Andrea L. Wirtz

Global epidemiology of HIV infection in men who have sex with men

Epidemics of HIV in men who have sex with men (MSM) continue to expand in most countries. We sought to understand the epidemiological drivers of the global epidemic in MSM and why it continues unabated. We did a comprehensive review of available data for HIV prevalence, incidence, risk factors, and the molecular epidemiology of HIV in MSM from 2007 to 2011, and modelled the dynamics of HIV transmission with an agent-based simulation. Our findings show that the high probability of transmission per act through receptive anal intercourse has a central role in explaining the disproportionate disease burden in MSM. HIV can be transmitted through large MSM networks at great speed. Molecular epidemiological data show substantial clustering of HIV infections in MSM networks, and higher rates of dual-variant and multiple-variant HIV infection in MSM than in heterosexual people in the same populations. Prevention strategies that lower biological transmission and acquisition risks, such as approaches based on antiretrovirals, offer promise for controlling the expanding epidemic in MSM, but their potential effectiveness is limited by structural factors that contribute to low health-seeking behaviours in populations of MSM in many parts of the world.

Burden of HIV among female sex workers in low-income and middle-income countries: a systematic review and meta-analysis

BACKGROUND Female sex workers are a population who are at heightened risk of HIV infection secondary to biological, behavioural, and structural risk factors. However, three decades into the HIV pandemic, understanding of the burden of HIV among these women remains limited. We aimed to assess the burden of HIV in this population compared with that of other women of reproductive age. METHODS We searched PubMed, Embase, Global Health, SCOPUS, PsycINFO, Sociological Abstracts, CINAHL (Cumulative Index to Nursing and Allied Health Literature), Web of Science, and POPLine for studies of female sex workers in low-income and middle-income countries published between Jan 1, 2007, and June 25, 2011. Studies of any design that measured the prevalence or incidence of HIV among female sex workers, even if sex workers were not the main focus of the study, were included. Meta-analyses were done with the Mantel-Haenszel method with a random-effects model characterising an odds ratio for the prevalence of HIV among female sex workers compared with that for all women of reproductive age. FINDINGS Of 434 selected articles and surveillance reports, 102 were included in the analyses, representing 99,878 female sex workers in 50 countries. The overall HIV prevalence was 11·8% (95% CI 11·6-12·0) with a pooled odds ratio for HIV infection of 13·5 (95% CI 10·0-18·1) with wide intraregional ranges in the pooled HIV prevalence and odds ratios for HIV infection. In 26 countries with medium and high background HIV prevalence, 30·7% (95% CI 30·2-31·3; 8627 of 28,075) of sex workers were HIV-positive and the odds ratio for infection was 11·6 (95% CI 9·1-14·8). INTERPRETATION Although data characterising HIV risk among female sex workers is scarce, the burden of disease is disproportionately high. These data suggest an urgent need to scale up access to quality HIV prevention programmes. Considerations of the legal and policy environments in which sex workers operate and actions to address the important role of stigma, discrimination, and violence targeting female sex workers is needed. FUNDING The World Bank, UN Population Fund.

Worldwide burden of HIV in transgender women: a systematic review and meta-analysis

BACKGROUND Previous systematic reviews have identified a high prevalence of HIV infection in transgender women in the USA and in those who sell sex (compared with both female and male sex workers). However, little is known about the burden of HIV infection in transgender women worldwide. We aimed to better assess the relative HIV burden in all transgender women worldwide. METHODS We did a systematic review and meta-analysis of studies that assessed HIV infection burdens in transgender women that were published between Jan 1, 2000, and Nov 30, 2011. Meta-analysis was completed with the Mantel-Haenszel method, and random-effects modelling was used to compare HIV burdens in transgender women with that in adults in the countries for which data were available. FINDINGS Data were only available for countries with male-predominant HIV epidemics, which included the USA, six Asia-Pacific countries, five in Latin America, and three in Europe. The pooled HIV prevalence was 19·1% (95% CI 17·4-20·7) in 11 066 transgender women worldwide. In 7197 transgender women sampled in ten low-income and middle-income countries, HIV prevalence was 17·7% (95% CI 15·6-19·8). In 3869 transgender women sampled in five high-income countries, HIV prevalence was 21·6% (95% CI 18·8-24·3). The odds ratio for being infected with HIV in transgender women compared with all adults of reproductive age across the 15 countries was 48·8 (95% CI 21·2-76·3) and did not differ for those in low-income and middle-income countries compared with those in high-income countries. INTERPRETATION Our findings suggest that transgender women are a very high burden population for HIV and are in urgent need of prevention, treatment, and care services. The meta-analysis showed remarkable consistency and severity of the HIV disease burden among transgender women. FUNDING Center for AIDS Research at Johns Hopkins and the Center for Public Health and Human Rights at the JHU Bloomberg School of Public Health.

Modified social ecological model: a tool to guide the assessment of the risks and risk contexts of HIV epidemics

BackgroundSocial and structural factors are now well accepted as determinants of HIV vulnerabilities. These factors are representative of social, economic, organizational and political inequities. Associated with an improved understanding of multiple levels of HIV risk has been the recognition of the need to implement multi-level HIV prevention strategies. Prevention sciences research and programming aiming to decrease HIV incidence requires epidemiologic studies to collect data on multiple levels of risk to inform combination HIV prevention packages.DiscussionProximal individual-level risks, such as sharing injection devices and unprotected penile-vaginal or penile-anal sex, are necessary in mediating HIV acquisition and transmission. However, higher order social and structural-level risks can facilitate or reduce HIV transmission on population levels. Data characterizing these risks is often far more actionable than characterizing individual-level risks. We propose a modified social ecological model (MSEM) to help visualize multi-level domains of HIV infection risks and guide the development of epidemiologic HIV studies. Such a model may inform research in epidemiology and prevention sciences, particularly for key populations including men who have sex with men (MSM), people who inject drugs (PID), and sex workers. The MSEM builds on existing frameworks by examining multi-level risk contexts for HIV infection and situating individual HIV infection risks within wider network, community, and public policy contexts as well as epidemic stage. The utility of the MSEM is demonstrated with case studies of HIV risk among PID and MSM.SummaryThe MSEM is a flexible model for guiding epidemiologic studies among key populations at risk for HIV in diverse sociocultural contexts. Successful HIV prevention strategies for key populations require effective integration of evidence-based biomedical, behavioral, and structural interventions. While the focus of epidemiologic studies has traditionally been on describing individual-level risk factors, the future necessitates comprehensive epidemiologic data characterizing multiple levels of HIV risk.

Stigma, Health Care Access, and HIV Knowledge Among Men Who Have Sex With Men in Malawi, Namibia, and Botswana

Same-sex practices are stigmatized in much of sub-Saharan Africa. Cross-sectional relationships between discrimination, access to and use of health care services, and HIV knowledge among men who have sex with men (MSM) were assessed in Malawi, Namibia, and Botswana. A survey and HIV screening were used to explore these variables and the prevalence of HIV. Overall, 19% of men screened positive for HIV infection. Ninety-three percent knew HIV is transmitted through anal sex with men, however, only 67% had ever received information of how to prevent this transmission. Few (17%) reported ever disclosing same sex practices to a health professional and 19% reported ever being afraid to seek health care. Men reported ever been denied health care services (5%) and 21% had ever been blackmailed because of their sexuality. Strong associations were observed between experiences of discrimination and fear of seeking health care services. Characterizing the relationship between stigma and health care seeking practices and attitudes can inform the development and implementation of HIV interventions for African MSM.

The Expanding Epidemics of HIV Type 1 Among Men Who Have Sex With Men in Low- and Middle-Income Countries: Diversity and Consistency

Men who have sex with men (MSM) have borne a disproportionate burden of human immunodeficiency virus (HIV) infection and remain a markedly underresourced population globally. To better describe HIV epidemics among MSM in low- and middle-income countries, the authors conducted a systematic review of published and unpublished literature available after January 1, 2000 (2000-2009). A total of 133 HIV prevalence studies from 50 countries met the search criteria. Data were used to develop an algorithmic approach to categorize these epidemics. The authors found that the HIV epidemic in low- and middle-income countries may be described using the following 4 scenarios: 1) settings where MSM are the predominant contributor to HIV cases; 2) settings where HIV transmission among MSM occurs in the context of epidemics driven by injection drug users; 3) settings where HIV transmission among MSM occurs in the context of well-established HIV transmission among heterosexuals; and 4) settings where both sexual and parenteral modes contribute significantly to HIV transmission. The authors focused on Peru, Ukraine, Kenya, and Thailand to describe the diversity across and similarities between proposed epidemic scenarios. This scenario-based categorization of HIV epidemics among MSM may assist public health agencies and civil societies to develop and implement better-targeted HIV prevention programs and interventions.

The increase in global HIV epidemics in MSM

Epidemics of HIV in MSM continue to expand in most low, middle, and upper income countries in 2013 and rates of new infection have been consistently high among young MSM. Current prevention and treatment strategies are insufficient for this next wave of HIV spread. We conducted a series of comprehensive reviews of HIV prevalence and incidence, risks for HIV, prevention and care, stigma and discrimination, and policy and advocacy options. The high per act transmission probability of receptive anal intercourse, sex role versatility among MSM, network level effects, and social and structural determinants play central roles in disproportionate disease burdens. HIV can be transmitted through large MSM networks at great speed. Molecular epidemiologic data show marked clustering of HIV in MSM networks, and high proportions of infections due to transmission from recent infections. Prevention strategies that lower biological risks, including those using antiretrovirals, offer promise for epidemic control, but are limited by structural factors including, discrimination, criminalization, and barriers to healthcare. Subepidemics, including among racial and ethnic minority MSM in the United States and UK, are particularly severe and will require culturally tailored efforts. For the promise of new and combined bio-behavioral interventions to be realized, clinically competent healthcare is necessary and community leadership, engagement, and empowerment are likely to be key. Addressing the expanding epidemics of HIV in MSM will require continued research, increased resources, political will, policy change, structural reform, community engagement, and strategic planning and programming, but it can and must be done.

HIV risk and preventive interventions in transgender women sex workers

Worldwide, transgender women who engage in sex work have a disproportionate risk for HIV compared with natal male and female sex workers. We reviewed recent epidemiological research on HIV in transgender women and show that transgender women sex workers (TSW) face unique structural, interpersonal, and individual vulnerabilities that contribute to risk for HIV. Only six studies of evidence-based prevention interventions were identified, none of which focused exclusively on TSW. We developed a deterministic model based on findings related to HIV risks and interventions. The model examines HIV prevention approaches in TSW in two settings (Lima, Peru and San Francisco, CA, USA) to identify which interventions would probably achieve the UN goal of 50% reduction in HIV incidence in 10 years. A combination of interventions that achieves small changes in behaviour and low coverage of biomedical interventions was promising in both settings, suggesting that the expansion of prevention services in TSW would be highly effective. However, this expansion needs appropriate sustainable interventions to tackle the upstream drivers of HIV risk and successfully reach this population. Case studies of six countries show context-specific issues that should inform development and implementation of key interventions across heterogeneous settings. We summarise the evidence and knowledge gaps that affect the HIV epidemic in TSW, and propose a research agenda to improve HIV services and policies for this population.

Global burden of HIV, viral hepatitis, and tuberculosis in prisoners and detainees

The prison setting presents not only challenges, but also opportunities, for the prevention and treatment of HIV, viral hepatitis, and tuberculosis. We did a comprehensive literature search of data published between 2005 and 2015 to understand the global epidemiology of HIV, hepatitis C virus (HCV), hepatitis B virus (HBV), and tuberculosis in prisoners. We further modelled the contribution of imprisonment and the potential impact of prevention interventions on HIV transmission in this population. Of the estimated 10·2 million people incarcerated worldwide on any given day in 2014, we estimated that 3·8% have HIV (389 000 living with HIV), 15·1% have HCV (1 546 500), 4·8% have chronic HBV (491 500), and 2·8% have active tuberculosis (286 000). The few studies on incidence suggest that intraprison transmission is generally low, except for large-scale outbreaks. Our model indicates that decreasing the incarceration rate in people who inject drugs and providing opioid agonist therapy could reduce the burden of HIV in this population. The prevalence of HIV, HCV, HBV, and tuberculosis is higher in prison populations than in the general population, mainly because of the criminalisation of drug use and the detention of people who use drugs. The most effective way of controlling these infections in prisoners and the broader community is to reduce the incarceration of people who inject drugs.

Injection drug use, sexual risk, violence and STI/HIV among Moscow female sex workers

Background/objectives The HIV prevalence in Eastern Europe and Central Asia continues to increase. While injection drug use (IDU) is leading factor, heterosexual transmission is on the rise. Little is known about female sex workers (FSWs) in the region despite the central role of commercial sex in heterosexual sexually transmitted infection (STI)/HIV transmission globally. The authors evaluated the prevalence of STI/HIV among Moscow-based FSWs and potential risk factors including IDU, sexual risks and violence victimisation. Methods Moscow-based FSWs (n=147) completed a clinic-based survey and STI/HIV testing over an 8-month period in 2005. Results HIV prevalence was 4.8%, and 31.3% were infected with at least one STI including HIV. Sexual behaviours significantly associated with STI/HIV included anal sex (adjusted odds ratio (AOR) 3.48), high client volume (three or more clients daily, AOR 2.71), recent subbotnik (sex demanded by police; AOR 2.50) and regularly being presented with more clients than initially agreed to (AOR 2.45). Past year experiences of physical violence from clients and threats of violence from pimps were associated with STI/HIV (AOR 3.14 and AOR 3.65, respectively). IDU was not significantly associated with STI/HIV. Anal sex and high client volume partially mediated the associations of abuse with STI/HIV. Conclusions Findings illustrate substantial potential for heterosexual STI/HIV transmission in a setting better known for IDU-related risk. Many of the STI/HIV risks observed are not modifiable by FSWs alone. STI/HIV prevention efforts for this vulnerable population will benefit from reducing coercion and abuse perpetrated by pimps and clients.