatment is unknown. As shown in Table I (opposite), 305 of the patients received only one course of treatment. The remaining 61 patients were treated two or more times, some for relapse or resistance, others for re-infection. No