Sexually transmitted infection screening uptake and knowledge of sexually transmitted infection symptoms among female sex workers participating in a community randomised trial in Peru

Abstract

This study aims to evaluate condom use, sexually transmitted infection (STI) screening, and knowledge of STI symptoms among female sex workers in Peru associated with sex work venues and a community randomised trial of STI control. One component of the Peru PREVEN intervention conducted mobile-team outreach to female sex workers to reduce STIs and increase condom use and access to government clinics for STI screening and evaluation. Prevalence ratios were calculated using multivariate Poisson regression models with robust standard errors, clustering by city. As-treated analyses were conducted to assess outcomes associated with reported exposure to the intervention. Care-seeking was more frequent in intervention communities, but differences were not statistically significant. Female sex workers reporting exposure to the intervention had a significantly higher likelihood of condom use, STI screening at public health clinics, and symptom recognition compared to those not exposed. Compared with street- or bar-based female sex workers, brothel-based female sex workers reported significantly higher rates of condom use with last client, recent screening exams for STIs, and HIV testing. Brothel-based female sex workers also more often reported knowledge of STIs and recognition of STI symptoms in women and in men. Interventions to promote STI detection and prevention among female sex workers in Peru should consider structural or regulatory factors related to sex work venues.

Keywords

Female sex workers Peru sexually transmitted infection health behavior

Introduction

Female sex workers (FSWs) are a vulnerable population at high risk for acquisition of sexually transmitted infections (STIs).¹ They have also been considered a bridge group in terms of transmission of STIs from high-risk to general populations.^2–5 They represent a key target population for promotion of health care-seeking for STI diagnosis, treatment, and prevention interventions. However, FSWs are often marginalised, isolated, and difficult to reach for intervention in many settings because sex work is illegal and covert in most countries, and sex workers are not always readily identifiable as such. Many FSWs are reluctant to self-identify for fear of violence or persecution by authorities.^6–8

There is an increasing body of evidence that demonstrates that multi-component interventions including peer support, condom promotion, and access to STI screening services are associated with decreased STI prevalence and improved condom use among sex workers.^9–14 While clinic-based screening interventions are effective, engaging FSWs to access clinic-based services in the context of fear of persecution, lack of knowledge and stigma is a challenge.¹⁵ And while outreach sites may engage FSWs outside of clinics, they often lack the scope to address the diversity of reproductive health issues experienced by FSWs.¹⁴ Few studies address FSWs’ linkage to and engagement in formal health care services. Furthermore, among community-based intervention studies, few are randomised trials.

Interventions that promote health care-seeking behavior as a component of a causal pathway toward improving biological endpoints can be placed within a broad conceptual framework that includes processes and factors operating at individual, socio-cultural, geographical, demographic, economic, and other structural levels.^16,17 While individual factors such as higher education and knowledge of STIs are protective against HIV/STI acquisition,¹⁸ structural interventions such as community mobilisation, venue-based support, or empowerment efforts have been identified as being promising mechanisms for decreasing FSW STI risk and improving linkage to health services.^14,19 It is important, therefore, to understand not only individual knowledge and demographic factors related to health-seeking behavior, but to also assess the association between structural factors and STI-related health care-seeking behaviors.

The present analysis was undertaken as a component of the Peru PREVEN Study, in which 20 cities with populations >50,000 underwent pair-wise randomisation to a multi-component STI intervention that included mobile team-based FSW outreach.²⁰ Pre-intervention baseline analyses for the PREVEN study demonstrated that self-medication, or treating oneself in the absence of medical advice, for symptomatic STIs was less likely among FSWs who reported being aware of STI services and those based at brothel venues.²¹ This present analysis further aims to evaluate uptake of health screening and HIV/STI preventive behaviors among FSWs in mid-sized cities in Peru, regardless of symptoms, associated with the community-randomised trial intervention. A second analysis further assesses screening outcomes associated with sex work venues.

Methods

Study design

The Peru PREVEN study was a community randomised trial conducted between 2003 and 2006 in medium-sized cities in Peru. Trial methods have been previously described elsewhere.^20,22 The primary study endpoints determined in 2006 were combined prevalence of the major curable STIs in the general population and among FSWs.²⁰ The PREVEN multi-component HIV/STI intervention consisted of three key components: strengthened STI syndromic management for the general population; mobile team outreach to FSWs; and condom promotion among the general population and FSWs. Training of clinicians and pharmacy workers, and a health communication campaign on STI recognition and care-seeking, were implemented in the general population in 2005 to support syndromic management.

The mobile team component aimed to increase condom use and increase care-seeking for screening, diagnosis, and treatment of STIs among FSWs.²³ Each outreach team was led by a health professional and an FSW peer educator, and later visit cycles included a counsellor. Intervention sites including brothels, bars, and street venues were identified continuously via key informant interviews. Each intervention cycle was eight weeks long, during which the mobile team visited every identified sex work venue in the city. In addition to presumptive periodic treatment with metronidazole 2 g orally every two months for trichomoniasis and/or bacterial vaginosis, counselling was provided at each visit and included promotion of condom use, information on STI symptom recognition, and information about available government-provided health services.

Ethical considerations

This study was approved by the Institutional Review Boards at the University of Washington (16764), Universidad Peruana Cayetano Heredia (99084), and the United States Naval Medical Research Center Detachment in Peru (NMRCD.2002.0016). The clinical trial registration number is ISRCTN43722548.

Data collection

Cross-sectional surveys were conducted among FSWs in intervention and control cities at baseline in 2002–2003, during 2005, and at the end of the intervention in late 2006. Interviews were conducted among women found offering sex services at increasing numbers of venues identified over the three-year intervention. These venues included street, brothel, and bar-based settings. FSWs who were 14 years of age or older and were willing and able to provide informed consent were included. Participation in previous surveys, including prior Peru-PREVEN surveys, did not preclude participation. Trained fieldworkers administered questionnaires through face-to-face interviews.

Definitions

For this analysis, outcomes of interest included seeking a periodic STI screening exam from a government health facility during the prior six months, HIV testing within the last year, and ability to describe symptoms of STIs in women and in men. Perceived risk of HIV is also included as it has frequently been included in conceptual models of health care-seeking behavior in terms of perceived threat of disease and need for medical support.^16,24–26 Symptoms were free-listed by participants and recorded where answered correctly. The median number of correctly identified symptoms was summarised, and a binary variable denoting report equal to or more than median number of reported symptoms was computed. Symptoms included lower abdominal pain, vaginal discharge, foul-smelling discharge, burning or pain on urination, genital ulcers or sores, swelling in the groin, genital itching, and genital warts among women; and urethral discharge, burning or pain on urination, genital sores or ulcers, swelling in the groin, and genital warts among men. Self-reported condom use outcomes with most recent client and non-client were also assessed. Uptake of services for STI treatment among symptomatic FSWs will be presented in a separate manuscript.

Statistical analysis

Statistical analyses used data from the 2006 FSW surveys, adjusting for city-specific baseline values from the 2002 surveys in measurement of intervention effects. Descriptive categorical variables were presented as frequencies and continuous variables as medians and interquartile ranges (IQR). FSW characteristics associated with sex work venues were tested using Chi square analysis and non-parametric tests of the equality of medians.²⁷ Prevalence ratios for behavioral outcomes associated with the intervention were calculated using non-paired, multivariate generalised linear models (STATACorp, College Station, TX), utilising Poisson family with robust standard errors and accounting for clustering by city. Intervention analyses were adjusted for city-specific 2002–2003 baseline responses, age, and brothel venue, as there were a higher proportion of brothels in intervention than in control cities, and FSWs in control cities were significantly older.²⁰ A secondary ‘as treated’ analysis was conducted using report of receiving services or participating in activities with the PREVEN mobile team as an exposure variable. Analyses of outcomes associated with brothel venues used similar statistical methods, though did not control for baseline, but rather for hypothesised confounders of age, marital/cohabitation status, geographical region, alcohol use, education, randomisation arm, and city cluster.

Results

Population and sample

In all, 4156 FSWs were enrolled in 20 cities; 2063 from control and 2093 from intervention cities. Key demographic characteristics of the sample are described elsewhere.²² Of the 4156 participants, 44% were located in coastal cities, 36% in highlands cities, and 20% in jungle cities. 21% of FSWs were brothel-based, 23% street-based, and 56% were bar- or nightclub-based. Median age at first paid sex was 21 years and median duration of sex work was 20 months. Sex work was relatively frequent, with a median of six days worked in the last week, four weeks in the last month and eight months in the last year. Frequency of sex work increased with age (p < 0.001). FSWs reported a median of nine paying sex partners within the last week and two clients on the last day of work. Approximately 30% reported a source of income other than sex work.

FSW characteristics and venue of sex work

Brothel-based and street-based sex workers were similar in terms of socio-demographic characteristics (Table 1); while bar-based sex workers were significantly younger, more likely to be from jungle and highlands regions than from the coast, less likely to have ever been married or to be currently living with a sex partner, had received more education, and received higher payment per sexual transaction. Bar-based sex workers reported more frequent use of alcohol before sex with a paying client, with more than half reporting alcohol use ‘most of the time’ or ‘always’. Patterns of sex work varied by work venue, with brothel-based workers reporting significantly more clients than bar- or street-based workers.

Table 1.

Characteristics of female sex workers (FSWs) by venue of sex work (2006 Survey).

	Brothel n = 846 (21.0%)	Bar n = 2263 (56.3%)	Street n = 913 (22.7%)
	n (%) or	n (%) or	n (%) or
Characteristic	Median (IQR)	Median (IQR)	Median (IQR)	p Value
Age	25 (22--30)	23 (20–27)	27 (22–36)	<0.001
Education
Incomplete primary	94 (11.1)	172 (7.6)	125 (13.7)	<0.001
Complete primary	353 (41.7)	885 (39.1)	420 (46.0)
Complete secondary	300 (35.5)	897 (39.6)	299 (32.8)
Any superior	52 (6.2)	176 (7.8)	35 (3.8)
Region
Coast	500 (59.1)	737 (32.6)	597 (65.4)	<0.001
Highlands	201 (23.8)	1009 (44.6)	164 (18.0)
Jungle	145 (17.1)	517 (22.9)	152 (16.7)
Ever married or cohabitating	668 (79.0)	1425 (63.0)	725 (79.4)	<0.001
Currently living with sex partner	356 (42.6)	588 (26.8)	410 (45.4)	<0.001
Partner does not know about sex work	55 (6.5)	397 (17.5)	106 (11.6)	<0.001
Number of clients (last seven days)	53 (25–80)	5 (3–10)	12 (6–20)	<0.001
Number of clients last day of sex work	9 (4–15)	1 (1–2)	3 (2–4)	<0.001
How much last regular client paid (soles)	15 (10–20)	60 (30–130)	20 (15–35)	<0.001
Number of months in sex work	24.5 (12–60)	13 (5–30)	36 (12–84)	<0.001
Number of days working in last week	7 (6–7)	5 (3–7)	6 (4–7)	<0.001
Other employment than sex work	108 (12.8)	709 (31.3)	297 (32.5)	<0.001
Frequency of alcohol use before sex with paying client
Never	414 (48.9)	160 (7.1)	369 (40.4)	<0.001
Some of the time	368 (43.5)	850 (37.6)	474 (51.9)
Most of the time	32 (3.8)	598 (26.4)	40 (4.4)
Always	28 (3.3)	588 (26.0)	13 (1.4)
Reside in intervention city	553 (65.4)	1197 (52.9)	330 (36.1)	<0.001

Intervention arm and reported exposure to intervention

Although proportions of FSWs accessing STI screening services and reporting knowledge of STI symptoms all were higher in intervention cities, these differences were not statistically significant (Table 2). Condom use outcomes are analysed in detail elsewhere and were similar between intervention and control groups.²⁰ Among FSWs surveyed in 2006, 4% in the control arm and 75% in the intervention arm reported receiving services from or ever participating in activities with the mobile PREVEN outreach team. Associations between outcomes of interest and reported exposure to the intervention are detailed in Table 3. Reported exposure to the mobile team intervention was associated with an increased likelihood of reported condom use with last non-client (PR 1.46; 95%CI 1.01–2.10), ever seeking an STI screening exam (PR = 1.28; 95%CI 1.03–1.59), ever receiving HIV testing (PR = 1.24; 95%CI 1.04–1.48), receiving recent HIV testing (PR = 1.26; 95%CI 1.02–1.57), knowledge of STIs (PR = 1.11; 95%CI 1.06–1.15), and awareness of female and male STI symptoms (PR = 1.32; 95%CI 1.07–1.64 and PR = 1.50; 95%CI 1.21–1.86, respectively). There was a trend towards increased frequency of recent screening exams at a public STI clinic.

Table 2.

Sexually transmitted infection (STI) screening and knowledge of STI symptoms associated with Peru PREVEN intervention (2006 Survey).

	Control n = 2063 (49.6%)	Intervention n = 2093 (50.4%)	aPR^a (95% CI)	p
STI screening
Aware that gov’t health centers provide screening exams to FSW	1498 (72.8)	1656 (79.3)	1.02 (0.90–1.16)	0.769
Ever sought a screening exam at gov’t health center^b	1132 (56.7)	1301 (63.1)	1.02 (0.81–1.27)	0.876
At least one attempt to receive screening exam in last six months^b	1062 (52.3)	1191 (57.3)	0.97 (0.76–1.23)	0.799
Ever HIV test	1272 (63.0)	1463 (70.4)	1.02 (0.86–1.21)	0.828
HIV test in last year^b	1118 (55.7)	1275 (61.5)	0.96 (0.77–1.20)	0.730
Believe self at high risk of acquiring HIV^c	854 (42.5)	1082 (52.9)	1.17 (0.76–1.78)	0.477
Knowledge of symptoms
Ever heard of STIs	1824 (90.6)	1931 (95.0)	1.04 (0.98–1.09)	0.201
Describe symptoms in women
Median (IQR) sum of symptoms mentioned	3 (1–4)	3 (1–4)	1.11 (0.82–1.51)	0.506
≥Overall median	1032 (50.1)	1234 (59.1)
Describe symptoms in men
Median (IQR) sum of symptoms mentioned	1 (0–2)	2 (1–3)	1.23 (0.90–1.68)	0.191
≥Overall median	1355 (65.8)	1595 (76.3)

Adjusted for 2002 baseline city proportions, age, brothel venue, and clustering by city.

Recoded as zero if skipped out of parent question.

Not adjusted for baseline, not asked in 2002 surveys.

Table 3.

Condom use, sexually transmitted infection (STI) screening, and knowledge of STI symptoms associated with reported exposure to Peru PREVEN intervention (2006 Survey).

	No exposure to PREVEN mobile teams n = 2475 (60.3%)	Reported exposure to PREVEN mobile teams n = 1628 (39.7%)	aPR^a (95% CI)	P
Condom use
One or more condoms on-hand right now or in your room	2011 (86.6)	1460 (90.7)	1.02 (0.94–1.11)	0.575
Condom use at last vaginal sex with a client	2209 (95.7)	1530 (97.3)	1.01 (0.99–1.03)	0.188
Condom use at last vaginal sex with a non-client	278 (23.7)	347 (33.1)	1.46 (1.01–2.10)	0.045
STI screening
Aware that gov’t health centers provide screening exams to FSW	1677 (67.8)	1440 (88.5)	1.22 (1.06–1.39)	0.004
Ever sought a screening exam at gov’t health center^b	1223 (50.7)	1183 (73.8)	1.28 (1.03–1.59)	0.028
At least one attempt to receive screening exam in last six months^b	1149 (47.0)	1077 (66.7)	1.22 (0.97–1.52)	0.083
Ever had a HIV test	1405 (57.8)	1296 (80.2)	1.24 (1.04–1.48)	0.014
HIV test in last year^b	1201 (49.7)	1161 (71.8)	1.26 (1.02–1.57)	0.036
Believe self at high risk of acquiring HIV	1057 (43.8)	853 (53.5)	1.09 (0.79–1.52)	0.598
Knowledge of symptoms
Ever heard of STIs	2145 (88.7)	1567 (99.0)	1.11 (1.06–1.15)	<0.001
Describe symptoms in women
Median (IQR) sum of symptoms mentioned	2 (1–4)	3 (2–4)	1.32 (1.07–1.64)	0.011
≥Overall median	1145 (46.3)	1094 (67.3)
Describe symptoms in men
Median (IQR) sum of symptoms mentioned	1 (0–2)	2 (1–3)	1.50 (1.21–1.86)	<0.001
≥Overall median	1044 (42.2)	1134 (69.7)

FSW survey asked: Have you received services from (or participated in activities of) the PREVEN Mobile Team?

Adjusted for baseline city proportions, age, brothel venue, education, cohabitation, randomisation arm, and region. Cluster by city.

Recoded as zero if skipped out of parent question.

Sex work venue, condom use, and uptake of STI screening services

Prevalence ratios evaluating relationships of sex work venues and uptake of STI screening services are described in Table 4. Outcomes for street-based and bar-based FSWs were initially analysed separately but were nearly identical, and were therefore combined. Brothel-based FSWs reported significantly higher rates of condom use with clients (PR = 1.04; 95%CI 1.02–1.06), recent STI screening exams (PR = 1.97; 95%CI 1.58–2.45), and HIV testing in the last year (PR = 1.74; 95% CI 1.45–2.09) compared with FSWs who were street- or bar-based. They more often reported perceived risk of HIV acquisition (PR = 1.38 95%CI 1.15–1.65) than street- or bar-based FSWs. Brothel-based FSWs also more frequently reported knowledge of STIs (PR = 1.07; 95%CI 1.04–1.09) and identified more symptoms of STIs in women (PR = 1.39; 95%CI 1.22–1.59) and in men (PR = 1.32; 95%CI 1.12–1.57).

Table 4.

Condom use, sexually transmitted infection (STI) screening, and knowledge of STI symptoms associated with venue of sex work (2006 Peru PREVEN Survey).

	Brothel n = 846 (21.0%)	Street/Bar n = 3310 (79.0%)	aPR^a (95% CI)	p
Condom use
One or more condoms on-hand right now in your room or on your person	831 (98.3)	2677 (85.6)	1.15 (1.08–1.23)	<0.001
Condom use at last vaginal sex with a client	837 (98.9)	2944 (95.7)	1.04 (1.02–1.06)	<0.001
Condom use at last vaginal sex with a non-client	169 (32.7)	462 (26.7)	1.28 (0.97–1.69)	0.081
STI screening
Aware that gov’t health centers provide screening exams to FSW	799 (94.7)	2355 (71.3)	1.29 (1.16–1.43)	<0.001
Ever sought a screening exam at gov’t health center^b	744 (91.1)	1689 (52.1)	1.75 (1.43–2.14)	<0.001
At least one attempt to receive screening exam in last six months^b	750 (89.5)	1503 (46.0)	1.97 (1.58–2.45)	<0.001
Ever had a HIV test	762 (91.5)	1973 (60.5)	1.47 (1.28–1.70)	<0.001
HIV test in last year^b	740 (88.1)	1653 (51.0)	1.74 (1.45–2.09)	<0.001
Believe self at high risk of acquiring HIV	563 (66.8)	1373 (42.8)	1.38 (1.15–1.65)	0.001
Knowledge of symptoms
Ever heard of STIs	810 (98.5)	2945 (91.3)	1.07 (1.04–1.09)	<0.001
Describe symptoms in women
Median (IQR) sum of symptoms mentioned	3 (2–4)	3 (1–4)	1.39 (1.22–1.59)	<0.001
≥overall median	601 (71.2)	1665 (50.4)
Describe symptoms in men
Median (IQR) sum of symptoms mentioned	2 (1–3)	1 (0–3)	1.33 (1.12–1.57)	<0.001
≥overall median	596 (70.5)	1612 (48.8)

Adjusted for age, education, cohabitation, region, randomisation arm, and alcohol use. Cluster by city.

Recoded as zero if skipped out of parent question.

Discussion

Despite significantly greater reductions in prevalence of curable STIs among FSWs from intervention cities than in control cities during the Peru PREVEN community randomised trial, we did not find statistically significant increases in uptake of STI screening services when comparing intervention and control cities after adjusting for baseline. One possible explanation is the mobility of FSWs, diffusion of the intervention across units of analysis (cities). Outcome surveys were performed at the city-level and enrolled FSWs separately from the intervention, thus one-quarter of the women completing outcome surveys in the intervention cities had not participated in the intervention. Furthermore, the mobile teams reported high turn-over among participants; after the fifth cycle of the intervention, more than half of FSWs were identified as first-time participants.²³ This is supported by consistent associations between increased health screening behaviors and reported exposure to the intervention. Another explanation could be the presence of social desirability bias in reporting sexual behaviors. In this study for example, more than 90% of participants in both cities reported condom use with their last client, numbers remarkably higher than most studies in other settings. Follow-up qualitative work revealed that participants were reluctant to admit non-condom use not only to research teams but also among their peers, especially in brothel settings where condom use was strictly enforced (C. Mejia, personal communication, 2012). However sex workers still acknowledged less condom use with non-clients than with clients and somewhat less condom use among FSWs not exposed to the intervention.

Another possible explanation is related to decreased statistical power when accounting for clustering by city.^28,29 In our study, the design was powered for STI endpoints, which were less frequent than reported uptake of health services. Similar studies reporting statistically significant outcomes have been critiqued for failing to account for clustering in study design or analysis.⁹ Finally, it is possible that reductions in curable STI rates were a result of periodic presumptive treatment for vaginal trichomoniasis, and testing and specific treatment for STIs, in addition to the moderate behavior change brought about by the counselling aspects of the intervention.

A recent systematic review of HIV risk among FSWs suggests an iterative and dynamic interaction between individual sex worker, client, work environment, community organization, and macrostructural factors.³⁰ An interesting finding in our analysis was that although street-based and brothel-based sex workers were more similar to each other than bar-based workers in demographic profiles, it was bar-based and street-based workers who had similar health-seeking behaviors, suggesting that structural factors operating in brothels could ‘override’ individual demographic risk characteristics. Similar findings were noted among injection drug-using FSWs in another semi-regulated setting in Tijuana, where policy environment and micro-social factors, such as having syringes confiscated by police, predominately drove increased HIV risk more so than individual level factors.⁷ In the Philippines, structural factors including trafficking or managerial practices of having condoms available in sex work venues were independently associated with FSWs’ ability to negotiate condom use with clients.³¹

In the context of Peru, as in many countries, prostitution has essentially had a quasi-legal status, in which sex work is generally not penalised, though efforts to promote it, especially with children, are considered criminal. Government health clinics in Peru offer free STI screening and treatment for FSWs, and regularly provided FSWs with documentation ‘carnets’ in order to verify health status. Although operation of brothels is not legal, they often operate and pay taxes under the auspices of a legally licensed establishment such as a bar or hotel. Outdated regulations required brothel-based FSWs to provide ‘carnet’ documentation of health status. Although these regulations were no longer enforced during the period of the study, many brothel owners continued to require condom use and health card documentation as a matter of practice.

Reported STI rates among FSWs have varied throughout the world by geographic location and type of sex work venue. However, which venues are of highest risk in any given setting has also varied tremendously. Bar-based or nightlife workers in Tijuana, Mexico, were characterised as at higher risk due to alcohol use and absence of regulatory enforcement,³² while street-based sex workers in Bangkok, Thailand, had higher HIV and syphilis prevalences than other sex workers.³³ In Queensland, Australia, sex workers employed at licensed brothels were less likely to report gonorrhea than illegal street-based workers,³⁴ but brothel-based workers in Karnataka State in India were found to have higher rates of HIV infection and lower risk-reduction behaviors than street- and home-based FSWs.¹⁰ The regulatory practices associated with the type of sex venue such as 100% condom use ‘house-rules’ or requirement of regular STI screening, more so than the venue type per se, may be a predominant driver of health-seeking and STI preventive behaviors among FSWs and should be examined further.

Modeling analyses suggest that decriminalisation of sex work could avert 33–46% of HIV infections over the next decade.³⁰ While regulation of sex work may promote positive health-seeking behaviors among FSWs, there is also concern that regulations have the potential to push the most vulnerable sex workers, such as those who are already HIV-infected, into less-protected settings.^35–37 In our study only 21% of the 4156 women identified were brothel-based. In general it has been more difficult to identify and access sex workers in bars, nightclubs, or streets than in brothels.^8,32 Our findings suggest that mobile teams that include FSW peers may be an effective method in reaching out to provide STI prevention, diagnosis, and treatment services to socially marginalised FSWs in all settings and to foster subsequent engagement in formal public health services.

These findings contribute to a body of evidence suggesting a role for health promotion interventions for sex workers utilising mobile outreach and peer services. Sex work venue is significantly associated with the health care-seeking and STI preventive behaviors of sex workers, thus health promotion interventions to increase STI prevention and detection among FSWs should consider structural factors related to all types of sex work venue.

Footnotes

Acknowledgments

Authors acknowledge the Peru PREVEN Study Team and the partnership of numerous local institutions including the Ministry of Health & local health directorates, and the National HIV/STI Program.

Note

References

Baral

Ketende

Green

et al.

Reconceptualizing the HIV Epidemiology and Prevention Needs of Female Sex Workers (FSW) in Swaziland. PLoS One 2014; 9: e115465.

Huang

Wang

Martin

et al.

‘Bridge population’: sex workers or their clients? STI prevalence and risk behaviors of clients of female sex workers in China. AIDS Care 2011; 23(Suppl 1): 45–53.

Boily

Lowndes

Alary

. The impact of HIV epidemic phases on the effectiveness of core group interventions: insights from mathematical models. Sex Transm Infect 2002; 78(Suppl 1): i78–i90.

Aral

Blanchard

. Phase specific approaches to the epidemiology and prevention of sexually transmitted diseases. Sex Transm Infect 2002; 78(Suppl 1): i1–i2.

Kinsler

Blas

Cabral

et al.

Understanding STI risk and condom use patterns by partner type among female sex workers in Peru. Open AIDS J 2014; 8: 17–20.

Scorgie

Chersich

Ntaganira

et al.

Socio-demographic characteristics and behavioral risk factors of female sex workers in Sub-Saharan Africa: a systematic review. AIDS Behav 2012; 16: 920–933. .

Strathdee

Lozada

Martinez

et al.

Social and structural factors associated with HIV infection among female sex workers who inject drugs in the Mexico-US border region. PLoS One 2011; 6: e19048.

Vandepitte

Lyerla

Dallabetta

et al.

Estimates of the number of female sex workers in different regions of the world. Sex Transm Infect 2006; 82(Suppl 3): iii18–iii25.

Shahmanesh

Patel

Mabey

et al.

Effectiveness of interventions for the prevention of HIV and other sexually transmitted infections in female sex workers in resource poor setting: a systematic review. Trop Med Int Health 2008; 13: 659–679.

10.

Ramesh

Beattie

Shajy

et al.

Changes in risk behaviours and prevalence of sexually transmitted infections following HIV preventive interventions among female sex workers in five districts in Karnataka state, south India. Sex Transm Infect 2010; 86(Suppl 1): i17–i24.

11.

Kerrigan

Moreno

Rosario

et al.

Environmental-structural interventions to reduce HIV/STI risk among female sex workers in the Dominican Republic. Am J Public Health 2006; 96: 120–125.

12.

Steen

Chersich

Gerbase

et al.

Periodic presumptive treatment of curable sexually transmitted infections among sex workers: a systematic review. AIDS 2012; 26: 437–445.

13.

Reza-Paul

Beattie

Syed

et al.

Declines in risk behaviour and sexually transmitted infection prevalence following a community-led HIV preventive intervention among female sex workers in Mysore, India. AIDS 2008; 22(Suppl 5): S91–S100.

14.

Chersich

Luchters

Ntaganira

et al.

Priority interventions to reduce HIV transmission in sex work settings in sub-Saharan Africa and delivery of these services. J Int AIDS Soc 2013; 16: 17980.

15.

Beyrer

Crago

Bekker

et al.

An action agenda for HIV and sex workers. Lancet 2015; 385: 287–301.

16.

Ward

Mertens

Thomas

. Health seeking behaviour and the control of sexually transmitted disease. Health Policy Plan 1997; 12: 19–28.

17.

Andersen

. Revisiting the behavioral model and access to medical care: does it matter? J Health Soc Behav 1995; 36: 1–10.

18.

Shahmanesh

Cowan

Wayal

et al.

The burden and determinants of HIV and sexually transmitted infections in a population-based sample of female sex workers in Goa, India. Sex Transm Infect 2009; 85: 50–59.

19.

Blanchard

Mohan

Shahmanesh

et al.

Community mobilization, empowerment and HIV prevention among female sex workers in south India. BMC Public Health 2013; 13: 234.

20.

García

Holmes

Cárcamo

et al.

Prevention of sexually transmitted infections in urban communities (Peru PREVEN): a multicomponent community-randomised controlled trial. Lancet 2012; 379: 1120–1128.

21.

Gomez

Campos

Buendia

et al.

Studying complex interactions among determinants of healthcare-seeking behaviours: self-medication for sexually transmitted infection symptoms in female sex workers. Sex Transm Infect 2010; 86: 285–291.

22.

Cárcamo

Campos

García

et al.

Prevalences of sexually transmitted infections in young adults and female sex workers in Peru: a national population-based survey. Lancet Infect Dis 2012; 12: 765–773.

23.

Campos

Buffardi

Carcamo

et al.

Reaching the unreachable: providing STI control services to female sex workers via mobile team outreach. PLoS One 2013; 8: e81041.

24.

Kroeger

. Anthropological and socio-medical health care research in developing countries. Soc Sci Med 1983; 17: 147–161.

25.

Becker

Maiman

. Sociobehavioral determinants of compliance with health and medical care recommendations. Med Care 1975; 13: 10–24.

26.

Rosenstock

Strecher

Becker

. Social learning theory and the Health Belief Model. Health Educ Q 1988; 15: 175–183.

27.

StataCorp

. STATA Base Reference Manual, College Station, TX: Stata Press, 1985-2009.

28.

Hayes

Alexander

Bennett

et al.

Design and analysis issues in cluster-randomized trials of interventions against infectious diseases. Stat Methods Med Res 2000; 9: 95–116.

29.

Hughes

Kulich

. Cluster randomized trials for HIV prevention. Curr Opin HIV AIDS 2006; 1: 471–475.

30.

Shannon

Strathdee

Goldenberg

et al.

Global epidemiology of HIV among female sex workers: influence of structural determinants. Lancet 2015; 385: 55–71.

31.

Urada

Morisky

Pimentel-Simbulan

et al.

Condom negotiations among female sex workers in the Philippines: environmental influences. PLoS One 2012; 7: e33282.

32.

Goldenberg

Strathdee

Gallardo

et al.

How important are venue-based HIV risks among male clients of female sex workers? A mixed methods analysis of the risk environment in nightlife venues in Tijuana, Mexico. Health Place 2011; 17: 748–756.

33.

Nhurod

Bollen

Smutraprapoot

et al.

Access to HIV testing for sex workers in Bangkok, Thailand: a high prevalence of HIV among street-based sex workers. Southeast Asian J Trop Med Public Health 2010; 41: 153–162.

34.

Seib

Debattista

Fischer

et al.

Sexually transmissible infections among sex workers and their clients: variation in prevalence between sectors of the industry. Sex Health 2009; 6: 45–50.

35.

Sirotin

Strathdee

Lozada

et al.

Effects of government registration on unprotected sex amongst female sex workers in Tijuana; Mexico. Int J Drug Policy 2010; 21: 466–470.

36.

Seib

Fischer

Najman

. The health of female sex workers from three industry sectors in Queensland, Australia. Soc Sci Med 2009; 68: 473–478.

37.

Samaranayake

Chen

Hocking

et al.

Legislation requiring monthly testing of sex workers with low rates of sexually transmitted infections restricts access to services for higher-risk individuals. Sex Transm Infect 2009; 85: 540–542.