Strengthening HIV surveillance in the antiretroviral therapy era: rationale and design of a longitudinal study to monitor HIV prevalence and incidence in the uMgungundlovu District, KwaZulu-Natal, South Africa

HIV incidence and associated risk factors in adolescent girls and young women in South Africa: A population-based cohort study

BACKGROUND

In sub-Saharan Africa, high HIV incidence rates in adolescent girls and young women (AGYW) persist despite extensive HIV prevention efforts.

METHODS

A prospective cohort of 2,710 HIV-negative AGYW (15-24 years) in KwaZulu-Natal, South Africa were interviewed at baseline and followed-up approximately 18 months later (2014-2017). Associations between HIV seroconversion and socio-demographic and behavioural variables measured at baseline and follow-up were examined using Cox regression and a proximate determinants framework. Inter-relationships between determinants were measured using logistic regression. Separate models were built for 15-19 and 20-24-year-olds.

RESULTS

Weighted HIV incidence was 3.92 per 100 person-years (95% confidence interval: 3.27-4.69; 163 seroconversions over 4,016 person-years). Among 15-19-year-olds, absence of family support (adjusted hazards ratio (aHR): 3.82 (1.89-7.72)), having a circumcised partner (aHR: 0.5 (0.27-0.94)) or one who was HIV-positive and not on antiretroviral therapy (ART) (aHR: 6.21 (2.56-15.06)) were associated with HIV incidence. Those reporting an absence of family support were also more likely to report >1 partner during follow-up (odds ratio (OR): 2.7(1.11-6.57)). Among 20-24-year-olds, failure to complete secondary school (aHR: 1.89 (1.11-3.21)), inconsistent condom use (aHR: 3.01 (1.14-7.96)) and reporting partner(s) who were HIV-positive and not on ART (aHR: 7.75 (3.06-19.66)) were associated with HIV incidence. Failure to complete secondary school among 20-24-year-olds was associated with inconsistent condom use (OR: 1.82 (1.20-2.77)) and reporting an HIV-positive partner not on ART (OR: 3.53(1.59-7.82)) or an uncircumcised partner (OR: 1.39 (1.08-1.82).

CONCLUSION

Absence of family support and incomplete schooling are associated with risky sexual behaviours and HIV acquisition in AGYW. In addition, partner-level prevention-condom use, medical circumcision, and viral suppression-continue to play an important role in reducing HIV risk in AGYW. These findings support the use of combination HIV prevention programs that consider structural as well as biological and behavioural HIV risk factors in their design.

Spatiotemporal Variation and Predictors of Unsuppressed Viral Load among HIV-Positive Men and Women in Rural and Peri-Urban KwaZulu-Natal, South Africa

Unsuppressed HIV viral load is an important marker of sustained HIV transmission. We investigated the prevalence, predictors, and high-risk areas of unsuppressed HIV viral load among HIV-positive men and women. Unsuppressed HIV viral load was defined as viral load of ≥400 copies/mL. Data from the HIV Incidence District Surveillance System (HIPSS), a longitudinal study undertaken between June 2014 to June 2016 among men and women aged 15−49 years in rural and peri-urban KwaZulu-Natal, South Africa, were analysed. A Bayesian geoadditive regression model which includes a spatial effect for a small enumeration area was applied using an integrated nested Laplace approximation (INLA) function while accounting for unobserved factors, non-linear effects of selected continuous variables, and spatial autocorrelation. The prevalence of unsuppressed HIV viral load was 46.1% [95% CI: 44.3−47.8]. Predictors of unsuppressed HIV viral load were incomplete high school education, being away from home for more than a month, alcohol consumption, no prior knowledge of HIV status, not ever tested for HIV, not on antiretroviral therapy (ART), on tuberculosis (TB) medication, having two or more sexual partners in the last 12 months, and having a CD4 cell count of <350 cells/μL. A positive non-linear effect of age, household size, and the number of lifetime HIV tests was identified. The higher-risk pattern of unsuppressed HIV viral load occurred in the northwest and northeast of the study area. Identifying predictors of unsuppressed viral load in a localized geographic area and information from spatial risk maps are important for targeted prevention and treatment programs to reduce the transmission of HIV.

Identifying Potential Factors Associated with High HIV viral load in KwaZulu-Natal, South Africa using Multiple Correspondence Analysis and Random Forest Analysis

Background

Sustainable Human Immunodeficiency Virus (HIV) virological suppression is crucial to achieving the Joint United Nations Programme of HIV/AIDS (UNAIDS) 95–95-95 treatment targets to reduce the risk of onward HIV transmission. Exploratory data analysis is an integral part of statistical analysis which aids variable selection from complex survey data for further confirmatory analysis.

Methods

In this study, we divulge participants’ epidemiological and biological factors with high HIV RNA viral load (HHVL) from an HIV Incidence Provincial Surveillance System (HIPSS) sequential cross-sectional survey between 2014 and 2015 KwaZulu-Natal, South Africa. Using multiple correspondence analysis (MCA) and random forest analysis (RFA), we analyzed the linkage between socio-demographic, behavioral, psycho-social, and biological factors associated with HHVL, defined as ≥400 copies per m/L.

Results

Out of 3956 in 2014 and 3868 in 2015, 50.1% and 41% of participants, respectively, had HHVL. MCA and RFA revealed that knowledge of HIV status, ART use, ARV dosage, current CD4 cell count, perceived risk of contracting HIV, number of lifetime HIV tests, number of lifetime sex partners, and ever diagnosed with TB were consistent potential factors identified to be associated with high HIV viral load in the 2014 and 2015 surveys. Based on MCA findings, diverse categories of variables identified with HHVL were, did not know HIV status, not on ART, on multiple dosages of ARV, with less likely perceived risk of contracting HIV and having two or more lifetime sexual partners.

Conclusion

The high proportion of individuals with HHVL suggests that the UNAIDS 95–95-95 goal of HIV viral suppression is less likely to be achieved. Based on performance and visualization evaluation, MCA was selected as the best and essential exploration tool for identifying and understanding categorical variables’ significant associations and interactions to enhance individual epidemiological understanding of high HIV viral load. When faced with complex survey data and challenges of variables selection in research, exploratory data analysis with robust graphical visualization and reliability that can reveal divers’ structures should be considered.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12874-022-01625-6.

Undisclosed Antiretroviral Therapy Use at Primary Health Care Clinics in Rural KwaZulu Natal South Africa: A DO-ART Trial Sub-study

Accurate reporting of antiretroviral therapy (ART) uptake is crucial for measuring the success of epidemic control. Programs without linked electronic medical records are susceptible to duplicating ART initiation events. We assessed the prevalence of undisclosed ART use at the time of treatment initiation and explored its correlates among people presenting to public ambulatory clinics in South Africa. Data were analyzed from the community-based delivery of ART (DO ART) clinical trial, which recruited people living with HIV who presented for ART initiation at two clinics in rural South Africa. We collected data on socioeconomic factors, clinical factors, and collected blood as part of study screening procedures. We estimated the proportion of individuals presenting for ART initiation with viral load suppression (< 20 copies/mL) and fitted regression models to identify social and clinical correlates of non-disclosure of ART use. We also explored clinical and national databases to identify records of ART use. Finally, to confirm surreptitious ART use, we measured tenofovir (TDF) and emtricitabine (FTC) levels in dried blood spots. A total of 193 people were screened at the two clinics. Approximately 60% (n = 114) were female, 40% (n = 78) reported a prior HIV test, 23% (n = 44) had disclosed to a partner, and 31% (n = 61) had a partner with HIV. We found that 32% (n = 62) of individuals presenting for ART initiation or re-initiation had an undetectable viral load. In multivariable regression models, female sex (AOR 2.16, 95% CI 1.08-4.30), having a prior HIV test and having disclosed their HIV status (AOR 2.48, 95% CI 1.13-5.46), and having a partner with HIV (AOR 1.94, 95% CI 0.95-3.96) were associated with having an undetectable viral load. In records we reviewed, we found evidence of ART use from either clinical or laboratory databases in 68% (42/62) and detected either TDF or FTC in 60% (37/62) of individuals with an undetectable viral load. Undisclosed ART use was present in approximately one in three individuals presenting for ART initiation or re-initiation at ambulatory HIV clinics in South Africa. These results have important implications for ART resource use and planning in the region. A better understanding of reasons for non-disclosure of ART at primary health care clinics in such settings is needed.

Association of medical male circumcision and sexually transmitted infections in a population-based study using targeted maximum likelihood estimation

Background

Epidemiological theory and many empirical studies support the hypothesis that there is a protective effect of male circumcision against some sexually transmitted infections (STIs). However, there is a paucity of randomized control trials (RCTs) to test this hypothesis in the South African population. Due to the infeasibility of conducting RCTs, estimating marginal or average treatment effects with observational data increases interest. Using targeted maximum likelihood estimation (TMLE), a doubly robust estimation technique, we aim to provide evidence of an association between medical male circumcision (MMC) and two STI outcomes.

Methods

HIV and HSV-2 status were the two primary outcomes for this study. We investigated the associations between MMC and these STI outcomes, using cross-sectional data from the HIV Incidence Provincial Surveillance System (HIPSS) study in KwaZulu-Natal, South Africa. HIV antibodies were tested from the blood samples collected in the study. For HSV-2, serum samples were tested for HSV-2 antibodies via an ELISA-based anti-HSV-2 IgG. We estimated marginal prevalence ratios (PR) using TMLE and compared estimates with those from propensity score full matching (PSFM) and inverse probability of treatment weighting (IPTW).

Results

From a total 2850 male participants included in the analytic sample, the overall weighted prevalence of HIV was 32.4% (n = 941) and HSV-2 was 53.2% (n = 1529). TMLE estimates suggest that MMC was associated with 31% lower HIV prevalence (PR: 0.690; 95% CI: 0.614, 0.777) and 21.1% lower HSV-2 prevalence (PR: 0.789; 95% CI: 0.734, 0.848). The propensity score analyses also provided evidence of association of MMC with lower prevalence of HIV and HSV-2. For PSFM: HIV (PR: 0.689; 95% CI: 0.537, 0.885), and HSV-2 (PR: 0.832; 95% CI: 0.709, 0.975). For IPTW: HIV (PR: 0.708; 95% CI: 0.572, 0.875), and HSV-2 (PR: 0.837; 95% CI: 0.738, 0.949).

Conclusion

Using a TMLE approach, we present further evidence of a protective association of MMC against HIV and HSV-2 in this hyper-endemic South African setting. TMLE has the potential to enhance the evidence base for recommendations that embrace the effect of public health interventions on health or disease outcomes.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12889-021-11705-9.

Depression symptoms, HIV testing, linkage to ART, and viral suppression among women in a high HIV burden district in KwaZulu-Natal, South Africa: A cross-sectional household study

Achieving the UNAIDS 90-90-90 targets by 2020 is contingent on identifying and addressing mental health challenges that may affect HIV testing and treatment-related behaviors. This study is based on survey data from KwaZulu-Natal, South Africa (2014–2015). HIV positive women who reported higher depression scores had a lower odds of having tested previously for HIV (15–25 years: AOR = 0.90, 95% CI [0.83, 0.98]; 26–49 years: AOR = 0.90, 95% CI [0.84, 0.96]). Because HIV testing behavior represents a gateway to treatment, the findings suggest mental health may be one challenge to attaining the UNAIDS 90-90-90 targets.

Male partners' influence on women's acceptance and use of PrEP products across two high HIV-burdened districts in South Africa

The demonstrated efficacy of pre-exposure prophylaxis (PrEP) has brought hope of controlling the epidemic among women with limited HIV preventation options. Several studies have demonstrated the importance of male partner involvement in female sexual and reproductive health but there is limited research on male involvement in the adoption of HIV prevention methods among women. Using a culture-centred approach, this article discusses perceptions of female-initiated HIV prevention methods among men and women. The data were collected using eight sex-specific focus group discussions with a sample of men and women aged between 18 and 49 years from selected urban and rural settings in two provinces of South Africa, KwaZulu-Natal and Mpumalanga. Thematic analysis was utilised to identify four key themes: increased infidelity in relationships and risky behaviour; association of PrEP with casual relationships; a partner's right to know that women are reducing their risk of HIV infection; and that men need to engage in decision-making on HIV risk reduction. The article highlights the importance of partner engagement and knowledge sharing of female-initiated prevention methods as part of a combination HIV-prevention strategy, and the urgency of creating enabling environments to utilise female-initiated methods.

Evaluating DREAMS HIV prevention interventions targeting adolescent girls and young women in high HIV prevalence districts in South Africa: protocol for a cross-sectional study

BACKGROUND

Young women in sub-Saharan Africa remain at the epicentre of the HIV epidemic, with surveillance data indicating persistent high levels of HIV incidence. In South Africa, adolescent girls and young women (AGYW) account for a quarter of all new HIV infections. Determined, Resilient, Empowered, AIDS-free, Mentored and Safe (DREAMS) is a strategy introduced by the United States President's Emergency Plan for AIDS Relief (PEPFAR) aimed at reducing HIV incidence among AGYW in 10 countries in sub-Saharan Africa by 25% in the programme's first year, and by 40% in the second year. This study will assess the change in HIV incidence and reduction in risk associated behaviours that can be attributed to the DREAMS initiative in South Africa, using a population-based cross-sectional survey.

METHODS

Data will be collected from a household-based representative sample of AGYW (between the ages 12-24 years) in four high prevalence districts (more than 10% of the population have HIV in these districts) in South Africa in which DREAMS has been implemented. A stratified cluster-based sampling approach will be used to select eligible participants for a cross-sectional survey with 18,500, to be conducted over 2017/2018. A questionnaire will be administered containing questions on sexual risk behaviour, selected academic and developmental milestones, prevalence of gender based violence, whilst examining exposure to DREAMS programmes. Biological samples, including two micro-containers of blood and self-collected vulvovaginal swab samples, are collected in each survey to test for HIV infection, HIV incidence, sexually transmitted infections (STIs) and pregnancy. This study will measure trends in population level HIV incidence using the Limiting antigen (LAg) Avidity Enzyme Immuno-Assay (EIA) and monitor changes in HIV incidence.

DISCUSSION

Ending the HIV/AIDS pandemic by 2030 requires the continual monitoring and evaluation of prevention programmes, with the aim of optimising efforts and ensuring the achievement of epidemic control. This study will determine the impact DREAMS interventions have had on HIV incidence among AGYW in a 'real world, non-trial setting'.

Recently formed age-disparate partnerships are associated with elevated HIV-incidence among young women in South Africa

OBJECTIVE

Cross-sectional and cohort studies draw different conclusions on whether age-disparate partnerships increase HIV-acquisition risk for young women. We investigated whether age-disparities were associated with HIV-infection risk early in relationships. This could result in the exclusion of women who seroconverted during high-risk age-disparate partnerships from cohort studies of HIV incidence - which exclude HIV-positive women - and explain null findings in these studies.

DESIGN

Prospective cohort study.

METHODS

We used data on 15-24-year-old, HIV-negative women in heterosexual partnerships (N = 830) in KwaZulu-Natal, South Africa. The association between age-disparate partnering (i.e., male partner ≥5 years older) and subsequent HIV seroconversion was assessed using Cox hazard models. We examined heterogeneity in HIV-acquisition risk by duration of partnership (defined by quartiles) at cohort enrolment.

RESULTS

During 1139 person-years (mean: 1.4 years) of follow-up, 54 (6.5%) women seroconverted, a weighted HIV-incidence estimate of 4.41/100 person-years [95% confidence interval (CI): 3.30-6.06]. HIV-acquisition risk did not differ significantly between women in age-disparate vs. age-similar partnerships (adjusted hazard ratios: 1.10, 95% CI: 0.55-2.21). However, for women in the shortest partnership quartile (<1.09 years) at baseline, risk of HIV seroconversion was higher for women in age-disparate partnerships (adjusted hazard ratios: 3.13, 95% CI: 1.02-9.65, P = 0.047). HIV acquisition was not statistically different by partnership type among women in longer partnerships.

CONCLUSION

The association between age-disparate partnerships and HIV-acquisition risk is evident early in young women's relationships. Results provide a potential explanation for null findings in cohort studies, whose research designs may exclude women in such partnerships, and affirms the elevated risk of HIV acquisition for young women in age-disparate relationships.

Factors associated with HIV in younger and older adult men in South Africa: findings from a cross-sectional survey

OBJECTIVE

This study investigated the behavioural, psychosocial and biological factors associated with HIV in a younger group of men (15 to 24 years) compared with an older group of men (25 to 35 years).

DESIGN

A household-based, cross-sectional study was conducted.

SETTING

Men were randomly selected using a two-stage random sampling method in KwaZulu-Natal, South Africa, between June 2014 and June 2015.

PARTICIPANTS

Overall, we interviewed 1472 younger men and 1138 older men. Only participants who could speak English or Zulu, were able to provide informed consent and who were expected to be living in the study area for the next 12 months were enrolled into the study.

PRIMARY AND SECONDARY OUTCOMES

HIV status was the primary outcome for the study. Men's HIV status was derived from blood samples collected in the study which were tested for HIV antibodies.

RESULTS

HIV prevalence was higher among older men (35.4%, 95% CI: 31.7 to 39.1) than younger men (7.6%, 95% CI: 6.2 to 9.4, p<0.01). Older men, who completed secondary school had a lower likelihood of being HIV positive (adjusted OR (AOR): 0.41, 95% CI: 0.27 to 0.63, p<0.001) and those with greater food insecurity had a higher likelihood of being HIV positive (AOR: 1.57, 95% CI: 1.05 to 2.34, p=0.04). Younger men with a higher number of lifetime sexual partners had a higher likelihood of being HIV positive (AOR: 1.04, 95% CI: 0.99 to 1.09, p=0.09).

CONCLUSION

Given that the HIV prevalence is higher in the older men, community based interventions need to target older men for medical circumcision and support HIV positive men to improve their material conditions early. For younger men intervening to reduce HIV risk behaviours at a young age before these behaviours become entrenched should be central to HIV prevention programmes.

Trends in HIV Prevention, Treatment, and Incidence in a Hyperendemic Area of KwaZulu-Natal, South Africa

IMPORTANCE

In Africa, the persistently high HIV incidence rate among young women is the major obstacle to achieving the goal of epidemic control.

OBJECTIVE

To determine trends in coverage of HIV prevention and treatment programs and HIV incidence.

DESIGN, SETTING, AND PARTICIPANTS

This cohort study consisted of 2 sequential, community-based longitudinal studies performed in the Vulindlela and Greater Edendale area in KwaZulu-Natal, South Africa. Participants enrolled from June 11, 2014, to June 22, 2015 (2014 survey), with a single follow-up visit from June 24, 2016, to April 3, 2017 (2016 cohort), or enrolled from July 8, 2015, to June 7, 2016 (2015 survey), with a single follow-up visit from November 7, 2016, to August 30, 2017 (2017 cohort). Men and women aged 15 to 49 years were enrolled in the 2014 and 2015 surveys, and HIV-seronegative participants aged 15 to 35 years were followed up in the 2016 and 2017 cohorts. Analysis was conducted from January 1 through December 31, 2018.

EXPOSURES

HIV prevention and treatment programs in a real-world, nontrial setting.

MAIN OUTCOMES AND MEASURES

Trends in sex- and age-specific HIV incidence rates, condom use, voluntary medical male circumcision, knowledge of HIV-seropositive status, uptake of antiretroviral therapy, and viral suppression.

RESULTS

A total of 9812 participants (6265 women [63.9%]; median age, 27 years [interquartile range, 20-36 years]) from 11 289 households were enrolled in the 2014 survey, and 10 236 participants (6341 women [61.9%]; median age, 27 years [interquartile range, 20-36 years]) from 12 247 households were enrolled in the 2015 survey. Of these, 3536 of 4539 (annual retention rate of 86.7%) completed follow-up in the 2016 cohort, and 3907 of 5307 (annual retention rate of 81.4%) completed follow-up in the 2017 cohort. From 2014 to 2015, condom use with last sex partner decreased by 10% from 24.0% (n = 644 of 3547) to 21.6% (n = 728 of 3895; P = .12) in men and by 17% from 19.6% (n = 1039 of 6265) to 16.2% (n = 871 of 6341; P = .002) in women. Voluntary medical male circumcision increased by 13% from 31.9% (1102 of 3547) to 36.1% (n = 1472 of 3895); P = .007) in men, and the proportion of women reporting that their partner was circumcised increased by 35% from 35.7% (n = 1695 of 4766) to 48.2% (n = 2519 of 5207; P < .001). Knowledge of HIV-seropositive status increased by 21% from 51.8% (n = 504 of 3547) to 62.9% (n = 570 of 3895; P < .001) in men and by 14% from 64.6% (n = 1833 of 6265) to 73.4% (n = 2182 of 6341; P < .001) in women. Use of antiretroviral therapy increased by 32% from 36.7% (n = 341 of 3547) to 48.6% (n = 432 of 3895; P < .001) in men and by 29% from 45.6% (n = 1251 of 6265) to 58.8% (n = 1743 of 6341; P < .001) in women; HIV viral suppression increased by 20% from 41.9% (n = 401 of 3547) to 50.3% (n = 456 of 3895; P = .005) in men and by 13% from 54.8% (n = 1547 of 6265) to 61.9% (n = 1828 of 6341; P < .001) in women. Incidence of HIV declined in women aged 15 to 19 years from 4.63 (95% CI, 3.29-6.52) to 2.74 (95% CI, 1.84-4.09) per 100 person-years (P = .04) but declined marginally or remained unchanged among men and women in other age groups.

CONCLUSIONS AND RELEVANCE

This study showed a significant decline in HIV incidence in young women; however, to further reduce HIV incidence, HIV prevention and treatment program coverage must be intensified and scaled up.

Impact of HIV testing and treatment services on risky sexual behaviour in the uMgungundlovu District, KwaZulu-Natal, South Africa: a cross-sectional study

INTRODUCTION

The South African public health system plays an important role in the delivery of HIV testing and treatment services. The health system is also an important conduit for targeted behaviour change communication with the expectation that clients who undergo counselling from health personnel, adopt safer sexual practices. Literature remains mixed on the impact these HIV services have on risky sexual behaviour. This analysis examines the sexual behaviour of clients following the utilisation of HIV testing and treatment services in Kwazulu-Natal, South Africa.

METHODS

Data were used from two consecutive cross-sectional household surveys undertaken from June 2014 to June 2015 (2014/2015 survey) and from July 2015 to June 2016 (2015/2016 survey) in the uMgungundlovu District of KwaZulu-Natal, South Africa. Collectively, 20,048 randomly selected individuals aged 15 to 49 years old were interviewed across the two surveys. Utilisation of HIV testing and treatment services were used as independent variables and three sexual risk behaviours were used as dependent variables. Multiple regression models assessed the impact HIV testing and treatment services had on sexual risk behaviour while controlling for socio-demographic characteristics.

RESULTS

Having tested for HIV had no association with any of the three sexual risk behaviours. However, receiving an HIV positive diagnosis reduced the likelihood of using condoms inconsistently with the respondents' most recent partner (AOR: 0.64; 95% CI 0.54-0.77). Antiretroviral use was negatively associated with inconsistent condom use (AOR: 0.45; 95% CI 0.35-0.58) and number of sexual partners in the previous year (AOR: 0.61; 95% CI 0.46-0.81).

CONCLUSIONS

Results indicate that HIV testing and treatment services and the assumed exposure of clients to behaviour change communication, had a limited effect in reducing risky sexual behaviour. Data suggests that the engagement between health personnel and individuals accessing HIV testing and treatment services does not necessarily translate into the adoption of safer sexual practices, with the exception of individuals testing positive for HIV and those on ARV treatment, who had adopted safer sexual practices.

Seroprevalence of hepatitis B virus: Findings from a population-based household survey in KwaZulu-Natal, South Africa

Background:

Hepatitis B virus (HBV) infection is a major cause of morbidity and mortality; however, little is known about the prevalence and distribution of HBV in some populations and regions.

Methods:

A total of 9791 participants, 15–49 years old, were enrolled in a household survey in KwaZulu-Natal, South Africa. Peripheral blood samples were tested for markers of HBV (hepatitis B surface antigen (HBsAg), hepatitis B e antigen (HBeAg), antibody to HBeAg (anti-HBe)) and analysed, accounting for multilevel sampling and weighted to represent the population.

Results:

Overall HBsAg prevalence was 4.0% (95% confidence interval (CI) 3.4–4.5%): 4.8% (95% CI 3.8–5.8%) in men and 3.2% (95% CI 2.5–3.9%) in women (p = 0.01). Among HBsAg-positive participants, 35.2% (95% CI 29.2–41.2%) were HBeAg-positive and 66.3% (95% CI 60.1–72.4%) were anti-HBe-positive. HBsAg prevalence was 6.4% (95% CI 5.3–7.5%) among HIV-positive participants compared to 2.6% (95% CI 1.9–3.2%) among HIV-negative participants (p < 0.01), and was higher among HIV-positive men (8.7%, 95% CI 6.3–11.2%) than among HIV-positive women (5.0%, 95% CI 3.8–6.2%) (p < 0.01).

Conclusions:

HBV infection among HIV-positive men remains an important public health problem in communities in KwaZulu-Natal, South Africa. The prevalence of HBsAg and HBeAg highlight the importance of surveillance and an important missed opportunity for the scale-up of programmes to achieve the goal of controlling HBV for public health benefit.

Does voluntary medical male circumcision protect against sexually transmitted infections among men and women in real-world scale-up settings? Findings of a household survey in KwaZulu-Natal, South Africa

INTRODUCTION

Male circumcision (MC) confers partial protection to men against HIV and, in research settings, some sexually transmitted infections (STIs). It is also associated with protection from some STIs among female partners. However, real-world data on changes in STI transmission associated with large-scale public African medical male circumcision (MMC) conducted for HIV prevention are lacking and would improve estimates of the health impact of MMC.

METHODS

The HIV Incidence Provincial Surveillance System is a community-based surveillance platform for HIV prevalence, incidence and intervention coverage trends in KwaZulu-Natal province, South Africa. HIPPS collected cross-sectional self-reported data on circumcision status (from men), partner circumcision status for past three partners (from women) and demographic characteristics and behavioural risk factors; and tested participants for HIV, herpes simplex virus type 2 (HSV-2), syphilis, hepatitis B, N eisseria gonorrhoeae, C hlamydia trachomatis, Trichomonas vaginalis and Mycoplasma genitalium. Bivariable and multivariable analyses were performed on associations between own (men) or partner's (women) circumcision status and each STI. Multivariable analyses adjusted for age, demographic characteristics and behavioural risk factors, and incorporated false discovery rate (FDR) correction.

RESULTS

Among men, MMC had a protective association with HSV-2 (OR 0.66, 95% CI 0.50 to 0.86), hepatitis B (OR 0.53, 95% CI 0.30 to 0.95), HIV (OR 0.50, 95% CI 0.38 to 0.65) and M. genitalium (OR 0.53, 95% CI 0.32 to 0.88). Among women, partner circumcision had a protective association with HSV-2 (OR 0.71, 95% CI 0.53 to 0.95) and HIV (OR 0.66, 95% CI 0.49 to 0.90). Associations with HIV and HSV-2 remained significant for men and all women after FDR correction.

CONCLUSION

These real-world data, supporting protective associations between MMC conducted for HIV prevention and STIs in men and women, can help clarify the full impact of MMC and support a role in broader sexual health programming.

Age-disparate partnerships and HSV-2 among adolescent girls and young women in South Africa: implications for HIV infection risk

OBJECTIVE

There is an urgent need to understand high HIV-infection rates among young women in sub-Saharan Africa. While age-disparate partnerships have been characterised with high-risk sexual behaviours, the mechanisms through which these partnerships may increase HIV-risk are not fully understood. This study assessed the association between age-disparate partnerships and herpes simplex virus type-2 (HSV-2) infection, a factor known to increase HIV-infection risk.

METHODS

Cross-sectional face-to-face questionnaire data, and laboratory HSV-2 and HIV antibody data were collected among a representative sample in the 2014/2015 household survey of the HIV Incidence Provincial Surveillance System in KwaZulu-Natal, South Africa. Among 15-24-year-old women who reported having ever had sex (n=1550), the association between age-disparate partnerships (ie, male partner ≥5 years older) and HSV-2 antibody status was assessed using multivariable Poisson regression models with robust variance. Analyses were repeated among HIV-negative women.

RESULTS

HSV-2 prevalence was 55% among 15-24-year-old women. Women who reported an age-disparate partnership with their most recent partner were more likely to test HSV-2 positive compared with women with age-similar partners (64% vs 51%; adjusted prevalence ratio (aPR):1.19 (95% CI 1.07 to 1.32, p<0.01)). HSV-2 prevalence was also significantly higher among HIV-negative women who reported age-disparate partnerships (51% vs 40 %; aPR:1.25 (95% CI 1.05 to 1.50, p=0.014)).

CONCLUSIONS

Results indicate that age-disparate partnerships are associated with a greater risk of HSV-2 among young women. These findings point towards an additional mechanism through which age-disparate partnerships could increase HIV-infection risk. Importantly, by increasing the HSV-2 risk, age-disparate partnerships have the potential to increase the HIV-infection risk within subsequent partnerships, regardless of the partner age-difference in those relationships.

Moderate-to-High Levels of Pretreatment HIV Drug Resistance in KwaZulu-Natal Province, South Africa

There is evidence of increasing levels of pretreatment HIV drug resistance (PDR) in Southern Africa. We used data from two large population-based HIV surveillance studies to estimate prevalence of PDR in KwaZulu-Natal, the province with the highest HIV prevalence in South Africa. Sanger sequencing was performed on samples obtained from a longitudinal HIV surveillance program (study A, 2013-2014) and the HIV Incidence Provincial Surveillance System (study B, 2014-2015). Sequences were included for adult HIV positive participants (age ≥15 years for study A, age 15-49 years for study B) with no documented prior exposure to antiretroviral therapy (ART). Overall and drug class-specific PDR was estimated using the World Health Organization 2009 surveillance drug resistance mutation (SDRM) list, and phylogenetic analysis was performed to establish evidence of drug resistance transmission linkage. A total of 1,845 sequences were analyzed (611 study A; 1,234 study B). An overall PDR prevalence of 9.2% [95% confidence interval (CI) 7.0-11.7] was observed for study A and 11.0% (95% CI 8.9-13.2) for study B. In study B, the prevalence of non-nucleoside reverse-transcriptase inhibitor (NNRTI) PDR exceeded 10% for sequences collected in 2014 (10.2%, 95% CI 7.5-12.9). The most prevalent SDRMs were K103NS (7.5%), M184VI (2.4%), and V106AM (1.4%). There was no evidence of large transmission chains of drug-resistant virus. High level NNRTI PDR (>10%) suggests a need to modify the standard first-line ART regimen and to focus attention on improving the quality of HIV prevention, treatment, and care.

Impact of Home-Based HIV Testing Services on Progress Toward the UNAIDS 90-90-90 Targets in a Hyperendemic Area of South Africa

BACKGROUND

In several subgroups of South Africa, the percentage of HIV-positive individuals aware of their status falls well below the UNAIDS 90% target. This study examined the impact that home-based HIV testing services (HBHTS) had on knowledge of status in a hyperendemic area of South Africa.

METHODS

We analysed data from the second cross-sectional HIV Incidence Provincial Surveillance System survey (2015/2016), a representative sample (n = 10,236) of individuals aged 15-49 years. Participants completed a questionnaire, provided blood samples for laboratory testing (used to estimate HIV prevalence), and were offered HBHTS. The proportion of people living with HIV (n = 3870) made aware of their status through HBHTS was measured, and factors associated with HBHTS uptake were identified.

RESULTS

Knowledge of HIV-positive status at the time of the survey was 62.9% among men and 73.4% among women. Through HBHTS, the percentage of HIV-positive men and women who knew their status rose to 74.2% and 80.5%, respectively. The largest impact was observed among youth (15-24 years). Knowledge of status increased from 36.6% to 59.3% and from 50.8% to 64.8% among young men and women, respectively. In addition, 51.4% of those who had previously never tested received their first test. Key reasons for declining HBHTS among undiagnosed HIV-positive individuals included fear and self-report of an HIV-negative status.

CONCLUSIONS

HBHTS was effective in increasing awareness of HIV-positive status, particularly among youth, men, and those who had never tested. HBHTS could have a marked impact on progress toward the UNAIDS 90-90-90 targets within these subgroups.

Community-based HIV prevalence in KwaZulu-Natal, South Africa: results of a cross-sectional household survey

BACKGROUND

In high HIV burden settings, maximising the coverage of prevention strategies is crucial to achieving epidemic control. However, little is known about the reach and effect of these strategies in some communities.

METHODS

We did a cross-sectional community survey in the adjacent Greater Edendale and Vulindlela areas in the uMgungundlovu district, KwaZulu-Natal, South Africa. Using a multistage cluster sampling method, we randomly selected enumeration areas, households, and individuals. One household member (aged 15-49 years) selected at random was invited for survey participation. After obtaining consent, questionnaires were administered to obtain sociodemographic, psychosocial, and behavioural information, and exposure to HIV prevention and treatment programmes. Clinical samples were collected for laboratory measurements. Statistical analyses were done accounting for multilevel sampling and weighted to represent the population. A multivariable logistic regression model assessed factors associated with HIV infection.

FINDINGS

Between June 11, 2014, and June 22, 2015, we enrolled 9812 individuals. The population-weighted HIV prevalence was 36·3% (95% CI 34·8-37·8, 3969 of 9812); 44·1% (42·3-45·9, 2955 of 6265) in women and 28·0% (25·9-30·1, 1014 of 3547) in men (p<0·0001). HIV prevalence in women aged 15-24 years was 22·3% (20·2-24·4, 567 of 2224) compared with 7·6% (6·0-9·3, 124 of 1472; p<0·0001) in men of the same age. Prevalence peaked at 66·4% (61·7-71·2, 517 of 760) in women aged 35-39 years and 59·6% (53·0-66·3, 183 of 320) in men aged 40-44 years. Consistent condom use in the last 12 months was 26·5% (24·1-28·8, 593 of 2356) in men and 22·7% (20·9-24·4, 994 of 4350) in women (p=0·0033); 35·7% (33·4-37·9, 1695 of 5447) of women's male partners and 31·9% (29·5-34·3, 1102 of 3547) of men were medically circumcised (p<0·0001), and 45·6% (42·9-48·2, 1251 of 2955) of women and 36·7% (32·3-41·2, 341 of 1014) of men reported antiretroviral therapy (ART) use (p=0·0003). HIV viral suppression was achieved in 54·8% (52·0-57·5, 1574 of 2955) of women and 41·9% (37·1-46·7, 401 of 1014) of men (p<0·0001), and 87·2% (84·6-89·8, 1086 of 1251) of women and 83·9% (78·5-89·3, 284 of 341; p=0·3670) of men on ART. Age, incomplete secondary schooling, being single, having more than one lifetime sex partner (women), sexually transmitted infections, and not being medically circumcised were associated with HIV-positive status.

INTERPRETATION

The HIV burden in specific age groups, the suboptimal differential coverage, and uptake of HIV prevention strategies justifies a location-based approach to surveillance with finer disaggregation by age and sex. Intensified and customised approaches to seek, identify, and link individuals to HIV services are crucial to achieving epidemic control in this community.

FUNDING

The President's Emergency Plan for AIDS Relief through the Centers for Disease Control and Prevention.

Tracking external introductions of HIV using phylodynamics reveals a major source of infections in rural KwaZulu-Natal, South Africa

Despite increasing access to antiretrovirals, HIV incidence in rural KwaZulu-Natal remains among the highest ever reported in Africa. While many epidemiological factors have been invoked to explain such high incidence, widespread human mobility and viral movement suggest that transmission between communities may be a major source of new infections. High cross-community transmission rates call into question how effective increasing the coverage of antiretroviral therapy locally will be at preventing new infections, especially if many new cases arise from external introductions. To help address this question, we use a phylodynamic model to reconstruct epidemic dynamics and estimate the relative contribution of local transmission versus external introductions to overall incidence in KwaZulu-Natal from HIV-1 phylogenies. By comparing our results with population-based surveillance data, we show that we can reliably estimate incidence from viral phylogenies once viral movement in and out of the local population is accounted for. Our analysis reveals that early epidemic dynamics were largely driven by external introductions. More recently, we estimate that 35 per cent (95% confidence interval: 20-60%) of new infections arise from external introductions. These results highlight the growing need to consider larger-scale regional transmission dynamics when designing and testing prevention strategies.

HIV Risk Among Adolescent Girls and Young Women in Age-Disparate Partnerships: Evidence From KwaZulu-Natal, South Africa

BACKGROUND

Evidence on the role of age-disparate partnerships in high HIV-infection rates among young women in sub-Saharan Africa remains inconclusive. This study examined the HIV-infection risk associated with age-disparate partnerships among 15- to 24-year-old women in a hyperendemic setting in South Africa.

METHODS

Face-to-face questionnaire, and laboratory HIV and viral load data were collected during 2014-2015 among a representative sample (15-49 years old) in KwaZulu-Natal. The association between age-disparate partnerships (age difference ≥5 years) and HIV status among 15- to 24-year-old women (N = 1459) was assessed using multiple logistic regression analyses. Data from the male sample on all on-going partnerships (N = 1229) involving 15- to 24-year-old women were used to assess whether young women's age-disparate male partners were more likely to have a viral load ≥1000 copies per milliliter, a marker of HIV-infection risk.

RESULTS

Women reporting an age disparity in any of their 3 most recent partnerships were more likely to test HIV positive compared to women with only age-similar partners [adjusted odds ratio (aOR): 1.58, 95% confidence interval (CI): 1.20 to 2.09, P < 0.01]. Among partnerships men reported with 15- to 24-year-old women, the age-disparate male partners were more likely to be HIV positive and have a viral load ≥1000 copies per milliliter (aOR: 2.05, 95% CI: 1.30 to 3.24, P < 0.01) compared with age-similar partners. Results were similar for each category of age disparity: partners 5-9 years older (aOR: 2.01, 95% CI: 1.18 to 3.43, P = 0.010) and those ≥10 years older (aOR: 2.17, 95% CI: 1.01-4.66, P = 0.048).

CONCLUSIONS

Results indicate that age-disparate partnerships increase young women's HIV risk, although conclusive evidence was not ascertained. Interventions addressing risk from age-disparate sexual partnering, including expanding antiretroviral treatment among older partners, may help to reduce HIV incidence among young women.

Misdiagnosis of HIV infection during a South African community-based survey: implications for rapid HIV testing

Introduction: We describe the overall accuracy and performance of a serial rapid HIV testing algorithm used in community-based HIV testing in the context of a population-based household survey conducted in two sub-districts of uMgungundlovu district, KwaZulu-Natal, South Africa, against reference fourth-generation HIV-1/2 antibody and p24 antigen combination immunoassays. We discuss implications of the findings on rapid HIV testing programmes.

Methods: Cross-sectional design: Following enrolment into the survey, questionnaires were administered to eligible and consenting participants in order to obtain demographic and HIV-related data. Peripheral blood samples were collected for HIV-related testing. Participants were offered community-based HIV testing in the home by trained field workers using a serial algorithm with two rapid diagnostic tests (RDTs) in series. In the laboratory, reference HIV testing was conducted using two fourth-generation immunoassays with all positives in the confirmatory test considered true positives. Accuracy, sensitivity, specificity, positive predictive value, negative predictive value and false-positive and false-negative rates were determined.

Results: Of 10,236 individuals enrolled in the survey, 3740 were tested in the home (median age 24 years (interquartile range 19–31 years), 42.1% males and HIV positivity on RDT algorithm 8.0%). From those tested, 3729 (99.7%) had a definitive RDT result as well as a laboratory immunoassay result. The overall accuracy of the RDT when compared to the fourth-generation immunoassays was 98.8% (95% confidence interval (CI) 98.5–99.2). The sensitivity, specificity, positive predictive value and negative predictive value were 91.1% (95% CI 87.5–93.7), 99.9% (95% CI 99.8–100), 99.3% (95% CI 97.4–99.8) and 99.1% (95% CI 98.8–99.4) respectively. The false-positive and false-negative rates were 0.06% (95% CI 0.01–0.24) and 8.9% (95% CI 6.3–12.53). Compared to true positives, false negatives were more likely to be recently infected on limited antigen avidity assay and to report antiretroviral therapy (ART) use.

Conclusions: The overall accuracy of the RDT algorithm was high. However, there were few false positives, and the sensitivity was lower than expected with high false negatives, despite implementation of quality assurance measures. False negatives were associated with recent (early) infection and ART exposure. The RDT algorithm was able to correctly identify the majority of HIV infections in community-based HIV testing. Messaging on the potential for false positives and false negatives should be included in these programmes.

Validation of the child and youth resilience measure among South African adolescents

Resilience is a dynamic, interactive process between resources that contribute to safeguarding a person and the adversities they experience. Within this promotional framework of resilience, this study sought to validate the Child and Youth Resilience Measure (CYRM-28) among a sample of South African adolescents (N = 1854). Confirmatory factor analysis supported a superior level of fit for a 24-item, three-factor model (i.e., individual/social, familial, and community/spiritual). Internal consistency and test-retest reliability estimates at a 12-month interval (N = 648) supported the reliability of the scales. Higher scores on the scales were associated with feeling more connected at school, greater parental monitoring perceptions, and lower sexual risk, confirming the convergent and criterion validity of the instrument. Partial discriminative power was evidenced based on selected scale distinctions according to age and sex groupings. Collectively, the findings suggest the 24-item CYRM is a valid and reliable self-report measure to assess the availability of resources associated with resilience in South African youth.

Detection and treatment of Fiebig stage I HIV-1 infection in young at-risk women in South Africa: a prospective cohort study

BACKGROUND

HIV incidence among young women in sub-Saharan Africa remains high and their inclusion in vaccine and cure efforts is crucial. We aimed to establish a cohort of young women detected during Fiebig stage I acute HIV infection in whom treatment was initiated immediately after diagnosis to advance research in this high-risk group.

METHODS

945 women aged 18-23 years in KwaZulu-Natal, South Africa, who were HIV uninfected and sexually active consented to HIV-1 RNA testing twice a week and biological sampling and risk assessment every 3 months during participation in a 48-96 week life-skills and job-readiness programme. We analysed the effect of immediate combination antiretroviral therapy (ART) on viraemia and immune responses, sexual risk behaviour, and the effect of the socioeconomic intervention.

FINDINGS

42 women were diagnosed with acute HIV infection between Dec 1, 2012, and June 30, 2016, (incidence 8·2 per 100 person-years, 95% CI 5·9-11·1), of whom 36 (86%) were diagnosed in Fiebig stage I infection with a median initial viral load of 2·97 log₁₀ copies per mL (IQR 2·42-3·85). 23 of these 36 women started ART at a median of 1 day (1-1) after detection, which limited the median peak viral load to 4·22 log₁₀ copies per mL (3·27-4·83) and the CD4 nadir to 685 cells per μL (561-802). ART also suppressed viral load (to <20 copies per mL) within a median of 16 days (12-26) and, in 20 (87%) of 23 women, prevented seroconversion, as shown with western blotting. 385 women completed the 48 week socioeconomic intervention, of whom 231 were followed up for 1 year. 202 (87%) of these 231 women were placed in jobs, returned to school, or started a business.

INTERPRETATION

Frequent HIV screening combined with a socioeconomic intervention facilitated sampling and risk assessment before and after infection. In addition to detection of acute infection and immediate treatment, we established a cohort optimised for prevention and cure research.

FUNDING

Bill & Melinda Gates Foundation, National Institute of Allergy and Infectious Diseases, International AIDS Vaccine Initiative, Wellcome Trust, Howard Hughes Medical Institute.

Uptake of health services among truck drivers in South Africa: analysis of routine data from nine roadside wellness centres

BACKGROUND

Long-distance truck drivers are occupationally susceptible to poor health outcomes. Their patterns of healthcare utilisation and the suitability of healthcare services available to them are not well documented. We report on truck driver healthcare utilisation across South Africa and characterise the client population of the clinics serving them for future service development.

METHODS

We analysed anonymised data routinely collected over a two-year period at nine Roadside Wellness Centres. Associations between services accessed and socio-demographic characteristics were assessed using univariable and multivariable logistic regression models.

RESULTS

We recorded 16,688 visits by 13,252 individual truck drivers (average of 1.26 visits/person) who accessed 17,885 services for an average of 1.07 services/visit and 1.35 services/person. The mean age of truck drivers was 39 years. Sixty-seven percent reported being in stable relationships. The most accessed services were primary healthcare (PHC)(62%) followed by HIV (32%). Low proportions (≤6%) accessed STI,TB and malaria services. Most visits were characterised by only one service being accessed (93%, n = 15,523/16,688). Of the remaining 7% of visits, up to five services were accessed per visit and the combination of TB /HIV services in one visit remained extremely low (<1%, n = 14/16,688). Besides PHC services at the beginning of the reporting period, all service categories displayed similar seasonal utilisation trends(i.e. service utilisation peaked in the immediate few months post clinics opening and substantially decreased before holidays). Across all service categories, younger truck drivers, those with a stable partner currently, and those of South African origin were the main clinic attendees. Older truck drivers (≥40 years) were more likely to access TB and PHC services, yet less likely to access HIV and STI services. Those with stable partners were less likely to access STI and TB services but more likely to access malaria and PHC services. South African attendees were more likely to access PHC, while attendees from other nationalities were more likely to access HIV and malaria services.

CONCLUSIONS

This utilisation analysis shows that tailored services assist in alleviating healthcare access challenges faced by truck drivers, but it underscores the importance of ensuring that service packages and clinics speak to truck drivers' needs in terms of services offered and clinic location.

Progress of UNAIDS 90-90-90 targets in a district in KwaZulu-Natal, South Africa, with high HIV burden, in the HIPSS study: a household-based complex multilevel community survey

BACKGROUND

With the goal of eliminating new HIV infections, UNAIDS set the ambitious 90-90-90 targets to be achieved by 2020. We assessed whether these targets are being met among participants of the HIV Incidence Provincial Surveillance System (HIPSS) in a high-burden district of South Africa.

METHODS

We used data from a HIPSS household-based, cross-sectional survey of HIV prevalence and incidence done in the uMgungundlovu district, KwaZulu-Natal, in 2014 and 2015. In randomly selected enumeration areas, 50 households were drawn systematically along a serpentine pattern from a random start point. One eligible individual in each household was asked to provide blood for HIV testing and to complete a questionnaire. If a household refused to participate, the house next to it was approached. Eligible participants were aged 15-49 years, lived in the household, were not planning to move away, and spoke English or Zulu. Viral load was measured in samples positive for HIV. We also assessed participants' HIV linkage to care and treatment. Data were population weighted to allow for multilevel sampling and non-response.

FINDINGS

9812 participants were enrolled, 3547 men (36%) and 6265 women (64%). Overall, 504 of 1014 men (estimate 52%, 95% CI 47-56) and 1833 of 2955 women (65%, 62-67) who were HIV positive knew their HIV status. Of those who knew, 344 of 522 men (69%, 63-75) and 1254 of 1845 women (70%, 68-73) were taking ART. Among recipients of ART, 294 of 341 men (85%, 80-90) and 1117 of 1249 women (90%, 87-92) had viral loads less than 1000 copies per mL. Among all HIV-positive participants, 427 of 1014 men (44%, 39-49) and 1680 of 2955 women (58%, 55-61) had viral loads lower than 1000 copies per mL.

INTERPRETATION

No UNAIDS 90-90-90 targets had been met in our study population. Major campaigns are needed to increase HIV testing, especially among men, and to ensure all HIV-positive patients are taking ART.

FUNDING

Centers for Disease Control and Prevention and the US Presidents Emergency Plan for AIDS Relief (PEPFAR).

Transmission networks and risk of HIV infection in KwaZulu-Natal, South Africa: a community-wide phylogenetic study

BACKGROUND

The incidence of HIV infection in young women in Africa is very high. We did a large-scale community-wide phylogenetic study to examine the underlying HIV transmission dynamics and the source and consequences of high rates of HIV infection in young women in South Africa.

METHODS

We did a cross-sectional household survey of randomly selected individuals aged 15-49 years in two neighbouring subdistricts (one urban and one rural) with a high burden of HIV infection in KwaZulu-Natal, South Africa. Participants completed structured questionnaires that captured general demographic, socioeconomic, psychosocial, and behavioural data. Peripheral blood samples were obtained for HIV antibody testing. Samples with HIV RNA viral load greater than 1000 copies per mL were selected for genotyping. We constructed a phylogenetic tree to identify clusters of linked infections (defined as two or more sequences with bootstrap or posterior support ≥90% and genetic distance ≤4·5%).

FINDINGS

From June 11, 2014, to June 22, 2015, we enrolled 9812 participants, 3969 of whom tested HIV positive. HIV prevalence (weighted) was 59·8% in 2835 women aged 25-40 years, 40·3% in 1548 men aged 25-40 years, 22·3% in 2224 women younger than 25 years, and 7·6% in 1472 men younger than 25 years. HIV genotyping was done in 1589 individuals with a viral load of more than 1000 copies per mL. In 90 transmission clusters, 123 women were linked to 103 men. Of 60 possible phylogenetically linked pairings with the 43 women younger than 25 years, 18 (30·0%) probable male partners were younger than 25 years, 37 (61·7%) were aged 25-40 years, and five (8·3%) were aged 41-49 years: mean age difference 8·7 years (95% CI 6·8-10·6; p<0·0001). For the 92 possible phylogenetically linked pairings with the 56 women aged 25-40 years, the age difference dropped to 1·1 years (95% CI -0·6 to 2·8; p=0·111). 16 (39·0%) of 41 probable male partners linked to women younger than 25 years were also linked to women aged 25-40 years. Of 79 men (mean age 31·5 years) linked to women younger than 40 years, 62 (78·5%) were unaware of their HIV-positive status, 76 (96·2%) were not on antiretroviral therapy, and 29 (36·7%) had viral loads of more than 50 000 copies per mL.

INTERPRETATION

Sexual partnering between young women and older men, who might have acquired HIV from women of similar age, is a key feature of the sexual networks driving transmission. Expansion of treatment and combination prevention strategies that include interventions to address age-disparate sexual partnering is crucial to reducing HIV incidence and enabling Africa to reach the goal of ending AIDS as a public health threat.

FUNDING

President's Emergency Program for AIDS Relief, US Centers for Disease Control and Prevention, South African Medical Research Council, and MAC AIDS Fund.