HIV-1 Infection Prevalence and Incidence Trends in Areas of Contrasting Levels of Infection in the Kagera Region, Tanzania, 1987-2000

Document Type



Institute for Educational Development, East Africa


This study aimed at assessing the extent to which decline in HIV infection prevalence reflects decline in incidence in 3 areas with contrasting initial exposure to the HIV epidemic in the Kagera region of Tanzania. A population sample was recruited for the baseline study in 1987 through a multistage cluster sampling technique to determine HIV prevalence. Seronegative individuals identified in the baseline and subsequent studies were followed up for 3 years to yield trends in incidence that were compared for the 3 areas. The overall age-adjusted HIV-1 prevalence in the high-prevalence area of Bukoba urban declined significantly from 24.2% in 1987 to 18.2% in 1993 and later to 13.3% in 1996 (P = 0.0001). In the medium-prevalence area of Muleba, overall age-adjusted prevalence declined significantly from 10.0% in 1987 to 6.8% in 1996 and later to 4.3% in 1999 (P = 0.0003), whereas in the low-prevalence area of Karagwe the prevalence declined from 4.5% in 1987 to 2.6% in 1999 (P = 0.01). In all 3 areas, the most significant decline was consistently observed among women in the age group 15-24 years. No age group exhibited a significant upward prevalence trend. The HIV-1 incidence for Bukoba urban declined from 47.5 to 9.1 per 1000 person-years of observation in 1989 and 1996, respectively, whereas in Muleba it decreased from 8.2 to 3.9 in 1989 and 2000, respectively. Sex-specific estimates indicated a significant decline among women in the high-prevalence area of Bukoba urban from 51.5 to 9.2 per 1000 person-years at risk (P = 0.001). It is concluded that the HIV-1 epidemic in Kagera is on the decrease as reflected by the decline in HIV-1 incidence and prevalence trends particularly among the 15-24 year olds. The decline in the 3 areas of differing magnitude implies that the HIV/AIDS epidemic may be arrested early without necessarily peaking to saturation levels.


This work was published before the author joined Aga Khan University.

Publication (Name of Journal)

Journal of Acquired Immune Deficiency Syndromes