Georges Reniers

Marital Strategies for Regulating Exposure to HIV

In a setting where the transmission of HIV occurs primarily through heterosexual contact and where no cure or vaccine is available, behavioral change is imperative for containing the epidemic. Abstinence, faithfulness, and condom use most often receive attention in this regard. In contrast, this article treats marriage as a resource for HIV risk management via mechanisms of positive selection (partner choice) and negative selection (divorce of an adulterous spouse). Retrospective marriage histories and panel data provide the evidence for this study, and results indicate that men and women in Malawi increasingly turned to union-based risk-avoidance strategies during the period that the threat of HIV/AIDS materialized. Although both sexes strategize in a similar fashion, men are better equipped than women to deploy these strategies to their advantage. The article concludes with reflections on the long-term and population-level implications of these coping mechanisms.

Steep declines in population-level AIDS mortality following the introduction of antiretroviral therapy in Addis Ababa, Ethiopia

Objectives:Assessments of population-level effects of antiretroviral therapy (ART) programmes in Africa are rare. We use data from burial sites to estimate trends in adult AIDS mortality and the mitigating effects of ART in Addis Ababa. ART has been available since 2003, and for free since 2005. Methods:To substitute for deficient vital registration, we use surveillance of burials at all cemeteries. We present trends in all-cause mortality, and estimate AIDS mortality (ages 20–64 years) from lay reports of causes of death. These lay reports are first used as a diagnostic test for the true cause of death. As reference standard, we use the cause of death established via verbal autopsy interviews conducted in 2004. The positive predictive value and sensitivity are subsequently used as anchors to estimate the number of AIDS deaths for the period 2001–2007. Estimates are compared with Spectrum projections. Results:Between 2001 and 2005, the number of AIDS deaths declined by 21.9 and 9.3% for men and women, respectively. Between 2005 and 2007, the number of AIDS deaths declined by 38.2 for men and 42.9% for women. Compared with the expected number in the absence of ART, the reduction in AIDS deaths in 2007 is estimated to be between 56.8 and 63.3%, depending on the coverage of the burial surveillance. Conclusion:Five years into the ART programme, adult AIDS mortality has been reduced by more than half. Following the free provision of ART in 2005, the decline accelerated and became more sex balanced. Substantial AIDS mortality, however, persists.

Polygyny and the spread of HIV in sub-Saharan Africa: a case of benign concurrency.

Objectives: Much of our understanding about the effect of concurrent sexual partnerships on the spread of HIV derives from mathematical models, but the empirical evidence is limited. In this contribution, we focus on polygyny, a common and institutionalized form of concurrency for which data are available, and study its relationship with HIV prevalence at the ecological level. Methods: First, we describe country-level variation in the prevalence of polygyny and HIV. Second, we test the relationship between HIV and polygyny at the subnational level using country fixed-effects regression models with data from 19 Demographic and Health Surveys. Results: The ecological association between polygyny and HIV prevalence is negative at the country as well as subnational level, HIV prevalence is lower in countries where the practice of polygyny is common, and within countries, it is lower in areas with higher levels of polygyny. Proposed explanations for the protective effect of polygyny include the distinctive structure of sexual networks produced by polygyny, the disproportionate recruitment of HIV-positive women into marriages with a polygynous husband, and the lower coital frequency in conjugal dyads of polygynous marriages. Conclusion: Existing mathematical models of concurrency are not sufficiently specific to account for the relatively benign effect of polygyny on the spread of HIV and require refinements before they are used to inform HIV prevention policies.

Refusal bias in HIV prevalence estimates from nationally representative seroprevalence surveys.

Objectives:To assess the relationship between prior knowledge of ones HIV status and the likelihood to refuse HIV testing in populations-based surveys and explore its potential for producing bias in HIV prevalence estimates. Methods:Using longitudinal survey data from Malawi, we estimate the relationship between prior knowledge of HIV-positive status and subsequent refusal of an HIV test. We use that parameter to develop a heuristic model of refusal bias that is applied to six Demographic and Health Surveys, in which refusal by HIV status is not observed. The model only adjusts for refusal bias conditional on a completed interview. Results:Ecologically, HIV prevalence, prior testing rates and refusal for HIV testing are highly correlated. Malawian data further suggest that amongst individuals who know their status, HIV-positive individuals are 4.62 (95% confidence interval, 2.60–8.21) times more likely to refuse testing than HIV-negative ones. On the basis of that parameter and other inputs from the Demographic and Health Surveys, our model predicts downward bias in national HIV prevalence estimates ranging from 1.5% (95% confidence interval, 0.7–2.9) for Senegal to 13.3% (95% confidence interval, 7.2–19.6) for Malawi. In absolute terms, bias in HIV prevalence estimates is negligible for Senegal but 1.6 (95% confidence interval, 0.8–2.3) percentage points for Malawi. Downward bias is more severe in urban populations. Because refusal rates are higher in men, seroprevalence surveys also tend to overestimate the female-to-male ratio of infections. Conclusion:Prior knowledge of HIV status informs decisions to participate in seroprevalence surveys. Informed refusals may produce bias in estimates of HIV prevalence and the sex ratio of infections.

On the history and selectivity of Turkish and Moroccan migration to Belgium.

This article challenges the oversimplified image of an uneducated and undifferentiated immigrant labor force for Turks and Moroccans through the concept of selectivity. Using a combination of data from two Migration History and Social Mobility surveys carried out among Turkish and Moroccan men living in Belgium, selectivity is discussed with respect to region of origin and in terms of educational attainment. Analysis of selectivity with respect to region indicate that Turkish and Moroccan migrants in Belgium were not all the representative of their countries of origin. It was also noted that network-mediated migration accentuated the unequal distribution of immigrants in terms of their region of origin. Selection with respect to educational attainment analysis confirmed the heterogeneous composition of Moroccan immigrants. Those from the rural Rif and Souss were generally not as well educated as non-migrants. In addition, immigrants from urbanized parts of the country were generally more educated. In the selection process, an explanation for migration emerged, which states that network connections may be a factor for increasing ones possibility of migrating.

Sexual and marital trajectories and HIV infection among ever-married women in rural Malawi

Objective: To explore how sexual and marital trajectories are associated with HIV infection among ever-married women in rural Malawi. Methods: Retrospective survey data and HIV biomarker data for 926 ever-married women interviewed in the Malawi Diffusion and Ideational Change Project were used. The associations between HIV infection and four key life course transitions considered individually (age at sexual debut, premarital sexual activity, entry into marriage and marital disruption by divorce or death) were examined. These transitions were then sequenced to construct trajectories that represent the variety of patterns in the data. The association between different trajectories and HIV prevalence was examined, controlling for potentially confounding factors such as age and region. Results: Although each life course transition taken in isolation may be associated with HIV infection, their combined effect appeared to be conditional on the sequence in which they occurred. Although early sexual debut, not marrying one’s first sexual partner and having a disrupted marriage each increased the likelihood of HIV infection, their risk was not additive. Women who both delayed sexual debut and did not marry their first partner are, once married, more likely to experience marital disruption and to be HIV-positive. Women who marry their first partner but who have sex at a young age, however, are also at considerable risk. Conclusions: These findings identify the potential of a life course perspective for understanding why some women become infected with HIV and others do not, as well as the differentials in HIV prevalence that originate from the sequence of sexual and marital transitions in one’s life. The analysis suggests, however, the need for further data collection to permit a better examination of the mechanisms that account for variations in life course trajectories and thus in lifetime probabilities of HIV infection.

Polygyny, partnership concurrency, and HIV transmission in Sub-Saharan Africa.

We study the relationship between polygyny and HIV infection using nationally representative survey data with linked serostatus information from 20 African countries. Our results indicate that junior wives in polygynous unions are more likely to be HIV positive than spouses of monogamous men, but also that HIV prevalence is lower in populations with more polygyny. With these results in mind, we investigate four explanations for the contrasting individual- and ecological-level associations. These relate to (1) the adverse selection of HIV-positive women into polygynous unions, (2) the sexual network structure characteristic of polygyny, (3) the relatively low coital frequency in conjugal dyads of polygynous marriages (coital dilution), and (4) the restricted access to sexual partners for younger men in populations where polygynous men presumably monopolize the women in their community (monopolizing polygynists). We find evidence for some of these mechanisms, and together they support the proposition that polygynous marriage systems impede the spread of HIV. We relate these results to the debate about partnership concurrency as a primary behavioral driver for the fast propagation of HIV in some parts of sub-Saharan Africa.

Evaluating the InterVA model for determining AIDS mortality from verbal autopsies in the adult population of Addis Ababa.

Objective  To evaluate the performance of a verbal autopsy (VA) expert algorithm (the InterVA model) for diagnosing AIDS mortality against a reference standard from hospital records that include HIV serostatus information in Addis Ababa, Ethiopia.

Implications of the HIV testing protocol for refusal bias in seroprevalence surveys

BackgroundHIV serosurveys have become important sources of HIV prevalence estimates, but these estimates may be biased because of refusals and other forms of non-response. We investigate the effect of the post-test counseling study protocol on bias due to the refusal to be tested.MethodsData come from a nine-month prospective study of hospital admissions in Addis Ababa during which patients were approached for an HIV test. Patients had the choice between three consent levels: testing and post-test counseling (including the return of HIV test results), testing without post-test counseling, and total refusal. For all patients, information was collected on basic sociodemographic background characteristics as well as admission diagnosis. The three consent levels are used to mimic refusal bias in serosurveys with different post-test counseling study protocols. We first investigate the covariates of consent for testing. Second, we quantify refusal bias in HIV prevalence estimates using Heckman regression models that account for sample selection.ResultsRefusal to be tested positively correlates with admission diagnosis (and thus HIV status), but the magnitude of refusal bias in HIV prevalence surveys depends on the study protocol. Bias is larger when post-test counseling and the return of HIV test results is a prerequisite of study participation (compared to a protocol where test results are not returned to study participants, or, where there is an explicit provision for respondents to forego post-test counseling). We also find that consent for testing increased following the introduction of antiretroviral therapy in Ethiopia. Other covariates of refusal are age (non-linear effect), gender (higher refusal rates in men), marital status (lowest refusal rates in singles), educational status (refusal rate increases with educational attainment), and counselor.ConclusionThe protocol for post-test counseling and the return of HIV test results to study participants is an important consideration in HIV prevalence surveys that wish to minimize refusal bias. The availability of ART is likely to reduce refusal rates.

Serosorting and the evaluation of HIV testing and counseling for HIV prevention in generalized epidemics

UNAIDS and the WHO recognize the importance of HIV Testing and Counseling (HTC) as a gateway to both treatment and prevention (1). Many studies aimed at identifying behavioral changes following HTC have, however, registered only modest reductions in risk behaviors: change –if any– is most commonly reported by women, HIV positives, and in serodiscordant couples. This is also the gist of the review of early studies from predominantly Europe and North America (2–4), and a review of seven studies set in developing countries (5). More recent studies from sub-Saharan Africa, summarized in Table 1, largely corroborate these conclusions. The most ambitious HTC impact evaluation studies target reductions in HIV incidence, but none have been detected so far (6–8). In serodiscordant couples, however, HTC is associated with a reduction in HIV transmission (9). Table 1 Description of selected HTC efficacy studies in sub-Saharan Africa and their main findings Skeptics argue that the meager benefits of HTC for HIV prevention will dilute further as efforts are mounted to increase HTC uptake. First, it is argued that the tested population will become less self-selective, and therefore less inclined to behavioral change (10). Second, some observers anticipate that the scaling up of HTC will affect the quality of counseling sessions, thereby reducing opportunities to promote behavioral change (11). We argue that this pessimistic outlook on the role of HTC in fostering behavioral change is premature. Existing studies may have under-estimated the preventative effects of HTC because they conceptualize behavioral change largely in terms of the ABC behaviors (abstinence, faithfulness and condom use), and because they almost exclusively measure the effects of HTC at the individual level (Table 1). There is ample evidence that individuals in sub-Saharan African countries are not confined to the ABCs when developing strategies to lower their exposure to HIV: some divorce an infected or unfaithful spouse (12–14), some discuss prevention measures with their primary partners (15, 16), and others deploy –sometimes elaborate– rules to choose new partners they deem safe(r) (12, 13, 17). One such strategy that has garnered less attention is serosorting; a practice whereby individuals seek partners of the same HIV serostatus and that was first described in men who have sex with men (MSM) in concentrated epidemics (18–21). Despite possible drawbacks –serosorting is not a foolproof preventative strategy (22–25) and HIV positives are at risk of infection with multiple strains of the virus (26)– serosorting and its associated changes in sexual networks could mitigate the spread of HIV (27–30). Serosorting has hardly been studied in generalized heterosexual epidemics, and we use it as a case in point to argue that new study designs are needed to evaluate the impact of HTC on (risky) sexual behaviors and the spread of HIV.