Critique of early models of the demographic impact of HIV/AIDS in sub-Saharan Africa based on contemporary empirical data from Zimbabwe.

Early mathematical models varied in their predictions of the impact of HIV/AIDS on population growth from minimal impact to reductions in growth, in pessimistic scenarios, from positive to negative values over a period of 25 years. Models predicting negative rates of natural increase forecast little effect on the dependency ratio. Twenty years later, HIV prevalence in small towns, estates, and rural villages in eastern Zimbabwe, has peaked within the intermediate range predicted by the early models, but the demographic impact has been more acute than was predicted. Despite concurrent declines in fertility, fueled in part by HIV infections (total fertility is now 8% lower than expected without an epidemic), and a doubling of the crude death rate because of HIV/AIDS, the rate of natural population increase between 1998 and 2005 remained positive in each socioeconomic stratum. In the worst-affected areas (towns with HIV prevalence of 33%), HIV/AIDS reduced growth by two-thirds from 2.9% to 1.0%. The dependency ratio fell from 1.21 at the onset of the HIV epidemic to 0.78, the impact of HIV-associated adult mortality being outweighed by fertility decline. With the benefit of hindsight, the more pessimistic early models overestimated the demographic impact of HIV epidemics by overextrapolating initial HIV growth rates or not allowing for heterogeneity in key parameters such as transmissibility and sexual risk behavior. Data collected since the late 1980s show that there was a mismatch between the observed growth in the HIV epidemic and assumptions made about viral transmission.

Impact and process evaluation of integrated community and clinic-based HIV-1 control: a cluster-randomised trial in eastern Zimbabwe.

BACKGROUND: HIV-1 control in sub-Saharan Africa requires cost-effective and sustainable programmes that promote behaviour change and reduce cofactor sexually transmitted infections (STIs) at the population and individual levels. METHODS AND FINDINGS: We measured the feasibility of community-based peer education, free condom distribution, income-generating projects, and clinic-based STI treatment and counselling services and evaluated their impact on the incidence of HIV-1 measured over a 3-y period in a cluster-randomised controlled trial in eastern Zimbabwe. Analysis of primary outcomes was on an intention-to-treat basis. The income-generating projects proved impossible to implement in the prevailing economic climate. Despite greater programme activity and knowledge in the intervention communities, the incidence rate ratio of HIV-1 was 1.27 (95% confidence interval [CI] 0.92-1.75) compared to the control communities. No evidence was found for reduced incidence of self-reported STI symptoms or high-risk sexual behaviour in the intervention communities. Males who attended programme meetings had lower HIV-1 incidence (incidence rate ratio 0.48, 95% CI 0.24-0.98), and fewer men who attended programme meetings reported unprotected sex with casual partners (odds ratio 0.45, 95% CI 0.28-0.75). More male STI patients in the intervention communities reported cessation of symptoms (odds ratio 2.49, 95% CI 1.21-5.12). CONCLUSIONS: Integrated peer education, condom distribution, and syndromic STI management did not reduce population-level HIV-1 incidence in a declining epidemic, despite reducing HIV-1 incidence in the immediate male target group. Our results highlight the need to assess the community-level impact of interventions that are effective amongst targeted population sub-groups.

HIV decline associated with behavior change in eastern Zimbabwe.

Few sub-Saharan African countries have witnessed declines in HIV prevalence, and only Uganda has compelling evidence for a decline founded on sexual behavior change. We report a decline in HIV prevalence in eastern Zimbabwe between 1998 and 2003 associated with sexual behavior change in four distinct socioeconomic strata. HIV prevalence fell most steeply at young ages-by 23 and 49%, respectively, among men aged 17 to 29 years and women aged 15 to 24 years-and in more educated groups. Sexually experienced men and women reported reductions in casual sex of 49 and 22%, respectively, whereas recent cohorts reported delayed sexual debut. Selective AIDS-induced mortality contributed to the decline in HIV prevalence.

Sexual mixing patterns and sex-differentials in teenage exposure to HIV infection in rural Zimbabwe.

BACKGROUND: HIV-1 prevalence typically rises more rapidly at young ages in women than in men in sub-Saharan Africa. Greater susceptibility to infection on exposure in women is believed to be a contributory factor as is greater exposure to previously infected sexual partners of the opposite sex. We investigated the latter hypothesis using data from a field study in rural Manicaland, Zimbabwe. METHODS: Quantitative data on onset and degree of sexual activity, numbers of partners, concurrent partnerships, condom use, and partner characteristics were used in conjunction with epidemiological data on age and sex specific prevalence of HIV infection to do statistical analyses of association between key variables. Mathematical models and qualitative data were used to aid analysis and interpretation. FINDINGS: Older age of sexual partner was associated with increased risk of HIV-1 infection in men (odds ratio 1.13 [95% CI 1.02-1.25]) and women (1.04 [1.01-1.07]). Young women form partnerships with men 5-10 years older than themselves, whereas young men have relationships with women of a similar age or slightly younger. Greater number of lifetime partners is also associated with increased risk of HIV (1.03 [1.00-1.05]). Young men report more partners than do women but infrequent coital acts and greater use of condoms. These behaviour patterns are underpinned by cultural factors including the expectation that women should marry earlier than men. A strong gender effect remains after factors that affect exposure to infected partners are controlled for (6.04 [1.49-24.47]). INTERPRETATION: The substantial age difference between female and male sexual partners in Manicaland is the major behavioural determinant of the more rapid rise in HIV prevalence in young women than in men. Theoretical studies have suggested that this difference is an important determinant of observed epidemiological patterns but the study reported in this paper provides clear empirical evidence of association.

Neuropsychiatric aspects of HIV disease progression: impact of traditional herbs on adult patients in Zimbabwe.

This cohort study examined the impact of phytotherapy (PT; traditional herbs) on neuropsychiatric aspects of HIV disease progression to antibody immunodeficiency syndrome (AIDS), CD4 counts, and viral load in adult patients in Harare, Zimbabwe. This is a community-based and nonintervention cohort study. The study was conducted in and around Harare City from June 1996 to May 1998. One hundred and five volunteers participated in the study. They were seen at the baseline and then followed up on a 3-month basis. The volunteers were interviewed, underwent physical examinations, and had blood drawn for laboratory tests, including the chest X-rays. The outcome measures were: prevalence of mental disorders and depressive symptoms, diagnosis of AIDS, and changes in CD4 cell counts and plasma HIV-I RNA concentrations. Instruments used were the Brief Psychiatric Rating Scale (BPRS), Montgomery-Asberg Depression Rating Scale (MADRS), Structured Interview Diagnosis of Dementia According to the DSM-IV (SIDAM), and Centre for Disease Control and Prevention (CDC) criteria as measurement tools. The findings were that patients on the PT had a mean (S.D.) age of 34.5 (7.4) years, whereas those on conventional therapy were a bit older with a mean (S.D.) age of 36.4 (6.6) years, range 19-55 years. The overall prevalence of psychiatric disorders according to the DSM-IV diagnostic criteria at the baseline was 44.8% (n=47, 95% CI=35.3-54.3) and by the end of the 6 months follow-up was 36% (n = 18, 95% CI = 23-49). The relative risks of psychiatric diagnoses were less in patients on PT (P = .046), including the diagnoses of depression (P = .035), than those on conventional therapy. Mean levels of a reported symptom of suicidal thoughts according to the MADRS were lowest in patients on PT than those on conventional therapy (F=5.44, P=.022). Finally, PT is protective against psychiatric disorders in our patients. However, our findings did not support HIV-I disease progression to AIDS in these patients.

Study of bias in antenatal clinic HIV-1 surveillance data in a high contraceptive prevalence population in sub-Saharan Africa.

OBJECTIVE: To describe patterns, sources and consequences of bias in antenatal clinic (ANC) HIV prevalence estimates in a high contraceptive prevalence population. BACKGROUND: HIV surveillance in Africa relies on data from pregnant women attending ANCs. HIV estimates from pregnant women understate female infection levels in low income, high fertility populations. Bias in high contraceptive use, delayed sexual debut populations remains undescribed. DESIGN AND METHOD: Comparison of parallel cross-sectional population and antenatal survey data from rural Zimbabwe, where 60% of women are recent contraceptive users. RESULTS: HIV prevalence in recently pregnant women (25.7%; n = 576) and all women (25.5%; n = 5138) is similar over the age-range 15-44 years. As in high fertility populations, HIV prevalence is higher in pregnant women at young ages and lower at older ages but the crossover point occurs later due to delayed sexual activity. HIV understatement at older ages due to HIV-associated infertility is mitigated by less HIV infection and less frequent ANC attendance in contraceptive users. The local ANC HIV prevalence estimate is lower [21.2%; n = 1215; risk ratio versus pregnant women in the general population, 0.8; 95% confidence interval (CI), 0.7-1.0], possibly because women from more remote areas are included. ANC estimates overstate the relative risk of HIV in more educated women (age-adjusted odds ratio, 1.1; 95% CI, 0.8-1.4 versus 0.7; 95% CI, 0.6-0.9). CONCLUSIONS: ANC estimates understate female HIV prevalence in this low fertility population but, here, the primary cause is not selection of pregnant women. ANC estimate adjustment procedures that control for contraceptive use and age at first sex are needed.