Concurrent sexual partnerships do not explain the HIV epidemics in Africa: a systematic review of the evidence

Variations in sexual network connectivity may explain dramatic variations in sexually transmitted infection prevalence between populations and over time: a selected four-country analysis

Background: The incidence of sexually transmitted infections (STIs) has been noted to vary dramatically between population groups and over time. Here, the hypothesis that changes in network connectivity underpin these changes is explored.

Methods: The incidence/prevalence estimates of HIV, herpes simplex virus-2, syphilis, chlamydia, and gonorrhoea, as well as two markers of sexual network connectivity (partner concurrency and multiple partnering) by ethnic group and sexual orientation in Kenya, South Africa, the United Kingdom (UK) and the United States (USA) were extracted from published studies. Pearson’s correlation was used to test the association between the markers of network connectivity and the incidence/prevalence of these five STIs. A literature review was performed to evaluate the possible causes of the increases and decreases in syphilis incidence over the past 60 years.

Results: In each country, the five STIs were found to cluster in particular ethnic groups and sexual orientations and to be positively associated with the two markers of network connectivity. Syphilis incidence in the UK and USA was found to increase dramatically in the 1960s/1970s, decline in the 1980s and again increase in the late 1990s. These changes took place predominantly in men who have sex with men, and were preceded by corresponding changes in network connectivity. The large decline in antenatal syphilis prevalence in Kenya and South Africa in the 1990s were likewise preceded by declines in network connectivity.

Conclusions: Although other explanatory variables are not controlled for, the present analysis is compatible with the hypothesis that differential network connectivity is a parsimonious explanation for variations in STI incidence over time and between populations.

Concurrency measures in the era of temporal network epidemiology: a review

Diseases spread over temporal networks of interaction events between individuals. Structures of these temporal networks hold the keys to understanding epidemic propagation. One early concept of the literature to aid in discussing these structures is concurrency-quantifying individuals' tendency to form time-overlapping 'partnerships'. Although conflicting evaluations and an overabundance of operational definitions have marred the history of concurrency, it remains important, especially in the area of sexually transmitted infections. Today, much of theoretical epidemiology uses more direct models of contact patterns, and there is an emerging body of literature trying to connect methods to the concurrency literature. In this review, we will cover the development of the concept of concurrency and these new approaches.

Risky sexual behaviour amidst predicament of acceptable sexually transmitted infection partner notification modalities: A cross-sectional survey amongst minibus taxi drivers in Gauteng Province, South Africa

Background

Sexually transmitted infection patient-initiated partner notification (PN) approach has been implemented over a decade in South Africa, however, use and update by patients has been limited. This study assessed the perceived use of patient-initiated PN by using referral slips and measured the level of acceptability of provider-initiated PN by using short message service (SMS) to the personal mobile phones of sexual partners.

Methods

A formative evaluation approach using a quantitative survey amongst 722 minibus taxi drivers in nine major taxi ranks in Tshwane Municipality, Gauteng Province. STATA IC version 13 was used for data analyses.

Results

The mean age of the participants was 37.2 years (59%) were single, 59.5% had multiple sexual partners, 52.2% did not use a condom during the last sexual act, 42.8% reported inconsistent use of condoms and 65% tested for HIV in the past 12 months. The majority (98.2%) understood the importance of PN, but 51% would prefer telling a sexual partner face to face. Perceived easiness of delivering a PN slip was 69.1%, and 93% would use a PN slip received from a partner. Acceptability of provider-initiated PN by using an SMS was 62.7% and about a third (32.5%) were not in favour of provider-initiated PN by SMS. Twenty four point 7 percent (24.7%) preferred patient-initiated PN and 24.3% preferred provider-initiated PN.

Conclusion

Preferred patient-initiated and provider-initiated PN was almost equal, hence, the provider-initiated PN should be augmented to support the current patient-initiated PN to increase the overall STI notification.

The differential impacts of non-locally acquired infections and treatment interventions on heterosexual HIV transmission in Hong Kong

Introduction

Heterosexual infections have contributed to a high proportion of the HIV burden in Asia and Eastern Europe. Human mobility and non-local infections are important features in some cities/countries. An understanding of the determinants of the sustained growth of the heterosexual HIV epidemics would enable the potential impacts of treatment-based interventions to be assessed.

Methods

We developed a compartmental model for heterosexual HIV transmissions, parameterized by clinical and surveillance data (1984–2014) in Hong Kong. HIV sequence data were included for examining genetic linkages and clustering pattern. We performed sensitivity analyses to evaluate effects of high-risk sexual partnership and proportions of non-locally acquired infections. Four hypothetical interventions (a) immediate treatment, (b) enhancement of retention in care, (c) HIV testing campaigns, and (d) test-and-treat strategy, were examined.

Results

Data of 2174 patients (723 female and 1451 male) diagnosed with HIV between 1984 and 2012 in Hong Kong were collected for model parameterization. Among 1229 sequences of non-MSM (men who have sex with men) patients, 70% were isolates and 17% were either dyads or triads. In base-case scenario, the total estimated number of new infections in 2012–2023 would be 672 for male and 452 for female. Following 100% retention in care intervention, the total proportion of averted new infections in 2012–2023 would be 7% for male and 10% for female. HIV testing campaign in 2012 and 2017 followed by 100% immediate treatment strategy would avert 5% and 9% of male and female new infections, respectively. In the epidemic model, an increase of high-risk sexual partnership from 6% to 9% would increase the epidemic growth (annual number of newly diagnosed and newly infected cases) by about 10%. If no non-locally acquired infection occurred as from 2012, the epidemic growth would slump. To control the heterosexual epidemic, periodic HIV testing at 5-year intervals with immediate treatment would avert 5–13% of annual new infections in 2013–2023.

Conclusions

Enhanced HIV testing with immediate treatment is most effective in controlling the heterosexual epidemic, the impacts of which might however be attenuated by any increase of non-locally acquired infection, assuming little variations of high risk partnership over time.

Mono-Causal and Multi-Causal Theories of Disease: How to Think Virally and Socially about the Aetiology of AIDS

In this paper, I utilise the tools of analytic philosophy to amalgamate mono-causal and multi-causal theories of disease. My aim is to better integrate viral and socio-economic explanations of AIDS in particular, and to consider how the perceived divide between mono-causal and multi-causal theories played a role in the tragedy of AIDS denialism in South Africa in the early 2000s. Currently, there is conceptual ambiguity surrounding the relationship between mono-causal and multi-causal theories in biomedicine and epidemiology. Mono-causal theories focus on single, typically microbial, sources of illness and are most concerned with infectious diseases. By contrast, multi-causal theories allow for multiple factors to underpin a disease's aetiology, including socio-economic and behavioural factors, and they usually focus on chronic non-communicable diseases. However, if these theories are taken to be strictly distinct, this prevents the inclusion of both microbial and socio-economic factors in a single explanation of any particular disease. This strict distinction became a problem when trying to explain the disproportionate prevalence of AIDS in southern Africa and ultimately contributed to the tragedy of AIDS denialism in South Africa. In tandem with viewing how the perceived divide between multi-causal and mono-causal theories underpinned AIDS denialism, I examine Thabo Mbeki's specific role, while acknowledging that AIDS is being deprioritised on a broader international level. Overall, I will demonstrate that any long-term plan to eliminate AIDS will require viral and socio-economic factors to be considered simultaneously and that such a theoretical approach requires a clearer understanding of the underlying concepts of disease aetiology.

Conflicting Views in Narratives on HIV Transmission via Medical Care

Molecular studies suggest that HIV arose in Africa between 1880 and 1940. During this period, there were campaigns by European colonial governments that involved unsterile injections of large numbers of Africans. That, along with other unsafe therapeutic interventions, may have propelled the evolution of HIV from SIV. Since subtype B in Africa may have been concentrated in white African homosexuals, it is possible that Westerners rather than Haitians introduced the virus to the New World. Amplification of HIV subtype B took place in Haiti, where transmission was facilitated by hazardous medical procedures including plasmapheresis. Representations in the media, however, largely ignore Western contributions to the spread of AIDS. This article focuses on the value of alternative narratives in fostering a balanced view that is less stigmatizing on developing nations.

Willingness to use PrEP among female university students in Lesotho

Oral pre-exposure prophylaxis (PrEP) for HIV-negative individuals at high risk was introduced in Lesotho in April 2016. To assess the feasibility and acceptability of PrEP in Lesotho and to study the attitudes and beliefs around HIV risk and prevention measures among young women, between September and December 2016 we asked 302 female university students at fourteen higher education institutions in Lesotho about their sexual behavior, experiences of sexual coercion and abuse, HIV risk perception, willingness to use PrEP, as well as their attitudes toward condom use and self-administration of daily medications. Overall, 57.3% of the sample reported perceiving themselves at risk of acquiring HIV and 32.1% reported being strongly willing to use PrEP if it were available in their community. In a multivariate mediation analysis, perceived HIV risk was associated with 11.5 percentage points increase in likelihood of using PrEP (p = 0.041). Multiple concurrent sexual partnership was associated with 16.1 percentage points increase in likelihood of self-perceived HIV risk (p = 0.007), while having sexual partners in polygamous relationships was associated with 17.8 percentage points increase in likelihood of self-perceived HIV risk (p = 0.002) and the mediated indirect effect accounted for 18.2% of its total effect. Those who reported strong adherence to antibiotics were 23.1 percentage points more likely to express willingness to use PrEP than those who did not (p = 0.004), and those who reported to dislike condoms were 19.1 percentage points more likely to be willing to use PrEP than those who did not report aversion to condom use: these effect were direct and not mediated by HIV risk perception. Intimate partner violence (IPV) in the network of peers was also directly associated with willingness to use PrEP and its effect was not significantly mediated by HIV risk perception: those who had friends who experienced intimate partner violence were 14.9 percentage points more likely to be willing to use PrEP than those who did not report IPV in their network of peers (p = 0.009). These findings support the inclusion of individuals with multiple concurrent sexual partners among the key populations for PrEP provision and confirm that willingness to use PrEP is not solely driven by HIV risk perception. They also indicate that the presence of IPV in peer networks is related to one’s willingness to use PrEP. PrEP service provision may generate synergies with IPV prevention programs when offered within this framework.

Sexual Concurrency and Contraceptive Use Among Young Adult Women

Leveraging 2.5 years of weekly data from the Relationship Dynamics and Social Life Study, we investigate the relationship between young women's sexual concurrency and their contraceptive behavior. Specifically, we (1) examine whether young women changed their contraceptive use when switching from one to multiple concurrent sexual partners in the same week; (2) explore the uniformity of contraceptive responses to concurrency across relationship context; and (3) compare the contraceptive behaviors of never-concurrent women with those of ever-concurrent women in weeks when they were not concurrent. Nearly one in five sexually active young women had sex with two or more people in the same week. When they were concurrent, these women's odds of using any contraception increased threefold, and their odds of using condoms increased fourfold. This pattern of contraceptive adjustments was the same across relationship characteristics, such as duration and exclusivity. Yet when they were not concurrent, ever-concurrent women were less likely to use any contraception and used condoms less consistently than women who were never concurrent. We discuss these findings in the context of ongoing debates about the role of sexual concurrency in STI transmission dynamics.

Association between substance use and concurrent sexual relationships among urban slum dwellers in Nairobi, Kenya

While the overall incidence and prevalence of HIV/AIDS are declining in Africa, substance use-related HIV/AIDS is on the rise. The main objectives of this study were to elicit the types of commonly used substances and to examine the association between substance use and concurrent sexual relationships among slum dwellers in Kenya. Freelisting elicitation techniques were used to identify the most commonly used substances using 53 key informants. This was followed by a self-administered, structured questionnaire using a convenience sample of 506 participants. Findings from our freelisting analysis produced 27 substances that were used in the community. Analysis of the survey data shows that participants who reported using substances in the past three months were more likely to be involved in concurrent sexual relationships than those who did not (86.2% vs. 74.0%; p = .002). In the multivariable model, the odds of ever having concurrent sexual relationships were higher among participants who used any substance in the past three months (aOR 2.46; 95% CI 1.37-4.42, p < .01). The observed association between substance use and concurrent sexual relationships may be influenced by social and economic factors such as poverty and lack of opportunity among urban slum dwellers.

HIV prevalence correlated with circumcision prevalence and high-risk sexual behavior in India's states: an ecological study

Background: HIV prevalence varies between 0% and 1.6% in India's states. The factors underpinning this variation are poorly defined.

Methods: We evaluated the relationship between HIV prevalence by state and a range of risk factors in the Indian 2015 National Family Health Survey. Pearson’s correlation was used to assess the relationship between HIV prevalence and each variable. The prevalence of each risk factor was compared between five high-HIV-prevalence states (>1% prevalence) and a large low-HIV-prevalence state (Uttar Pradesh; HIV prevalence, 0.06%).

Results: There was an association between HIV prevalence and men's mean lifetime number of partners (r = 0.55; P = 0.001) and men reporting sex with a non-married, non-cohabiting partner (r = 0.40; P = 0.014). In general, men in high-prevalence states were less likely to be circumcised and (with the exception of Chandigarh) use condoms at last sex. In two high prevalence states (Mizoram and Nagaland), men reported a higher number of lifetime partners and a higher prevalence of multiple partners and high-risk sex in the past year.

Conclusions: Variation in circumcision prevalence and sexual behavior may contribute to the large variations in HIV prevalence by state in India.

Differential sexual network connectivity offers a parsimonious explanation for population-level variations in the prevalence of bacterial vaginosis: a data-driven, model-supported hypothesis

BACKGROUND

The prevalence of bacterial vaginosis (BV) and vaginal microbiota types varies dramatically between different populations around the world. Understanding what underpins these differences is important, as high-diversity microbiotas associated with BV are implicated in adverse pregnancy outcomes and enhanced susceptibility to and transmission of sexually transmitted infections.

MAIN TEXT

We hypothesize that these variations in the vaginal microbiota can, in part, be explained by variations in the connectivity of sexual networks. We argue: 1) Couple-level data suggest that BV-associated bacteria can be sexually transmitted and hence high sexual network connectivity would be expected to promote the spread of BV-associated bacteria. Epidemiological studies have found positive associations between indicators of network connectivity and the prevalence of BV; 2) The relationship between BV prevalence and STI incidence/prevalence can be parsimoniously explained by differential network connectivity; 3) Studies from other mammals are generally supportive of the association between network connectivity and high-diversity vaginal microbiota.

CONCLUSION

To test this hypothesis, we propose a combination of empirical and simulation-based study designs.

Application of Core Processes for Understanding Multiple Concurrent Sexual Partnerships Among Adolescents in Uganda

Introduction: Adolescents in Uganda, as in other sub-Saharan countries, engage in sex with multiple concurrent partners, thus placing them at risk for HIV and unplanned pregnancies, but it is not clear why. This study explored why adolescents in Uganda engage in multiple concurrent sexual partnerships (MCSP). Methods: This study used a Core Processes methodology. We used the processes of brainstorming, and identification of evidence and theoretical support, in various phases/steps of intervention planning, to provide possible explanations for adolescent MCSP. Results: Adolescents were found to have limited knowledge of the risks associated with MCSP and perceived a low risk for HIV. Peer influence to engage in MCSP exacerbated the problem among adolescents. Poor communication with sexual partners and parents and societal indifference to multiple sexual partnerships increased permissive attitudes toward infidelity. The unclear adolescent sexual and reproductive health policies hampered access to services, and transactional sexual relationships with older (polygamous) sexual partners increased the HIV risk. Adolescents were found to be more concerned about unplanned pregnancies than HIV risk. Discussion: From the empirical evidence, adolescent health programs in Uganda should incorporate comprehensive sexual health education on HIV and teenage pregnancy risk-reduction strategies. Programs should strengthen parental and community support through enhanced collaborative training on communication with and for adolescents. Forming strategic partnerships with various stakeholders for concerted efforts to address the MCSP problem among adolescents is critical.

It's the network, stupid: a population's sexual network connectivity determines its STI prevalence

There is little consensus as to why sexually transmitted infections (STIs), including HIV and bacterial vaginosis (BV) are more prevalent in some populations than others. Using a broad definition of sexual network connectivity that includes both structural and conductivity-related factors, we argue that the available evidence suggests that high prevalence of traditional STIs, HIV and BV can be parsimoniously explained by these populations having more connected sexual networks. Positive feedback, whereby BV and various STIs enhance the spread of other STIs, then further accentuates the spread of BV, HIV and other STIs. We review evidence that support this hypothesis and end by suggesting study designs that could further evaluate the hypothesis, as well as implications of this hypothesis for the prevention and management of STIs.

Strong association between higher-risk sex and HIV prevalence at the regional level: an ecological study of 27 sub-Saharan African countries

Background: It is unclear why HIV prevalence varies by nearly two orders of magnitude between regions within countries in sub-Saharan Africa. In this ecological study, we assess if HIV prevalence by region is associated with any of four markers of higher risk sexual behavior: lifetime number of partners, multiple partners in past year, higher risk sex (defined as sex with non-cohabiting, non-marital partners) and age at debut. Methods: We performed Pearson's correlation between the 4 behavioral risk factors and HIV prevalence by region in 47 nationally representative surveys from 27 sub-Saharan African countries, separately by gender. In addition, principal components analysis was used to reduce the eight risk factors (four for each gender) to two principal components (PCs). Mixed effects linear regression was used to assess the relationship between the resulting two PCs and HIV prevalence after controlling for the prevalence of male circumcision. Results: HIV prevalence varied by a median 3.7 fold (IQR 2.9-7.9) between regions within countries. HIV prevalence was strongly associated with higher risk sex and, to a lesser extent, the other risk factors evaluated. Both PCs were strongly associated with HIV prevalence when assessed via linear regression. Conclusions: Differences in sexual behavior may underpin the large differences in HIV-prevalence between subpopulation within sub-Saharan African countries.

It's the network, stupid: a population's sexual network connectivity determines its STI prevalence

There is little consensus as to why sexually transmitted infections (STIs), including HIV and bacterial vaginosis (BV) are more prevalent in some populations than others. Using a broad definition of sexual network connectivity that includes both structural and conductivity-related factors, we argue that the available evidence suggests that high prevalence of traditional STIs, HIV and BV can be parsimoniously explained by these populations having more connected sexual networks. Positive feedback, whereby BV and various STIs enhance the spread of other STIs, then further accentuates the spread of BV, HIV and other STIs. We review evidence that support this hypothesis and end by suggesting study designs that could further evaluate the hypothesis, as well as implications of this hypothesis for the prevention and management of STIs.

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.

Modelling the human immunodeficiency virus (HIV) epidemic: A review of the substance and role of models in South Africa

We review key mathematical models of the South African human immunodeficiency virus (HIV) epidemic from the early 1990s onwards. In our descriptions, we sometimes differentiate between the concepts of a model world and its mathematical or computational implementation. The model world is the conceptual realm in which we explicitly declare the rules – usually some simplification of ‘real world’ processes as we understand them. Computing details of informative scenarios in these model worlds is a task requiring specialist knowledge, but all other aspects of the modelling process, from describing the model world to identifying the scenarios and interpreting model outputs, should be understandable to anyone with an interest in the epidemic.

Sexual Behavior and Sexually Transmitted Infections Among Swingers: Results From an Online Survey in Belgium

Swingers are couples practicing consensual extradyadic heterosexual relations. This subculture is defined by venues and online communities. This study aimed to assess swingers' lifestyle, sexual health, and history of testing for sexually transmitted infections (STIs) and to review risk factors for sexual risk behavior and STI transmission. An online survey was distributed through venues, chat websites, and dating websites. Most of 480 swingers starting the survey completed it (n = 392, 81.6%). Women (n = 146) reported more frequent swinging (p = 0.013), same-sex contacts (p < 0.001), and more sex under influence of alcohol (p < 0.001). Men (n = 334) reported more anal sex (p = 0.002) and condomless vaginal sex (p = 0.004). Of respondents tested, 25.7% ever received an STI diagnosis. Using logistical regression, being male, older, single, and party drug use were associated with sexual risk behavior (p = 0.009). Higher frequency of swinging was associated with an STI diagnosis (p = 0.036). Swingers were sexually active, reported factors associated with sexual risk behavior, and were more diagnosed with an STI compared to the general population. Many swingers were tested for STIs. Nonetheless, implementation of tailored testing strategies should be considered given their elevated risk for STI acquisition.

Saturation effects and the concurrency hypothesis: Insights from an analytic model

Sexual partnerships that overlap in time (concurrent relationships) may play a significant role in the HIV epidemic, but the precise effect is unclear. We derive edge-based compartmental models of disease spread in idealized dynamic populations with and without concurrency to allow for an investigation of its effects. Our models assume that partnerships change in time and individuals enter and leave the at-risk population. Infected individuals transmit at a constant per-partnership rate to their susceptible partners. In our idealized populations we find regions of parameter space where the existence of concurrent partnerships leads to substantially faster growth and higher equilibrium levels, but also regions in which the existence of concurrent partnerships has very little impact on the growth or the equilibrium. Additionally we find mixed regimes in which concurrency significantly increases the early growth, but has little effect on the ultimate equilibrium level. Guided by model predictions, we discuss general conditions under which concurrent relationships would be expected to have large or small effects in real-world settings. Our observation that the impact of concurrency saturates suggests that concurrency-reducing interventions may be most effective in populations with low to moderate concurrency.

'Good culture, bad culture': polygyny, cultural change and structural drivers of HIV in Papua New Guinea

Culture is often problematised as a key structural driver of HIV transmission in Papua New Guinea. Official HIV programmes, as well as church teachings, tend to focus on customary marital practices of polygyny and bride price payments as 'harmful traditions'. This focus can oversimplify the effects of current and historical nuances of cultural, political and economic change on sexual concurrency and gender inequality. Community-based healthcare workers in Southern Highlands Province explain that customary marital practices are now highly reconfigured from their traditional forms. A recent mining boom has financially advantaged local and travelling men, who are driving an increase of sexual concurrency, transactional sex and inflation of bride price payments. Healthcare workers suggest that the erosion of important social relationships and kinship obligations by the expanding cash economy has caused an intensification of individual male power while enhancing the vulnerability of women. Yet without the means to challenge the effects of uneven economic development, healthcare workers are left to target 'culture' as the central influence on individual behaviours. A commitment to address structural inequality by political leadership and in HIV prevention programmes and a careful contextualisation of cultural change is needed.

HIV Epidemic in Tanzania: The Possible Role of the Key Populations

HIV remains a public health concern in Tanzania and other Eastern and Southern African countries. Estimates show that there were about 1.4 million people living with HIV in Tanzania in the year 2013. HIV is a generalized epidemic in Tanzania with heterosexual transmission being the main route of transmission. Recently, however, there has been growing concern on the potential role of the key populations in HIV epidemic in the country. Studies done have shown significantly higher HIV prevalence in these populations compared to the general population. These studies have also reported high risky behaviors among members of these populations. This review aims at discussing the possible role of the key populations in the HIV epidemic in Tanzania.

Partnership duration, concurrency, and HIV in sub-Saharan Africa

A widely accepted explanation for the exceptionally high HIV prevalence in sub-Saharan Africa is the practice of long-term overlapping heterosexual partnering. This article shows that long-duration concurrent partnering can be protective against HIV transmission rather than promoting it. Monogamous partnering prevents sexual transmission to anyone outside the partnership and, in an initially concordant-seronegative partnership, prevents sexual acquisition of HIV by either partner. Those protections against transmission and acquisition last as long as the partnership persists without new outside partnerships. Correspondingly, these two protective effects characterise polygynous partnerships, whether or not the polygyny is formal or informal, until a partner initiates a new partnership. Stable and exclusive unions of any size protect against HIV transmission, and more durable unions provide a longer protective effect. Survey research provides little information on partnership duration in sub-Saharan Africa and sheds no light on the interaction of duration, concurrency, and HIV. This article shows how assumptions about partnership duration in individual-based sexual-network models affect the contours of simulated HIV epidemics. Longer mean partnership duration slows the pace at which simulated epidemics grow. With plausible assumptions about partnership duration and at levels of concurrency found in the region, simulated HIV epidemics grow slowly or not at all. Those results are consistent with the hypothesis that long-duration partnering is protective against HIV and inconsistent with the hypothesis that long-term concurrency drives the HIV epidemics in sub-Saharan Africa.

Gender asymmetry in concurrent partnerships and HIV prevalence

The structure of the sexual network of a population plays an essential role in the transmission of HIV. Concurrent partnerships, i.e. partnerships that overlap in time, are important in determining this network structure. Men and women may differ in their concurrent behavior, e.g. in the case of polygyny where women are monogamous while men may have concurrent partnerships. Polygyny has been shown empirically to be negatively associated with HIV prevalence, but the epidemiological impacts of other forms of gender-asymmetric concurrency have not been formally explored. Here we investigate how gender asymmetry in concurrency, including polygyny, can affect the disease dynamics. We use a model for a dynamic network where individuals may have concurrent partners. The maximum possible number of simultaneous partnerships can differ for men and women, e.g. in the case of polygyny. We control for mean partnership duration, mean lifetime number of partners, mean degree, and sexually active lifespan. We assess the effects of gender asymmetry in concurrency on two epidemic phase quantities (R₀ and the contribution of the acute HIV stage to R₀) and on the endemic HIV prevalence. We find that gender asymmetry in concurrent partnerships is associated with lower levels of all three epidemiological quantities, especially in the polygynous case. This effect on disease transmission can be attributed to changes in network structure, where increasing asymmetry leads to decreasing network connectivity.

Young Men's Social Network Characteristics and Associations with Sexual Partnership Concurrency in Tanzania

Social network influence on young people's sexual behavior is understudied in sub-Saharan Africa. Previous research identified networks of mostly young men in Dar es Salaam who socialize in "camps". This study describes network characteristics within camps and their relationship to young men's concurrent sexual partnerships. We conducted surveys with a nearly complete census of ten camp networks (490 men and 160 women). Surveys included name generators to identify camp-based networks. Fifty seven percent of sexually active men (n = 471) reported past year concurrency, measured using the UNAIDS method. In a multivariable model, men's individual concurrency was associated with being a member of a closer knit camp in which concurrency was the normative behavior. Younger men who had older members in their networks were more likely to engage in concurrency. Respondent concurrency was also associated with inequitable personal gender norms. Our findings suggest strategies for leveraging social networks for HIV prevention among young men.

Reducing the overall HIV-burden in South Africa: is 'reviving ABC' an appropriate fit for a complex, adaptive epidemiological HIV landscape?

This article questions the recommendations to 'revive ABC (abstain, be faithful, condomise)' as a mechanism to 'educate' people in South Africa about HIV prevention as the South African National HIV Prevalence, Incidence and Behaviour Survey, 2012, suggests. We argue that ABC was designed as a response to a particular context which has now radically changed. In South Africa the contemporary context reflects the mass roll-out of antiretroviral treatment; significant bio-medical knowledge gains; a generalised population affected by HIV that has made sense of and embodied those diverse experiences; and a government committed to confronting the epidemic. We suggest that the situation can now be plausibly conceptualised as a complex, adaptive epidemiological landscape that could benefit from an expansion of the existing, 'descriptive' prevention paradigm towards strategies that focus on the dynamics of transmission. We argue for this shift by proposing a theoretical framework based on complexity theory and pattern management. We interrogate one educational prevention heuristic that emphasises the importance of risk-reduction through the lens of transmission, called A-3B-4C-T. We argue that this type of approach provides expansive opportunities for people to engage with the epidemic in contextualised, innovative ways that supersede the opportunities afforded by ABC. We then suggest that framing the prevention imperative through the lens of 'dynamic prevention' at scale opens more immediate opportunities, as well as developing a future-oriented mind-set, than the 'descriptive prevention' parameters can facilitate. The parameters of the 'descriptive prevention' paradigm, that maintain - and partially reinforce - the presence of ABC, do not have the flexibility required to develop the armamentarium of tools required to contribute to the management of a complex epidemiological landscape. Uncritically adhering to both the 'descriptive paradigm', and ABC, represents an historically dislocated form of prevention - with restrictive options for reducing the overall burden of HIV-related challenges in South Africa.

Concurrent sexual partnerships among married Zimbabweans - implications for HIV prevention

BACKGROUND

Concurrent sexual partnerships play a key role in sustaining the HIV epidemic in Zimbabwe. Married couples are at an increased risk of contracting HIV from sexual networks produced by concurrent sexual partnerships. Addressing these partnerships is an international HIV prevention priority.

METHODS

Our qualitative study presents the socioeconomic factors that contribute to the occurrence of concurrent sexual partnerships among married people in Zimbabwe. We conducted 36 in-depth interviews and four focus group discussions with married men and women in Zimbabwe in 2008 to understand the organizations of concurrent sexual partnerships. Data were analyzed using framework analysis.

RESULTS

Our study indicates that relationship dissatisfaction played a key role in the engagement of concurrent sexual partnerships. Depending on the source of the dissatisfaction, there were four possible types of concurrent sexual relationships that were formed: sex worker, casual partner, regular girlfriend or informal polygyny which was referred to as "small house". These relationships had different levels of intimacy, which had a bearing on practicing safer sex. Participants described three characteristics of hegemonic masculinity that contributed to the sources of dissatisfaction leading to concurrent sexual activity. Similarly, various aspects of emphasized femininity were described as creating opportunities for the occurrence of concurrent sexual relationships. Economic status was also listed as a factor that contributed to the occurrence of concurrent sexual partnerships.

CONCLUSION

Marital dissatisfaction was indicated as a contributing factor to the occurrence of concurrent sexual relationships. There were several reports of satisfying marital relationships in which affairs did not occur. Lessons from these marriages can be made part of future HIV prevention interventions targeted at preventing concurrent sexual partnerships by married couples.

Programmatic Implications of Acute and Early HIV Infection

Human immunodeficiency virus (HIV) infection includes acute, early, chronic, and late stages. Acute HIV infection lasts approximately 3 weeks and early HIV infection, which includes acute HIV infection, lasts approximately 7 weeks. Many testing and blood screening algorithms detect HIV antibodies about 3 weeks after HIV infection. Incidence estimates are based on results of modeling, cohort studies, surveillance, and/or assays. Viral load is the key modifiable risk factor for HIV transmission and peaks during acute and early HIV infection. Empirical evidence characterizing the impact of acute and early HIV infection on the spread of the HIV epidemic are limited. Time trends of HIV prevalence collected from concentrated and generalized epidemics suggest that acute and early HIV infection may have a limited role in population HIV transmission. Collectively, these data suggest that acute and early HIV infection is relatively short and does not currently require fundamentally different programmatic approaches to manage the HIV/AIDS epidemic in most settings. Research and surveillance will inform which epidemic contexts and phases may require tailored strategies for these stages of HIV infection.

Sampling dynamic networks with application to investigation of HIV epidemic drivers

We propose a method for randomly sampling dynamic networks that permits isolation of the impact of different network features on processes that propagate on networks. The new methods permit uniform sampling of dynamic networks in ways that ensure that they are consistent with both a given cumulative network and with specified values for constraints on the dynamic network properties. Development of such methods is challenging because modifying one network property will generally tend to modify others as well. Methods to sample constrained dynamic networks are particularly useful in the investigation of network-based interventions that target and modify specific dynamic network properties, especially in settings where the whole network is unobservable and therefore many network properties are unmeasurable. We illustrate this method by investigating the incremental impact of changes in networks properties that are relevant for the spread of infectious diseases, such as concurrency in sexual relationships. Development of the method is motivated by the challenges that arise in investigating the role of HIV epidemic drivers due to the often limited information available about contact networks. The proposed methods for randomly sampling dynamic networks facilitate investigation of the type of network data that can best contribute to an understanding of the HIV epidemic dynamics as well as of the limitations of conclusions drawn in the absence of such information. Hence, the methods are intended to aid in the design and interpretation of studies of network-based interventions.

Ecological association between HIV and concurrency point-prevalence in South Africa's ethnic groups

HIV prevalence between different ethnic groups within South Africa exhibits considerable variation. Numerous authors believe that elevated sexual partner concurrency rates are important in the spread of HIV. Few studies have, however, investigated if differential concurrency rates could explain differential HIV spread within ethnic groups in South Africa. This ecological analysis, explores how much of the variation in HIV prevalence by ethnic group is explained by differential concurrency rates. Using a nationally representative survey (the South African National HIV Prevalence, HIV Incidence, Behaviour and Communication Survey, 2005) the HIV prevalence in each of eight major ethnic groups was calculated. Linear regression analysis was used to assess the association between an ethnic group's HIV prevalence and the point-prevalence of concurrency. Results showed that HIV prevalence rates varied considerably between South Africa's ethnic groups. This applied to both different racial groups and to different ethnic groups within the black group. The point-prevalence of concurrency by ethnic group was strongly associated with HIV prevalence (R(2) = 0.83; p = 0.001). Tackling the key drivers of high HIV transmission in this population may benefit from more emphasis on partner reduction interventions.

Concurrency can drive an HIV epidemic by moving R0 across the epidemic threshold

OBJECTIVE

The objective of this study is to investigate whether concurrency can drive an HIV epidemic by moving R0 across the epidemic threshold.

DESIGN AND METHODS

We use a mathematical framework for a dynamic partnership network and the spread of a one-stage infection to study how concurrency is related to the basic reproduction number R0. Two concurrency indices were used to measure the level of concurrency. The model allows varying the level of concurrency in the population, while other key network properties such as partnership duration and lifetime number of partners are kept fixed. In this way, the effect of concurrency on R0 is investigated as an isolated phenomenon.

RESULTS

We find that an increase in concurrency is associated with an increase of R0. For plausible parameter sets for MSM populations, R0 is always above the epidemic threshold of 1. For scenarios that are plausible for sub-Saharan African populations, we show that increasing the level of concurrency can lead to R0 crossing the epidemic threshold. This occurs already at low levels of concurrency. Only a slight shift of the network structure from a purely monogamous population to one wherein individuals are allowed to have at most two partners is enough for this to happen.

CONCLUSION

Concurrency can be a driver of an HIV epidemic in sub-Saharan Africa for low levels of concurrency, although it is not decisive in MSM populations. A small increase in the level of concurrency can lead to R0 crossing the epidemic threshold in a sub-Saharan African setting.

Self-reported sex partner dates for use in measuring concurrent sexual partnerships: correspondence between two assessment methods

Although prevalence of concurrent sexual partnerships is increasingly investigated as a driver of HIV epidemics, its measurement varies and its role in transmission dynamics remains contested. Relying on different methods of obtaining self-reported partnership histories may lead to significant differences in prevalence. This study examined the reliability of two methods for assessing dates of sex and the implications for measuring concurrent sexual partnerships. We conducted a cross-sectional reliability study using self-reported survey data from 650 women ages 18-65 years, recruited online nationwide for human papillomavirus natural history studies from 2007 to 2012. Intermethod reliability of first and last sex with the most recent partner was assessed using weighted kappa. Intraclass correlation coefficient was estimated for intramethod reliability across two consecutive questionnaires administered 4 months apart. Point prevalence of concurrent sexual partnerships at 6 months prior to the questionnaire date was similar between the two question formats (10.5 % for categorical and 10.9 % for continuous). The range between the minimum and maximum cumulative prevalence for 12 months was larger when using the categorical questions (17.0-29.6 % compared to 27.6-28.6 % using the continuous questions). Agreement between the two question formats was moderate for the date of first sex with the most recent partner (κ = 0.56, 95 % CI 0.48-0.64) and almost perfect for the date of last sex (κ = 0.93, 95 % CI 0.91-0.94). Longitudinal agreement for date of first sex was high for the continuous date question (ICC = 0.89, 95 % CI 0.86-0.92). Results of this reliability study can be used to inform the design of future studies of concurrent sexual partnerships and their association with HIV.

Circumcision as a primary HIV preventive: extrapolating from the available data

Billions of dollars to circumcise millions of African males as an HIV infection prevention have been sought, yet the effectiveness of circumcision has not been demonstrated. Data from 109 populations comparing HIV prevalence and incidence in men based on circumcision status were evaluated using meta-regression. The impact on the association between circumcision and HIV incidence/prevalence of the HIV risk profile of the population, the circumcision rates within the population and whether the population was in Africa were assessed. No significant difference in the risk of HIV infection based on the circumcision status was seen in general populations. Studies of high-risk populations and populations with a higher prevalence of male circumcision reported significantly greater odds ratios (odds of intact man having HIV) (p < .0001). When adjusted for the impact of a high-risk population and the circumcision rate of the population, the baseline odds ratio was 0.78 (95% CI = 0.56-1.09). No consistent association between presence of HIV infection and circumcision status of adult males in general populations was found. When adjusted for other factors, having a foreskin was not a significant risk factor. This undermines the justification for using circumcision as a primary preventive for HIV infection.

The racial disparities in STI in the U.S.: Concurrency, STI prevalence, and heterogeneity in partner selection

Background

There is a large and persistent racial disparity in STI in the U.S. which has placed non-Hispanic-Blacks at disproportionately high risk. We tested a hypothesis that both individual-level risk factors (partner number, anal sex, condom use) and local-network features (concurrency and assortative mixing by race) combine to account for the association between race and chlamydia status.

Methods

Data from the Longitudinal Survey of Adolescent Health Wave III were used. Chlamydia status was determined using biomarkers. Individual-level risk behaviors were self-reported. Network location variables for concurrency and assortative mixing were imputed using egocentrically sample data on sexual partnerships.

Results

After controlling for demographic attributes including age, sex, marital status, education and health care access there remained a strong association between race and chlamydia status (OR = 5.23, 95% CI] 3.83–7.15], p < .001 for Non-Hispanic Blacks with Non-Hispanic Whites as the reference category). The inclusion of individual-level risk factors did not alter the association between race and chlamydia(OR = 5.23 for Non-Hispanic Blacks). The inclusion of concurrency and assortative mixing by race substantially reduced the association between race and chlamydia status (OR = 1.87, 95% CI [0.89–3.91] p > .05 for Non-Hispanic Blacks).

Reprint of: "This is the medicine:" a Kenyan community responds to a sexual concurrency reduction intervention

We report the results of the first study designed to evaluate the feasibility and acceptability of an HIV prevention intervention focused on concurrent sexual partnerships. Mathematical models and longitudinal studies of stable couples indicate concurrency plays a critical role in sustaining generalized HIV epidemics in heterosexual populations, and East and Southern African nations identified concurrency reduction as a priority for HIV prevention. "Know Your Network" (KYN) is a single-session community-level concurrency awareness intervention designed to address this need. It is rooted in traditional social network research, but takes advantage of new network methodology and years of participatory action research with communities living in a region of Kenya with the highest HIV prevalence nationally. KYN combines didactic presentation, interactive exercises, high-impact graphics, and a network survey with immediate visualization of the results, to prompt a community conversation about sexual norms. We combined focus group discussions and the traditional east African baraza to evaluate the feasibility and acceptability of KYN for use with adults living in rural Nyanza Province, Kenya. We were able to implement KYN with fidelity to its components. Participants understood the intervention's messages about concurrency and its role in HIV transmission through sexual networks. They agreed to provide anonymous egocentric data on their sexual partnerships, and in return we successfully simulated a representation of their local network for them to view and discuss. This launched a dynamic conversation about concurrency and sexual norms that persisted after the intervention. The concurrency message was novel, but resonant to participants, who reported sharing it with their children, friends, and sexual partners. With clear evidence of KYN's feasibility and acceptability, it would be appropriate to evaluate the effectiveness of the intervention using a community-randomized trial. If effective, KYN would offer an inexpensive complement to ongoing comprehensive HIV prevention efforts in generalized epidemic settings.

Concurrent partnerships and HIV risk among men who have sex with men in New York City

BACKGROUND

Concurrent partnerships are a significant public health concern among men who have sex with men (MSM). This study describes the prevalence of concurrency and its association with serodiscordant/serostatus unknown unprotected anal or vaginal intercourse (SDUI) among MSM in New York City.

METHODS

A total of 1458 MSM completed a social and sexual network inventory about their male and female sex partners, including concurrency, in the last 3 months. Logistic regression identified factors associated with SDUI.

RESULTS

Median age was 29 years. The proportion of participants who reported being HIV+ was 23.5%. The men reported a mean of 3.2 male partners in the last 3 months. The proportion of MSM who reported having recent SDUI was 16.6%. More than half (63.2%) described having concurrent sex partners (individual concurrency based on overlapping dates of relationships); 71.5% reported having partners whom they believed had concurrent partners (perceived partner concurrency); and 56.1% reported that both they and their partners had concurrent partners (reciprocal concurrency). Among HIV+ men by self-report, having SDUI was positively associated with individual concurrency, any alcohol use during sex, having more male sex partners, and not having a main partner. Among self-reported HIV- men, having SDUI was positively associated with perceived partner concurrency, lower education level, any alcohol and drug use during sex, having more male sex partners, and having an anonymous partner.

CONCLUSIONS

Concurrency was common among MSM. The association of SDUI with individual and perceived partner concurrency, along with substance use during sex, having an anonymous partner, and having many sex partners likely further increases HIV acquisition and transmission risk among MSM. HIV prevention interventions should address concurrency among MSM.

The role of relationship types on condom use among urban men with concurrent partners in Ghana and Tanzania

Multiple concurrent partnerships are hypothesized to be important drivers of HIV transmission. Despite the demonstrated importance of relationship type (i.e., wife, girlfriend, casual partner, sex worker) on condom use, research on concurrency has not examined how different combinations of relationship types might affect condom use. We address this gap, using survey data from a sample of men from Ghana (GH: n = 807) and Tanzania (TZ: n = 800) who have at least three sexual partners in the past three months. We found that approximately two-thirds of men's reported relationships were classified as a girlfriend. Men were more likely to use a condom with a girlfriend if their other partner was a wife compared to if their other partner was a sex worker (GH: OR 3.10, 95% CI, 1.40, 6.86; TZ: OR 2.34, 95% CI 1.35, 4.06). These findings underscore the importance of considering relationship type when designing HIV prevention strategies in these settings.

"Dying a hero": parents' and young people's discourses on concurrent sexual partnerships in rural Tanzania

Background

Concurrent sexual partnerships (CSPs) have been speculated to drive the HIV pandemic in many sub-Saharan African countries. We have limited understanding of how people think and talk about CSPs, how beliefs are transmitted across generations, and how this might affect the practice. This paper explores these issues to understand how CSPs are perpetuated and help identify opportunities for interventions to modify them.

Methods

The study employed an ethnographic research design involving: participant observation in 10 households, 60 in-depth interviews (IDIs), and nine participatory focus group discussions (FGDs). Participants were young people aged 14-24 and parents/carers of young people within this age group. The 60 IDIs were conducted with: 17 fathers, 13 mothers, 13 young men and 17 young women (six of whom had had unplanned pregnancies and 11 had no children). The nine FGDs were conducted with groups of: fathers (2), mothers (2), young women (2), and young men (3). A discourse analysis was carried out with all the transcripts. Data were analysed with the aid of NVIVO 8 software.

Results

Six distinct discourses were identified from the way participants talked about CSPs and the norms driving the practice: 1) predatory masculine sexuality; 2) masculine respectability; 3) feminine respectability; 4) empowered modern women; 5) traditional health beliefs; 6) public health. Discourses legitimating CSPs were drawn on and reproduced primarily by young people and the media and only indirectly by parents. Discourses discouraging CSPs were used primarily by parents, religious leaders and learning institutions and only indirectly by young people themselves.

Conclusion

Better knowledge of the discourses through which young people CSPs, and how these discourses are transmitted across generations, might help develop “culturally compelling” interventions that modify these discourses to enhance sexual health.

Effects of partnership change on microbicide gel adherence in a clinical trial (HPTN 035)

Use of HIV prevention methods may vary for women by types of sexual partners. In a microbicide safety and effectiveness trial (HPTN 035) differences in adherence to a microbicide study gel were compared between women with new versus ongoing partnerships over time. 1,757 women in the three HPTN 035 trial's arms completed the Follow-up Partner Status (FPS) questionnaire at their last study visit. Women married at baseline were asked if they had the same husband, new husband or new partner. Unmarried women were asked if they had changed partners or married. Self-reported gel adherence during the last sex act was compared at each quarterly visit between women with ongoing versus new partners. High gel adherence was compared with low gel adherence (85-100 vs. <85 % of last vaginal sex acts reported with gel use, respectively) in multivariable models to assess associations with partner change. Overall 7 % of women (n = 123) reported a new partner and 41 % (51) of those reported a new husband. Median gel adherence was reported to be 100 % in women with ongoing partners and 75 % for women with new partners (p < 0.001). In women reporting no gel use in their last sex act, only 12.5 % of the women with a new partner and none of those with an ongoing partner reported using condoms (p < 0.001). Fewer women with new partners reported using both the gel and condom during the last sex act as compared to women with ongoing partners (median 50 vs. 71.4 %, p < 0.001). After adjusting for age, site, education level, and sexual frequency, women with ongoing partners were more likely to report high gel adherence than those with new partners (AOR 2.5, 95 % CI 1.6, 3.9). This pattern persisted when gel use over time was compared between women with new versus ongoing partners. In the HPTN 035 trial, women with new partners had higher HIV incidence and reported less gel use and higher condom use. Specific counseling and support are needed to help women use potential HIV prevention methods, including microbicides, when they are changing partners.

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.

Prevalence and correlates of sexual partner concurrency among Australian gay men aged 18-39 years

Mathematical models predict higher rates of HIV and sexually transmitted infections (STIs) in populations with higher rates of concurrent sexual partnerships. Although gay men and other men who have sex with men (MSM) have disproportionately high rates of HIV/STIs, little is known about the prevalence and correlates of sexual concurrency in these populations. This paper reports findings from a national community-based survey of 1,034 Australian gay-identified men aged 18-39 years, who gave detailed information about their sexual partners over the past 12 months. In all, 237 (23 %) reported two or more concurrent sexual partners. For their most recent period of concurrency, 44 % reported three or more partners and 66 % reported unprotected sex with one or more of their partners. A multivariate logistic regression found sexual concurrency was significantly more likely among men on higher incomes (P = 0.02), who first had anal sex at a relatively young age (P = 0.03), and who reported a large number of partners in the past 12 months (P < 0.001). Age, education, HIV status, and other sociodemographic and sexual behavior variables were not significant correlates. However, men who reported sexual concurrency were significantly more likely to have been diagnosed with an STI in the past 12 months (P = 0.04). Findings from this study suggest sexual concurrency is common among younger Australian gay men. With many of these men not always using condoms, health agencies should consider the potential impact of concurrency on HIV/STI epidemics among gay men and other MSM.

Determinants of concurrent sexual partnerships within stable relationships: a qualitative study in Tanzania

OBJECTIVE

Concurrent sexual partnerships (CP) have been identified as a potential driver in the HIV epidemic in southern Africa, making it essential to understand motivating factors for engagement in CP. We aimed to assess community attitudes and beliefs about relationship factors that influence men and women in stable relationships to engage in CP in Tanzania. Social exchange theory was used for interpreting the data.

DESIGN

Qualitative study with focus group discussions (FGDs).

SETTING

Semiurban/rural communities in four regions across Tanzania (Dar es Salaam, Shinyanga, Iringa and Mbeya).

PARTICIPANTS

120 women aged 17-45 years and 111 men aged 18-49 years from four study areas participated in 32 FGDs.

OUTCOME MEASURES

FGD participants were asked the following questions about CP: definitions and types, motivations and justifications for engaging or not engaging, cultural factors, gender and socialisation, and local resources and efforts available for addressing CP. Our analysis focused specifically on beliefs about how relationship factors influence engagement in CP.

RESULTS

Dissatisfaction with a stable relationship was believed to be a contributing factor for engagement in CP for both men and women. Participants more commonly reported financial dissatisfaction as a contributing factor for women engaging in CP within stable relationships, whereas emotional and sexual dissatisfaction were reported as contributing factors for men and women. Furthermore, participants described how potential outside partners are often evaluated based on what they are able to offer compared with stable partners.

CONCLUSIONS

Efforts to reach men and women in stable relationships with HIV prevention messages must consider the various dimensions of motivation for engaging in CP, including relationship dynamics.

"This is the medicine:" A Kenyan community responds to a sexual concurrency reduction intervention

We report the results of the first study designed to evaluate the feasibility and acceptability of an HIV prevention intervention focused on concurrent sexual partnerships. Mathematical models and longitudinal studies of stable couples indicate concurrency plays a critical role in sustaining generalized HIV epidemics in heterosexual populations, and East and Southern African nations identified concurrency reduction as a priority for HIV prevention. "Know Your Network" (KYN) is a single-session community-level concurrency awareness intervention designed to address this need. It is rooted in traditional social network research, but takes advantage of new network methodology and years of participatory action research with communities living in a region of Kenya with the highest HIV prevalence nationally. KYN combines didactic presentation, interactive exercises, high-impact graphics, and a network survey with immediate visualization of the results, to prompt a community conversation about sexual norms. We combined focus group discussions and the traditional east African baraza to evaluate the feasibility and acceptability of KYN for use with adults living in rural Nyanza Province, Kenya. We were able to implement KYN with fidelity to its components. Participants understood the intervention's messages about concurrency and its role in HIV transmission through sexual networks. They agreed to provide anonymous egocentric data on their sexual partnerships, and in return we successfully simulated a representation of their local network for them to view and discuss. This launched a dynamic conversation about concurrency and sexual norms that persisted after the intervention. The concurrency message was novel, but resonant to participants, who reported sharing it with their children, friends, and sexual partners. With clear evidence of KYN's feasibility and acceptability, it would be appropriate to evaluate the effectiveness of the intervention using a community-randomized trial. If effective, KYN would offer an inexpensive complement to ongoing comprehensive HIV prevention efforts in generalized epidemic settings.

An association between neighbourhood wealth inequality and HIV prevalence in sub-Saharan Africa

This paper investigates whether community-level wealth inequality predicts HIV serostatus using DHS household survey and HIV biomarker data for men and women ages 15-59 pooled from six sub-Saharan African countries with HIV prevalence rates exceeding 5%. The analysis relates the binary dependent variable HIV-positive serostatus and two weighted aggregate predictors generated from the DHS Wealth Index: the Gini coefficient, and the ratio of the wealth of households in the top 20% wealth quintile to that of those in the bottom 20%. In separate multilevel logistic regression models, wealth inequality is used to predict HIV prevalence within each statistical enumeration area, controlling for known individual-level demographic predictors of HIV serostatus. Potential individual-level sexual behaviour mediating variables are added to assess attenuation, and ordered logit models investigate whether the effect is mediated through extramarital sexual partnerships. Both the cluster-level wealth Gini coefficient and wealth ratio significantly predict positive HIV serostatus: a 1 point increase in the cluster-level Gini coefficient and in the cluster-level wealth ratio is associated with a 2.35 and 1.3 times increased likelihood of being HIV positive, respectively, controlling for individual-level demographic predictors, and associations are stronger in models including only males. Adding sexual behaviour variables attenuates the effects of both inequality measures. Reporting eleven plus lifetime sexual partners increases the odds of being HIV positive over five-fold. The likelihood of having more extramarital partners is significantly higher in clusters with greater wealth inequality measured by the wealth ratio. Disaggregating logit models by sex indicates important risk behaviour differences. Household wealth inequality within DHS clusters predicts HIV serostatus, and the relationship is partially mediated by more extramarital partners. These results emphasize the importance of incorporating higher-level contextual factors, investigating behavioural mediators, and disaggregating by sex in assessing HIV risk in order to uncover potential mechanisms of action and points of preventive intervention.

Love, lust and the emotional context of multiple and concurrent sexual partnerships among young Swazi adults

Men and women in Swaziland who are engaged in multiple or concurrent sexual partnerships, or who have sexual partners with concurrent partners, face a very high risk of HIV infection. Ninety-four in-depth interviews were conducted with 28 Swazi men and women (14 of each sex) between the ages of 20 and 39 to explore participants' sexual partnership histories, including motivations for sexual relationships which carried high HIV risk. Concurrency was normative, with most men and women having had at least one concurrent sexual partnership, and all women reporting having had at least one partner who had a concurrent partner. Men distinguished sexual partnerships that were just for sex from those that were considered to be 'real relationships', while women represented most of their relationships, even those which included significant financial support, as being based on love. Besides being motivated by love, concurrent sexual partnerships were described as motivated by a lack of sexual satisfaction, a desire for emotional support and/or as a means to exact revenge against a cheating partner. Social and structural factors were also found to play a role in creating an enabling environment for high-risk sexual partnerships. These factors included social pressure and norms; a lack of social trust; poverty and a desire for material goods; and geographical separation of partners.

Classification of incidence and prevalence of certain sexually transmitted infections by world regions

OBJECTIVES

This study sought to assess if there is a meaningful way in which variations in sexually transmitted infection (STI) prevalence can be classified at the level of world regions.

METHODS

Linear regression was performed to assess if the incidence and prevalence of six STIs (HIV, herpes simplex virus type 2, chlamydia, gonorrhea, syphilis, and trichomoniasis) by world region was positively correlated. Partitioning around medoids (PAM) was then used to assess if the regions of the world can be classified according to the incidence and prevalence of these STIs.

RESULTS

We found evidence that STI incidence/prevalence varies considerably in different regions around the world. Linear regression revealed that the incidence and prevalence of certain STIs by world region was positively correlated (Pearson's correlation coefficient varied from 0.664 to 0.985). PAM provided support for dividing the world regions into two, three, or four STI incidence/prevalence categories, but it provided most support for the two-category system. In each of these systems the East Asia/Pacific and North Africa/Middle East regions were in the lowest STI category and Sub-Saharan Africa was the only region in the high STI category.

CONCLUSIONS

The incidence and prevalence of certain STIs by world region are positively correlated. The world regions can be meaningfully classified according to STI incidence/prevalence.

Strong association between the prevalence of bacterial vaginosis and male point-concurrency

OBJECTIVE

The prevalence of bacterial vaginosis (BV) differs considerably between different populations, and individual-level risk factors such as number of sex partners seem unable to explain these differences. The effect of network-level factors, such as the prevalence of partner concurrency (the proportion of sexual partnerships that overlap in time as opposed to running sequentially) on BV prevalence has not hitherto been investigated.

STUDY DESIGN

We performed linear regression to assess the relationship between the prevalence of male concurrency and prevalence of BV in each of 11 countries for which we could obtain comparable data. The data for concurrency prevalence were taken from the WHO/Global Programme on AIDS (GPA) sexual behavioural surveys. BV prevalence rates were obtained from a systematic review of the global patterning of BV.

RESULTS

We found a strong relationship between the prevalence of male concurrency and BV prevalence (Pearson's R(2)=0.57; P=0.007).

CONCLUSIONS

The findings of a strong ecological-level association between BV and partner concurrency need to be replicated and augmented with different types of studies such as multilevel prospective studies tracking the incidence of BV and associated individual, partner and network level risk factors.