Syphilis and neurosyphilis in a human immunodeficiency virus type-1 seropositive population: Evidence for frequent serologic relapse after therapy

To describe clinical and treatment aspects of syphilis infection among patients seropositive for the human immunodeficiency virus (HIV). Results of serologic tests for syphilis, CD4+ T-lymphocyte counts, and clinical response to therapy were retrospectively monitored in 100 HIV-infected adults with syphilis from a tertiary-care military HIV program. Of the 1,206 HIV-infected patients, 100 (8.3%) in the cohort had syphilis; 61 patients were treated for active syphilis. Serologic or clinical relapse eventually occurred in 10 of the 56 treated patients (17.9%) with follow-up available; 7 of the 10 who relapsed had previously received high-dose intravenous or procaine penicillin therapy. Relapse occurred more than 12 months after initial therapy in 6 of 10 patients (60%) who experienced relapse; 5 patients experienced multiple relapses. The mean CD4+ T-lymphocyte count was not predictive of relapse. Patients with reactive cerebrospinal fluid (CSF) Venereal Disease Research Laboratory (VDRL) test titers (4 of 7 patients [57%]) or the rash of secondary syphilis (4 of 14 patients [29%]) were at highest risk of subsequent relapse or treatment failure when monitored for an average of 2 years. Standard penicillin regimens, including high-dose intravenous penicillin, transiently lowered serum VDRL titers in nearly all cases, but were sometimes inadequate in preventing serologic and clinical relapse in patients infected with HIV type-1, especially among those with secondary syphilis and reactive CSF VDRL titers. Careful long-term follow-up is essential, and repeated courses of therapy may be needed for patients infected with HIV type-1 who have syphilis.