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Global Epidemiology of HIV Infection and Related Syndemics Affecting Transgender People

Poteat, Tonia PhD, MPH, PA-C; Scheim, Ayden BA; Xavier, Jessica MPH; Reisner, Sari ScD, MA; Baral, Stefan MD, MPH, MBA

JAIDS Journal of Acquired Immune Deficiency Syndromes: August 15th, 2016 - Volume 72 - Issue - p S210–S219
doi: 10.1097/QAI.0000000000001087
Supplement Article
Open

Introduction: Transgender populations have been underrepresented in HIV epidemiologic studies and consequently in HIV prevention, care, and treatment programs. Since 2012, there has been a dramatic increase in research focused on transgender people. Studies highlight the burden of HIV and risk determinants, including intersecting stigmas, as drivers of syndemics among transgender populations. This review synthesizes the most recent global epidemiology of HIV infection and describes current gaps in research and interventions to inform prioritization of HIV research for transgender populations.

Methods: A systematic review was conducted of the medical literature published between January 1, 2012 and November 30, 2015. The data focused on HIV prevalence, determinants of risk, and syndemics among transgender populations.

Results: Estimates varied dramatically by location and subpopulation. Transfeminine individuals have some of the highest concentrated HIV epidemics in the world with laboratory-confirmed prevalence up to 40%. Data were sparse among trans masculine individuals; however, they suggest potential increased risk for trans masculine men who have sex with men (MSM). No prevalence data were available for transgender people across Sub-Saharan Africa or Eastern Europe/Central Asia. Emerging data consistently support the association of syndemic conditions with HIV risk in transgender populations.

Discussion: Addressing syndemic conditions and gender-specific challenges is critical to ensure engagement and retention in HIV prevention by transgender populations. Future research should prioritize: filling knowledge gaps in HIV epidemiology; elucidating how stigma shapes syndemic factors to produce HIV and other deleterious effects on transgender health; and understanding how to effectively implement HIV interventions for transgender people.

*Department of Epidemiology, Johns Hopkins Bloomberg School of Public Health, Baltimore, MD;

Department of Epidemiology and Biostatistics, Western University, London, Canada;

U.S. Department of Health and Human Services, Health Resources and Services Administration, Rockville, Maryland; and

§Boston Children's Hospital/Harvard Medical School, Harvard T.H. Chan School of Public Health, Boston, MA.

Correspondence to: Tonia Poteat, PhD, MPH, PA-C, 615 North Wolfe Street, E7138, Baltimore, MD 21205 (e-mail: tpoteat@jhu.edu).

This research has been facilitated by the infrastructure and resources provided by the Johns Hopkins University Center for AIDS Research, an NIH funded program (P30AI094189), which is supported by the following NIH Co-Funding and Participating Institutes and Centers: NIAID, NCI, NICHD, NHLBI, NIDA, NIMH, NIA, FIC, NIGMS, NIDDK, and OAR. A.S. was supported by Pierre Elliott Trudeau Foundation and Vanier Canada Graduate Scholarships. S.R. was partly supported by the National Institute of Mental Health of the National Institutes of Health under award number R34 MH104072. The content is solely the responsibility of the authors and does not represent the official views of the U.S. Department of Health and Human Services, the National Institutes of Health, or the Health Resources and Services Administration. The other authors have no funding or conflicts of interest to disclose.

This is an open access article distributed under the terms of the Creative Commons Attribution-NonCommercial-NoDerivatives License 4.0 (CC BY-NC-ND), which permits downloading and sharing the work provided it is properly cited. The work cannot be changed in any way or used commercially.

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INTRODUCTION

The term “transgender” refers to a diverse population of people whose gender identities and/or expressions differ from the sex assigned to them at birth, typically via birth certificate. The variety of terms and ways of expressing gender preclude an exhaustive list of terms. Therefore, “trans feminine” refers to individuals who were assigned a male sex at birth and express their gender along a feminine spectrum—that is, as women, female, transgender women, male-to-female, and other diverse trans feminine gender identities and expressions. “Trans masculine” refers to people who were assigned female at birth and express their gender along a masculine spectrum, as men, male, transgender men, female-to-male, and other heterogeneous trans masculinities. Some transgender people do not identify within this binary of masculine and feminine. Unfortunately, at this time, there is still too little data to review among this nonbinary population; future research is needed to elucidate HIV-related risks and resiliencies in that group.

Reliable estimates of the size of the transgender population are sparse. Where they exist, data vary by location and study design. Data from gender clinics in Europe estimate that anywhere from 4.28 per 100,0001 to 600 per 100,0002 members of the population seek medical care for gender transition, and that 72%–80% of those seeking gender care identify along the trans feminine spectrum. However, recent population-based studies have found that 0.5%–0.9% of adults was identified with a gender different from their birth sex and the proportion is similar for birth-assigned males and females.3–5 The most recent population-based data from the United States estimate that 0.5% of the population was identified as transgender.6 This proportion is consistent with passport identity data from New Zealand7, yet much lower than the 1.2% who identified as transgender in a recent nationally representative sample of New Zealand high school students.8

Historically, HIV data have conflated gender with anatomy and subsumed trans feminine people under the category of men who have sex with men (MSM).9 Subsuming trans feminine individuals in the category of MSM is not only inaccurate, it also typically results in very small numbers of trans feminine people included in much larger samples of MSM and makes it difficult to distinguish their unique HIV vulnerabilities. Current HIV risk categories also make it difficult to identify HIV risk among trans masculine individuals. Where surveillance exists for this population, reported data have categorized trans masculine MSM under “heterosexual contact,” making their risks invisible.10

HIV risk among transgender populations is driven by multilevel factors (Figure 1).11,12 At the biological level, transgender people with anatomically male partners face a high HIV transmission probability via condomless anal sex with serodiscordant and viremic partners.13,14 Coinfection with perigenital or perianal STIs may also potentiate the acquisition and transmission of HIV.15,16 Hormone-related determinants of HIV risk include testosterone use among trans masculine individuals, which may cause vaginal atrophy and increase the risk of HIV acquisition during vaginal intercourse.17 Network level risks include a high prevalence of HIV and limited awareness of HIV status within transgender-inclusive sexual networks.18,19 Community-level stigma and structural-level discriminatory laws also contribute to the high burden of HIV by limiting the provision and uptake of services as well as by driving transgender women, in particular to engage in sex work for economic survival and gender affirmation.20–23

Figure 1

Figure 1

A systematic review and meta-analysis of the burden of HIV in trans feminine populations was published in 2012.24 In that analysis, Baral et al documented a worldwide HIV prevalence of 19% and a 49-fold increased odds of HIV infection compared with non-transgender adults of reproductive age. The review was limited to studies published between 2000 and 2011, with at least 50 participants, and laboratory-confirmed HIV-infection data. The most recent systematic review of HIV prevalence to include trans masculine individuals was published in 2008 and was limited to the United States.25 In that review, Herbst et al found only 5 studies among transgender men, and HIV prevalence ranged from 0% to 2%. Given the dramatic increase in research among transgender populations in recent years,26 an update and synthesis of HIV data among transgender populations is due.

Regardless of geographic location, transgender people exist within social contexts that stigmatize them.27 Stigma is a powerful social determinant of health28 and a key driver of HIV disparities among transgender populations.11 Therefore, transgender HIV data are best understood within the social context and consequences of widespread stigma. Moreover, HIV infection is only one of the multiple stigma-related health conditions that disproportionately impact transgender populations. Syndemics have been defined as “the concentration and deleterious interaction of 2 or more disease or other health conditions in a population, especially as a consequence of social inequity and the unjust exercise of power.”29 Syndemic psychosocial health problems, such as depression, substance use or abuse, violence or victimization, and internalized transphobia, may potentiate HIV risk and contribute to poor HIV treatment outcomes for transgender populations.30 A recent review of the use of syndemic theory in HIV research found that most studies focused on MSM, and the most frequently studied psychosocial problems included mental health (83%), substance abuse (90%), and violence (68%). The most frequently studied outcome variables were HIV risk behaviors (73%) or HIV infection (23%).31 No systematic review has yet examined the data on syndemic production of HIV among transgender populations.

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METHODS

PubMed (MEDLINE), EMBASE, and Cumulative Index to Nursing and Allied Health Literature (CINAHL) were searched for English language articles. In addition, experts in HIV infection among transgender populations were contacted to request access to unpublished HIV prevalence data. Commonly used terms for transgender (including “transsexual,” “cross dresser,” “transvestite,” and “travesti”) were cross-referenced with medical subject headings (MeSH) terms for HIV. Two reviewers independently conducted title and abstract reviews on unduplicated references for relevance, with subsequent full-text review for data abstraction.

The search was limited to data published between January 1, 2012 and November 30, 2015 to avoid overlap with Baral et al's review.32 All studies with original quantitative HIV data that disaggregated transgender participants from other populations were included. Both self-reported and laboratory-tested HIV statuses and data on location of study, sampling strategies, sample size, and HIV prevalence and/or incidence were extracted. When present, data on syndemics among transgender populations were also abstracted. Where more than one manuscript reported on the same data set, the most recent publication is cited. Where a manuscript included both self-reported HIV status and HIV testing, the results of HIV tests were recorded. Where available, nonadjusted HIV-prevalence estimates were recorded for studies that used respondent-driven sampling.

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RESULTS

HIV Prevalence

United States

Twenty-one studies published between 2012 and 2015 described HIV prevalence among transgender people in the United States of which only one also measured incidence.33 (Table 1.) Four studies were national, regional, or state-level in scope, whereas the rest were single city or multicity. Three cities (San Francisco and Los Angeles, CA; Boston, MA) accounted for more than half (n = 12) of study sites. One study49 used respondent-driven sampling, whereas the rest drew upon convenience or clinic-based samples. Eight studies included prevalence estimates for very small samples (ie, n < 100), predominantly for trans masculine individuals. Four articles did not disaggregate prevalence data by trans feminine or trans masculine gender spectrum.34,35,41,43 However, one of these articles used data from a previously published report that did disaggregate by gender spectrum.35,36

TABLE 1

TABLE 1

Self-reported HIV prevalence in trans feminine adults13,37,40,47,48,50,51 ranged from 2.0% in a national internet-based sample16 to 29.9%18 in a sample of trans women with a history of sex work in San Francisco and Oakland, CA. Laboratory-confirmed HIV prevalence reached 35.0% and 40.1% in community samples in San Francisco49 and New York,33 respectively. Among trans feminine testing events at the US Centers for Disease Control sites nationally, 2.7% were positive.39 HIV prevalence among trans feminine youth was between 4.5% and 7.9% in 3 studies42,45,46 and 15.9% in 1 study.44

Since 2014, 5 publications38,39,42,52,53 have described laboratory-confirmed HIV prevalence among trans masculine people in the United States, ranging from 0.9%52 to 4.3%.53 Of trans masculine CDC testing events,39 0.5% were positive.

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Global

Trans Masculine

Table 2 summarizes the very few data available regarding HIV prevalence among trans masculine individuals outside the United States. Four of 5 studies had very small samples (n = 14–92). Two Canadian respondent-driven sampling studies72,86 found no prevalent known HIV infections. Among gender clinic patients in Catalonia, Spain, 2.2% of trans masculine individuals had laboratory-confirmed HIV infection.85 In 2 internet studies of trans masculine people who have sex with men, self-reported prevalence was 1.4% in a global sample,87 and 8.0% in a sample from Spanish-speaking and Portuguese-speaking countries.83

TABLE 3

TABLE 3

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Trans Feminine

Thirty-three studies published between 2012 and 2015 described the HIV infection burden among trans feminine individuals globally16,54–83; 3 included incidence data.58,74,84 (Table 3). All were from countries with male-predominant, concentrated epidemics. Seven studies used respondent-driven sampling and 1 abstract reported an unspecified probability-based sampling method. Three countries in Latin America (Peru, Brazil, and Argentina) and 3 in Asia (India, Pakistan, and Thailand) accounted for over half of reports. For Colombia, El Salvador, China, Vanuatu, Italy, and Portugal, all HIV burden data were based on samples with fewer than 100 participants. In Latin America and the Caribbean, laboratory-confirmed HIV prevalence ranged from 13.8% to 34.1%; in half of such studies, more than one-quarter of trans feminine persons were HIV-positive. Only self-reports were available from East and Southeast Asia, where data were limited by low levels of HIV testing.48,56,77,79 Laboratory-confirmed HIV prevalence in India varied by sampling design, but was 18.1% in a probability sampling study.81 Among hijra sex workers in Pakistan, laboratory-confirmed prevalence was 6.4%–7.2% in 2 studies,71,75 and 21.6% in a third.69 Laboratory-confirmed and self-reported HIV prevalence, and sampling approaches were highly variable in other countries, primarily in southern Europe.

TABLE 2

TABLE 2

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Syndemics

Eight studies were identified that examined syndemics and HIV among transgender populations23,44,53,88–92 (Table 4). Only one study was conducted outside the United States.88 Two studies were among trans masculine individuals23,53; and both were conducted in Boston, MA. Half of all studies were conducted in California. One study did not specify trans feminine or trans masculine gender spectrum of transgender participants.89 All studies were cross-sectional and none used population-based sampling methods, limiting the ability to make causal inferences or generalize beyond the study population.

TABLE 4

TABLE 4

The most common syndemic factors studied included alcohol/substance use (n = 6), mental health (n = 5), and abuse/violence (n = 4). One study measured self-reported HIV status as an outcome; 7 studies measured sexual risk behaviors, including condomless intercourse, multiple partners, and history of STIs as primary outcomes. One study among people living with HIV examined only biomedical conditions (tuberculosis, viral hepatitis, and STIs) as syndemics with HIV infection.89 Antitransgender stigma, discrimination, or victimization factors were included in all studies of syndemics in trans feminine individuals (n = 5). These variables were modeled both as component conditions of syndemics (n = 3) and as potential determinants of syndemic production (n = 2). Stigma was not measured in any of the studies among trans masculine individuals.

Central to syndemics theory is that harmful social factors and health conditions are concentrated in affected populations and interact to enhance deleterious consequences, such as increased HIV risk.29 All of the identified studies found support for the concentration of harmful social factors and/or co-occurring health conditions among transgender people and most found that these factors/conditions were associated with HIV risk. However, few studies included methods to test for associations between the factors or synergistic (interactive) effects on health. Four studies report dose–response relationships between syndemic factors and HIV-related outcomes that suggest additive, rather than synergistic effects.44,88,89,91 Five studies23,44,88,90,91 operationalized syndemics by creating a composite index of scales to measure each included factor.

Two studies explored syndemic factors among trans masculine individuals. A small clinic sample (n = 23) of trans masculine individuals found that both alcohol use and psychosocial distress were associated with sexual risk behaviors.53 A larger study (n = 173) of trans masculine adults who had sex with nontransgender men found an association between the number of negative psychosocial conditions (alcohol and substance use, depression, anxiety, childhood abuse, and intimate partner violence) and increased odds of sexual risk.23 This study also found a significant interaction between the number of psychosocial conditions and social gender transition; however, interactions between the psychosocial conditions themselves were not examined.

The 2 studies that examined syndemics among trans feminine youth were both based in Los Angeles. Wilson et al found that an index including depression, trauma, bullying, stigma, and parental rejection was associated with both HIV risk behaviors and self-reported HIV (n = 282)91, and Brennan et al found associations between HIV risk and self-esteem, substance use, and victimization (n = 151).44

Among trans feminine adults, a San Francisco-based study developed a syndemic index of alcohol, drug use, and condomless anal intercourse and found that stigma was independently associated with this index (n = 191).90 However, no significant association was found between the index itself and self-reported HIV status. The study did identify significant correlations between the syndemic factors themselves. Zimmerman et al92 used structural equation modeling to test whether components of a syndemic of mental health problems, drug use, and alcohol use mediate the relationship between stigma and HIV risk behaviors among trans feminine people (n = 117) in Richmond and Washington, DC. This method was unique in allowing for multiple co-occurring HIV risk outcomes (eg, multiple partners, condomless sex, etc.) and multiple associated psychosocial risk factors. However, the model did not allow for correlations between the syndemic factors themselves.

Within a syndemic framework, Chu et al examined coinfection with HIV and at least one other disease (including tuberculosis, viral hepatitis, and sexually transmitted infections) among over 15,000 people living with HIV in San Francisco and found that comorbidity was more common among transgender people than nontransgender people.89 They also found a significant positive correlation between the number of co-occurring infections and mean viral loads. The one study from outside the United States recruited participants from 4 states in India. Chakrapani et al found that depression, alcohol, and victimization were associated with sexual risk for trans feminine participants (n = 300).88

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DISCUSSION

These data make it clear that trans feminine populations in the United States and around the world have a remarkably high prevalence and incidence of HIV infection. The discrepancy between self-reported HIV prevalence and laboratory-confirmed HIV suggests that many trans feminine individuals remain unaware of their HIV status and thus cannot benefit from early treatment and may be at risk of onward HIV transmission. While limited, data among trans masculine populations suggest low risk relative to trans feminine populations, with the potential exception of transgender men who have sex with nontransgender men. Public health agencies should increase HIV testing in these populations39 to identify those who are unaware of their HIV-positive status and effectively link them to HIV care and treatment programs.

The quality and quantity of HIV data on transgender populations are improving, but remain limited. HIV burden estimates from the reviewed studies should be cautiously interpreted in light of data limitations, particularly small sample sizes and convenience sampling from HIV prevention programs, sex work venues, and other settings that are likely to generate higher-risk samples. Globally, the lack of available HIV prevalence data among transgender people in sub-Saharan Africa and Eastern Europe/Central Asia represents a priority area for future epidemiologic research. In the United States, most recent HIV data in transgender populations have come from specialized centers in Massachusetts and California serving high numbers of lesbian, gay, bisexual, and transgender individuals in metropolitan urban areas. It will be important to identify the specific HIV-related needs of transgender people in rural areas of the United States, especially in the South where prevalence of HIV infection is highest.93

Accurate data capture of HIV risk in transgender populations requires gender-affirmative sexual and behavioral risk assessments that assess anatomical structures in a sensitive way while being socially affirming of individual gender identities. Although condomless receptive anal sex appears the most predominant proximal risk behavior for trans feminine people globally, trans feminine people may also have condomless insertive anal sex.13,42 Similarly, trans masculine people may have receptive vaginal sex with nontransgender male partners,15,42 and condomless vaginal sex may be more common than condomless anal sex for this population.72 Additionally, the types of sex transgender people have, and levels of risk behaviors they engage in, may differ by partner type (eg, transactional sex partners, casual partners, main/primary partners).94

The variability in HIV prevalence estimates within and across geographic locations indicates the importance of context. In the United States, trans feminine people of color have the highest prevalence of HIV in every study that included an analysis by race. Trans feminine people of color face unique social and economic vulnerabilities created by the intersection of gender identity stigma and the systemic racism that potentiates a higher prevalence of HIV among people of color in the general US population.21,93,95,96 Even within racial groups in close geographic proximity, access to care can vary widely by municipality.97 Similar dynamics impact racial/ethnic minorities and migrants in Europe and elsewhere, who face additional barriers to health care and social inclusion if they are undocumented.98 For example, data from Spain and Portugal indicate that HIV infection disproportionately impacts trans feminine sex workers who have migrated from Latin America.70,73,76,85 Lower access to healthcare, increased levels of poverty and housing instabilities, treatable STIs, lower levels of health literacy, higher HIV prevalence in social networks, and higher network or community viral load are all potential explanatory factors producing and maintaining inequities in HIV infection for trans feminine people of color and migrants. The combination of high burden of HIV, systemic disadvantage, and unmet need for gender affirming services make trans feminine people of color an underserved and priority population for HIV testing, prevention, and treatment.

Existing data on syndemics suggest difficulty in successfully treating and preventing HIV infection in isolation from the other social, behavioral, and medical conditions that co-occur and interact to limit successful and sustained engagement in health care. However, research on syndemic production of HIV among transgender populations is nascent. Studies that aim to examine syndemics often do not use methods that capture both the concentration of co-occurring psychosocial conditions and their interaction to produce synergistic deleterious effects.99 As the importance of syndemics becomes increasingly clear, more sophisticated analytic methods are needed.31,99 This includes examining the developmental trajectories of syndemics, such as timing, onset, and antecedents, to inform early prevention efforts and identifying appropriate multimodal interventions that address syndemics and the barriers they present to effective engagement in HIV prevention and treatment programs, including initiation of and adherence to oral pre-exposure prophylaxis (PrEP) and antiretroviral medications (ART) for those living with HIV.100,101

ART and PrEP have emerged as powerful tools in the HIV response. However, unless HIV services are acceptable and accessible to transgender people, coverage and ultimate effectiveness of these interventions will be limited. Emerging data suggest that HIV services are more acceptable to transgender people when they are destigmatizing and include access to gender-affirming care.102,103 Although there are specialized centers in a few urban settings that provide primary care and HIV wrap-around services, the clearly identified and urgent need for transgender-competent HIV services has largely gone unmet globally. Programs designed for MSM are inappropriate for trans feminine populations104 and are likely to be unacceptable to individuals who do not identify as men.105 At the same time, MSM programs may be unwelcoming to trans masculine individuals who have sex with men who may desire and benefit from MSM services.15,87

Although many of the syndemic conditions described for transgender populations are also well-known determinants of health for other groups,29 transgender populations face additional challenges of gender-related stigma, unmet gender affirmation needs, and inadequately trained health care providers.106 In combination, these factors form significant challenges to engagement in HIV prevention and treatment. The enormous burden of HIV, especially among trans feminine individuals, suggest a growing epidemic that requires us to address these challenges to engage transgender people and meet global objectives for HIV prevention and care. Future research should prioritize filling critical gaps in HIV epidemiology among transgender people in sub-Saharan Africa and Eastern Europe and rural areas globally. Studies are needed to clarify how stigma shapes syndemic factors to produce HIV and other deleterious effects on transgender health and ultimately to understand how best to implement acceptable, accessible, and effective HIV interventions for transgender people.

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ACKNOWLEDGMENTS

The authors are grateful to the numerous transgender people across the globe who contributed their data to the research studies summarized in this manuscript. We would like to acknowledge Nicolette Roque and Zhiyu Xia for their assistance with the literature search and data abstraction.

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REFERENCES

1. Cuypere GD, Hemelrijck MV, Michel A, et al. Prevalence and demography of transsexualism in Belgium. Eur Psychiatry. 2007;22:137–141.
2. Reed B, Rhodes S, Schofield P, et al. Gender Identity Research and Education Society. Gender Variance in the UK: Prevalence, Incidence, Growth, and Geographic Distribution; Available at: http://www.gires.org.uk/assets/Medpro-Assets/GenderVarianceUK-report.pdf. Accessed June 14, 2016.
3. Glen F, Hurrell K. Technical Note: Measuring Gender Identity. Manchester: Equality and Human Rights Commission; 2012.
4. Kuyper L, Wijsen C. Gender identities and gender dysphoria in the Netherlands. Arch Sex Behav. 2014;43:377–385.
5. Van Caenegem E, Wierckx K, Elaut E, et al. Prevalence of gender nonconformity in Flanders, Belgium. Arch Sex Behav. 2015;44:1281–1287.
6. Conron KJ, Scott G, Stowell GS, et al. Transgender health in Massachusetts: results from a household probability sample of adults. Am J Public Health. 2012;102:118–122.
7. Veale JF. Prevalence of transsexualism among New Zealand passport holders. Aust N Z J Psychiatry. 2008;42:887–889.
8. Clark T, Lucassen M, Bullen P, et al. The health and wellbeing of transgender high school students: results from the New Zealand adolescent health survey (Youth'12). J Adolesc Health. 2014;55:93–99.
9. Poteat T, German D, Flynn C. The conflation of gender and sex: gaps and opportunities in HIV data among transgender women and MSM. Glob Public Health.
10. Health Resources and Services Administration. Ryan White HIV/AIDS Program Annual Client-Level Data Report, 2014; 2015. Available at: http://hab.hrsa.gov/data/servicesdelivered/2014RWHAPDataReport.pdf. Accessed 20 March, 2016.
11. Poteat T, Reisner SL, Radix A. HIV epidemics among transgender women. Curr Opin HIV AIDS. 2014;9:168–173.
12. De Santis JP. HIV infection risk factors among male-to-female transgender persons: a review of the literature. J Assoc Nurses AIDS Care. 2009;20:362–372.
13. Nemoto T, Bodeker B, Iwamoto M, et al. Practices of receptive and insertive anal sex among transgender women in relation to partner types, sociocultural factors, and background variables. AIDS Care. 2014;26:434–440.
14. Coan D, Scharage W, Packer T. The role of male sexual partners in HIV infection among male-to-female transgendered individuals. In: Bockting W, Avery E, eds. Transgender Health and HIV Prevention: Needs Assessment Studies From Transgender Communities Across the United States. Vol. 8. Binghamton, NY: Haworth Medical Press; 2005.
15. Reisner SL, Murchison GR. A global research synthesis of HIV and STI biobehavioural risks in female-to-male transgender adults. Glob Public Health. 2016:1–22.
16. Veronese V, van Gemert C, Bulu S, et al. Sexually transmitted infections among transgender people and men who have sex with men in Port Vila, Vanuatu. Western Pac Surveill Response J. 2015;6:55–59.
17. Hembree WC, Cohen-Kettenis P, Delemarre-van de Waal HA, et al. Endocrine treatment of transsexual persons: an Endocrine society clinical practice guideline. J Clin Endocrinol Metab. 2009;94:3132–3154.
18. Wilson EC, Chen YH, Raad N, et al. Who are the sexual partners of transgender individuals? Differences in demographic characteristics and risk behaviours of San Francisco HIV testing clients with transgender sexual partners compared with overall testers. Sex Health. 2014;11:319–323.
19. Operario D, Nemoto T, Iwamoto M, et al. Risk for HIV and unprotected sexual behavior in male primary partners of transgender women. Arch Sex Behav. 2011;40:1255–1261.
20. Poteat T, Wirtz AL, Radix A, et al. HIV risk and preventive interventions in transgender women sex workers. Lancet. 2015;385:274–286.
21. Sevelius JM. Gender affirmation: a framework for conceptualizing risk behavior among transgender women of color. Sex Roles. 2013;68:675–689.
22. de Lind van Wijngaarden JW, Schunter BT, Iqbal Q. Sexual abuse, social stigma and HIV vulnerability among young feminised men in Lahore and Karachi, Pakistan. Cult Health Sex. 2013;15:73–84.
23. Reisner SL, White Hughto JM, Pardee D, et al. Syndemics and gender affirmation: HIV sexual risk in female-to-male trans masculine adults reporting sexual contact with cisgender males. Int J STD AIDS..
24. Baral S, Poteat T, Wirtz A, et al. Global burden of HIV infection among transgender persons: a systematic review and meta-analysis. J Int AIDS Soc. 2012;15:98–99.
25. Herbst JH, Jacobs ED, Finlayson TJ, et al. Estimating HIV prevalence and risk behaviors of transgender persons in the United States: a systematic review. AIDS Behav. 2008;12:1–17.
26. MacCarthy S, Reisner SL, Nunn A, et al. The time is now: attention increases to transgender health in the United States but scientific knowledge gaps remain. LGBT Health. 2015;2:287–291.
27. Baral S, Beyrer C, Poteat T. Human rights, the law, and HIV among transgender people. 2011. Paper prepared at: Third Meeting of the Technical Advisory Group of the Global Commission on HIV and the Law, New York, NY, July 7–9, 2011.
28. Hatzenbuehler ML, Phelan JC, Link BG. Stigma as a fundamental cause of population health inequalities. Am J Public Health. 2013;103:813–821.
29. Singer M. Introduction to Syndemics: A Critical Systems Approach to Public and Community Health. San Francisco, CA: Jossey-Bass; 2009.
30. Operario D, Nemoto T. HIV in transgender communities: syndemic dynamics and a need for multicomponent interventions. J Acquir Immune Defic Syndr. 2010;55(suppl 2):S91–S93.
31. Tsai AC, Burns BF. Syndemics of psychosocial problems and HIV risk: a systematic review of empirical tests of the disease interaction concept. Soc Sci Med. 2015;139:26–35.
32. Baral SD, Poteat T, Stromdahl S, et al. Worldwide burden of HIV in transgender women: a systematic review and meta-analysis. Lancet Infect Dis. 2013;13:214–222.
33. Nuttbrock L, Bockting W, Rosenblum A, et al. Gender abuse and incident HIV/STI among transgender women in New York city: buffering effect of involvement in a transgender community. AIDS Behav. 2015;19:1446–1453. 1448p.
34. Benotsch EG, Zimmerman R, Cathers L, et al. Non-medical use of prescription drugs, polysubstance use, and mental health in transgender adults. Drug Alcohol Depend. 2013;132:391–394.
35. Bradford J, Reisner SL, Honnold JA, et al. Experiences of transgender-related discrimination and implications for health: results from the Virginia transgender health initiative study. Am J Public Health. 2013;103:1820–1829.
36. Xavier J, Honnold JA, Bradford J. The health, health-related needs, and lifecourse experiences of transgender Virginians. Richmond, Virgina: Virginia department of health; Available at: https://www.vdh.virginia.gov/epidemiology/DiseasePrevention/documents/pdf/THISFINALREPORTVol1.pdf. Accessed June 14, 2016.
37. Feldman J, Romine RS, Bockting WO. HIV risk behaviors in the U.S. transgender population: prevalence and predictors in a large internet sample. J Homosex. 2014;61:1558–1588.
38. Green N, Hoenigl M, Morris S, et al. Risk behavior and sexually transmitted infections among transgender women and men undergoing community-based screening for acute and early HIV infection in San Diego. Medicine (Baltimore). 2015;94:e1830.
39. Habarta N, Wang G, Mulatu MS, et al. HIV testing by transgender status at centers for disease control and prevention-funded sites in the United States, Puerto Rico, and us Virgin Islands, 2009–2011. Am J Public Health. 2015;105:1917–1925.
40. Leinung MC, Urizar MF, Patel N, et al. Endocrine treatment of transsexual persons: extensive personal experience. Endocr Pract. 2013;19:644–650.
41. Reisner SL, White JM, Bradford JB, et al. Transgender health disparities: comparing full cohort and nested matched-pair study designs in a community health center. LGBT Health. 2014;1:177–184.
42. Reisner SL, Vetters R, White JM, et al. Laboratory-confirmed HIV and sexually transmitted infection seropositivity and risk behavior among sexually active transgender patients at an adolescent and young adult urban community health center. AIDS Care. 2015;27:1031–1036. 1036p.
43. Castel AD, Magnus M, Peterson J, et al. Implementing a novel citywide rapid HIV testing campaign in Washington, D.C.: findings and lessons learned. Public Health Rep. 2012;127:422–431.
44. Brennan J, Kuhns LM, Johnson AK, et al. Syndemic theory and HIV-related risk among young transgender women: the role of multiple, co-occurring health problems and social marginalization. Am Journal Public Health. 2012;102:1751–1757.
45. Garofalo R, Johnson AK, Kuhns LM, et al. Life skills: evaluation of a theory-driven behavioral HIV prevention intervention for young transgender women. J Urban Health. 2012;89:419–431.
46. Rowe C, Santos G-M, McFarland W, et al. Prevalence and correlates of substance use among trans*female youth ages 16–24 years in the San Francisco Bay Area. Drug Alcohol Depend. 2015;147:160–166. 167p.
47. Bowers JR, Branson CM, Fletcher JB, et al. Predictors of HIV sexual risk behavior among men who have sex with men, men who have sex with men and women, and transgender women. Int J Sex Health. 2012;24:290–302.
48. Fletcher JB, Kisler KA, Reback CJ. Housing status and HIV risk behaviors among transgender women in Los Angeles. Arch Sex Behav. 2014;43:1651–1661.
49. Rapues J, Wilson EC, Packer T, et al. Correlates of HIV infection among transfemales, San Francisco, 2010: results from a respondent-driven sampling study. Am J Public Health. 2013;103:1485–1492.
50. Reback CJ, Fletcher JB. HIV prevalence, substance use, and sexual risk behaviors among transgender women recruited through outreach. AIDS Behav. 2014;18:1359–1367.
51. Reisner SL, Gamarel KE, Nemoto T, et al. Dyadic effects of gender minority stressors in substance use behaviors among transgender women and their non-transgender male partners. Psychol Sex Orientat Gend Divers. 2014;1:63–71.
52. Peitzmeier SM, Reisner SL, Harigopal P, et al. Female-to-male patients have high prevalence of unsatisfactory Paps compared to non-transgender females: implications for cervical cancer screening. J Gen Intern Med. 2014;29:778–784.
53. Reisner SL, White JM, Mayer KH, et al. Sexual risk behaviors and psychosocial health concerns of female-to-male transgender men screening for STDs at an urban community health center. AIDS Care. 2014;26:857–864.
54. Aguayo N, Munoz SR, Aguilar G. HIV and SYPHILIS prevalence and behaviour, practises and attitudes of the TRANS population in Paraguay. Sex Transm Infect. 2011;2013:89.
55. Barrington C, Wejnert C, Guardado ME, et al. Social network characteristics and HIV vulnerability among transgender persons in San Salvador: identifying opportunities for HIV prevention strategies. AIDS Behav. 2012;16:214–224.
56. Best J, Tang W, Zhang Y, et al. Sexual behaviors and HIV/syphilis testing among transgender individuals in China: implications for expanding HIV testing services. Sex Transm Dis. 2015;42:281–285. 285p.
57. Carobene M, Bolcic F, Farías MSDR, et al. HIV, HBV, and HCV molecular epidemiology among trans (transvestites, transsexuals, and transgender) sex workers in Argentina. J Med Virol. 2014;86:64–70.
58. Castillo R, Konda KA, Leon SR, et al. HIV and sexually transmitted infection incidence and associated risk factors among high-risk MSM and male-to-female transgender women in Lima, Peru. J Acquir Immune Defic Syndr. 2015;69:567–575.
59. Costa AB, Fontanari AM, Jacinto MM, et al. Population-based HIV prevalence and associated factors in male-to-female transsexuals from Southern Brazil. Arch Sex Behav. 2015;44:521–524.
60. Fernandes FRP, Zanini PB, Rezende GR, et al. Syphilis infection, sexual practices and bisexual behaviour among men who have sex with men and transgender women: a cross-sectional study. Sex Transm Infect. 2015;91:142–149.
61. Lipsitz MC, Segura ER, Castro JL, et al. Bringing testing to the people - benefits of mobile unit HIV/syphilis testing in Lima, Peru, 2007–2009. Int J STD AIDS. 2014;25:325–331.
62. Martins TA, Kerr LR, Macena RH, et al. Travestis, an unexplored population at risk of HIV in a large metropolis of northeast Brazil: a respondent-driven sampling survey. AIDS Care. 2013;25:606–612.
63. Pinheiro Júnior FML, Kendall C, Martins TA, et al. Risk factors associated with resistance to HIV testing among transwomen in Brazil. AIDS Care. 2016;28:92–97.
64. Silva-Santisteban A, Raymond HF, Salazar X, et al. Understanding the HIV/AIDS epidemic in transgender women of Lima, Peru: results from a sero-epidemiologic study using respondent driven sampling. AIDS Behav. 2012;16:872–881.
65. Solomon MM, Nureña CR, Tanur JM, et al. Transactional sex and prevalence of STIs: a cross-sectional study of MSM and transwomen screened for an HIV prevention trial. Int J STD AIDS. 2015;26:879–886.
66. Subramanian T, Ramakrishnan L, Aridoss S, et al. Increasing condom use and declining STI prevalence in high-risk MSM and TGs: evaluation of a large-scale prevention program in Tamil Nadu, India. BMC Public Health. 2013;13:857.
67. Verre MC, Peinado J, Segura ER, et al. Socialization patterns and their associations with unprotected anal intercourse, HIV, and syphilis among high-risk men who have sex with men and transgender women in Peru. AIDS Behav. 2014;18:2030–2039.
68. Zea MC, Reisen CA, del Río-González AM, et al. HIV prevalence and awareness of positive serostatus among men who have sex with men and transgender women in Bogotá, Colombia. Am J Public Health. 2015;105:1588–1595. 1588p.
69. Akhtar H, Badshah Y, Akhtar S, et al. Prevalence of human immunodeficiency virus infection among transgender men in Rawalpindi (Pakistan). Virol J. 2012;9:229.
70. Almeida A, Brasileiro A, Costa J, et al. Prevalence of and factors mediating HIV infection among sex workers in Lisbon, Portugal: the 5-year experience of a community organisation. Sex Transm Infect. 2014;90:497.
71. Altaf A, Zahidie A, Agha A. Comparing risk factors of HIV among hijra sex workers in Larkana and other cities of Pakistan: an analytical cross sectional study. BMC Public Health. 2012;12:279.
72. Bauer GR, Travers R, Scanlon K, et al. High heterogeneity of HIV-related sexual risk among transgender people in Ontario, Canada: a province-wide respondent-driven sampling survey. BMC Public Health. 2012;12:292.
73. Dias S, Gama A, Fuertes R, et al. Risk-taking behaviours and HIV infection among sex workers in Portugal: results from a cross-sectional survey. Sex Transm Infect. 2015;91:346–352.
74. Diez M, Bleda MJ, Varela JA, et al. Trends in HIV testing, prevalence among first-time testers, and incidence in most-at-risk populations in Spain: the EPI-VIH study, 2000 to 2009. Euro Surveill. 2014;19:20971.
75. Emmanuel F, Salim M, Akhtar N, et al. Second-generation surveillance for HIV/AIDS in Pakistan: results from the 4th round of integrated behavior and biological survey 2011–2012. Sex Transm Infect. 2013;89(suppl 3):iii23–iii28.
76. Fernandez-Balbuena S, Belza MJ, Urdaneta E, et al. Serving the underserved: an HIV testing program for populations reluctant to attend conventional settings. Int J Public Health. 2015;60:121–126.
77. Nemoto T, Iwamoto M, Perngparn U, et al. HIV-related risk behaviors among kathoey (male-to-female transgender) sex workers in Bangkok, Thailand. AIDS Care. 2012;24:210–219.
78. Sahastrabuddhe S, Gupta A, Stuart E, et al. Sexually transmitted infections and risk behaviors among transgender persons (hijras) of Pune, India. J Acquir Immune Defic Syndr. 2012;59:72–78.
79. Yadegarfard M, Ho R Fau - Bahramabadian F, Bahramabadian F. Influences on loneliness, depression, sexual-risk behaviour and suicidal ideation among Thai transgender youth. Cult Health Sex. 2013;15:726–737.
80. Manieri C, Castellano E, Crespi C, et al. Medical treatment of subjects with gender identity disorder: the experience in an Italian public health center. Int J Transgenderism. 2014;15:53–65. 13p.
81. Ramakrishnan L, Goswami P, Subramaniam T, et al. Transgender in Tamil Nadu are still highly vulnerable to HIV and STIs: findings from bio-behavioral surveys. J Int AIDS Soc. 2012;15:154–155.
82. Socias ME, Marshall BD, Aristegui I, et al. Factors associated with healthcare avoidance among transgender women in Argentina. Int J Equity Health. 2014;13:81.
83. Reisner SL, Biello K, Rosenberger JG, et al. Using a two-step method to measure transgender identity in Latin America/the Caribbean, Portugal, and Spain. Arch Sex Behav. 2014;43:1503–1514.
84. Buchbinder SP, Glidden DV, Liu AY, et al. HIV pre-exposure prophylaxis in men who have sex with men and transgender women: a secondary analysis of a phase 3 randomised controlled efficacy trial. Lancet Infect Dis. 2014;14:468–475.
85. Patrasciouiu I, Lopez CQ, Porta MM, et al. Characteristics of the HIV positive transgender population of Catalonia. 15th European Congress of Endocrinology, Copenhagen; 2013.
86. Rich A, Lachowsky NJ, Blackwell ED, et al. Making sense of the inclusion of transgender men and their HIV risk profile within a biobehavioural population study of gay and other men who have sex with men (MSM) in Vancouver, British Columbia. Can J Infect Dis Med Microbiol. 2015;26:115B.
87. Scheim AI, Santos GM, Arreola S, et al. Inequities in access to HIV prevention services for transgender men: results of a global survey of men who have sex with men. J Int AIDS Soc. 2016. In press. Under review.
88. Chakrapani V, Newman PA, Shunmugam M, et al. Syndemics of depression, alcohol use, and victimisation, and their association with HIV-related sexual risk among men who have sex with men and transgender women in India. Glob Public Health. 2015 Oct;12:1–16.
89. Chu PL, Santos GM, Vu A, et al. Impact of syndemics on people living with HIV in San Francisco. J Int AIDS Soc. 2012;15:102–103.
90. Operario D, Yang MF, Reisner SL, et al. Stigma and the syndemic of HIV-related health risk behaviors in a diverse sample of transgender women. J Community Psychol. 2014;42:544–557.
91. Wilson EC, Chen YH, Arayasirikul S, et al. Differential HIV risk for racial/ethnic minority trans*female youths and socioeconomic disparities in housing, residential stability, and education. Am J Public Health. 2015;105(suppl 3):e41–e47.
92. Zimmerman RS, Benotsch EG, Shoemaker S, et al. Mediational models linking psychosocial context, mental health problems, substance use, and HIV risk behaviors in transgender women. Health Psychol Behav Med. 2015;3:379–390.
93. Centers for Disease Control and Prevention. HIV Surveillance Report, 2014. Vol. 26; 2015. Available at: http://www.cdc.gov/hiv/library/reports/surveillance. Accessed January 22, 2016.
94. Operario D, Nemoto T, Iwamoto M, et al. Unprotected sexual behavior and HIV risk in the context of primary partnerships for transgender women. AIDS Behav. 2011;15:674–682.
95. Maulsby C, Millett G, Lindsey K, et al. HIV among Black men who have sex with men (MSM) in the United States: a review of the literature. AIDS Behav. 2014;18:10–25.
96. Mizuno Y, Borkowf C, Millett GA, et al. Homophobia and racism experienced by Latino men who have sex with men in the United States: correlates of exposure and associations with HIV risk behaviors. AIDS Behav. 2012;16:724–735.
97. Nemoto T, Cruz TM, Iwamoto M, et al. A tale of two cities: access to care and services among African-American transgender women in Oakland and san Francisco. LGBT Health. 2015;2:235–242.
98. Deblonde J, Sasse A, Del Amo J, et al. Restricted access to antiretroviral treatment for undocumented migrants: a bottle neck to control the HIV epidemic in the EU/EEA. BMC Public Health. 2015;15:1228.
99. Tsai AC, Venkataramani AS. Syndemics and health disparities: a methodological note. AIDS Behav. 2016;20:423–30.
100. Deutsch MB, Glidden DV, Sevelius J, et al. HIV pre-exposure prophylaxis in transgender women: a subgroup analysis of the iPrEx trial. Lancet HIV. 2015;2:e512–519.
101. Wilson EC, Chen Y-H, Arayasirikul S, et al. Connecting the dots: examining transgender women's utilization of transition-related medical care and associations with mental health, substance use, and HIV. J Urban Health. 2015;92:182–192. 111p.
102. Reisner SL, Bradford J, Hopwood R, et al. Comprehensive transgender healthcare: the gender affirming clinical and public health model of fenway health. J Urban Health. 2015;92:584–592.
103. Reback CJ, Ferlito D, Kisler KA, et al. Recruiting, linking, and retaining high-risk transgender women into HIV prevention and care services: an overview of barriers, strategies, and lessons learned. Int J Transgenderism. 2015;16:209–221.
104. Poteat T, German D, Flynn C. The conflation of gender and sex: gaps and opportunities in HIV data among transgender women and MSM. Glob Public Health. 2016 January;20:1–14.
105. Sevelius JM, Keatley J, Calma N, Arnold E. ‘I am not a man’: Trans-specific barriers and facilitators to PrEP acceptability among transgender women. Global Public Health. 2016 Mar;10:1–16.
106. Poteat T, German D, Kerrigan D. Managing uncertainty: a grounded theory of stigma in transgender health care encounters. Social Sci Med. 2013;84:22–29. 28p.
Keywords:

transgender; HIV epidemiology; HIV treatment; prevention; syndemics

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