High potential of escalating HIV transmission in a low prevalence setting in rural Tanzania

BACKGROUND: Previous surveillance among antenatal clinic (ANC) attendees within the remote rural Manyara and Singida regions in Tanzania identified an imminent but still, relatively low HIV epidemic. We conducted a population-based HIV study to identify risk factors and validate the representativeness of ANC-based estimates. METHODS: Using a two-stage cluster sampling approach, we enrolled and then interviewed and collected saliva samples from 1,698 adults aged 15-49 years between December 2003 and May 2004. We anonymously tested saliva samples for IgG antibodies against HIV using Bionor HIV-1&2 assays (R). Risk factors for HIV infection were analysed by multivariate logistic regression using the rural population of the two regions as a standard. RESULTS: The prevalence of HIV in the general population was 1.8% (95% CI: 1.1-2.4), closely matching the ANC-based estimate (2.0%, 95% CI: 1.3-3.0). The female to male prevalence ratio was 0.8 (95% CI 0.4-1.7). HIV was associated with being a resident in a fishing community, and having recently moved into the area. Multiple sexual partners increased likelihood of HIV infection by 4.2 times (95% CI; 1.2-15.4) for men. In women, use of contraceptives other than condoms was associated with HIV infection (OR 6.5, 95% CI; 1.7-25.5), while most of the population (78%) have never used condoms. CONCLUSION: The HIV prevalence from the general population was comparable to that of pregnant women attending antenatal clinics. The revealed patterns of sexual risk behaviours, for example, close to 50% of men having multiple partners and 78% of the population have never used a condom; it is likely that HIV infection will rapidly escalate. Immediate and effective preventive efforts that consider the socio-cultural contexts are necessary to reduce the spread of the infection.