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 was 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.