Declining HIV prevalence and incidence in perinatal women in Harare, Zimbabwe.
ABSTRACT In several recent papers it has been suggested that HIV prevalence and incidence are declining in Zimbabwe as a result of changing sexual behavior. We provide further support for these suggestions, based on an analysis of more extensive, age-stratified, HIV prevalence data from 1990 to 2009 for perinatal women in Harare, as well as data on incidence and mortality.
Pooled prevalence, incidence and mortality were fitted using a simple susceptible-infected (SI) model of HIV transmission; age-stratified prevalence data were fitted using double-logistic functions. We estimate that incidence peaked at 5.5% per year in 1991 declining to 1% per year in 2010. Prevalence peaked in 1998/9 [35.9% (CI95: 31.3-40.7)] and decreased by 67% to 11.9% (CI95: 10.1-13.8) in 2009. For women <20y, 20-24y, 25-29y, 30-34y and ≥35y, prevalence peaked at 25.4%, 34.2%, 47.1%, 44.0% and 33.5% in 1993, 1996, 1997, 1998 and 1999, respectively, declining thereafter in every age group. Among women <25y, prevalence peaked in 1994 at 28.8% declining thereafter by 69% to 8.9% (CI95: 6.8-11.5) in 2009.
HIV prevalence declined substantially among perinatal women in Harare after 1998 consequent upon a decline in incidence starting in the early 1990s. Our model suggests that this was primarily a result of changes in behavior which we attribute to a general increase in awareness of the dangers of AIDS and the ever more apparent increases in mortality.
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ABSTRACT: In several countries in southern Africa, including South Africa, the prevalence of HIV remains stubbornly high in spite of considerable efforts to reduce transmission and to provide anti-retroviral therapy (ART). It is important to know the extent to which the high prevalence of HIV reflects the increasing number of people on ART in which case the prevalence of those not on ART may be falling. Unfortunately, direct measures of the proportion of HIV-positive people who are on ART are lacking in most countries and we need to use dynamical models to estimate the impact of ART on the prevalence of HIV. In this paper we show that the current level of ART provision in South Africa has probably reduced the prevalence of HIV among those not on ART by 1.9 million, averted 259 thousand new infections and 428 thousand deaths.09/2011;