Spillover HIV prevention effects of a cash transfer trial in East Zimbabwe: evidence from a cluster-randomised trial and general-population survey.

BACKGROUND: Benefits of cash transfers (CTs) for HIV prevention have been demonstrated largely in purposively designed trials, commonly focusing on young women. It is less clear if CT interventions not designed for HIV prevention can have HIV-specific effects, including adverse effects. The cluster-randomised Manicaland Cash Transfer Trial (2010-11) evaluated effects of CTs on children's (2-17 years) development in eastern Zimbabwe. We evaluated whether this CT intervention with no HIV-specific objectives had unintended HIV prevention spillover effects (externalities). METHODS: Data on 2909 individuals (15-54 years) living in trial households were taken from a general-population survey, conducted simultaneously in the same communities as the Manicaland Trial. Average treatment effects (ATEs) of CTs on sexual behaviour (any recent sex, condom use, multiple partners) and secondary outcomes (mental distress, school enrolment, and alcohol/cigarette/drug consumption) were estimated using mixed-effects logistic regressions (random effects for study site and intervention cluster), by sex and age group (15-29; 30-54 years). Outcomes were also evaluated with a larger synthetic comparison group created through propensity score matching. RESULTS: CTs did not affect sexual debut but reduced having any recent sex (past 30 days) among young males (ATE: - 11.7 percentage points [PP] [95% confidence interval: -26.0PP, 2.61PP]) and females (- 5.68PP [- 15.7PP, 4.34PP]), with similar but less uncertain estimates when compared against the synthetic comparison group (males: -9.68PP [- 13.1PP, - 6.30PP]; females: -8.77PP [- 16.3PP, - 1.23PP]). There were no effects among older individuals. Young (but not older) males receiving CTs reported increased multiple partnerships (8.49PP [- 5.40PP, 22.4PP]; synthetic comparison: 10.3PP (1.27PP, 19.2PP). No impact on alcohol, cigarette, or drug consumption was found. There are indications that CTs reduced psychological distress among young people, although impacts were small. CTs increased school enrolment in males (11.5PP [3.05PP, 19.9PP]). Analyses with the synthetic comparison group (but not the original control group) further indicated increased school enrolment among females (5.50PP [1.62PP, 9.37PP]) and condom use among younger and older women receiving CTs (9.38PP [5.90PP, 12.9PP]; 5.95PP [1.46PP, 10.4PP]). CONCLUSIONS: Non-HIV-prevention CT interventions can have HIV prevention outcomes, including reduced sexual activity among young people and increased multiple partnerships among young men. No effects on sexual debut or alcohol, cigarette, or drug consumption were observed. A broad approach is necessary to evaluate CT interventions to capture unintended outcomes, particularly in economic evaluations. TRIAL REGISTRATION: ClinicalTrials.gov , NCT00966849 . Registered August 27, 2009.

Wealth differentials in the impact of conditional and unconditional cash transfers on education: findings from a community-randomised controlled trial in Zimbabwe.

We investigated (1) how household wealth affected the relationship between conditional cash transfers (CCT) and unconditional cash transfers (UCT) and school attendance, (2) whether CCT and UCT affected educational outcomes (repeating a year of school), (3) if baseline school attendance and transfer conditions affected how much of the transfers participants spent on education and (4) if CCT or UCT reduced child labour in recipient households. Data were analysed from a cluster-randomized controlled trial of CCT and UCT in 4043 households from 2009 to 2010. Recipient households received $18 dollars per month plus $4 per child. CCT were conditioned on above 80% school attendance, a full vaccination record and a birth certificate. In the poorest quintile, the odds ratio of above 80% school attendance at follow-up for those with below 80% school attendance at baseline was 1.06 (p = .67) for UCT vs. CCT. UCT recipients reported spending slightly more (46.1% (45.4-46.7)) of the transfer on school expenses than did CCT recipients (44.8% (44.1-45.5)). Amongst those with baseline school attendance of below 80%, there was no statistically significant difference between CCT and UCT participants in the proportion of the transfer spent on school expenses (p = .63). Amongst those with above 80% baseline school attendance, CCT participants spent 3.5% less (p = .001) on school expenses than UCT participants. UCT participants were no less likely than those in the control group to repeat a grade of school. CCT participants had .69 (.60-.79) lower odds vs. control of repeating the previous school grade. Children in CCT recipient households spent an average of .31 fewer hours in paid work than those in the control group (p < .001) and children in the UCT arm spent an average of .15 fewer hours in paid work each week than those in the control arm (p = .06).

Effects of cash transfers on Children's health and social protection in Sub-Saharan Africa: differences in outcomes based on orphan status and household assets.

BACKGROUND: Unconditional and conditional cash transfer programmes (UCT and CCT) show potential to improve the well-being of orphans and other children made vulnerable by HIV/AIDS (OVC). We address the gap in current understanding about the extent to which household-based cash transfers differentially impact individual children's outcomes, according to risk or protective factors such as orphan status and household assets. METHODS: Data were obtained from a cluster-randomised controlled trial in eastern Zimbabwe, with random assignment to three study arms - UCT, CCT or control. The sample included 5,331 children ages 6-17 from 1,697 households. Generalized linear mixed models were specified to predict OVC health vulnerability (child chronic illness and disability) and social protection (birth registration and 90% school attendance). Models included child-level risk factors (age, orphan status); household risk factors (adults with chronic illnesses and disabilities, greater household size); and household protective factors (including asset-holding). Interactions were systematically tested. RESULTS: Orphan status was associated with decreased likelihood for birth registration, and paternal orphans and children for whom both parents' survival status was unknown were less likely to attend school. In the UCT arm, paternal orphans fared better in likelihood of birth registration compared with non-paternal orphans. Effects of study arms on outcomes were not moderated by any other risk or protective factors. High household asset-holding was associated with decreased likelihood of child's chronic illness and increased birth registration and school attendance, but household assets did not moderate the effects of cash transfers on risk or protective factors. CONCLUSION: Orphaned children are at higher risk for poor social protection outcomes even when cared for in family-based settings. UCT and CCT each produced direct effects on children's social protection which are not moderated by other child- and household-level risk factors, but orphans are less likely to attend school or obtain birth registration. The effects of UCT and CCT are not moderated by asset-holding, but greater household assets predict greater social protection outcomes. Intervention efforts need to focus on ameliorating the additional risk burden carried by orphaned children. These efforts might include caregiver education, and additional incentives based on efforts made specifically for orphaned children.

Effects of unconditional and conditional cash transfers on child health and development in Zimbabwe: a cluster-randomised trial.

BACKGROUND: Cash-transfer programmes can improve the wellbeing of vulnerable children, but few studies have rigorously assessed their effectiveness in sub-Saharan Africa. We investigated the effects of unconditional cash transfers (UCTs) and conditional cash transfers (CCTs) on birth registration, vaccination uptake, and school attendance in children in Zimbabwe. METHODS: We did a matched, cluster-randomised controlled trial in ten sites in Manicaland, Zimbabwe. We divided each study site into three clusters. After a baseline survey between July, and September, 2009, clusters in each site were randomly assigned to UCT, CCT, or control, by drawing of lots from a hat. Eligible households contained children younger than 18 years and satisfied at least one other criteria: head of household was younger than 18 years; household cared for at least one orphan younger than 18 years, a disabled person, or an individual who was chronically ill; or household was in poorest wealth quintile. Between January, 2010, and January, 2011, households in UCT clusters collected payments every 2 months. Households in CCT clusters could receive the same amount but were monitored for compliance with several conditions related to child wellbeing. Eligible households in all clusters, including control clusters, had access to parenting skills classes and received maize seed and fertiliser in December, 2009, and August, 2010. Households and individuals delivering the intervention were not masked, but data analysts were. The primary endpoints were proportion of children younger than 5 years with a birth certificate, proportion younger than 5 years with up-to-date vaccinations, and proportion aged 6-12 years attending school at least 80% of the time. This trial is registered with ClinicalTrials.gov, number NCT00966849. FINDINGS: 1199 eligible households were allocated to the control group, 1525 to the UCT group, and 1319 to the CCT group. Compared with control clusters, the proportion of children aged 0-4 years with birth certificates had increased by 1·5% (95% CI -7·1 to 10·1) in the UCT group and by 16·4% (7·8-25·0) in the CCT group by the end of the intervention period. The proportions of children aged 0-4 years with complete vaccination records was 3·1% (-3·8 to 9·9) greater in the UCT group and 1·8% (-5·0 to 8·7) greater in the CCT group than in the control group. The proportions of children aged 6-12 years who attended school at least 80% of the time was 7·2% (0·8-13·7) higher in the UCT group and 7·6% (1·2-14·1) in the CCT group than in the control group. INTERPRETATION: Our results support strategies to integrate cash transfers into social welfare programming in sub-Saharan Africa, but further evidence is needed for the comparative effectiveness of UCT and CCT programmes in this region. FUNDING: Wellcome Trust, the World Bank through the Partnership for Child Development, and the Programme of Support for the Zimbabwe National Action Plan for Orphans and Vulnerable Children.

Involving Communities in the Targeting of Cash Transfer Programs for Vulnerable Children: Opportunities and Challenges.

We used baseline data, collected in July-September 2009, from a randomized controlled trial of a cash transfer program for vulnerable children in eastern Zimbabwe to investigate the effectiveness, coverage, and efficiency of census- and community-based targeting methods for reaching vulnerable children. Focus group discussions and in-depth interviews with beneficiaries and other stakeholders were used to explore community perspectives on targeting. Community members reported that their participation improved ownership and reduced conflict and jealousy. However, all the methods failed to target a large proportion of vulnerable children and there was poor agreement between the community- and census-based methods.

Asset ownership among households caring for orphans and vulnerable children in rural Zimbabwe: the influence of ownership on children's health and social vulnerabilities.

The high prevalence of human immunodeficiency virus/acquired immune deficiency syndrome in sub-Saharan Africa has resulted in a dramatic increase in orphans and vulnerable children (OVC) over the past decade. These children typically rely on extended family networks for support, but the magnitude of the crisis has resulted in traditional familial networks becoming overwhelmed and more economically and socially vulnerable. Previous research consistently demonstrates the positive influence of household asset ownership on children's well-being. Using data from impoverished households caring for OVC in rural Manicaland Province, Zimbabwe, this study explores the influence of household asset ownership on OVC health vulnerability (HV) and social vulnerability (SV). Findings indicate that asset ownership is associated with significantly lower SV, in terms of school attendance and birth registration. Yet, assets do not emerge as a direct influence of OVC HV as measured by disease and chronic illness, although having a chronically ill adult in the household increases HV. These findings suggest that asset ownership, specifically a combination of fixed and movable assets, may offset the influence of other risk factors for children's SV.

Social acceptability and perceived impact of a community-led cash transfer programme in Zimbabwe.

BACKGROUND: Cash transfer programmes are increasingly recognised as promising and scalable interventions that can promote the health and development of children. However, concerns have been raised about the potential for cash transfers to contribute to social division, jealousy and conflict at a community level. Against this background, and in our interest to promote community participation in cash transfer programmes, we examine local perceptions of a community-led cash transfer programme in Eastern Zimbabwe. METHODS: We collected and analysed data from 35 individual interviews and three focus group discussions, involving 24 key informants (community committee members and programme implementers), 24 cash transfer beneficiaries, of which four were youth, and 14 non-beneficiaries. Transcripts were subjected to thematic analysis and coding to generate concepts. RESULTS: Study participants described the programme as participatory, fair and transparent - reducing the likelihood of jealousy. The programme was perceived to have had a substantial impact on children's health and education, primarily through aiding parents and guardians to better cater for their children's needs. Moreover, participants alluded to the potential of the programme to facilitate more transformational change, for example by enabling families to invest money in assets and income generating activities and by promoting a community-wide sense of responsibility for the support of orphaned and vulnerable children. CONCLUSION: Community participation, combined with the perceived impact of the cash transfer programme, led community members to speak enthusiastically about the programme. We conclude that community-led cash transfer programmes have the potential to open up for possibilities of participation and community agency that enable social acceptability and limit social divisiveness.

Antiretroviral therapy uptake and coverage in four HIV community cohort studies in sub-Saharan Africa.

OBJECTIVE: To compare socio-demographic patterns in access to antiretroviral therapy (ART) across four community HIV cohort studies in Africa. METHODS: Data on voluntary counselling and testing and ART use among HIV-infected persons were analysed from Karonga (Malawi), Kisesa (Tanzania), Masaka (Uganda) and Manicaland (Zimbabwe), where free ART provision started between 2004 and 2007. ART coverage was compared across sites by calculating the proportion on ART among those estimated to need treatment, by age, sex and educational attainment. Logistic regression was used to identify socio-demographic characteristics associated with undergoing eligibility screening at an ART clinic within 2 years of being diagnosed with HIV, for three sites with information on diagnosis and screening dates. RESULTS: Among adults known to be HIV-infected from serological surveys, the proportion who knew their HIV status was 93% in Karonga, 37% in Kisesa, 46% in Masaka and 25% in Manicaland. Estimated ART coverage was highest in Masaka (68%) and lowest in Kisesa (2%). The proportion of HIV-diagnosed persons who were screened for ART eligibility within 2 years of diagnosis ranged from 14% in Kisesa to 84% in Masaka, with the probability of screening uptake increasing with age at diagnosis in all sites. CONCLUSIONS: Higher HIV testing rates among HIV-infected persons in the community do not necessarily correspond with higher uptake of ART, nor more equitable treatment coverage among those in need of treatment. In all sites, young adults tend to be disadvantaged in terms of accessing and initiating ART, even after accounting for their less urgent need.

Did national HIV prevention programs contribute to HIV decline in Eastern Zimbabwe? Evidence from a prospective community survey.

OBJECTIVE: To add to the evidence on the impact of national HIV prevention programs in reducing HIV risk in sub-Saharan African countries. METHODS: Statistical analysis of prospective data on exposure to HIV prevention programs, relatives with AIDS and unemployment, and sexual behavior change and HIV incidence, in a population cohort of 4047 adults, collected over a period (1998-2003) when HIV prevalence and risk-behavior declined in eastern Zimbabwe. RESULTS: Exposure to HIV prevention programs and relatives with AIDS-but not unemployment-increased from 1998 to 2003. Men and women exposed to media campaigns and HIV/AIDS meetings had greater knowledge and self-efficacy, attributes that were concomitantly protective against HIV infection. Women attending community HIV/AIDS meetings before recruitment were more likely than other women to adopt lower-risk behavior (96.4% vs. 90.8%; adjusted odds ratio, 3.09; 95% confidence interval [CI], 1.27-7.49) and had lower HIV incidence (0.9% vs. 1.8%; adjusted incidence rate ratio, 0.63; 95% CI, 0.32-1.24) during the intersurvey period. Prior exposure to relatives with AIDS was not associated with differences in behavior change. More newly unemployed men as compared with employed men adopted lower-risk behavior (84.2% vs. 76.0%; adjusted odds ratio, 2.13; 95% CI, 0.98-4.59). CONCLUSIONS: Community-based HIV/AIDS meetings reduced risk-behavior amongst women who attended them, contributing to HIV decline in eastern Zimbabwe.

The effects of household wealth on HIV prevalence in Manicaland, Zimbabwe - a prospective household census and population-based open cohort study.

INTRODUCTION: Intensified poverty arising from economic decline and crisis may have contributed to reductions in HIV prevalence in Zimbabwe. OBJECTIVES: To assess the impact of the economic decline on household wealth and prevalent HIV infection using data from a population-based open cohort. METHODS: Household wealth was estimated using data from a prospective household census in Manicaland Province (1998 to 2011). Temporal trends in summed asset ownership indices for sellable, non-sellable and all assets combined were compared for households in four socio-economic strata (small towns, agricultural estates, roadside settlements and subsistence farming areas). Multivariate logistic random-effects models were used to measure differences in individual-level associations between prevalent HIV infection and place of residence, absolute wealth group and occupation. RESULTS: Household mean asset scores remained similar at around 0.37 (on a scale of 0 to 1) up to 2007 but decreased to below 0.35 thereafter. Sellable assets fell substantially from 2004 while non-sellable assets continued increasing until 2008. Small-town households had the highest wealth scores but the gap to other locations decreased over time, especially for sellable assets. Concurrently, adult HIV prevalence fell from 22.3 to 14.3%. HIV prevalence was highest in better-off locations (small towns) but differed little by household wealth or occupation. Initially, HIV prevalence was elevated in women from poorer households and lower in men in professional occupations. However, most recently (2009 to 2011), men and women in the poorest households had lower HIV prevalence and men in professional occupations had similar prevalence to unemployed men. CONCLUSIONS: The economic crisis drove more households into extreme poverty. However, HIV prevalence fell in all socio-economic locations and sub-groups, and there was limited evidence that increased poverty contributed to HIV prevalence decline.

Finger Prick Dried Blood Spots for HIV Viral Load Measurement in Field Conditions in Zimbabwe.

BACKGROUND: In the context of a community-randomized trial of antiretrovirals for HIV prevention and treatment among sex workers in Zimbabwe (the SAPPH-IRe trial), we will measure the proportion of women with HIV viral load (VL) above 1000 copies/mL ("VL>1000") as our primary endpoint. We sought to characterize VL assay performance by comparing results from finger prick dried blood spots (DBS) collected in the field with plasma samples, to determine whether finger prick DBS is an acceptable sample for VL quantification in the setting. METHODS: We collected whole blood from a finger prick onto filter paper and plasma samples using venipuncture from women in two communities. VL quantification was run on samples in parallel using NucliSENS EasyQ HIV-1 v2.0. Our trial outcome is the proportion of women with VL>1000, consistent with WHO guidelines relating to regimen switching. We therefore focused on this cut-off level for assessing sensitivity and specificity. Results were log transformed and the mean difference and standard deviation calculated, and correlation between VL quantification across sample types was evaluated. RESULTS: A total of 149 HIV-positive women provided DBS and plasma samples; 56 (63%) reported being on antiretroviral therapy. VL ranged from undetectable-6.08 log10 using DBS and undetectable-6.40 log10 using plasma. The mean difference in VL (plasma-DBS) was 0.077 log10 (95%CI = 0.025-0.18 log10; standard deviation = 0.63 log10,). 78 (52%) DBS and 87 (58%) plasma samples had a VL>1000. Based on plasma 'gold-standard', DBS sensitivity for detection of VL>1000 was 87.4%, and specificity was 96.8%. CONCLUSION: There was generally good agreement between DBS and plasma VL for detection of VL>1000. Overall, finger prick DBS appeared to be an acceptable sample for classifying VL as above or below 1000 copies/mL using the NucliSENS assay.

Community group participation: can it help young women to avoid HIV? An exploratory study of social capital and school education in rural Zimbabwe.

The lifetime risk of acquiring HIV infection in many rural as well as urban areas of southern Africa is currently as high as two-in-three. For women, much of this risk still accrues rapidly at young ages despite high levels of knowledge about HIV/AIDS. Thus, programmes that are more participatory and address underlying structural and community-level factors appear to be essential. We use cross-sectional data from a large-scale, population-based survey in rural eastern Zimbabwe to describe the relationships between membership of different forms of community group and young women's chances of avoiding HIV. Our results show that participation in local community groups is often positively associated with successful avoidance of HIV, which, in turn, is positively associated with psychosocial determinants of safer behaviour. However, whether or not these relationships hold depends on a range of factors that include how well the group functions, the purpose of the group, and the education level of the individual participant. We identify factors that may influence the social capital value of community groups in relation to HIV prevention at the individual, group, and community levels. Young women with secondary education participate disproportionately in well-functioning community groups and are more likely to avoid HIV when they do participate. Longitudinal studies are needed: (i) to establish whether community group membership supports the development of safer lifestyles or merely has greater appeal to individuals already predisposed towards such lifestyles, and (ii) to pinpoint directions of causality between hypothesised mediating factors. In-depth research is needed on the specific qualities of community groups that enhance their contribution to HIV control. However, our findings suggest that promotion of and organisational development and training among community groups could well be an effective HIV control strategy.

Acceptability of conditions in a community-led cash transfer programme for orphaned and vulnerable children in Zimbabwe.

Evidence suggests that a regular and reliable transfer of cash to households with orphaned and vulnerable children has a strong and positive effect on child outcomes. However, conditional cash transfers are considered by some as particularly intrusive and the question on whether or not to apply conditions to cash transfers is an issue of controversy. Contributing to policy debates on the appropriateness of conditions, this article sets out to investigate the overall buy-in of conditions by different stakeholders and to identify pathways that contribute to an acceptability of conditions. The article draws on data from a cluster-randomized trial of a community-led cash transfer programme in Manicaland, eastern Zimbabwe. An endpoint survey distributed to 5167 households assessed community members' acceptance of conditions and 35 in-depth interviews and 3 focus groups with a total of 58 adults and 4 youth examined local perceptions of conditions. The study found a significant and widespread acceptance of conditions primarily because they were seen as fair and a proxy for good parenting or guardianship. In a socio-economic context where child grants are not considered a citizen entitlement, community members and cash transfer recipients valued the conditions associated with these grants. The community members interpreted the fulfilment of the conditions as a proxy for achievement and merit, enabling them to participate rather than sit back as passive recipients of aid. Although conditions have a paternalistic undertone and engender the sceptics' view of conditions being pernicious and even abominable, it is important to recognize that community members, when given the opportunity to participate in programme design and implementation, can take advantage of conditions and appropriate them in a way that helps them manage change and overcome the social divisiveness or conflict that otherwise may arise when some people are identified to benefit and others not.

The distribution of sex acts and condom use within partnerships in a rural sub-Saharan African population.

INTRODUCTION: In an HIV/AIDS epidemic driven primarily by heterosexual transmission, it is important to have an understanding of the human sexual behaviour patterns that influence transmission. We analysed the distribution and predictors of within-partnership sexual behaviour and condom use in rural Zimbabwe and generated parameters for use in future modelling analyses. METHODS: A population-based cohort was recruited from a household census in 12 communities. A baseline survey was carried out in 1998-2000 with follow-up surveys after 3 and 5 years. Statistical distributions were fitted to reported within-partnership numbers of total, unprotected and protected sex acts in the past two weeks. Multilevel linear and logistic regression models were constructed to assess predictors of the frequency of unprotected sex and consistent condom use. RESULTS: A normal distribution of ln(sex acts+1) provided the best fit for total and unprotected sex acts for men and women. A negative binomial distribution applied to the untransformed data provided the best fit for protected sex acts. Condom use within partnerships was predominantly bimodal with at least 88% reporting zero or 100% use. Both men and women reported fewer unprotected sex acts with non-regular compared to regular partners (men: 0.26 fewer every two weeks (95% confidence interval 0.18-0.34); women: 0.16 (0.07-0.23)). Never and previously married individuals reported fewer unprotected sex acts than currently married individuals (never married men: 0.64 (0.60-0.67); previously married men: 0.59 (0.50-0.67); never married women: 0.51 (0.45-0.57); previously married women: 0.42 (0.37-0.47)). These variables were also associated with more consistent condom use. DISCUSSION: We generated parameters that will be useful for defining transmission models of HIV and other STIs, which rely on a valid representation of the underlying sexual network that determines spread of an infection. This will enable a better understanding of the spread of HIV and other STDs in this rural sub-Saharan population.

Household-based cash transfer targeting strategies in Zimbabwe: are we reaching the most vulnerable children?

Census data, collected in July 2009, from 27,672 children were used to compare the effectiveness, coverage and efficacy of three household-based methods for targeting cash transfers to vulnerable children in eastern Zimbabwe: targeting the poorest households using a wealth index; targeting HIV-affected households using socio-demographic information (households caring for orphans, chronically-ill or disabled members; child-headed households); and targeting labour-constrained households using dependency ratios. All three methods failed to identify large numbers of children with poor social and educational outcomes. The wealth index approach was the most efficient at reaching children with poor outcomes whilst socio-demographic targeting reached more vulnerable children but was less efficient.

Social capital and women's reduced vulnerability to HIV infection in rural Zimbabwe.

Social capital­especially through its "network" dimension (high levels of participation in local community groups)­is thought to be an important determinant of health in many contexts. We investigate its effect on HIV prevention, using prospective data from a general population cohort in eastern Zimbabwe spanning a period of extensive behavior change (1998­2003). Almost half of the initially uninfected women interviewed were members of at least one community group. In an analysis of 88 communities, individuals with higher levels of community group participation had lower incidence of new HIV infections and more of them had adopted safer behaviors, although these effects were largely accounted for by differences in socio-demographic composition. Individual women in community groups had lower HIV incidence and more extensive behavior change, even after controlling for confounding factors. Community group membership was not associated with lower HIV incidence in men, possibly refecting a propensity among men to participate in groups that allow them to develop and demonstrate their masculine identities­often at the expense of their health. Support for women's community groups could be an effective HIV prevention strategy in countries with large-scale HIV epidemics.

HIV incidence in 3 years of follow-up of a Zimbabwe cohort--1998-2000 to 2001-03: contributions of proximate and underlying determinants to transmission.

BACKGROUND: In recent years, HIV prevalence has begun to decline in Zimbabwe, which has been associated with reductions in sexual risk behaviour. Here, we analyse the determinants of HIV incidence in this period of decline and estimate the population-level impact of identified risk factors. METHODS: A population-based cohort of 1672 HIV-negative adult males and 2465 HIV-negative adult females was recruited between 1998 and 2000. Each individual was then followed-up 3 years later. The influence and inter-relationship of social, behavioural and demographic variables were examined using a proximate determinants framework. To explore the population-level influence of a variable, methods were developed for estimating a risk factor's contribution to the reproductive number (CRN). RESULTS: HIV incidence was 19.9 [95% confidence interval (CI) 16.3-24.2] per 1000 person years in men and 15.7 (95% CI 13.0-18.9) in women. Multiple sexual partners, having an unwell partner, and reporting another sexually transmitted disease were risk factors that captured the main aspects of the proximate determinants framework: individual behaviour, partnership characteristics and the probability of transmission, respectively. If the proximate determinants fully captured risk of HIV infection, underlying factors would not influence a fully parameterized model. However, a number of underlying social and demographic determinants remained important in regression models after including the proximate determinants. For both sexes, having multiple sexual partners made a substantial CRN, but, for women, no behaviour explained more than 10% of new infections. CONCLUSIONS: The proximate determinants did not explain the majority of new infections at the population level. This may be because we have been unable to measure some risks, but identifying risk factors assumes that those acquiring infections are somehow different from others who do not acquire infections. That they are not suggests that in this generalized epidemic there is little difference in readily identifiable characteristics of the individual between those who acquire infection and those who do not.

Adult mortality and erosion of household viability in AIDS-afflicted towns, estates, and villages in eastern Zimbabwe.

BACKGROUND: Households form the basic social and economic building blocks of sub-Saharan African societies. Household viability is threatened by sustained crisis-level mortality in widely disseminated HIV epidemics. This article describes the impact of adult deaths on households in small towns, estates, and villages in eastern Zimbabwe. METHODS: A stratified baseline household census was conducted, and 9842 adults were interviewed, tested for HIV infection, and followed up after 3 years. For 374 (93%) of 404 respondents who died, verbal autopsies were conducted with caregivers and data were collected on income foregone, health care and funeral expenditure, and household dissolution and relocation. The household impact of AIDS and non-AIDS deaths was compared. RESULTS: Deaths occurred disproportionately in more urban and low-income households, with AIDS deaths more often resulting in the loss of the household head (57% vs. 46%, adjusted odds ratio [AOR] = 2.47; P = 0.003). The median gross expenditure on health care and funerals was 25 US dollars (interquartile ratio [IQR]: 5-88) and 73 US dollars (IQR: 43-128), respectively, with external contributions being substantial for funerals (25 US dollars, IQR: 10-54). Households with AIDS deaths spent more on health care (incidence rate ratio = 1.83; 95% confidence interval: 1.06 to 3.15) and had more frequently dissolved or relocated (39% vs. 27%, AOR = 1.87; P = 0.038) than those with non-AIDS deaths. Households migrated disproportionately to rural villages. CONCLUSION: Despite the extended family system, adult deaths undermine the viability of sub-Saharan African households. HIV epidemics have greatly increased adult mortality, and AIDS deaths can be particularly destabilizing.

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.

Changing patterns of adult mortality as the HIV epidemic matures in Manicaland, eastern Zimbabwe.

BACKGROUND: HIV prevalence declined in Manicaland, eastern Zimbabwe, between 1998 and 2003. During this period, adult mortality in men was stable, whereas female mortality increased to levels similar to those of men. We examine the trends in mortality from 2003 to 2005. METHODS: A population-based cohort was recruited from a household census in 12 communities. A baseline survey was conducted between 1998 and 2000, with the first and second follow-up surveys occurring after 3 and 5 years, respectively. Using checklists of the resident population at the previous round, adult deaths were reported to enumerators by surviving household members or community informants. RESULTS: Age-standardized adult mortality rates for men increased slightly but not significantly over time (1998-2000: 24/1000 person-years; 2001-2002: 26/1000 person-years; 2003-2005: 31/1000 person-years), reflecting a sharp rise in mortality among HIV-positive individuals (62, 79 and 105 per 1000 person-years). Female mortality rose sharply initially but levelled off after 2001 (15, 26 and 26 per 1000 person-years) also caused by the pronounced increase in mortality among HIV-positive women (35, 75 and 88/1000 person-years; 7/1000 person-years for HIV-negative men and women in all periods); 69% of adult male deaths and 74% of adult female deaths were attributable to HIV/AIDS in 2003-2005. In men, mortality was similar and stable in towns, estates, roadside business centres and subsistence farming areas. In women, mortality rose in towns and subsistence farming areas between 1998 and 2002 and was greater in towns than in other locations. CONCLUSION: Recent data indicate that adult mortality may be stabilizing in eastern Zimbabwe after the recent downturn in HIV prevalence.