A high prevalence of HIV-1 infection among pregnant women living in a rural district of north Uganda severely affected by civil strife.

This study aims at estimating the recent trends in HIV-1 prevalence and the factors associated with infection among pregnant women in the Gulu District of north Uganda, a rural area severely affected by civil strife. In 2000-2003, a total of 4459 antenatal clinic attendees of Lacor Hospital were anonymously tested for HIV-1 infection. The overall and age-specific prevalence did not show any significant trend over time. The age-standardized prevalence slightly declined, from 12.1% in 2000 to 11.3% in 2003. Increased age [20-24 years: adjusted odds ratio (AOR) 1.63; 95% CI 1.18-2.25; >or=25 years: AOR 2.56; 95% CI 1.91-3.44], residence in urban areas (AOR 1.76; 95% CI 1.41-2.18), being unmarried (AOR 1.60; 95% CI 1.27-2.01), increased age of partner (25-34 years: AOR 1.87; 95% CI 1.29-2.73; >or=35 years: AOR 2.68; 95% CI 1.72-4.16), modern occupation of partner (AOR 1.98; 95% CI 1.53-2.58), and short time of residence at the current address (AOR 1.36; 95% CI 1.05-1.76) were associated with infection. The HIV-1 prevalence in this rural district is high and similar to that observed in urban antenatal clinics, probably reflecting the effect of the last 18 years of civil strife.

Using prevalence data from the programme for the prevention of mother-to-child-transmission for HIV-1 surveillance in North Uganda.

OBJECTIVES: To validate the use of data from a programme for the prevention of mother-to-child transmission (PMTCT) in estimating HIV-1 prevalence in North Uganda. METHODS: The study was conducted at St. Mary's Hospital Lacor. We compared the estimated prevalence for 3580 attendees at the antenatal clinic who were selected for anonymous surveillance to that for 6785 pregnant women who agreed to undergo voluntary counselling and testing (VCT) for enrolment in the PMTCT programme. Log-binomial regression models were used to identify the factors associated with both VCT uptake and HIV-1 infection, which could bias the prevalence estimates based on PMTCT data. RESULTS: In 2001-2003, the age-standardized prevalence was similar (11.1% in the anonymous surveillance group and 10.9% in the VCT group). The estimates were also similar when compared for each year tested. Analogously, no important differences were observed in age-specific prevalence. Of the factors associated with HIV-1 infection, only time of residence at current address [prevalence proportion ratio (PPR) = 1.05; 95% confidence interval (CI), 1.00-1.10], marital status (PPR = 1.05; 95% CI, 1.01-1.10) and partner's occupation (PPR = 1.05; 95% CI, 1.01-1.10) were associated with VCT uptake, yet the associations were weak. CONCLUSIONS: The prevalence estimated based on the VCT data collected as part of the PMTCT programme could be used for HIV-1 surveillance in North Uganda. At the national level, however, it needs to be evaluated whether PMTCT data could replace, or instead be combined with, the data from sentinel surveillance.

Evaluating two adjustment methods to extrapolate HIV prevalence from pregnant women to the general female population in sub-Saharan Africa.

OBJECTIVE: To evaluate two methods for estimating HIV prevalence among the general female population of reproductive age by adjusting data observed among antenatal clinic (ANC) attendees. METHODS: We adjusted the HIV prevalence among ANC attendees in Fort Portal (Uganda; 1994-1995), Mwanza municipality (Tanzania; 1990-1991), rural Mwanza (Tanzania; 1991-1993), Mposhi district (Zambia; 1994), Chelston (Lusaka, Zambia; 1994, 1996 and 1998) and Ndola (Zambia; 1998), using firstly a method that accounts for differences in age-specific fertility by HIV serostatus and secondly a method that accounts for differences in HIV prevalence by fertility risk category and parity. RESULTS: The non-adjusted HIV prevalence among ANC attendees underestimates the prevalence among the general female population by 8.0% in Chelston in 1998 and by between 20.7% and 31.9% in all other cases. The adjusted prevalence obtained using the first method underestimates the prevalence among the general female population by about 0.5% in Fort Portal and Mposhi; it overestimates that observed in Chelston in 1994 and 1996 by about 3.5%, and that observed in Ndola, urban Mwanza and rural Mwanza, by 6.5%, 10.6% and 12.8%, respectively. The second method (applied for only four sites) provides an overestimate of 7.0% in Chelston in 1994 and an underestimate of 3.8% and 2.1% in Ndola and rural Mwanza, respectively. Both adjustment methods overestimate the 1998 prevalence in Chelston, producing less accurate estimates than the non-adjusted data. CONCLUSIONS: The HIV prevalence among women in the general population could be estimated fairly accurately by these methods in settings with mature epidemics.

Differences in fertility by HIV serostatus and adjusted HIV prevalence data from an antenatal clinic in northern Uganda.

OBJECTIVES: To estimate differences in fertility by HIV serostatus and to validate an adjustment method for estimating the HIV prevalence in the general female population using data from an antenatal clinic. METHODS: We used Cox regression models to retrospectively estimate the age-specific relative fertility (RF) of HIV-positive compared to HIV-negative women among 3314 antenatal clinic attenders in northern Uganda. RF and the age distribution of women in the general female population were used to extrapolate the antenatal clinic-based HIV prevalence. This procedure was indirectly validated by comparing the adjusted estimate with those based on standard adjustment factors derived from general female populations in Uganda and Tanzania. RESULTS: HIV-positive women reported a lower fertility than HIV-negative women [age-adjusted RF=0.83, 95% confidence interval (CI): 0.75-0.93]. Except for girls aged 15-19 (RF=0.96, 95% CI: 0.74-1.24) HIV-positive women in all age groups were less fertile (20-24 year: RF=0.83, 95% CI: 0.67-1.01; 25-29 years: RF=0.79, 95% CI: 0.62-1.00; 30-49 year: RF=0.79, 95% CI: 0.65-0.96]. Adjusting the antenatal clinic-based HIV prevalence (11.6%) for these differences yields a higher estimate (13.8%) that is lower than those based on standard adjustment factors derived from general female populations (from 14.6% to 17.7%). CONCLUSIONS: The age-specific pattern of differential fertility by HIV serostatus derived from antenatal clinic data is consistent with findings from population-based studies conducted in Africa. However, differences in fertility between HIV positive and HIV-negative clients underestimate those in the general female population yielding inaccurate estimates when used to extrapolate the HIV prevalence.