New Injectors and HIV-1 Risk

Most persons who inject drugs for the first time are likely to be uninfected with HIV-1 unless they are men who have sex with men or residents of a country characterized by very high rates of heterosexual transmission. Indeed, there is a considerable literature showing that new drug injectors are less likely to be infected with HIV-1 than longer-term injectors (De Rossi et al., 1988; Friedman et al, 1989; Lima et al., 1994; van den Hoek et al., 1988; Vlahov et al., 1990; Zunzunegui-Pastor et al., 1993). It has been suggested that the seroconversion rates of new injectors may vary in a complicated relationship with the overall seroprevalence and seroconversion rates of an area (Friedman et al., 1994a), with new injectors having higher seroconversion rates than longer-term injectors in cities with high but stable seroprevalence (Ciaffi et al., 1992), lower serocon-version rates in cities of medium-to-high but increasing seroprevalence, and equally low seroconversion rates in cities with low seroprevalence. New male injectors seem to become infected later in their injection careers than do women in New York, as well as in some (but not all) other American cities (Des Jarlais et al., 1994; Friedman et al., 1993, 1994a; Neaigus et al, 1995).