HIV-1 infection prevalence and incidence trends in areas of contrasting levels of infection in the Kagera region, Tanzania, 1987-2000.
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.
Kwesigabo
Gideon
G
Department of Epidemiology and Biostatistics, Muhimbili University College of Health Sciences, Dar es Salaam, Tanzania. gkwesigabo@muchs.ac.tz
Killewo
Japhet
J
Urassa
Willy
W
Lugalla
Joe
J
Emmelin
Maria
M
Mutembei
Aldin
A
Mhalu
Fred
F
Biberfeld
Gunnel
G
Wall
Stig
S
Sandstrom
Anita
A
D000293:Adolescent; D000328:Adult; D002648:Child; D003430:Cross-Sectional Studies; D004196:Disease Outbreaks; D005260:Female; D015658:HIV Infections / Q000453:epidemiology* / Q000821:virology; D015497:HIV-1; D006801:Humans; D015994:Incidence; D008297:Male; D015995:Prevalence; D013636:Tanzania / Q000453:epidemiology