Risk networks and racial/ethnic differences in the prevalence of HIV infection among injection drug users.

Studies among injection drug users (IDUs) find a higher prevalence of HIV infection among black and Puerto Rican IDUs than among white IDUs. Risk behaviors seldom explain these differences. We examine how risk networks contribute to racial/ethnic variations in HIV prevalence. Six hundred sixty-two IDUs were recruited on the street in Bushwick (New York City), interviewed, and tested for HIV. Risk behaviors and networks were analyzed to explain racial/ethnic variations in HIV. Forty percent of IDUs were infected with HIV. HIV prevalence was greater for Puerto Ricans (45%) and blacks (44%) than for whites (32%). Egocentric sexual and drug risk networks were predominantly racially/ethnically homogeneous. After multivariate adjustments for risk behaviors and risk networks, black-white differences in HIV prevalence were no longer significant. Although differences between Puerto Ricans and whites persisted, post hoc analyses suggested that network partner characteristics might explain these differences. In Bushwick, racially/ethnically discordant risk partnerships involving black IDUs may function as potential bridges of transmission between groups.