High HIV-1 incidence in young women masked by stable overall seroprevalence among childbearing women in Kinshasa, Zaïre: estimating incidence from serial seroprevalence data.
OBJECTIVE
To describe the dynamics of the HIV-1 epidemic in childbearing women in Kinshasa, Zaïre, by estimating incidence from serial seroprevalence studies.


METHODS
In 1986 and 1989, 5937 and 4623 pregnant women, respectively, were screened for HIV-1 in Kinshasa. We estimated age-specific incidence from two seroprevalence surveys by using a birth-year cohort analysis and adjusting for differences in mortality and fertility between HIV-1-infected and uninfected women. Mortality and fertility data were measured in a cohort of women recruited from the survey in 1986 and followed until 1989.


RESULTS
While the overall HIV-1 seroprevalence changed little (5.8% in 1986 and 6.5% in 1989; P = 0.17), the prevalence increased in birth-year cohorts of women under 25 years of age in 1989 from 3.2 to 6.2% (P < 0.001), but decreased for women above 25 years of age from 6.9 to 6.7% (P = 0.7). In addition, new HIV infections between 1986 and 1989 were balanced by a higher mortality and lower fertility observed in HIV-infected women. After adjusting for these effects, we estimated an overall 3-year cumulative HIV-1 incidence of 2.8 per 100 uninfected women [95% confidence interval (CI), 1.4-4.2]. The highest incidence, 5.7 per 100 (95% CI, 3.5-8.0), was in women aged 20-24 years in 1989.


CONCLUSIONS
Despite an overall relatively stable HIV-1 prevalence in childbearing women in Kinshasa between 1986 and 1989, approximately 40% of all HIV-1 infections detected in the 1989 survey occurred between 1986 and 1989, and 60% occurred in women under 25 years of age in 1989.
Batter
V
V
Projet SIDA, Kinshasa, Zaïre.
Matela
B
B
Nsuami
M
M
Manzila
T
T
Kamenga
M
M
Behets
F
F
Ryder
R W
RW
Heyward
W L
WL
Karon
J M
JM
St Louis
M E
ME
D000328:Adult; D015331:Cohort Studies; D015023:Democratic Republic of the Congo / Q000453:epidemiology; D005260:Female; D005298:Fertility; D015528:HIV Seroprevalence; D015497:HIV-1; D006801:Humans; D015994:Incidence; D011247:Pregnancy; D011251:Pregnancy Complications, Infectious / Q000453:epidemiology*