Using data from 'visible' populations to estimate the size and importance of 'hidden' populations in an epidemic: A modelling technique.

We used reported behavioural data from cisgender men who have sex with men and transgender women (MSM/TGW) in Bangalore, mainly collected from 'hot-spot' locations that attract MSM/TGW, to illustrate a technique to deal with potential issues with the representativeness of this sample. A deterministic dynamic model of HIV transmission was developed, incorporating three subgroups of MSM/TGW, grouped according to their reported predominant sexual role (insertive, receptive or versatile). Using mathematical modelling and data triangulation for 'balancing' numbers of partners and role preferences, we compared three different approaches to determine if our technique could be useful for inferring characteristics of a more 'hidden' insertive MSM subpopulation, and explored their potential importance for the HIV epidemic. Projections for 2009 across all three approaches suggest that HIV prevalence among insertive MSM was likely to be less than half that recorded in the surveys (4.5-6.5% versus 13.1%), but that the relative size of this subgroup was over four times larger (61-69% of all MSM/TGW versus 15%). We infer that the insertive MSM accounted for 10-20% of all prevalent HIV infections among urban males aged 15-49. Mathematical modelling can be used with data on 'visible' MSM/TGW to provide insights into the characteristics of 'hidden' MSM. A greater understanding of the sexual behaviour of all MSM/TGW is important for effective HIV programming. More broadly, a hidden subgroup with a lower infectious disease prevalence than more visible subgroups, has the potential to contain more infections, if the hidden subgroup is considerably larger in size.

Factors Associated with Variations in Population HIV Prevalence across West Africa: Findings from an Ecological Analysis.

BACKGROUND: Population HIV prevalence across West Africa varies substantially. We assess the national epidemiological and behavioural factors associated with this. METHODS: National, urban and rural data on HIV prevalence, the percentage of younger (15-24) and older (25-49) women and men reporting multiple (2+) partners in the past year, HIV prevalence among female sex workers (FSWs), men who have bought sex in the past year (clients), and ART coverage, were compiled for 13 countries. An Ecological analysis using linear regression assessed which factors are associated with national variations in population female and male HIV prevalence, and with each other. FINDINGS: National population HIV prevalence varies between 0 4-2 9% for men and 0 4-5.6% for women. ART coverage ranges from 6-23%. National variations in HIV prevalence are not shown to be associated with variations in HIV prevalence among FSWs or clients. Instead they are associated with variations in the percentage of younger and older males and females reporting multiple partners. HIV prevalence is weakly negatively associated with ART coverage, implying it is not increased survival that is the cause of variations in HIV prevalence. FSWs and younger female HIV prevalence are associated with client population sizes, especially older men. Younger female HIV prevalence is strongly associated with older male and female HIV prevalence. INTERPRETATION: In West Africa, population HIV prevalence is not significantly higher in countries with high FSW HIV prevalence. Our analysis suggests, higher prevalence occurs where more men buy sex, and where a higher percentage of younger women, and older men and women have multiple partnerships. If a sexual network between clients and young females exists, clients may potentially bridge infection to younger females. HIV prevention should focus both on commercial sex and transmission between clients and younger females with multiple partners.

Declines in violence and police arrest among female sex workers in Karnataka state, south India, following a comprehensive HIV prevention programme.

INTRODUCTION: Female sex workers (FSWs) frequently experience violence, harassment and arrest by the police or their clients, but there is little evidence as to the impact that such factors may have on HIV risk or whether community interventions could mitigate this impact. METHODS: As part of the evaluation of the Avahan programme in Karnataka, serial integrated behavioural and biological assessment (IBBA) surveys (four districts) (2005 to 2011) and anonymous polling booth surveys (PBS) (16 districts) (2007 to 2011) were conducted with random samples of FSWs. Logistic regression analysis was used to assess 1) changes in reported violence and arrests over time and 2) associations between violence by non-partners and police arrest and HIV/STI risk and prevalence. Mediation analysis was used to identify mediating factors. RESULTS: 5,792 FSWs participated in the IBBAs and 15,813 participated in the PBS. Over time, there were significant reductions in the percentages of FSWs reporting being raped in the past year (PBS) (30.0% in 2007, 10.0% in 2011, p<0.001), being arrested in the past year [adjusted odds ratio (AOR) 0.57 (0.35, 0.93), p=0.025] and being beaten in the past six months by a non-partner (clients, police, pimps, strangers, rowdies) [AOR 0.69 (0.49, 0.95), p=0.024)] (IBBA). The proportion drinking alcohol (during the past week) also fell significantly (32.5% in 2005, 24.9% in 2008, 16.8% in 2011; p<0.001). Violence by non-partners (being raped in the past year and/or beaten in the past six months) and being arrested in the past year were both strongly associated with HIV infection [AOR 1.59 (1.18, 2.15), p=0.002; AOR 1.91 (1.17, 3.12), p=0.01, respectively]. They were also associated with drinking alcohol (during the past week) [AOR 1.98 (1.54, 2.53), p<0.001; AOR 2.79 (1.93, 4.04), p<0.001, respectively], reduced condom self-efficacy with clients [AOR 0.36 (0.27, 0.47), p<0.001; AOR 0.62 (0.39, 0.98), p=0.039, respectively], symptomatic STI (during the past year) [AOR 2.62 (2.07, 3.30), p<0.001; AOR 2.17 (1.51, 3.13), p<0.001, respectively], gonorrhoea infection [AOR 2.79 (1.51, 5.15), p=0.001; AOR 2.69 (0.96, 7.56), p=0.060, respectively] and syphilis infection [AOR 1.86 (1.04, 3.31), p=0.036; AOR 3.35 (1.78, 6.28), p<0.001, respectively], but not with exposure to peer education, community mobilization or HIV testing uptake. Mediation analysis suggests that alcohol use and STIs may partially mediate the association between violence or arrests and HIV prevalence. DISCUSSION: Violence by non-partners and arrest are both strongly associated with HIV infection among FSWs. Large-scale, comprehensive HIV prevention programming can reduce violence, arrests and HIV/STI infection among FSWs.

Childhood sexual abuse and suicidal behavior: a meta-analysis.

BACKGROUND AND OBJECTIVE: Self-inflicted injuries are one of the major causes of disease burden and death globally. Understanding the extent to which this is associated with childhood sexual abuse (CSA) exposure can help inform prevention strategies. We aimed to quantify to what extent CSA was associated with incident suicide attempts in men and women. METHODS: We searched 20 health and social science databases from first record until February 2009 and updated the search in Medline from February 2009 to February 1, 2013. Longitudinal studies and cotwin analyses from twin studies in any population from any year were eligible for inclusion. Of 22 235 abstracts screened as part of a series of reviews, 9 studies met the inclusion criteria for this review. Characteristics, effect estimates, and quality data were extracted. Random-effects meta-analysis was used to generate pooled odds ratios (ORs). RESULTS: Seven longitudinal and 2 twin studies with 8733 participants met the inclusion criteria. The overall pooled estimate for longitudinal studies was OR = 2.43 (95% confidence interval: 1.94-3.05), I(2) = 87.5%, P < .0001. The pooled OR from cotwin analysis was 2.65 (95% confidence interval: 0.82-4.49, I(2) = 0%, P = .867). Studies adjusted for a range of confounders, but baseline suicidal behavior was not well-controlled. Too few studies met the inclusion criteria to quantitatively examine sources of heterogeneity. CONCLUSIONS: CSA exposure is associated with suicide attempts when a range of different confounders are controlled for, but the temporality of the association is not well established, and the association is highly heterogeneous.

Cost-effectiveness of tenofovir gel in urban South Africa: model projections of HIV impact and threshold product prices.

BACKGROUND: There is urgent need for effective HIV prevention methods that women can initiate. The CAPRISA 004 trial showed that a tenofovir-based vaginal microbicide had significant impact on HIV incidence among women. This study uses the trial findings to estimate the population-level impact of the gel on HIV and HSV-2 transmission, and price thresholds at which widespread product introduction would be as cost-effective as male circumcision in urban South Africa. METHODS: The estimated 'per sex-act' HIV and HSV-2 efficacies were imputed from CAPRISA 004. A dynamic HIV/STI transmission model, parameterised and fitted to Gauteng (HIV prevalence of 16.9% in 2008), South Africa, was used to estimate the impact of gel use over 15 years. Uptake was assumed to increase linearly to 30% over 10 years, with gel use in 72% of sex-acts. Full economic programme and averted HIV treatment costs were modelled. Cost per DALY averted is estimated and a microbicide price that equalises its cost-effectiveness to that of male circumcision is estimated. RESULTS: Using plausible assumptions about product introduction, we predict that tenofovir gel use could lead to a 12.5% and 4.9% reduction in HIV and HSV-2 incidence respectively, by year 15. Microbicide introduction is predicted to be highly cost-effective (under $300 per DALY averted), though the dose price would need to be just $0.12 to be equally cost-effective as male circumcision. A single dose or highly effective (83% HIV efficacy per sex-act) regimen would allow for more realistic threshold prices ($0.25 and $0.33 per dose, respectively). CONCLUSIONS: These findings show that an effective coitally-dependent microbicide could reduce HIV incidence by 12.5% in this setting, if current condom use is maintained. For microbicides to be in the range of the most cost-effective HIV prevention interventions, product costs will need to decrease substantially.

Can the UNAIDS modes of transmission model be improved? A comparison of the original and revised model projections using data from a setting in west Africa.

OBJECTIVE: The UNAIDS modes of transmission model (MoT) is a user-friendly model, developed to predict the distribution of new HIV infections among different subgroups. The model has been used in 29 countries to guide interventions. However, there is the risk that the simplifications inherent in the MoT produce misleading findings. Using input data from Nigeria, we compare projections from the MoT with those from a revised model that incorporates additional heterogeneity. METHODS: We revised the MoT to explicitly incorporate brothel and street-based sex-work, transactional sex, and HIV-discordant couples. Both models were parameterized using behavioural and epidemiological data from Cross River State, Nigeria. Model projections were compared, and the robustness of the revised model projections to different model assumptions, was investigated. RESULTS: The original MoT predicts 21% of new infections occur in most-at-risk-populations (MARPs), compared with 45% (40-75%, 95% Crl) once additional heterogeneity and updated parameterization is incorporated. Discordant couples, a subgroup previously not explicitly modelled, are predicted to contribute a third of new HIV infections. In addition, the new findings suggest that women engaging in transactional sex may be an important but previously less recognized risk group, with 16% of infections occurring in this subgroup. CONCLUSION: The MoT is an accessible model that can inform intervention priorities. However, the current model may be potentially misleading, with our comparisons in Nigeria suggesting that the model lacks resolution, making it challenging for the user to correctly interpret the nature of the epidemic. Our findings highlight the need for a formal review of the MoT.

Intimate partner violence and incident depressive symptoms and suicide attempts: a systematic review of longitudinal studies.

BACKGROUND: Depression and suicide are responsible for a substantial burden of disease globally. Evidence suggests that intimate partner violence (IPV) experience is associated with increased risk of depression, but also that people with mental disorders are at increased risk of violence. We aimed to investigate the extent to which IPV experience is associated with incident depression and suicide attempts, and vice versa, in both women and men. METHODS AND FINDINGS: We conducted a systematic review and meta-analysis of longitudinal studies published before February 1, 2013. More than 22,000 records from 20 databases were searched for studies examining physical and/or sexual intimate partner or dating violence and symptoms of depression, diagnosed major depressive disorder, dysthymia, mild depression, or suicide attempts. Random effects meta-analyses were used to generate pooled odds ratios (ORs). Sixteen studies with 36,163 participants met our inclusion criteria. All studies included female participants; four studies also included male participants. Few controlled for key potential confounders other than demographics. All but one depression study measured only depressive symptoms. For women, there was clear evidence of an association between IPV and incident depressive symptoms, with 12 of 13 studies showing a positive direction of association and 11 reaching statistical significance; pooled OR from six studies = 1.97 (95% CI 1.56-2.48, I²  =  50.4%, p(heterogeneity = 0.073). There was also evidence of an association in the reverse direction between depressive symptoms and incident IPV (pooled OR from four studies = 1.93, 95% CI 1.51-2.48, I²  =  0%, p = 0.481). IPV was also associated with incident suicide attempts. For men, evidence suggested that IPV was associated with incident depressive symptoms, but there was no clear evidence of an association between IPV and suicide attempts or depression and incident IPV. CONCLUSIONS: In women, IPV was associated with incident depressive symptoms, and depressive symptoms with incident IPV. IPV was associated with incident suicide attempts. In men, few studies were conducted, but evidence suggested IPV was associated with incident depressive symptoms. There was no clear evidence of association with suicide attempts.

Addressing the structural drivers of HIV: a luxury or necessity for programmes?

The social, economic, political and environmental structural factors that increase susceptibility to HIV infection and undermine prevention and treatment efforts continue to pose a challenge. The papers in this series highlight the importance of sustaining those efforts to address the structural drivers of the HIV epidemic, and that initiatives to achieve HIV elimination will only come about through a comprehensive HIV response, that includes meaningful responses to the social, political, economic and environmental factors that affect HIV risk and vulnerability. In the context of declining resources for HIV/AIDS, the papers speak to the need to integrate responses to the structural drivers of HIV/AIDS into future HIV investments, with both initiatives to integrate HIV into broader gender and development initiatives, as well as adaptations of current service models, to ensure that they are sensitive to and able to respond to the broader economic and social responsibilities that their clients face.

What factors are associated with recent intimate partner violence? findings from the WHO multi-country study on women's health and domestic violence.

BACKGROUND: Intimate partner violence (IPV) against women is a global public health and human rights concern. Despite a growing body of research into risk factors for IPV, methodological differences limit the extent to which comparisons can be made between studies. We used data from ten countries included in the WHO Multi-country Study on Women's Health and Domestic Violence to identify factors that are consistently associated with abuse across sites, in order to inform the design of IPV prevention programs. METHODS: Standardised population-based household surveys were done between 2000 and 2003. One woman aged 15-49 years was randomly selected from each sampled household. Those who had ever had a male partner were asked about their experiences of physically and sexually violent acts. We performed multivariate logistic regression to identify predictors of physical and/or sexual partner violence within the past 12 months. RESULTS: Despite wide variations in the prevalence of IPV, many factors affected IPV risk similarly across sites. Secondary education, high SES, and formal marriage offered protection, while alcohol abuse, cohabitation, young age, attitudes supportive of wife beating, having outside sexual partners, experiencing childhood abuse, growing up with domestic violence, and experiencing or perpetrating other forms of violence in adulthood, increased the risk of IPV. The strength of the association was greatest when both the woman and her partner had the risk factor. CONCLUSIONS: IPV prevention programs should increase focus on transforming gender norms and attitudes, addressing childhood abuse, and reducing harmful drinking. Development initiatives to improve access to education for girls and boys may also have an important role in violence prevention.

Economic evaluation of a combined microfinance and gender training intervention for the prevention of intimate partner violence in rural South Africa.

OBJECTIVE: Assess the cost-effectiveness of an intervention combining microfinance with gender and HIV training for the prevention of intimate partner violence (IPV) in South Africa. METHODS: We performed a cost-effectiveness analysis alongside a cluster-randomized trial. We assessed the cost-effectiveness of the intervention in both the trial and initial scale-up phase. RESULTS: We estimated the cost per DALY gained as US$7688 for the trial phase and US$2307 for the initial scale-up. The findings were sensitive to the statistical uncertainty in effect estimates but otherwise robust to other key assumptions employed in the analysis. CONCLUSIONS: The findings suggest that this combined economic and health intervention was cost-effective in its trial phase and highly cost-effective in scale-up. These estimates are probably conservative, as they do not include the health and development benefits of the intervention beyond IPV reduction.

Modelling the interactions between herpes simplex virus type 2 and HIV: implications for the HIV epidemic in southern India.

BACKGROUND: The role of herpes simplex virus type 2 (HSV-2) in the HIV epidemic and the potential impact of HSV-2 suppressive therapy have previously been explored only within the context of sub-Saharan Africa. In this analysis, modelling is used to estimate the contribution of HSV-2 to HIV transmission from clients to female sex workers (FSW) in a southern Indian setting and the maximum potential impact of 'perfect' HSV-2 suppressive therapy on HIV incidence. METHODS: A dynamic HSV-2/HIV model was developed, parameterised and fitted to Mysore data. The model estimated the attributable fractions of HIV infections due to HSV-2. Multivariate sensitivity analyses and regression analyses were conducted. RESULTS: The model suggests that 36% (95% CI 22% to 62%) of FSW HIV infections were due to HSV-2, mostly through HSV-2 asymptomatic shedding. Even if HSV-2 suppressive therapy could eliminate the effect of HSV-2 on HIV infectivity among all co-infected clients, only 15% (95% CI 3% to 41%) of HIV infections among FSW would have been averted. 36% (95% CI 18% to 61%) of HIV infections among HSV-2-infected FSW could have been averted if suppressive therapy reduced their risk of HIV acquisition to that of HSV-2-uninfected FSW. CONCLUSIONS: HSV-2 contributes substantially to HIV in this southern Indian context. However, even in the best case scenario, HSV-2 suppressive therapy is unlikely to reduce HIV transmission or acquisition by more than 50% (as aimed for in recent trials), because of the limited strength of the interaction effect between HSV-2 and HIV.

Sexual violence and conflict in Africa: prevalence and potential impact on HIV incidence.

BACKGROUND AND AIMS: Sexual violence (SV) is common during conflict. Despite reports of rape-related incidents of HIV infection, ecological analyses have found no association between SV and HIV at a population level. This has led to debate in the humanitarian, security and public health arenas about whether SV is an important HIV risk factor in conflict-affected settings. This paper uses published evidence on sexual violence in Africa and modelling to explore when SV may increase individual HIV risk and community HIV incidence. METHODS: Publications on sexual violence in conflict settings were reviewed and a mathematical model describing the probability of HIV acquisition was adapted to include the potential effect of genital injury and used to estimate the relative risk of HIV acquisition in 'conflict' versus 'non-conflict' situations. An analytical equation was developed to estimate the impact of SV on HIV incidence. RESULTS: A rape survivor's individual HIV risk is determined by potentially compounding effects of genital injury, penetration by multiple perpetrators and the increased likelihood that SV perpetrators are HIV infected. Modelling analysis suggests risk ratios of between 2.4 and 27.1 for the scenarios considered. SV could increase HIV incidence by 10% if rape is widespread (>40%); genital injury increases HIV transmission (threefold or more); at least 10% of perpetrators are HIV infected and underlying HIV incidence is low (<0.5%). CONCLUSION: The analysis illustrates that SV is likely to be an important HIV risk factor in some conflict-affected settings. More generally, it indicates the limitations of using broad aggregate analysis to derive epidemiological conclusions. Conflict-related initiatives offer important opportunities to assist survivors and prevent future abuses through collaborative programming on reconstruction, HIV and sexual violence.

Dynamic modeling of herpes simplex virus type-2 (HSV-2) transmission: issues in structural uncertainty.

The sexually transmitted infection (STI) Herpes simplex virus type-2 (HSV-2) is of public health concern because it is a very common frequently unrecognized lifelong infection, which may facilitate HIV transmission. Within HIV/STI modeling, structural uncertainty has received less attention than parametric uncertainty. By merging the compartments of a "complex" model, a "simple" HSV-2 model is developed. Sexual interactions between female sex workers (FSWs) and clients are modeled using data from India. Latin Hypercube Sampling selects from parameter distributions and both models are run for each of the 10,000 parameter sets generated. Outputs are compared (except for 2,450 unrealistic simulations). The simple model is a good approximation to the complex model once the HSV-2 epidemic has reached 60% of the equilibrium prevalence (95% of the 7,550 runs produced <10% relative error). The simple model is a reduced version of the complex model that retains details implicitly. For late-stage epidemics, the simple model gives similar prevalence trends to the complex model. As HSV-2 epidemics in many populations are advanced, the simple model is accurate in most instances, although the complex model may be preferable for early epidemics. The analysis highlights the issue of structural uncertainty and the value of reducing complexity.

Can social capital be intentionally generated? a randomized trial from rural South Africa.

While much descriptive research has documented positive associations between social capital and a range of economic, social and health outcomes, there have been few intervention studies to assess whether social capital can be intentionally generated. We conducted an intervention in rural South Africa that combined group-based microfinance with participatory gender and HIV training in an attempt to catalyze changes in solidarity, reciprocity and social group membership as a means to reduce women's vulnerability to intimate partner violence and HIV. A cluster randomized trial was used to assess intervention effects among eight study villages. In this paper, we examined effects on structural and cognitive social capital among 845 participants and age and wealth matched women from households in comparison villages. This was supported by a diverse portfolio of qualitative research. After two years, adjusted effect estimates indicated higher levels of structural and cognitive social capital in the intervention group than the comparison group, although confidence intervals were wide. Qualitative research illustrated the ways in which economic and social gains enhanced participation in social groups, and the positive and negative dynamics that emerged within the program. There were numerous instances where individuals and village loan centres worked to address community concerns, both working through existing social networks, and through the establishment of new partnerships with local leadership structures, police, the health sector and NGOs. This is among the first experimental trials suggesting that social capital can be exogenously strengthened. The implications for community interventions in public health are further explored.

Intimate partner violence and women's physical and mental health in the WHO multi-country study on women's health and domestic violence: an observational study.

BACKGROUND: This article summarises findings from ten countries from the WHO multi-country study on women's health and domestic violence against women. METHODS: Standardised population-based surveys were done between 2000 and 2003. Women aged 15-49 years were interviewed about their experiences of physically and sexually violent acts by a current or former intimate male partner, and about selected symptoms associated with physical and mental health. The women reporting physical violence by a partner were asked about injuries that resulted from this type of violence. FINDINGS: 24,097 women completed interviews. Pooled analysis of all sites found significant associations between lifetime experiences of partner violence and self-reported poor health (odds ratio 1.6 [95% CI 1.5-1.8]), and with specific health problems in the previous 4 weeks: difficulty walking (1.6 [1.5-1.8]), difficulty with daily activities (1.6 [1.5-1.8]), pain (1.6 [1.5-1.7]), memory loss (1.8 [1.6-2.0]), dizziness (1.7 [1.6-1.8]), and vaginal discharge (1.8 [1.7-2.0]). For all settings combined, women who reported partner violence at least once in their life reported significantly more emotional distress, suicidal thoughts (2.9 [2.7-3.2]), and suicidal attempts (3.8 [3.3-4.5]), than non-abused women. These significant associations were maintained in almost all of the sites. Between 19% and 55% of women who had ever been physically abused by their partner were ever injured. INTERPRETATION: In addition to being a breach of human rights, intimate partner violence is associated with serious public-health consequences that should be addressed in national and global health policies and programmes.

Is social capital associated with HIV risk in rural South Africa?

The role of social capital in promoting health is now widely debated within international public health. In relation to HIV, the results of previous observational and cross-sectional studies have been mixed. In some settings it has been suggested that high levels of social capital and community cohesion might be protective and facilitate more effective collective responses to the epidemic. In others, group membership has been a risk factor for HIV infection. There have been few attempts to strengthen social capital, particularly in developing countries, and examine its effect on vulnerability to HIV. Employing data from an intervention study, we examined associations between social capital and HIV risk among 1063 14 to 35-year-old male and female residents of 750 poor households from 8 villages in rural Limpopo province, South Africa. We assessed cognitive social capital (CSC) and structural social capital (SSC) separately, and examined associations with numerous aspects of HIV-related psycho-social attributes, risk behavior, prevalence and incidence. Among males, after adjusting for potential confounders, residing in households with greater levels of CSC was linked to lower HIV prevalence and higher levels of condom use. Among females, similar patterns of relationships with CSC were observed. However, while greater SSC was associated with protective psychosocial attributes and risk behavior, it was also associated with higher rates of HIV infection. This work underscores the complex and nuanced relationship between social capital and HIV risk in a rural African context. We suggest that not all social capital is protective or health promotive, and that getting the balance right is critical to informing HIV prevention efforts.

Understanding the impact of a microfinance-based intervention on women's empowerment and the reduction of intimate partner violence in South Africa.

OBJECTIVES: We sought to obtain evidence about the scope of women's empowerment and the mechanisms underlying the significant reduction in intimate partner violence documented by the Intervention With Microfinance for AIDS and Gender Equity (IMAGE) cluster-randomized trial in rural South Africa. METHODS: The IMAGE intervention combined a microfinance program with participatory training on understanding HIV infection, gender norms, domestic violence, and sexuality. Outcome measures included past year's experience of intimate partner violence and 9 indicators of women's empowerment. Qualitative data about changes occurring within intimate relationships, loan groups, and the community were also collected. RESULTS: After 2 years, the risk of past-year physical or sexual violence by an intimate partner was reduced by more than half (adjusted risk ratio=0.45; 95% confidence interval=0.23, 0.91). Improvements in all 9 indicators of empowerment were observed. Reductions in violence resulted from a range of responses enabling women to challenge the acceptability of violence, expect and receive better treatment from partners, leave abusive relationships, and raise public awareness about intimate partner violence. CONCLUSIONS: Our findings, both qualitative and quantitative, indicate that economic and social empowerment of women can contribute to reductions in intimate partner violence.

Could the CARE-SHAKTI intervention for injecting drug users be maintaining the low HIV prevalence in Dhaka, Bangladesh?

AIMS: To explore whether the low HIV prevalence observed in Bangladesh results from prevention activities, this study uses mathematical modelling to estimate the impact of a needle/syringe exchange intervention for injecting drug users (IDUs) in Dhaka, Bangladesh. DESIGN: Epidemiological, behavioural and intervention monitoring data were used to parameterize a dynamic mathematical model, and fit it to National HIV Sero-surveillance data among IDUs (2000-02). The model was used to estimate the impact of the intervention on HIV transmission among IDUs and their sexual partners. SETTING: Dhaka, Bangladesh, where the HIV prevalence has remained low despite high-risk sexual and injecting behaviours, and growing HIV epidemics in neighbouring countries. FINDINGS: The model predicts that the intervention may have reduced the incidence of HIV among IDUs by 90% (95% CI 74-94%), resulting in an IDU HIV prevalence of 10% (95% CI 4-19%) after 8 years of intervention activity instead of 42% (95% CI 30-47%) if the intervention had not occurred. CONCLUSIONS: The analysis highlights the potential for rapid HIV spread among IDUs in Dhaka, and suggests that the intervention may have substantially reduced IDU HIV transmission. However, there is no room for complacency. Sustained and expanded funding for interventions in Dhaka and other regions of Bangladesh are crucial to maintaining the low HIV prevalence.