Decline in the Prevalence of HIV-1 Infection in Young Women in the Kagera Region of Tanzania

In northwestern Tanzania, a population-based survey of HIV-1 infection in the Kagera region in 1987 demonstrated a high prevalence (24.2%) in adults of Bukoba town, whereas it was lower (10.0%) in the surrounding rural district of Bukoba. In 1993 and 1996, population-based cross-sectional studies were carried out in urban and rural Bukoba districts, respectively, to monitor the time trend in the prevalence of HIV-1 infection in the region. In both studies, a multistage cluster sampling technique was adopted in selecting study individuals. Consenting individuals between 15 and 54 years of age were interviewed using a structured questionnaire. Following individual counseling, blood samples were drawn and tested for HIV infection using enzyme-linked immunosorbent assay (ELISA) antibody detection tests. The overall age-adjusted HIV-1 seroprevalence in urban Bukoba decreased from 24.2% (134 of 553) in 1987 to 18.3% (118 of 653) in 1993 (p = .008). The age-adjusted gender-specific prevalence declined significantly in women, from 29.1% (95 of 325) to 18.7% (74 of 395; p = .0009). Except for menor = 35 years of age, whose prevalence appeared to have an upward trend between the two studies, all other age groups in both genders had a downward trend; this finding was most significant in women between 15 and 24 years of age (from 27.6% to 11.2%; p = .0004). For the rural population, the overall prevalence decreased from 10.0% (54 of 538) in 1987 to 6.8% (118 of 1728) in 1996 (p = .01). Except for rural women between 15 and 24 years of age whose prevalence decreased from 9.7% (12 of 124) to 3.1% (12 of 383; p = .002), other age groups in the rural populations showed no change in prevalence. Ongoing interventions in this area leading to behavioral change may have contributed to this observation. An incidence study is under way to confirm this observation and to investigate the factors that are responsible for the decline in the HIV-1 prevalence.A population-based survey of HIV-1 infection conducted in northwestern Tanzania's Kagera region in 1987 identified a 24.2% HIV prevalence among adults in Bukoba town and a prevalence of 10.0% in the surrounding rural district. In response to these findings, various interventions and community support activities (e.g., IEC, condom distribution, spiritual counseling, home-based care for AIDS patients, and the supply of safe blood for transfusion) were initiated. Additional population-based cross-sectional studies were conducted in the region in 1993 (urban population) and 1996 (rural population) to assess HIV prevalence trends over time. The overall age-adjusted HIV-1 seroprevalence among adults in urban Bukoba decreased from 24.2% in 1987 to 18.3% in 1993; most significant was the decline among women, from 29.1% in 1987 to 18.7% in 1993. With the exception of men 35 years of age and above, whose prevalence showed an upward trend between studies, all other age groups and both genders had a downward trend; this trend was most significant among women 15-24 years of age (from 27.6% to 11.2%). For the rural population, overall HIV-1 seroprevalence declined from 10.0% in 1987 to 6.8% in 1996. With the exception of rural women 15-24 years of age, whose prevalence decreased from 9.7% to 3.1%, other age groups showed no significant change in prevalence. An incidence study is underway to confirm these trends and identify the specific interventions responsible for the decline in HIV-1 prevalence.