A prospective study of syphilis and HIV infection among injection drug users receiving methadone in the Bronx, NY

Objectives. The purpose of this study was to assess the relationship between syphilis and human immunodeficiency virus (HIV) infection in injection drug users. Methods. A 6-year prospective study of 790 injection drug users receiving methadone maintenance treatment in the Bronx, NY, was conducted. Results. Sixteen percent (4/25) of HIV-seroconverting patients, 4.8% (16/335) of prevalent HIV-seropositive patients, and 3.5% (15/430) of persistently HIV-seronegative patients were diagnosed with syphilis. Incidence rates for early syphilis (cases per 1000 person-years) were 15.9 for HIV-seroconverting patients, 8.9 for prevalent HIV-seropositive patients, and 2.9 for persistently HIV-seronegative patients. Early syphilis incidence was higher among women than men (8.4 vs 3.2 cases per 1000 person- years). Independent risks for early syphilis included multiple sex partners. HIV seroconversion, paid sex, and young age. All HIV seroconverters with syphilis were female. Conclusions. Diagnosis of syphilis in drug-using women reflects high-risk sexual activity and is associated with acquiring HIV infection. Interventions to reduce the risk of sexually acquired infections are urgently needed among female drug users.