Objective

To examine the extent to which the regional and neighborhood distribution of HIV in Tanzania is caused by the differential distribution of individual correlates and risk factors.
Methods

Nationally representative, cross-sectional data on 12 522 women and men aged 15–49 years from the 2003–2004 Tanzanian AIDS Indicator Survey. Three-level multilevel binary logistic regression models were specified to estimate the relative contribution of regions and neighborhoods to the variation in HIV seroprevalence.
Results

Spatial distribution of individual correlates (and risk factors) of HIV do not explain the neighborhood and regional variation in HIV seroprevalence. Neighborhoods and regions accounted for approximately 14 and 6% of the total variation in HIV. HIV prevalence ranged from 1.8% (Kigoma) to 6.7% (Iringa) even after adjusting for the compositional make-up of these regions. An inverse association was observed between log odds of being HIV positive and neighborhood poverty [odds ratio (OR) 0.24, 95% confidence interval (CI) 0.09–0.61] and regional poverty (OR 0.97, 95% CI 0.95–0.99).
Conclusion

Our study provides evidence for independent contextual variations in HIV, above and beyond that which can be ascribed to geographical variations in individual-level correlates and risk factors. We emphasize the need to adopt both a group-based and a place-based approach, as opposed to the dominant high-risk group approach, for understanding the epidemiology of HIV as well as for developing HIV intervention activities.