Elsevier

The Lancet

Volume 385, Issue 9962, 3–9 January 2015, Pages 55-71
The Lancet

Series
Global epidemiology of HIV among female sex workers: influence of structural determinants

https://doi.org/10.1016/S0140-6736(14)60931-4Get rights and content

Summary

Female sex workers (FSWs) bear a disproportionately large burden of HIV infection worldwide. Despite decades of research and programme activity, the epidemiology of HIV and the role that structural determinants have in mitigating or potentiating HIV epidemics and access to care for FSWs is poorly understood. We reviewed available published data for HIV prevalence and incidence, condom use, and structural determinants among this group. Only 87 (43%) of 204 unique studies reviewed explicitly examined structural determinants of HIV. Most studies were from Asia, with few from areas with a heavy burden of HIV such as sub-Saharan Africa, Russia, and eastern Europe. To further explore the potential effect of structural determinants on the course of epidemics, we used a deterministic transmission model to simulate potential HIV infections averted through structural changes in regions with concentrated and generalised epidemics, and high HIV prevalence among FSWs. This modelling suggested that elimination of sexual violence alone could avert 17% of HIV infections in Kenya (95% uncertainty interval [UI] 1–31) and 20% in Canada (95% UI 3–39) through its immediate and sustained effect on non-condom use) among FSWs and their clients in the next decade. In Kenya, scaling up of access to antiretroviral therapy among FSWs and their clients to meet WHO eligibility of a CD4 cell count of less than 500 cells per μL could avert 34% (95% UI 25–42) of infections and even modest coverage of sex worker-led outreach could avert 20% (95% UI 8–36) of infections in the next decade. Decriminalisation of sex work would have the greatest effect on the course of HIV epidemics across all settings, averting 33–46% of HIV infections in the next decade. Multipronged structural and community-led interventions are crucial to increase access to prevention and treatment and to promote human rights for FSWs worldwide.

Introduction

Worldwide, sex workers are disproportionately affected by the HIV pandemic.1 The authors of a review of HIV burden in female sex workers (FSWs) in 50 low-income and middle-income countries reported an overall HIV prevalence of 11·8% (95% CI 11·6–12·0), with a pooled odds of HIV infection of 13·5 (10·0–18·1) compared with the general population of women of reproductive age.2 In many high-income countries and regions, such as Canada, the USA, and Europe, epidemics that initially escalated in people who inject drugs in the mid-1990s shifted to FSWs.3, 4 In settings such as Russia and central and eastern Europe, the scarce data available suggests emerging or established epidemics among FSWs who inject drugs.5, 6 Heterogeneity in HIV prevalence among FSWs varies substantially both across and within regions due to social, political, economic, and cultural factors,7 yet an understanding of how structural factors (eg, contextual factors external to the individual) shape HIV acquisition and transmission risks has only just begun to emerge.

Sex workers—those who exchange sex for money—can be female, male, or transgender. Although most sex workers are female and patronised by male clients (sex buyers), sizeable populations of male and transgender sex workers are present in many settings.8, 9 The work environment and community organisation of sex work varies substantially, including formal sex work establishments (eg, massage parlours, brothels, or other in-call venues), entertainment establishments (eg, bars and nightclubs), informal or out-call venues (eg, hotels, lodges, and saunas), and outdoor settings (eg, streets, parks, and markets). Sex workers might solicit clients independently, both on-street and off-street (eg, self-advertisement online, in newspapers, or by phone or text), or might work for a manager or pimp. In some cases, sex workers might additionally work cooperatively in microbrothels (two or more sex workers working together).

Key messages

  • Sex workers face a disproportionately large burden of HIV across concentrated and generalised epidemic settings, with substantial heterogeneity in HIV epidemics and structural determinants, as well as features that are very context specific.

  • Fewer than half of epidemiological studies on HIV acquisition and transmission risk among female sex workers explicitly considered structural determinants.

  • Epidemiology of HIV and structural determinants among female sex workers is disproportionately drawn from Asia, with large gaps in heavy burden regions of sub-Saharan Africa, Russia, and eastern Europe.

  • In Canada and Kenya, where sexual violence has an immediate and sustained effect on non-condom use, elimination of violence by clients, police, and strangers could avert 17–20% of HIV infections among female sex workers and their clients over the next decade.

  • Coverage of and access to prevention and treatment among female sex workers lag behind the general population and scale-up to optimal coverage of condoms and HIV care continuum will probably only be feasible alongside other structural change. In heavy HIV-burden settings, such as Mombasa, where antiretroviral therapy and condom access remain suboptimal, scale-up of antiretroviral therapy access to WHO guidelines of a CD4 cell count of less than 500 cells per μL for both FSWs and their clients could avert 34% of HIV infections and even modest scale-up of sex worker-led outreach could avert 20% of HIV infections among FSWs and their clients over the next decade.

  • Interventions to promote access to safer sex work environments (eg, changes to venue, management, and policing policies, and access to prevention) could avert a substantial proportion of infections across diverse settings.

  • Modelling suggests that across both generalised and concentrated HIV epidemics, decriminalisation of sex work could have the largest effect on the course of the HIV epidemic, averting 33–46% of incident infections over the next decade through combined effects on violence, police harassment, safer work environments, and HIV transmission pathways.

Research and programmes in the past decade suggest that behavioural and biomedical interventions among FSWs alone have had only modest effects on the reduction of HIV at the population-level,2, 10 which has led to calls for combination HIV prevention that includes structural interventions. For example, efforts to roll out antiretroviral therapy (ART) or distribute condoms to FSWs in settings where criminalisation and stigma deter access to condoms or health services continue to hamper HIV prevention, treatment, and care efforts.1, 11, 12 Growing interest has arisen in structural determinants of HIV risk and ecological models that account for these risks among FSWs and other key affected populations (eg, people who inject drugs and men who have sex with men).13, 14, 15 Social epidemiology efforts in sex work have increasingly considered both structure and biology (and behaviour) within a structural determinants framework (figure 1) to better delineate the complex interplay and heterogeneity of HIV acquisition and transmission, and, more aptly, predict epidemic trajectories and intervention targets.13, 16, 17, 18

Despite efforts to consider structural HIV determinants in programmes,16 social science,14, 18 and epidemiological15, 17 literature, the extent to which empirical work characterises the epidemiology of structural factors and HIV among FSWs worldwide, alongside behavioural and biological factors, has yet to be considered. We did a comprehensive search for recent published reports on HIV and FSWs (Jan 1, 2008, to Dec 31, 2013), and assessed the extent to which this literature regarded structural determinants in the mitigation or potentiation of HIV acquisition and transmission risk (panel 1). To further consider key structural factors from our report and available context-specific epidemiological, qualitative, and grey literature, we then modelled potential aversion of HIV infections through structural changes in three cities with high HIV prevalence among FSWs: two low-income and middle-income countries—one concentrated (India) and one generalised (Kenya) epidemic—and one high-income city with overlap with an epidemic of injecting drug use (Canada). These models allowed us to assess heterogeneity of epidemics and key structural determinants, and the potential effect of single and combined interventions (eg, structural changes) in different epidemic contexts.

Section snippets

Systematic review

To consider the centrality of structural determinants in HIV epidemics among FSWs, we mapped present epidemiological reports on a structural determinants framework for HIV and sex work (figure 1).19 Of the 3214 relevant publications retrieved, 149 (73%) of 204 unique studies reported at least one structural determinant (table, appendix), but only 87 (43%) were designed a priori to examine one or more structural determinants of HIV, HIV and sexually transmitted infection (STI), or condom use. Of

Modelling HIV epidemics in female sex work

We assessed the population-level effect of some of the structural drivers with deterministic transmission dynamic models to simulate the course of HIV epidemics and potential HIV infections averted through structural changes in regions with concentrated and generalised epidemics and high HIV prevalence among FSWs (appendix). Guided by our systematic review and context-specific epidemiological, qualitative, and grey literature, our modelling considers exposures to context-specific structural

Case 1: Vancouver, Canada

Vancouver provides a key example of a concentrated, high-prevalence epidemic among key populations. As elsewhere in North America, the epidemic in Vancouver first emerged in men who have sex with men in the 1980s.110 By the mid-1990s, an explosive HIV outbreak occurred in people who inject drugs, with HIV incidence peaking at around 18 cases per 100 person-years in 1996 and 1997,111 declining to fewer than three per 100 person-years in 2007 because of substantially improved coverage of syringe

Policy and prevention implications

In our report, fewer than half the recent epidemiological studies on HIV acquisition and transmission risk among FSWs explicitly considered structural determinants, yet the literature underscores the centrality of structural determinants for this component of the worldwide HIV epidemic. Because sub-Saharan Africa has a substantial portion of the HIV epidemic among FSWs, and Russia and eastern Europe have growing (and in some cases rapidly expanding) HIV epidemics among FSWs, gaps in data for

Conclusion

Macrostructural changes are urgently needed to laws and policies (eg, decriminalisation of sex work) and the work environment features (eg, reductions to policing and violence and safer work environments) they engender in order to stem HIV epidemics among FSWs and their clients across diverse epidemic settings. Coverage and equitable access to condoms, ART, and HIV prevention, treatment, and care lag unacceptably behind that of the general population. To generate substantial change among FSWs,

Search strategy and selection criteria

We searched PubMed, EMBASE, Science Citation Index, BIOSIS Previews, PsycINFO, CINAHL, Social Sciences Citation Index, Sociological Abstracts, and CAB Direct (CAB Abstracts & Global Health) for peer reviewed reports published in any language from Jan 1, 2008, to Dec 31, 2013, assessing determinants of HIV infection or incidence, or condom use among female sex workers. The search terms used were “Sex work*” OR “sex worker” OR prostitute* OR prostitut* OR “prostitution” OR “commercial sex

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