Elsevier

The Lancet

Volume 364, Issue 9428, 3–9 July 2004, Pages 35-40
The Lancet

Articles
HIV prevalence and trends in sub-Saharan Africa: no decline and large subregional differences

https://doi.org/10.1016/S0140-6736(04)16587-2Get rights and content

Summary

Background

Expansion of HIV surveillance systems in sub-Saharan Africa is leading to downward adjustments to the size of the AIDS epidemic. However, only analysis of surveillance data from the same populations over time can provide insight into trends of HIV prevalence. We have used data from the same antenatal clinics to document recent empirical trends.

Methods

We collated data from antenatal clinics on HIV prevalence between 1997 and 2003. Data were obtained from 140 000 pregnant women attending more than 300 antenatal clinics in 22 countries in sub-Saharan Africa. Additionally, long-term trend data are available for 57 urban areas and provinces.

Findings

Median HIV prevalence in 148 antenatal clinic sites in southern Africa increased from 21·3% (IQR 11·5–28·2%) in 1997/98 to 23·8% (15·6–29·2%) in 2002. At more than half the sites (58%) an increase of at least one-tenth was noted, but at a fifth of sites, prevalence dropped by at least one-tenth. In eastern Africa, median HIV prevalence decreased from 12·9% (7·0–16·9%) in 1997/98 to 8·5% (5·3–13·0%) in 2002, with prevalence rising in four (7%) sites, but falling at 25 (43%) sites. In west Africa, median HIV prevalence was 3·5% (2·2–5·9%) and 3·2% (2·3–6·1%) for 1997/98 and 2002, respectively, with reductions and increases in prevalence being noted in equal proportions. The long-term trends in urban areas in sub-Saharan Africa show a similar pattern, with increasing evidence of stabilisation during the past 2–3 years compared with the previous decade.

Interpretation

Evidence from surveillance of mostly urban antenatal clinic attendees indicates that the growth in the AIDS epidemic in sub-Saharan Africa has levelled off since the late 1990s but only eastern Africa shows a decline in HIV prevalence. Very large differences persist between subregions. Workers planning a response to the AIDS epidemic must take more careful consideration of these variations to allow locally appropriate responses to the epidemic.

Introduction

Assessment of trends in the HIV epidemic involves a substantial amount of uncertainty. Expansion of surveillance systems in antenatal clinics and the inclusion of HIV testing in nationally representative population-based surveys have improved the availability of data on HIV prevalence in sub-Saharan Africa. As a result, estimates of the number of people living with HIV infection in sub-Saharan Africa have been reduced by about 10% in 2003.1 Adjustments to estimates of the size of the epidemic made because of better data or improvements in estimation methodology could lead to faulty interpretations about a decline in the epidemic at regional and national levels. A careful analysis of empirical trends is crucial.

Since the late 1980s, antenatal clinics have been the primary source of data for national estimates and the mainstay for tracking the epidemic in countries in sub-Saharan Africa.2 The large differences in HIV prevalence seen within the region—with eastern and, later, southern Africa having much higher levels than western Africa—have been downplayed with suggestions that these differences may diminish with time. This prevention perspective prevailed throughout the 1990s and still dominates interpretations of the large differences in the rate of HIV within sub-Saharan Africa. If, however, large differences between the subregions persist into the new millennium, it would be important to pay more attention to the heterogeneity of the HIV/AIDS epidemic and consider different responses in accordance with severity of the epidemic in subregions and countries. Here, we analyse recent trends in HIV prevalence in pregnant women to ascertain the course of the HIV epidemic in sub-Saharan Africa, with special focus on subregional patterns.

Section snippets

Methods

Data collection in women attending antenatal clinics is the primary method of monitoring trends in HIV prevalence in countries where HIV has spread beyond high-risk populations. Typically, sentinel antenatal clinics are simultaneously surveyed for about 6–12 weeks in a year, until samples from a predetermined number (300–500) of pregnant women have been collected. Unlinked anonymous HIV testing is done on residual blood from samples taken for other purposes (usually syphilis testing). Most

Results

Table 1 presents information on the most recent round of HIV surveillance by country with median HIV prevalence for all antenatal clinics. Table 2 shows HIV prevalence trends in clinics that provided data over a number of years in 1997–2003, but excluding clinics with no data for the 1990s.

Discussion

Recent trends in HIV prevalence in women attending antenatal clinics suggest that the epidemic has levelled off since the late 1990s in all countries in Sub-saharan Africa. In eastern Africa, there is an indication of a gradual and modest decline. In western and central Africa there is no consistent evidence of changes in HIV prevalence in recent years and in southern Africa most countries report either a stabilisation or at worst a small increase in HIV prevalence.

The extent to which these

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