Objectives: To identify risks associated with HIV infection among young adult short-term injection drug users.
Methods: Current injection drug users, between 18 and 29 years of age, were recruited through street outreach to participate in a cross-sectional survey of HIV prevalence by circumstances of drug injection initiation, HIV-related risk behaviors, and a follow-up to estimate HIV incidence.
Results: At enrollment, 33 (14.4%) of 229 participants were HIV-seropositive. Significant bivariate associations with HIV at the time injection drug use was initiated included age less than or equal to 18 years, having receptive anal sex with the person who assisted with initiation, and having two or more 'trainers' before being able to self-inject. Injecting risks positively associated with HIV included cocaine or speedball (heroin and cocaine together) injection versus heroin or amphetamine injection, injecting five or more times per day, daily crack smoking, backloading, sharing needles at peak drug use, and not using a new needle for every injection. Sexual practices associated with HIV included reporting > 100 lifetime sex partners, a history of sexual assault, being gay or bisexual, and trading sex for money or drugs after starting to inject. In a multivariate model, trading anal sex for money or drugs after initiating injection drug use [odds ratio (OR), 14.2; 95% confidence interval (CI) 3.2-62.3], cocaine/speedball injection (OR, 10.3; 95% CI, 2.2-47.9), daily crack smoking (OR, 4.2; 95% CI, 1.7-10.5), and having two or more trainers (OR, 2.6; 95% CI, 1.1 - 5.9) were independently associated with HIV. During 12 months of follow-up, four persons seroconverted for HIV (annual incidence: 2.6%; 95% CI, 1.1 -5.9%)
Conclusions: Among short-term injectors, both sexual and injecting practices were important predictors of HIV infection, indicating that a proportion of HIV infections among young injection drug users can be attributed to sexual transmission. The incidence rate for HIV infection suggests that immediate steps should be taken to prevent new infections among young injection drug users.