BACKGROUND: To control the global HIV epidemic targeted interventions to reduce the incidence of HIV infections are urgently needed until an effective HIV vaccine is available. This study describes HIV-1 incidence and associated risk factors in a general population cohort of adults from Mbeya Region, Tanzania, who participated in a vaccine preparedness study.
METHODS: We conducted a closed prospective cohort study with six-monthly follow-up from 2002-2006, enrolling adults from the general population. HIV-1 incidence and risk factors for HIV-1 acquisition were analysed using Cox regression.
RESULTS: We observed 2,578 sero-negative participants for a mean period of 3.06 PY (7,471 PY in total). Overall HIV-1 incidence was 1.35 per 100 PY (95% confidence interval [CI]=1.10-1.64/100 PY). The highest overall HIV-1 incidence was found in females from Itende village (1.55 per 100 PY, 95%CI=0.99-2.30/100 PY), the highest age-specific incidence was observed in semi-urban males aged 30-34 years (2.75 per 100 PY, 95%CI=0.75-7.04). HIV-1 acquisition was independently associated with female gender (hazard ratio [HR]=1.64, 95%CI=1.05-2.57), younger age at enrolment (age 18-19 vs. 35-39: HR=0.29, 95%CI=0.11-0.75), alcohol consumption (almost daily vs. none: HR 2.01, 95%CI=1.00-4.07), education level (secondary school vs. none: HR 0.39, 95%CI=0.17-0.89) and number of lifetime sex partners (more than five vs. one: HR 2.22, 95%CI=1.13-4.36).
CONCLUSIONS: A high incidence of HIV was observed in this cohort, and incident infection was strongly associated with young age, alcohol consumption, low school education level and number of sex partners. Targeted interventions are needed to address the elevated risk associated with these factors.