Extra-couple HIV transmission in sub-Saharan Africa: a mathematical modelling study of survey data

Cost of Home-Based Couples Human Immunodeficiency Virus Counseling and Testing and Human Immunodeficiency Virus Self-Testing During Pregnancy and Postpartum in Southwestern Kenya

OBJECTIVE

Home-based couples HIV testing and counseling and HIV self-testing (HIVST) for pregnant women can promote HIV status disclosure and male partner testing; however, cost data are lacking. We examined a home-based couples intervention (HBCI) and HIVST intervention costs per couple (unit cost) during pregnancy and postpartum in Kenya.

METHODS

This randomized controlled trial is comparing HBCI and HIVST for couples among pregnant women attending antenatal care clinics in two counties in southwestern Kenya. We used micro-costing to estimate the unit cost per couple receiving the intervention as the total of direct and indirect costs for each study arm in 2019 US$. We used a one-month window to conduct a time and motion study to determine personnel effort and resources. We then compared the unit cost by arm, identified key cost drivers, and conducted sensitivity analyses for cost uncertainties.

RESULTS

At base-case, the unit cost was $129.01 and $41.99, respectively, for HBCI and HIVST. Personnel comprised half of the unit cost for both arms. Staff spent more time on activities related to participant engagement in HBCI (accounting for 6.4% of the unit cost) than in HIVST (2.3%). Staff training was another key cost driver in HBCI (20.1% of the unit cost compared to 12.5% in HIVST). Sensitivity analyses revealed that the unit cost ranges were $104.64-$154.54 for HBCI and $30.49-$56.59 for HIVST.

CONCLUSIONS

Our findings may guide spending decisions for future HIV prevention and treatment programs for pregnant couples in resource-limited settings such as Kenya.

Effects of the Waya Intervention on Marital Satisfaction and HIV Risk Behaviors in Western Kenya: A Pre-Post Study Design

Poor marital satisfaction is associated with high-risk sexual behavior and HIV transmission. We tested whether a counselor-led couple education and counseling intervention dubbed Waya (paternal aunt) would improve marital satisfaction and reduce HIV risk behavior among married couples in Kisumu County, western Kenya. In a pre-post design, we enrolled 60 heterosexual married couples at high risk for HIV to undergo five 1-h couple education and counseling sessions over 56 days. We collected self-reported data on marital satisfaction, the number of sex partners, and condom use with extramarital partners at pre- and post-intervention visits. We used Wilcoxon and McNemar tests to examine the association of our intervention with marital relationship satisfaction and reduction in HIV risk sexual behavior. The intervention was associated with marital relationship satisfaction score improvement from a median of 5 (interquartile range [IQR], 4-5) to 6 (IQR, 6-7) among men and 4 (IQR, 3-5) to 6 (IQR, 5-6) among women (p < .01). The intervention was also associated with reducing HIV risk sexual behaviors depicted by a reduction in the number of sex partners in the past one month and an increase in consistent extramarital condom use. The number of sex partners reduced from a median of 2 (IQR, 1-2) to 1 (IQR, 1-2) and consistent extramarital condom use increased from 4% at baseline to 56% among men. Our intervention was associated with improvements in marital relationship satisfaction and reductions in HIV high-risk behaviors necessary for achieving epidemic control in HIV hotspots such as fishing communities in western Kenya.

Development of a Blended Learning Approach to Delivering HIV-Assisted Contact Tracing in Malawi: Applied Theory and Formative Research

Background

Despite progress toward the Joint United Nations Programme on HIV/AIDS “95-95-95” targets (95% of HIV-positive persons tested, 95% of tested persons on treatment, and 95% of treated persons virally suppressed), a gap remains in achieving the first 95% target. Assisted contact tracing (ACT), in which health workers support HIV-positive index clients to recruit their contacts (sexual partners and children) for HIV testing, efficiently identifies HIV-positive persons in need of treatment. Although many countries, including Malawi, began implementing ACT, testing outcomes in routine settings have been worse than those in trial settings.

Objective

The aim of this paper is to use formative research and frameworks to develop and digitize an implementation package to bridge the gap between ACT research and practice.

Methods

Semistructured qualitative research was conducted in 2019 in Malawi with key informants. Barriers and facilitators to intervention delivery were identified using the Consolidated Framework for Implementation Research. Approaches to digitization were examined using human-centered design principles.

Results

Limited clinic coordination and health worker capacity to address the complexities of ACT were identified as barriers. Ongoing individual training consisting of learning, observing, practicing, and receiving feedback, as well as group problem-solving were identified as facilitators. Important features of digitization included (1) culturally relevant visual content, (2) capability of offline use, and (3) simple designs and basic editing to keep costs low.

Conclusions

Formative research and frameworks played a key role in designing and digitizing an implementation package for ACT delivery in a low-income setting such as Malawi.

Pre-exposure prophylaxis use among HIV serodiscordant couples: a qualitative study in Mozambique

Background

Pre-exposure prophylaxis (PrEP) has the potential to reduce HIV transmission and stem the HIV epidemic. Unfortunately, PrEP uptake in rural sub-Saharan Africa has been slow and medication adherence has been suboptimal.

Objective

To explore the perspectives, attitudes, and experiences of HIV serodiscordant partners taking PrEP and develop a messaging campaign to improve PrEP uptake in rural Mozambique to reduce HIV transmission among serodiscordant partners.

Methods

In this qualitative study, we interviewed 20 people in serodiscordant relationships using PrEP at a rural health center in Zambézia province, Mozambique and employed inductive and deductive coding to elicit their perspectives, attitudes, and experiences related to learning their partner’s HIV status, barriers to PrEP uptake, obstacles to PrEP adherence, and decisions to disclose their PrEP use with family and friends using thematic analysis.

Results

Our analysis generated nine themes across various levels of the socioecological model. Participants reported a strong desire to stay in the discordant relationship and highlighted the importance of working together to ensure PrEP and antiretroviral therapy adherence, with the majority skeptical that adherence could be achieved without both partners’ support (individual and interpersonal). Although most participants were reticent about sharing their serodiscordant status with family and friends (individual and interpersonal), those who did found their family and friends supportive (interpersonal). Participants suggested increasing community health agent availability to help people navigate HIV prevention and treatment (organizational). We then created three oral stories, using themes from the interviews, with examples from various levels of the socioecological model that will be used to generate support for PrEP use among community members.

Conclusions

Our findings informed oral template stories that will be used to emphasize how couples can work together to improve PrEP uptake and reduce incident HIV infections in serodiscordant couples elsewhere in rural Mozambique.

Women's perspectives on relationship dynamics with their partners and their role in HIV acquisition, HIV disclosure, hormonal contraceptive uptake, and condom use

Background: Limited information exists about relationship dynamics and their role in HIV acquisition, HIV disclosure, hormonal contraceptive uptake, and condom use among women in Malawi.Methods: Ninety-seven women aged 18-45 years were randomly assigned to initiate the depot medroxyprogesterone acetate injectable or levonorgestrel implant from May 2014 to April 2015 in Lilongwe, Malawi. Women were recruited after randomisation to participate in semi-structured interviews about HIV and family planning using purposive sampling. Interviews were thematically analysed using within and between group comparisons.Results: We conducted individual interviews and/or focus group discussions with 41 women: 30 (73%) women living with HIV and 11 (27%) women not living with HIV. Most women living with HIV who participated in in-depth interviews disclosed their status to their partners, and most partners agreed to get HIV tested only after disclosure. Nearly all women said their partners agreed to use condoms, but few used them consistently. Nearly all women believed their current and former partners had outside partners. Most women living with HIV who participated in in-depth interviews believed their current or other serious partners were the source of their infection. Some women thought their partner's infidelity was due to their partner's disinterest in sex with them during menstrual/ breakthrough bleeding. Some women included their partners in contraceptive decision-making when the partner was supportive.Discussion: Relationship dynamics affected decision-making for contraceptive and condom use, as well as serodisclosure for the women living with HIV in the study. All women reported challenges with consistent condom use with their male partners, although contraceptive use was generally more acceptable. Women included their partners in their decision-making concerning contraceptive use when they were supportive.

Dried Blood Spot Tests for the Diagnosis and Therapeutic Monitoring of HIV and Viral Hepatitis B and C

Blood collected and dried on a paper card – dried blood spot (DBS) – knows a growing interest as a sampling method that can be performed outside care facilities by capillary puncture, and transported in a simple and safe manner by mail. The benefits of this method for blood collection and transport has recently led the World Health Organization to recommend DBS for HIV and hepatitis B and C diagnosis. The clinical utility of DBS sampling to improve diagnostics and care of HIV and hepatitis B and C infection in hard to reach populations, key populations and people living in low-income settings was highlighted. Literature about usefulness of DBS specimens in the therapeutic cascade of care – screening, confirmation, quantification of nucleic acids, and resistance genotyping -, was reviewed. DBS samples are suitable for testing antibodies, antigens, or nucleic acids using most laboratory methods. Good sensibility and specificity have been reported for infant HIV diagnosis and diagnosis of hepatitis B and C. The performance of HIV RNA testing on DBS to identified virological failure on antiretroviral therapy is also high but not optimal because of the dilution of dried blood in the elution buffer, reducing the analytical sensitivity, and because of the contamination by intracellular HIV DNA. Standardized protocols are needed for inter-laboratory comparisons, and manufacturers should pursue regulatory approval for in vitro diagnostics using DBS specimens. Despite these limitations, DBS sampling is a clinically relevant tool to improve access to infectious disease diagnosis worldwide.

Post-test adverse psychological effects and coping mechanisms amongst HIV self-tested individuals living in couples in urban Blantyre, Malawi

Introduction

Mandatory face-to-face counselling is necessary during HIV testing but difficult to implement within the context of HIV self-testing. We investigated adverse psychological effects and coping mechanisms following HIV-positive and HIV-discordant test results amongst self-tested individuals living in couples in urban Blantyre, Malawi.

Methods

Qualitative data from 35 in-depth interviews with self-tested individuals living in couples for more than 3 months were collected and analysed using thematic content analysis.

Results

Adverse psychological effects seemed to mostly occur among individuals learning for the first-time that they were HIV-positive or living in HIV-discordant relationship. Irrespective of test outcomes, women living in couples expressed difficulty making important decisions about the future of their relationships while men seemed to shoulder the emotional burden associated with feeling or being seen as responsible for introducing HIV into the relationship. Post-test psychosocial support and ascertained positive behaviour change of the perceived index partner allowed some couples to overcome adverse psychological effects linked to test results.

Conclusion

Self-tested individuals living in couples may lack collective coping capability to collaboratively manage post-test adverse events after new HIV-positive or HIV-discordant results. Psychosocial support seemed to enable couples to foster both an individual and a collective ability to manage adverse psychological effects within the context of a couple. More research is needed to ascertain the magnitude of the deficiency of collective coping competency in couples following an HIV test.

Exploring social harms during distribution of HIV self-testing kits using mixed-methods approaches in Malawi

INTRODUCTION

HIV self-testing (HIVST) provides couples and individuals with a discreet, convenient and empowering testing option. As with all HIV testing, potential harms must be anticipated and mitigated to optimize individual and public health benefits. Here, we describe social harms (SHs) reported during HIVST implementation in Malawi, and propose a framework for grading and responding to harms, according to their severity.

METHODS

We report findings from six HIVST implementation studies in Malawi (2011 to 2017) that included substudies investigating SH reports. Qualitative methods included focus group discussions, in-depth interviews and critical incident interviews. Earlier studies used intensive quantitative methods (post-test questionnaires for intimate partner violence, household surveys, investigation of all deaths in HIVST communities). Later studies used post-marketing reporting with/without community engagement. Pharmacovigilance methodology (whereby potentially life-threatening/changing events are defined as "serious") was used to grade SH severity, assuming more complete passive reporting for serious events.

RESULTS

During distribution of 175,683 HIVST kits, predominantly under passive SH reporting, 25 serious SHs were reported from 19 (0.011%) self-testers, including 15 partners in eight couples with newly identified HIV discordancy, and one perinatally infected adolescent. There were no deaths or suicides. Marriage break-up was the most commonly reported serious SH (sixteen individuals; eight couples), particularly among serodiscordant couples. Among new concordant HIV-positive couples, blame and frustration was common but rarely (one episode) led to serious SHs. Among concordant HIV-negative couples, increased trust and stronger relationships were reported. Coercion to test or disclose was generally considered "well-intentioned" within established couples. Women felt empowered and were assertive when offering HIVST test kits to their partners. Some women who persuaded their partner to test, however, did report SHs, including verbal or physical abuse and economic hardship.

CONCLUSIONS

After more than six years of large-scale HIVST implementation and in-depth investigation of SHs in Malawi, we identified approximately one serious reported SH per 10,000 HIVST kits distributed, predominantly break-up of married serodiscordant couples. Both "active" and "passive" reporting systems identified serious SH events, although with more complete capture by "active" systems. As HIVST is scaled-up, efforts to support and further optimize community-led SH monitoring should be prioritized alongside HIVST distribution.

Modeling epidemics: A primer and Numerus Model Builder implementation

Epidemiological models are dominated by compartmental models, of which SIR formulations are the most commonly used. These formulations can be continuous or discrete (in either the state-variable values or time), deterministic or stochastic, or spatially homogeneous or heterogeneous, the latter often embracing a network formulation. Here we review the continuous and discrete deterministic and discrete stochastic formulations of the SIR dynamical systems models, and we outline how they can be easily and rapidly constructed using Numerus Model Builder, a graphically-driven coding platform. We also demonstrate how to extend these models to a metapopulation setting using NMB network and mapping tools.

Individual, Partner, and Couple Predictors of HIV Infection among Pregnant Women in Malawi: A Case-Control Study

We aimed to understand drivers of HIV-infection in pregnant women in Malawi. The study was conducted in antenatal and labor and delivery wards. HIV-infected women and their partners (cases) were frequency matched in a 1:2 ratio based on age and screening location to HIV-uninfected women and their partners (controls) in a prevalent case-control study. Characteristics associated with female HIV infection were assessed using logistic regression modeling. At screening, HIV-infected women were more likely to have partners outside Lilongwe than HIV-uninfected women (24% vs. 0%, p < 0.0001). Case females were more likely to have HIV-infected study partners than control females (75% vs. 4%, p < 0.0001). The odds of female HIV-infection were higher if either couple member reported ≥ 2 lifetime marriages (OR 9.0, CI 2.6-30.9) or ≥ 3 lifetime partners (OR 18.0, CI 3.1-103.6) and lower if either reported past couple HIV testing and counseling (OR 0.1, CI 0.04-0.3). Targeting women with migrating partners, promoting couple HIV testing and counseling, and limiting partners could slow HIV transmission.

Temporal evolution of HIV sero-discordancy patterns among stable couples in sub-Saharan Africa

INTRODUCTION

Objective was to examine the temporal variation of HIV sero-discordancy in select representative countries (Kenya, Lesotho, Mali, Niger, Tanzania, and Zimbabwe) in sub-Saharan Africa at different HIV epidemic scales. A sero-discordant couple is defined as a stable couple (SC) in which one partner is HIV-positive while the other is HIV-negative.

METHODS

A deterministic compartmental mathematical model was constructed to describe HIV transmission dynamics. The model was pair-based, that is explicitly modeling formation of SCs and infection dynamics in both SCs and in single individuals. The model accommodated for different forms of infection statuses in SCs. Using population-based nationally-representative epidemiologic and demographic input data, historical (1980-2014) and future (2015-2030) trends of sero-discordancy and other demographic and epidemiologic indicators were projected throughout HIV epidemic phases.

RESULTS

As the epidemics emerged, about 90% of SCs affected by HIV were sero-discordant. This proportion declined to 45%-88% at epidemic peak and stabilized as the epidemics started their natural decline. The largest reductions in sero-discordancy were in high HIV-prevalence countries. As the epidemics further declined with antiretroviral therapy (ART) scale-up, the proportion of sero-discordant couples among HIV-affected couples was projected to increase to 70%-92% by 2030. The proportion of sero-discordant couples among all SCs increased as the epidemics emerged and evolved, then peaked at 2%-20% as the epidemics peaked, and then declined as the epidemics declined to reach 0.3%-16% by 2030.

CONCLUSIONS

Sero-discordancy patterns varied with the evolution of the epidemics, and were affected by both epidemic phase and scale. The largest variations were found in high HIV-prevalence countries. The fraction of stable couples that are sero-discordant, as opposed to being sero-concordant positive, was projected to increase with ART scale-up and further HIV incidence decline over the coming two decades. These findings inform strategic planning and resource allocation for interventions among sero-discordant couples.

Couple serostatus patterns in sub-Saharan Africa illuminate the relative roles of transmission rates and sexual network characteristics in HIV epidemiology

HIV prevalence has surpassed 30% in some African countries while peaking at less than 1% in others. The extent to which this variation is driven by biological factors influencing the HIV transmission rate or by variation in sexual network characteristics remains widely debated. Here, we leverage couple serostatus patterns to address this question. HIV prevalence is strongly correlated with couple serostatus patterns across the continent; in particular, high prevalence countries tend to have a lower ratio of serodiscordancy to concordant positivity. To investigate the drivers of this continental pattern, we fit an HIV transmission model to Demographic and Health Survey data from 45,041 cohabiting couples in 25 countries. In doing so, we estimated country-specific HIV transmission rates and sexual network characteristics reflective of pre-couple and extra-couple sexual contact patterns. We found that variation in the transmission rate could parsimoniously explain between-country variation in both couple serostatus patterns and prevalence. In contrast, between-country variation in pre-couple or extra-couple sexual contact rates could not explain the observed patterns. Sensitivity analyses suggest that future work should examine the robustness of this result to between-country variation in how heterogeneous infection risk is within a country, or to assortativity, i.e. the extent to which individuals at higher risk are likely to partner with each other.

Treatment of HIV for the Prevention of Transmission in Discordant Couples and at the Population Level

The scientific breakthrough proving that antiretroviral therapy (ART) can halt heterosexual HIV transmission came in the form of a landmark clinical trial conducted among serodiscordant couples. Study findings immediately informed global recommendations for the use of treatment as prevention in serodiscordant couples. The extent to which these findings are generalizable to other key populations or to groups exposed to HIV through nonsexual transmission routes (i.e., anal intercourse or unsafe injection of drugs) has since driven a large body of research. This review explores the history of HIV research in serodiscordant couples, the implications for management of couples, subsequent research on treatment as prevention in other key populations, and challenges in community implementation of these strategies.

The Impact of Couple HIV Testing and Counseling on Consistent Condom Use Among Pregnant Women and Their Male Partners: An Observational Study

BACKGROUND

In sub-Saharan Africa couple HIV testing and counseling (CHTC) has been associated with substantial increases in safe sex, especially when at least one partner is HIV infected. However, this relationship has not been characterized in an Option B+ context.

SETTING

The study was conducted at the antenatal clinic at Bwaila District Hospital in Lilongwe, Malawi in 2016 under an Option B+ program.

METHODS

Ninety heterosexual couples with an HIV-infected pregnant woman (female-positive couples) and 47 couples with an HIV-uninfected pregnant woman (female-negative couples) were enrolled in an observational study. Each couple member was assessed immediately before and 1 month after CHTC for safe sex (abstinence or consistent condom use in the last month). Generalized estimating equations were used to model change in safe sex before and after CHTC and to compare safe sex between female-positive and female-negative couples.

RESULTS

Mean age was 26 years among women and 32 years among men. Before CHTC, safe sex was comparable among female-positive couples (8%) and female-negative couples (2%) [risk ratio (RR): 3.7, 95% confidence interval (CI): 0.5 to 29.8]. One month after CHTC, safe sex was higher among female-positive couples (75%) than among female-negative couples (3%) (RR: 30.0, 95% CI: 4.3 to 207.7). Safe sex increased substantially after CTHC for female-positive couples (RR 9.6, 95% CI: 4.6 to 20.0), but not for female-negative couples (RR: 1.2, 95% CI: 0.1 to 18.7).

CONCLUSIONS

Engaging pregnant couples in CHTC can have prevention benefits for couples with an HIV-infected pregnant woman, but additional prevention approaches may be needed for couples with an HIV-uninfected pregnant woman.

Sero-discovering versus sero-cognisant: initial challenges and needs of HIV-serodiscordant couples in Porto Alegre, Brazil

This paper focuses on challenges faced by heterosexual couples of mixed HIV status in Porto Alegre, Brazil, and argues for more conceptual nuance in our understanding of 'serodiscordance'. Couples' stories, collected over 11 months of qualitative research, demonstrate how profoundly serodiscordance involves both partners and suggest that the timing of relationship formation relative to HIV diagnosis influenced the particular challenges they confronted. In recognition of this variation, we propose the distinction of 'sero-discovering' from 'sero-cognisant' couples. Though Brazilian health policy strives to address the needs of individuals diagnosed with HIV, the needs of seronegative partners in this cohort received relatively little attention. In addition, the transformation of HIV from a death sentence to a chronic condition both facilitated the formation of serodiscordant unions and raised special challenges for such couples. Conceiving of any person receiving an HIV diagnosis as 'potentially partnered' may help address some of these lacunae while promoting primary prevention within mixed-status couples, and HIV testing more generally. More research with this population is needed.

Modeling the Cost-Effectiveness of Home-Based HIV Testing and Education (HOPE) for Pregnant Women and Their Male Partners in Nyanza Province, Kenya

Supplemental Digital Content is Available in the Text.

Introduction:

Women in sub-Saharan Africa face a 2-fold higher risk of HIV acquisition during pregnancy and postpartum and the majority do not know the HIV status of their male partner. Home-based couple HIV testing for pregnant women can reduce HIV transmission to women and infants while increasing antiretroviral therapy (ART) coverage in men. However, the cost-effectiveness of this program has not been evaluated.

Methods:

We modeled the health and economic impact of implementing a home-based partner education and HIV testing (HOPE) intervention for pregnant women and their male partners in a region of Western Kenya (formally Nyanza Province). We used data from the HOPE randomized clinical trial conducted in Kisumu, Kenya, to parameterize a mathematical model of HIV transmission. We conducted an in-country microcosting of the HOPE intervention (payer perspective) to estimate program costs as well as a lower cost scenario of task-shifting to community health workers.

Results:

The incremental cost of adding the HOPE intervention to standard antenatal care was $31–37 and $14–16 USD per couple tested with program and task-shifting costs, respectively. At 60% coverage of male partners, HOPE was projected to avert 6987 HIV infections and 2603 deaths in Nyanza province over 10 years with an incremental cost-effectiveness ratio (ICER) of $886 and $615 per disability-adjusted life year averted for the program and task-shifting scenario, respectively. ICERs were robust to changes in intervention coverage, effectiveness, and ART initiation and dropout rates.

Conclusions:

The HOPE intervention can moderately decrease HIV-associated morbidity and mortality by increasing ART coverage in male partners of pregnant women. ICERs fall below Kenya's per capita gross domestic product ($1358) and are therefore considered cost-effective. Task-shifting to community health workers can increase intervention affordability and feasibility.

History matching of a complex epidemiological model of human immunodeficiency virus transmission by using variance emulation

Complex stochastic models are commonplace in epidemiology, but their utility depends on their calibration to empirical data. History matching is a (pre)calibration method that has been applied successfully to complex deterministic models. In this work, we adapt history matching to stochastic models, by emulating the variance in the model outputs, and therefore accounting for its dependence on the model's input values. The method proposed is applied to a real complex epidemiological model of human immunodeficiency virus in Uganda with 22 inputs and 18 outputs, and is found to increase the efficiency of history matching, requiring 70% of the time and 43% fewer simulator evaluations compared with a previous variant of the method. The insight gained into the structure of the human immunodeficiency virus model, and the constraints placed on it, are then discussed.

'It is not expected for married couples': a qualitative study on challenges to safer sex communication among polygamous and monogamous partners in southeastern Tanzania

Background

Behavioral change approaches for human immunodeficiency virus (HIV) prevention in Tanzania encourage married partners to observe safe sex practices (condom use, avoidance of, or safe sex with multiple partners). To implement this advice, partners need to communicate with each other about safer sex, which is often challenging. Although social-structural factors are crucial in understanding sexual behavior, only a few studies focus on understanding safer sex dialogue in a broader social context.

Design

Drawing on the WHO-Commission on the Social Determinants of Health (WHO-CSDH) framework, this study explored key social-structural constructs for studying health in the context of improving safer sex dialogue between polygamous and monogamous partners. Twenty-four in-depth interviews (IDIs) and six focus group discussions (FGDs) with 38 men and women aged 18–60 years were conducted in Ifakara town located in Kilombero district, Tanzania. The study was nested within the community health surveillance project MZIMA (Kiswahili: ‘being healthy’). Partners’ experiences of safer sex dialogue in polygamous and monogamous relations were investigated and the challenges to safer sex dialogue explored.

Results

The study revealed that open safer sex dialogue in marriage is limited and challenged by social norms about marriage (a view that safer sex dialogue imply that partners are ‘not really’ married); marital status (a belief that safer sex dialogue is not practical in polygamous marriages, the elder wife should be exempted from the dialogue since she is at lower risk of engaging in extramarital affairs); relationship quality (marital conflicts, extramarital affairs, trust, and sexual dissatisfaction); and gender power relations (the notion that females’ initiative to discuss condom use and HIV couple counseling and testing may lead to conflict or divorce).

Conclusions

Implementing safer sex practices requires interventions beyond promotion messages. HIV prevention interventions in Tanzania should be carefully adapted to the local context including respective social norms, gender systems, marital context and relationship uncertainties as aspects that facilitate or hinder safer sex dialogue between partners. The WHO-CSDH framework could be strengthened by explicitly integrating relationship quality, marital status, and social norms as additional determinants of health.

Factors that lead to changes in sexual behaviours after a negative HIV test: protocol for a prospective cohort study in Kinshasa

Background

Considering the high percentage of couples in which one or both members are HIV negative, the frequency of transmission among non-regular partners and the probabilities of non-disclosure, attention should be paid to people getting a negative HIV test at the Voluntary Counseling and Testing (VCT). Research has shown that a negative HIV test may be followed by a change in sexual behaviours. In Sub-Saharan Africa, where most HIV infections occur, there are few studies that have analysed the factors associated with changes in sexual risk behaviours after a negative HIV test at the VCT clinic. The aim of this project is to evaluate the specific factors associated with changes in sexual behaviours, three months after a negative result in an HIV test, and to analyse the effect of counseling and testing on HIV-related knowledge of participants in an outpatient centre of Kinshasa (Democratic Republic of Congo).

Methods and design

Prospective cohort study from December 2014 until March 2016. People 15–60 year old that received VCT at Monkole Hospital (Kinshasa) were followed three months after they got a negative HIV test. In a face-to-face interview, participants replied to a baseline and a follow-up research questionnaire on HIV-related knowledge, attitudes and behaviours. At follow-up respondents were also offered a new HIV test and additional HIV counseling. Four hundred and fifteen participants completed the baseline questionnaire and 363 (87 %) came back for their 3-month follow up.

Discussion

This is the first longitudinal study in the DRC that evaluates the factors associated with changes in sexual behaviours after a negative HIV test at the VCT. Participants attending the VCT services within a clinical setting are a good study population as they can be good transmitters of preventive information for other people with no access to health facilities.

Sexual behaviour of women in rural South Africa: a descriptive study

Background

Sexual behaviour is a core determinant of the HIV and sexually transmitted infection (STI) epidemics in women living in rural South Africa. Knowledge of sexual behaviour in these areas is limited, but constitutes essential information for a combination prevention approach of behavioural change and biomedical interventions.

Methods

This descriptive study was conducted in rural Mopani District, South Africa, as part of a larger study on STI. Women of reproductive age (18–49 years) who reported sexual activity were included regardless of the reason for visiting the facility. Questionnaires were administered to 570 women. We report sexual behaviour by age group, ethnic group and self-reported HIV status.

Results

Young women (<25 years) were more likely to visit bars, practice fellatio, have concurrent sexual partners and report a circumcised partner than older women (>34 years); there was no difference for condom use during last sex act (36 % overall). Sotho women were more likely to report concurrent sexual partners whereas Shangaan women reported more frequent intravaginal cleansing and vaginal scarring practice in our analysis. HIV-infected women were older, had a higher number of lifetime sexual partners, reported more frequent condom use during the last sex act and were more likely to have a known HIV-infected partner than women without HIV infection; hormonal contraceptive use, fellatio, and a circumcised partner were less often reported.

Conclusions

This study provides insight into women’s sexual behaviour in a rural South African region. There are important differences in sexual behaviour by age group and ethnicity and HIV status; these should be taken into account when designing tailor-made prevention packages.

Effectiveness of combination packages for HIV-1 prevention in sub-Saharan Africa depends on partnership network structure: a mathematical modelling study

OBJECTIVES

Combination packages for HIV prevention can leverage the effectiveness of biomedical and behavioural elements to lower disease incidence with realistic targets for individual and population risk reduction. We investigated how sexual network structures can maximise the effectiveness of a package targeting sexually active adults in sub-Saharan Africa (SSA) with intervention components for medical male circumcision (MMC) and sexual partnership concurrency (having >1 ongoing partner).

METHODS

Network-based mathematical models of HIV type 1 (HIV-1) transmission dynamics among heterosexual couples were used to explore how changes to MMC alone and in combination with changes to concurrency impacted endemic HIV-1 prevalence and incidence. Starting from a base model parameterised from empirical data from West Africa, we simulated the prevalence of circumcision from 10% to 90% and concurrency was modelled at four discrete levels corresponding to values observed across SSA.

RESULTS

MMC and concurrency could contribute to the empirical variation in HIV-1 disease prevalence across SSA. Small reductions in concurrency resulted in large declines in HIV-1 prevalence. Scaling up circumcision in low-concurrency settings yields a greater relative benefit, but the absolute number of infections averted depends on both the circumcision coverage and baseline incidence. Epidemic extinction with this package will require substantial scale-up of MMC in low-concurrency settings.

CONCLUSIONS

Dynamic sexual network structure should be considered in the design and targeting of MMC within combination HIV-1 prevention packages. Realistic levels of coverage for these packages within southern Africa could lead to a reduction of incidence to the low levels observed in western Africa, and possibly, epidemic extinction.

Estimating the impact of universal antiretroviral therapy for HIV serodiscordant couples through home HIV testing: insights from mathematical models

INTRODUCTION

Antiretroviral therapy (ART) prevents HIV transmission within HIV serodiscordant couples (SDCs), but slow implementation and low uptake has limited its impact on population-level HIV incidence. Home HIV testing and counselling (HTC) campaigns could increase ART uptake among SDCs by incorporating couples' testing and ART referral. We estimated the reduction in adult HIV incidence achieved by incorporating universal ART for SDCs into home HTC campaigns in KwaZulu-Natal (KZN), South Africa, and southwestern (SW) Uganda.

METHODS

We constructed dynamic, stochastic, agent-based network models for each region. We compared adult HIV incidence after 10 years under three scenarios: (1) "Current Practice," (2) "Home HTC" with linkage to ART for eligible persons (CD4 <350) and (3) "ART for SDCs" regardless of CD4, delivered alongside home HTC.

RESULTS

ART for SDCs reduced HIV incidence by 38% versus Home HTC: from 1.12 (95% CI: 0.98-1.26) to 0.68 (0.54-0.82) cases per 100 person-years (py) in KZN, and from 0.56 (0.50-0.62) to 0.35 (0.30-0.39) cases per 100 py in SW Uganda. A quarter of incident HIV infections were averted over 10 years, and the proportion of virally suppressed HIV-positive persons increased approximately 15%.

CONCLUSIONS

Using home HTC to identify SDCs and deliver universal ART could avert substantially more new HIV infections than home HTC alone, with a smaller number needed to treat to prevent new HIV infections. Scale-up of home HTC will not diminish the effectiveness of targeting SDCs for treatment. Increasing rates of couples' testing, disclosure, and linkage to care is an efficient way to increase the impact of home HTC interventions on HIV incidence.

Targeting HIV services to male migrant workers in southern Africa would not reverse generalized HIV epidemics in their home communities: a mathematical modeling analysis

Background

Migrant populations such as mine workers contributed to the spread of HIV in sub-Saharan Africa. We used a mathematical model to estimate the community-wide impact of targeting treatment and prevention to male migrants.

Methods

We augmented an individual-based network model, EMOD-HIV v0.8, to include an age-dependent propensity for males to migrate. Migrants were exposed to HIV outside their home community, but continued to participate in HIV transmission in the community during periodic visits.

Results

Migrant-targeted interventions would have been transformative in the 1980s to 1990s, but post-2015 impacts were more modest. When targetable migrants comprised 2% of adult males, workplace HIV prevention averted 3.5% of community-wide infections over 20 years. Targeted treatment averted 8.5% of all-cause deaths among migrants. When migrants comprised 10% of males, workplace prevention averted 16.2% of infections in the community, one-quarter of which were among migrants. Workplace prevention and treatment acted synergistically, averting 17.1% of community infections and 11.6% of deaths among migrants. These estimates do not include prevention of secondary spread of HIV or tuberculosis at the workplace.

Conclusions

Though cost-effective, targeting migrants cannot collapse generalized epidemics in their home communities. Such a strategy would only have been possible prior to the early 1990s. However, migrant-targeted interventions synergize with general-population expansion of HIV services.

The Impact of Married Individuals Learning HIV Status in Malawi: Divorce, Number of Sexual Partners, and Condom Use With Spouses

This article assesses how married individuals' knowledge of HIV status gained through HIV testing and counseling (HTC) affects divorce, the number of sexual partners, and the use of condoms within marriage. This study improves upon previous studies on this topic because the randomized incentives affecting the propensity to be tested for HIV permit control for selective testing. Instrumental variable probit and linear models are estimated, using a randomized experiment administered as part of the Malawi Longitudinal Study of Families and Health (MLSFH). The results indicate that knowledge of HIV status (1) does not affect chances of divorce for either HIV-negative or HIV-positive respondents; (2) reduces the number of reported sexual partners among HIV-positive respondents; and (3) increases reported condom use with spouses for both HIV-negative and HIV-positive respondents. These results imply that individuals actively respond to information about their HIV status that they learn during HTC, invoking protective behavior against future risk of HIV/AIDS for themselves and their actual and potential sexual partners. Some limitations of this study are a small sample size for those who are HIV-positive and dependence on self-reported sexual behaviors.

Advances in HIV prevention for serodiscordant couples

Serodiscordant couples play an important role in maintaining the global HIV epidemic. This review summarizes biobehavioral and biomedical HIV prevention options for serodiscordant couples focusing on advances in 2013 and 2014, including World Health Organization guidelines and best evidence for couples counseling, couple-based interventions, and the use of antiviral agents for prevention. In the past few years, marked advances have been made in HIV prevention for serodiscordant couples and numerous ongoing studies are continuously expanding HIV prevention tools, especially in the area of pre-exposure prophylaxis. Uptake and adherence to antiviral therapy remains a key challenge. Additional research is needed to develop evidence-based interventions for couples, and especially for male-male couples. Randomized trials have demonstrated the prevention benefits of antiretroviral-based approaches among serodiscordant couples; however, residual transmission observed in recognized serodiscordant couples represents an important and resolvable challenge in HIV prevention.

Estimation and Short-Term Prediction of the Course of the HIV Epidemic Using Demographic and Health Survey Methodology-Like Data

BACKGROUND

Mathematical models have played important roles in the understanding of epidemics and in the study of the impacts of various behavioral or medical measures. However, modeling accurately the future spread of an epidemic requires context-specific parameters that are difficult to estimate because of lack of data. Our objective is to propose a methodology to estimate context-specific parameters using Demographic and Health Survey (DHS)-like data that can be used in mathematical modeling of short-term HIV spreading.

METHODS AND FINDINGS

The model splits the population according to sex, age, HIV status, and antiretroviral treatment status. To estimate context-specific parameters, we used individuals' histories included in DHS-like data and a statistical analysis that used decomposition of the Poisson likelihood. To predict the course of the HIV epidemic, sex- and age-specific differential equations were used. This approach was applied to recent data from Kenya. The approach allowed the estimation of several key epidemiological parameters. Women had a higher infection rate than men and the highest infection rate in the youngest age groups (15-24 and 25-34 years) whereas men had the highest infection rate in age group 25-34 years. The immunosuppression rates were similar between age groups. The treatment rate was the highest in age group 35-59 years in both sexes. The results showed that, within the 15-24 year age group, increasing male circumcision coverage and antiretroviral therapy coverage at CD4 ≤ 350/mm3 over the current 70% could have short-term impacts.

CONCLUSIONS

The study succeeded in estimating the model parameters using DHS-like data rather than literature data. The analysis provides a framework for using the same data for estimation and prediction, which can improve the validity of context-specific predictions and help designing HIV prevention campaigns.

Sociodemographic drivers of multiple sexual partnerships among women in three rural districts of Tanzania

Background

This study examines prevalence and correlates of multiple sexual partnerships (MSP) among women aged 15+ years in Rufiji, Kilombero, and Ulanga districts of Tanzania.

Materials and methods

Data were collected in a cross-sectional household survey in Rufiji, Kilombero, and Ulanga districts in Tanzania in 2011. From the survey, a total of 2,643 sexually active women ages 15+ years were selected for this analysis. While the chi-square test was used for testing association between MSP and each of the independent variables, logistic regression was used for multivariate analysis.

Results

Number of sexual partners reported ranged from 1 to 7, with 7.8% of the women reporting multiple sexual partners (2+) in the past year. MSP was more likely among both ever married women (adjusted odds ratio [AOR] =3.83, 95% confidence interval [CI] 1.40–10.49) and single women (AOR =6.13, 95% CI 2.45–15.34) than currently married women. There was an interaction between marital status and education, whereby MSP was 85% less likely among single women with secondary or higher education compared to married women with no education (AOR =0.15, 95% CI 0.03–0.61). Furthermore, women aged 40+ years were 56% less likely compared to the youngest women (<20 years) to report MSP (AOR =0.44, 95% CI 0.24–0.80). The odds of MSP among Muslim women was 1.56 times as high as that for Christians women (AOR =1.56, 95% CI 1.11–2.21). Ndengereko women were 67% less likely to report MSP compared to Pogoro women (AOR =0.33, 95% CI 0.18–0.59).

Conclusion

Eight percent of the women aged 15+ in Rufiji, Kilombero, and Ulanga districts of Tanzania are engaged in MSP. Encouraging achievement of formal education, especially at secondary level or beyond, may be a viable strategy toward partner reduction among unmarried women. Age, religion, and ethnicity are also important dimensions for partner reduction efforts.

Modeling infectious disease dynamics in the complex landscape of global health

Despite some notable successes in the control of infectious diseases, transmissible pathogens still pose an enormous threat to human and animal health. The ecological and evolutionary dynamics of infections play out on a wide range of interconnected temporal, organizational, and spatial scales, which span hours to months, cells to ecosystems, and local to global spread. Moreover, some pathogens are directly transmitted between individuals of a single species, whereas others circulate among multiple hosts, need arthropod vectors, or can survive in environmental reservoirs. Many factors, including increasing antimicrobial resistance, increased human connectivity and changeable human behavior, elevate prevention and control from matters of national policy to international challenge. In the face of this complexity, mathematical models offer valuable tools for synthesizing information to understand epidemiological patterns, and for developing quantitative evidence for decision-making in global health.

Reassessment of HIV-1 acute phase infectivity: accounting for heterogeneity and study design with simulated cohorts

BACKGROUND

The infectivity of the HIV-1 acute phase has been directly measured only once, from a retrospectively identified cohort of serodiscordant heterosexual couples in Rakai, Uganda. Analyses of this cohort underlie the widespread view that the acute phase is highly infectious, even more so than would be predicted from its elevated viral load, and that transmission occurring shortly after infection may therefore compromise interventions that rely on diagnosis and treatment, such as antiretroviral treatment as prevention (TasP). Here, we re-estimate the duration and relative infectivity of the acute phase, while accounting for several possible sources of bias in published estimates, including the retrospective cohort exclusion criteria and unmeasured heterogeneity in risk.

METHODS AND FINDINGS

We estimated acute phase infectivity using two approaches. First, we combined viral load trajectories and viral load-infectivity relationships to estimate infectivity trajectories over the course of infection, under the assumption that elevated acute phase infectivity is caused by elevated viral load alone. Second, we estimated the relative hazard of transmission during the acute phase versus the chronic phase (RHacute) and the acute phase duration (dacute) by fitting a couples transmission model to the Rakai retrospective cohort using approximate Bayesian computation. Our model fit the data well and accounted for characteristics overlooked by previous analyses, including individual heterogeneity in infectiousness and susceptibility and the retrospective cohort's exclusion of couples that were recorded as serodiscordant only once before being censored by loss to follow-up, couple dissolution, or study termination. Finally, we replicated two highly cited analyses of the Rakai data on simulated data to identify biases underlying the discrepancies between previous estimates and our own. From the Rakai data, we estimated RHacute = 5.3 (95% credibility interval [95% CrI]: 0.79-57) and dacute = 1.7 mo (95% CrI: 0.55-6.8). The wide credibility intervals reflect an inability to distinguish a long, mildly infectious acute phase from a short, highly infectious acute phase, given the 10-mo Rakai observation intervals. The total additional risk, measured as excess hazard-months attributable to the acute phase (EHMacute) can be estimated more precisely: EHMacute = (RHacute - 1) × dacute, and should be interpreted with respect to the 120 hazard-months generated by a constant untreated chronic phase infectivity over 10 y of infection. From the Rakai data, we estimated that EHMacute = 8.4 (95% CrI: -0.27 to 64). This estimate is considerably lower than previously published estimates, and consistent with our independent estimate from viral load trajectories, 5.6 (95% confidence interval: 3.3-9.1). We found that previous overestimates likely stemmed from failure to account for risk heterogeneity and bias resulting from the retrospective cohort study design. Our results reflect the interaction between the retrospective cohort exclusion criteria and high (47%) rates of censorship amongst incident serodiscordant couples in the Rakai study due to loss to follow-up, couple dissolution, or study termination. We estimated excess physiological infectivity during the acute phase from couples data, but not the proportion of transmission attributable to the acute phase, which would require data on the broader population's sexual network structure.

CONCLUSIONS

Previous EHMacute estimates relying on the Rakai retrospective cohort data range from 31 to 141. Our results indicate that these are substantial overestimates of HIV-1 acute phase infectivity, biased by unmodeled heterogeneity in transmission rates between couples and by inconsistent censoring. Elevated acute phase infectivity is therefore less likely to undermine TasP interventions than previously thought. Heterogeneity in infectiousness and susceptibility may still play an important role in intervention success and deserves attention in future analyses.

HIV status, gender, and marriage dynamics among adults in Rural Malawi

Awareness of and responses to HIV health risks stemming from relations between sexual partners have been well documented in sub-Saharan Africa, but few studies have estimated the effects of observed HIV status on marriage decisions and outcomes. We study marriage dissolution and remarriage in rural Malawi using longitudinal data with repeated HIV and marital status measurements. Results indicate that HIV-positive individuals face greater risks of union dissolution (via both widowhood and divorce) and lower remarriage rates. Modeling studies suggest that the exclusion of HIV-positive individuals from the marriage or partnership pools will reduce the spread of HIV.

Transformation of HIV from pandemic to low-endemic levels: a public health approach to combination prevention

Large declines in HIV incidence have been reported since 2001, and scientific advances in HIV prevention provide strong hope to reduce incidence further. Now is the time to replace the quest for so-called silver bullets with a public health approach to combination prevention that understands that risk is not evenly distributed and that effective interventions can vary by risk profile. Different countries have different microepidemics, with very different levels of transmission and risk groups, changing over time. Therefore, focus should be on high-transmission geographies, people at highest risk for HIV, and the package of interventions that are most likely to have the largest effect in each different microepidemic. Building on the backbone of behaviour change, condom use, and medical male circumcision, as well as expanded use of antiretroviral drugs for infected people and pre-exposure prophylaxis for uninfected people at high risk of infection, it is now possible to consider the prospect of what would be one of the most remarkable achievements in the history of public health: reduction of HIV transmission from a pandemic to low-level endemicity.

Factors shaping initial decision-making to self-test amongst cohabiting couples in urban Blantyre, Malawi

In sub-Saharan Africa, most new HIV infections occur in stable relationships, making couples testing an important intervention for HIV prevention. We explored factors shaping the decision-making of cohabiting couples who opted to self-test in Blantyre, Malawi. Thirty-four self-tested participants (17 couples) were interviewed. Motivators for HIV self-testing (HIVST) emerged at three main levels. Individual motivations included perceived benefits of access to treatment, and self-checking of serostatus in the hope of having been cured by prolonged treatment or faith-healing. HIVST was considered convenient, confidential, reassuring and an enabling new way to test with one's partner. Partnership motivations included both positive (mutual encouragement) and negative (suspected infidelity) aspects. For women, long-term health and togetherness were important goals that reinforced motivations for couples testing, whereas men often needed persuasion despite finding HIVST more flexible and less onerous than facility-based testing. Internal conflict prompted some partners to use HIVST as a way of disclosing their previously concealed HIV positive serostatus. Thus, the implementation of community-based HIVST should acknowledge and appropriately respond to decision-making processes within couples, which are shaped by gender roles and relationship dynamics.

Predictors of extra-marital partnerships among women married to fishermen along Lake Victoria in Kisumu County, Kenya

BACKGROUND

The vulnerability of women to HIV infection makes establishing predictors of women's involvement in extra-marital partnerships critical. We investigated the predictors of extra-marital partnerships among women married to fishermen.

METHODS

The current analyses are part of a mixed methods cross-sectional survey of 1090 gender-matched interviews with 545 couples and 12 focus group discussions (FGDs) with 59 couples. Using a proportional to size simple random sample of fishermen as our index participants, we asked them to enrol in the study with their spouses. The consenting couples were interviewed simultaneously in separate private rooms. In addition to socio-economic and demographic data, we collected information on sexual behaviour including extra-marital sexual partnerships. We analysed these data using descriptive statistics and multivariate logistic regression. For FGDs, couples willing to participate were invited, consented and separated for simultaneous FGDs by gender-matched moderators. The resultant audiofiles were transcribed verbatim and translated into English for coding and thematic content analysis using NVivo 9.

RESULTS

The prevalence of extra-marital partnerships among women was 6.2% within a reference time of six months. Factors that were independently associated with increased likelihood of extra-marital partnerships were domestic violence (aOR, 1.45; 95% CI 1.09-1.92), women reporting being denied a preferred sex position (aOR, 3.34; 95% CI 1.26-8.84) and spouse longer erect penis (aOR, 1.34; 95% CI 1.00-1.78). Conversely, women's age--more than 24 years (aOR, 0.33; 95% CI 0.14-0.78) and women's increased sexual satisfaction (aOR, 0.92; 95% CI 0.87-0.96) were associated with reduced likelihood of extra-marital partnerships.

CONCLUSION

Domestic violence, denial of a preferred sex positions, longer erect penis, younger age and increased sexual satisfaction were the main predictors of women's involvement in extra-marital partnerships. Integration of sex education, counselling and life skills training in couple HIV prevention programs might help in risk reduction.

Putting the C back into the ABCs: a multi-year, multi-region investigation of condom use by Ugandan youths 2003-2010

A major strategy for preventing transmission of HIV and other STIs is the consistent use of condoms during sexual intercourse. Condom use among youths is particularly important to reduce the number of new cases and the national prevalence. Condom use has been often promoted by the Uganda National AIDS Commission. Although a number of studies have established an association between condom use at one’s sexual debut and future condom use, few studies have explored this association over time, and whether the results are generalizable across multiple locations. This multi time point, multi district study assesses the relationship between sexual debut and condom use and consistent use of condoms thereafter. Uganda has used Lot Quality Assurance Sampling surveys since 2003 to monitor district level HIV programs and improve access to HIV health services. This study includes 4518 sexually active youths interviewed at five time points (2003–2010) in up to 23 districts located across Uganda. Using logistic regression, we measured the association of condom use at first sexual intercourse on recent condom usage, controlling for several factors including: age, sex, education, marital status, age at first intercourse, geographical location, and survey year. The odds of condom use at last intercourse, using a condom at last intercourse with a non-regular partner, and consistently using a condom are, respectively, 9.63 (95%WaldCI = 8.03–11.56), 3.48 (95%WaldCI = 2.27–5.33), and 11.12 (95%WaldCI = 8.95–13.81) times more likely for those individuals using condoms during their sexual debut. These values did not decrease by more than 20% when controlling for potential confounders. The results suggest that HIV prevention programs should encourage condom use among youth during sexual debut. Success with this outcome may have a lasting influence on preventing HIV and other STIs later in life.

Marital concurrency and HIV risk in 16 African countries

Research has identified sexual concurrency as a potential underlying driver of high HIV infection levels in sub-Saharan Africa, though few studies have explicitly examined the contribution of marital concurrency. Utilizing a multi-level model of Demographic and Health Surveys with HIV-biomarkers for sixteen African countries, this study assessed the relationship between an individual's HIV serostatus and rates of formal and informal marital concurrency (% polygamous unions, % extramarital partner past year) among married men and women. Mutually exclusive regional-level variables were constructed and modeled to test the contextual risk posed by living in a region with higher levels of formal and informal marital concurrency controlling for individual sexual partnerships and other covariates. Compared with regions where monogamous unions were more prevalent, the odds of having HIV were higher among individuals living in regions with more informal marital concurrency, but lower in regions with more polygamy, even accounting for individual-level sexual behavior. These results can help inform prevention policy and practice in sub-Saharan Africa.

The role of viral introductions in sustaining community-based HIV epidemics in rural Uganda: evidence from spatial clustering, phylogenetics, and egocentric transmission models

BACKGROUND

It is often assumed that local sexual networks play a dominant role in HIV spread in sub-Saharan Africa. The aim of this study was to determine the extent to which continued HIV transmission in rural communities--home to two-thirds of the African population--is driven by intra-community sexual networks versus viral introductions from outside of communities.

METHODS AND FINDINGS

We analyzed the spatial dynamics of HIV transmission in rural Rakai District, Uganda, using data from a cohort of 14,594 individuals within 46 communities. We applied spatial clustering statistics, viral phylogenetics, and probabilistic transmission models to quantify the relative contribution of viral introductions into communities versus community- and household-based transmission to HIV incidence. Individuals living in households with HIV-incident (n = 189) or HIV-prevalent (n = 1,597) persons were 3.2 (95% CI: 2.7-3.7) times more likely to be HIV infected themselves compared to the population in general, but spatial clustering outside of households was relatively weak and was confined to distances <500 m. Phylogenetic analyses of gag and env genes suggest that chains of transmission frequently cross community boundaries. A total of 95 phylogenetic clusters were identified, of which 44% (42/95) were two individuals sharing a household. Among the remaining clusters, 72% (38/53) crossed community boundaries. Using the locations of self-reported sexual partners, we estimate that 39% (95% CI: 34%-42%) of new viral transmissions occur within stable household partnerships, and that among those infected by extra-household sexual partners, 62% (95% CI: 55%-70%) are infected by sexual partners from outside their community. These results rely on the representativeness of the sample and the quality of self-reported partnership data and may not reflect HIV transmission patterns outside of Rakai.

CONCLUSIONS

Our findings suggest that HIV introductions into communities are common and account for a significant proportion of new HIV infections acquired outside of households in rural Uganda, though the extent to which this is true elsewhere in Africa remains unknown. Our results also suggest that HIV prevention efforts should be implemented at spatial scales broader than the community and should target key populations likely responsible for introductions into communities.

Sources of HIV incidence among stable couples in sub-Saharan Africa

Introduction

The recent availability of efficacious prevention interventions among stable couples offers new opportunities for reducing HIV incidence in sub-Saharan Africa. Understanding the dynamics of HIV incidence among stable couples is critical to inform HIV prevention strategy across sub-Saharan Africa.

Methods

We quantified the sources of HIV incidence arising among stable couples in sub-Saharan Africa using a cohort-type mathematical model parameterized by nationally representative data. Uncertainty and sensitivity analyses were incorporated.

Results

HIV incidence arising among stable concordant HIV-negative couples contribute each year, on average, 29.4% of total HIV incidence; of those, 22.5% (range: 11.1%–39.8%) are infections acquired by one of the partners from sources external to the couple, less than 1% are infections acquired by both partners from external sources within a year and 6.8% (range: 3.6%–11.6%) are transmissions to the uninfected partner in the couple in less than a year after the other partner acquired the infection from an external source. The mean contribution of stable HIV sero-discordant couples to total HIV incidence is 30.4%, with most of those, 29.7% (range: 9.1%–47.9%), being due to HIV transmissions from the infected to the uninfected partner within the couple. The remaining incidence, 40.2% (range: 23.7%–64.6%), occurs among persons not in stable couples.

Conclusions

Close to two-thirds of total HIV incidence in sub-Saharan Africa occur among stable couples; however, only half of this incidence is attributed to HIV transmissions from the infected to the uninfected partner in the couple. The remaining incidence is acquired through extra-partner sex. Substantial reductions in HIV incidence can be achieved only through a prevention approach that targets all modes of HIV exposure among stable couples and among individuals not in stable couples.

HIV sexual transmission is predominantly driven by single individuals rather than discordant couples: a model-based approach

Understanding the relative contribution to HIV transmission from different social groups is important for public-health policy. Information about the importance of stable serodiscordant couples (when one partner is infected but not the other) relative to contacts outside of stable partnerships in spreading disease can aid in designing and targeting interventions. However, the overall importance of within-couple transmission, and the determinants and correlates of this importance, are not well understood. Here, we explore how mechanistic factors – like partnership dynamics and rates of extra-couple transmission – affect various routes of transmission, using a compartmental model with parameters based on estimates from Sub-Saharan Africa. Under our assumptions, when sampling model parameters within a realistic range, we find that infection of uncoupled individuals is usually the predominant route (median 0.62, 2.5%–97.5% quantiles: 0.26–0.88), while transmission within discordant couples is usually important, but rarely represents the majority of transmissions (median 0.33, 2.5%–97.5% quantiles: 0.10–0.67). We find a strong correlation between long-term HIV prevalence and the contact rate of uncoupled individuals, implying that this rate may be a key driver of HIV prevalence. For a given level of prevalence, we find a negative correlation between the proportion of discordant couples and the within-couple transmission rate, indicating that low discordance in a population may reflect a relatively high rate of within-couple transmission. Transmission within or outside couples and among uncoupled individuals are all likely to be important in sustaining heterosexual HIV transmission in Sub-Saharan Africa. Hence, intervention policies should be broadly targeted when practical.

Effect of early antiretroviral therapy on sexual behaviors and HIV-1 transmission risk among adults with diverse heterosexual partnership statuses in Côte d'Ivoire

Background. The effect of early initiation of antiretroviral therapy (ART; ie, at CD4⁺ T-cell counts >350 cells/mm³) on sexual behaviors and human immunodeficiency virus type 1 (HIV) transmission risk has not been documented in populations other than HIV-serodiscordant couples in stable relationships.

Methods. On the basis of data from a behavioral study nested in a randomized, controlled trial (Temprano-ANRS12136) of early ART, we compared proportions of risky sex (ie, unprotected sex with a partner of negative/unknown HIV status) reported 12 months after inclusion between participants randomly assigned to initiate ART immediately (hereafter, “early ART”) or according to ongoing World Health Organization criteria. Group-specific HIV transmission rates were estimated on the basis of sexual behaviors and viral load–specific per-act HIV transmission probabilities. The ratio of transmission rates was computed to estimate the protective effect of early ART.

Results. Among 957 participants (baseline median CD4⁺ T-cell count, 478 cells/mm³), 46.0% reported sexual activity in the past month; of these 46.0%, sexual activity for 41.5% involved noncohabiting partners. The proportion of subjects who engaged in risky sex was 10.0% in the early ART group, compared with 12.8% in the standard ART group (P = .17). After accounting for sexual behaviors and viral load, we estimated that the protective effect of early ART was 90% (95% confidence interval, 81%–95%).

Conclusion. Twelve months after inclusion, patients in the early and standard ART groups reported similar sexual behaviors. Early ART decreased the estimated risk of HIV transmission by 90%, suggesting a major prevention benefit among seronegative sex partners in stable or casual relationships with seropositive individuals.

Integrated strategies for combination HIV prevention: principles and examples for men who have sex with men in the Americas and heterosexual African populations

Combination HIV prevention is of high priority for increasing the impact of partially efficacious HIV prevention interventions for specific populations and settings. Developing the package requires critical review of local epidemiology of HIV infection regarding most-impacted populations and those at high risk of HIV transmission and acquisition, drivers of HIV infection, and available interventions to address these risk factors. Interventions should be considered in terms of the evidence basis for efficacy, potential synergies, and feasibility of delivery at scale, which is important to achieve high coverage and impact, coupled with high acceptability to populations, which will impact uptake, adherence, and retention. Evaluation requires process measures of uptake, adherence, retention, and outcome measures of reduction in HIV infectiousness and acquisition. Three examples of combination prevention concepts are summarized for men who have sex with men in the Americas, young women in sub-Saharan Africa, and HIV serodiscordant couples.

Future of phylogeny in HIV prevention

The success of the HIV Prevention Trials Network 052 trial has led to revisions in HIV-1 treatment guidelines. Antiretroviral therapy may reduce the risk of HIV-1 transmissions at the population level. The design of successful treatment as prevention interventions will be predicated on a comprehensive understanding of the spatial, temporal, and biological dynamics of heterosexual men who have sex with men and intravenous drug user epidemics. Viral phylogenetics can capture the underlying structure of transmission networks based on the genetic interrelatedness of viral sequences and cluster networks that could not be otherwise identified. This article describes the phylogenetic expansion of the Montreal men who have sex with men epidemic over the last decade. High rates of coclustering of primary infections are associated with 1 infection leading to 13 onward transmissions. Phylogeny substantiates the role of primary and recent stage infection in transmission dynamics, underlying the importance of timely diagnosis and immediate antiretroviral therapy initiation to avert transmission cascades.

Trends in HIV counseling and testing uptake among married individuals in Rakai, Uganda

Background

Despite efforts to promote HIV counseling and testing (HCT) among couples, few couples know their own or their partners’ HIV status. We assessed trends in HCT uptake among married individuals in Rakai district, southwestern Uganda.

Methods

We analysed data for 21,798 married individuals aged 15-49 years who were enrolled into the Rakai Community Cohort Study (RCCS) between 2003 and 2009. Married individuals were interviewed separately but were retrospectively linked to their partners at analysis. All participants had serologic samples obtained for HIV testing, and had the option of receiving HCT together (couples’ HCT) or separately (individual HCT). Individuals were categorized as concordant HIV-positive if both partners had HIV; concordant HIV-negative if both did not have HIV; or HIV-discordant if only one of the partners had HIV. We used χ² tests to assess linear trends in individual and couples’ HCT uptake in the entire sample and conducted multinomial logistic regression on a sub-sample of 10,712 individuals to assess relative risk ratios (RRR) and 95% Confidence Intervals (95% CI) associated with individual and couples’ HCT uptake. Analysis was done using STATA version 11.0.

Results

Uptake of couples’ HCT was 27.2% in 2003/04, 25.1% in 2005/06, 28.5% in 2006/08 and 27.8% in 2008/09 (χ² for trend = 2.38; P = 0.12). Uptake of individual HCT was 57.9% in 2003/04, 60.2% in 2005/06, 54.0% in 2006/08 and 54.4% in 2008/09 (χ² for trend = 8.72; P = 0.003). The proportion of couples who had never tested increased from 14.9% in 2003/04 to 17.8% in 2008/09 (χ² for trend = 18.16; P < 0.0001). Uptake of couples’ HCT was significantly associated with prior HCT (Adjusted [Adj.] RRR = 6.80; 95% CI: 5.44, 8.51) and being 25-34 years of age (Adj. RRR = 1.81; 95% CI: 1.32, 2.50). Uptake of individual HCT was significantly associated with prior HCT (Adj. RRR = 6.26; 95% CI: 4.24, 9.24) and the female partner being HIV-positive (Adj. RRR = 2.46; 95% CI: 1.26, 4.80).

Conclusion

Uptake of couples’ HCT remained consistently low (below 30%) over the years, while uptake of individual HCT declined over time. These findings call for innovative strategies to increase demand for couples’ HCT, particularly among younger couples and those with no prior HCT.