Relationships and diseases among drug users and nonusers.

Human immunodeficiency virus (HIV) and syphilis are relationship-based diseases that are typically transmitted by the cooperative activities (sex or drug injection) of two persons. A sample of 215 drug users and 52 sociodemographically matched nonusers was collected to examine the behaviors and relationships related to HIV and syphilis transmission. Results showed that, although drug users had more risk opportunities (more sex partners and, of course, more injection partners) than nonusers, actual sex risk behaviors (never using condoms) did not differ appreciably among drug users and nonusers or with opposite-sex partners and same-sex partners. The similarity of sexual risk was supported by the similar levels of syphilis between drug users and nonusers. The unique risk to drug users was drug injection, although drug users were found to engage in fewer risky injection behaviors (sharing of drug injection equipment) than the risky sexual behaviors in which all participants engaged. Although drug users interacted as frequently with partners as nonusers, nonuser relationships were longer lasting and emotionally closer.