HIV-1 and HIV-2 prevalence and associated risk factors among postnatal women in Harare, Zimbabwe

Abstract

Studies of antenatal women form the predominant source of data on HIV-1 prevalence in Africa. Identifying factors associated with prevalent HIV is important in targeting diagnostic services and care. Between November 1997 and January 2000, 14,110 postnatal women from Harare, Zimbabwe were tested by ELISAs reactive to both HIV-1 and HIV-2; a subset of positive samples was confirmed with assays specific for HIV-1 and HIV-2. Baseline characteristics were elicited and modelled to identify risk factors for prevalent HIV infection. HIV-1 and HIV-2 prevalences were 32.0% (95% CI 31.2-32.8) and 1.3% (95% CI 1.1-1.5), respectively; 4% of HIV-1-positive and 99% of HIV-2-positive women were co-infected. HIV-1 prevalence increased from 0% among 14-year-olds to >45% among women aged 29-31 years, then fell to <20% among those aged>40 years. In multivariate analyses, prevalence increased with parity, was lower in married women than in single women, divorcees and widows, and higher in women with the lowest incomes and those professing no religion. Adjusted HIV-1 prevalence increased during 1998 and decreased during 1999. Age modified the effects of parity, home ownership and parental education. Among older women, prevalence was greater for women who were not homeowners. Among younger women, prevalence increased with parity and low parental education. None of these factors distinguished women co-infected with HIV-2 from those infected with HIV-1 alone. Prevalent HIV-1 infection is associated with financial insecurity and weak psychosocial support. The ZVITAMBO study apparently spanned the peak of the HIV-1 epidemic among reproductive women in Harare.

Fig. 1

Flow of participants through study.

Fig. 2

HIV-1 prevalence among women enrolled in the ZVITAMBO trial as a function of month of recruitment. Error bars indicate the 95% confidence interval about the estimate. Function fitted: Prevalence (%)=29·1+0·552t – 0·0188t² where t is the month of recruitment. Standard errors for linear and quadratic coefficients 0·23 and 0·008, respectively. P<0·05 (t test) in each case.

Fig. 3

The relationship between age and HIV-1 prevalence among new mothers in maternity clinics in Harare between November 1997 and January 2000. Error bars indicate the 95% confidence interval about the estimate.

Fig. 4

The relationship between age and HIV-1 prevalence among new mothers in maternity clinics in Harare between November 1997 and January 2000; the effect of parity. Error bars indicate the 95% confidence interval about the estimate.