Sexual transmission risk among noninjecting heroin users infected with human immunodeficiency virus or hepatitis C virus.

To assess whether human immunodeficiency virus (HIV)-infected and/or hepatitis C virus (HCV)-infected noninjecting heroin users (NIUs) are a potential sexual transmission bridge to "lower risk" partners, 180 HIV- or HCV-infected NIUs recruited in New York City were interviewed about their sexual behaviors and partnerships. Sixty-two percent were former injecting drug users (IDUs). Partners reported not to be HIV infected, IDUs, or men who have sex with men were defined as lower risk. Among 54 HIV-infected NIUs, lower risk partners were reported by 54% of never IDUs and 23% of former IDUs (P=.02). Among 155 HCV-infected NIUs, lower risk partners were reported by 54% of never IDUs and 45% of former IDUs (not significant). Engaging in unprotected vaginal or anal sex and having lower risk partners was reported by 29% of HIV-infected never IDUs, 12% of HIV-infected former IDUs, 29% of HCV-infected never IDUs, and 34% of HCV-infected former IDUs. HIV-infected NIUs, particularly never IDUs, and, possibly, HCV-infected NIUs, are a potential sexual transmission bridge.