Abstract
Objective
To investigate the prevalence and risk factors of HIV and syphilis infection among men who have sex with men (MSM) in male sex workers (MSW).
Design
Cross-sectional survey.
Setting
Hangzhou, China.
Participants
259 MSW in MSM were recruited by respondent-driven sampling from May 2011 to December 2011.The inclusion criteria were: (1) age ≥18 years; (2) engaging in sex with men in the previous year and (3) willing to cooperate in the implementation of the study.
Outcome measures
HIV-related knowledge, high-risk behaviour and condom use.
Results
Among these MSW in MSM, 23.2% were infected with HIV and/or syphilis, 8.9% were infected only with HIV, 12.7% only with syphilis and 1.5% with HIV/syphilis co-infection; 96.6% sold sex to males, 8.9% bought sex from males and 15.4% sold sex to females; 49.0% had non-commercial sex behaviours with males and 24.3% with females. The rate of condom use while having commercial sex with clients was 86.9% and 53.3% (selling anal and oral sex to males, respectively), 95.5% (buying sex from males) and 77.5% (selling sex to females), respectively. Regarding their non-commercial sex behaviour, the rate of condom use was 77.2% (with males) and 49.2% (with females), respectively. Multivariate analysis showed that age >30 years (OR 1.055; 95% CIs 1.015 to 1.095) and having ≥10 non-commercial male sex partners (OR, 1.573; 95% CI 1.018 to 2.452) were significantly associated with HIV/syphilis infection, while heterosexuality (OR, 0.238; 95% CI 0.066 to 0.855) was significantly associated with a low HIV/syphilis infection rate.
Conclusions
The MSW in MSM population in Hangzhou has a high prevalence of HIV/syphilis infection, poor perceived risks of HIV and more engagement in unsafe sex with its clients and partners, in addition to a low rate of condom use. These risk factors may account for their relatively high infection rate of HIV/syphilis.
Keywords: EPIDEMIOLOGY
Strengths and limitations of this study.
Our findings are helpful in elucidating the current risk factors for HIV/syphilis infection in the male sex worker (MSW) men who have sex with men population of China.
Our findings are useful to direct further health education and behavioural interventions.
Selection bias may exist, due to the snowball methods sampling method and outreach site service, which might restrict the representativeness of the study.
It is unavoidable that the participants may not provide honest responses to the sensitive questions covered in the questionnaire, though this may have been ameliorated by using self-administered questionnaires and the established good relations between data collectors and MSWs.
Introduction
AIDS has become a serious public health problem worldwide. It has been estimated that there were approximately 35.3 (95% CI 32.2 to 38.8) million people worldwide living with HIV in 2012; among them, 2.3 (1.9 to 2.7) million were new HIV infections.1 The high prevalence and incidence burden of HIV has been globally identified in the men who have sex with men (MSM) population.2 In developed countries of Western and East Asia, new HIV infections have continued to increase in this population, while in developing countries, HIV prevalence in MSM is also considerably high.3–5 For example, in China, 21.4% of new HIV cases were transmitted via same-sex interactions in 2013, and the HIV epidemic in the MSM population keeps growing.6
With the rapid economic development in China, the migrant population moving from rural areas to urban areas is increasing. The migrants are more likely to engage in high-risk sexual behaviour, have sexually transmitted infections (STI) and transmit HIV. In this regard, the migrant subgroup of MSM, male sex workers (MSWs) known as ‘money boys’ (MB), who engage in same-sex sexual activities for economic survival, has become a serious concern of the society. As expected, there is a high risk of HIV and other STIs among the MSW population.7 8 In Mainland China, the HIV/STI infection rate in MSW is high. Furthermore, MSMs have poor awareness of the epidemiological trend of AIDS/STI that makes them more vulnerable to such diseases.9 10 Hangzhou is one of the most economically developed and socially inclusive areas in China; in addition, the MSW population represents an emerging social entity along with the so-called ‘golden-10-year generation’ of modern China (1998–2008). There is an especially large proportion of MSMs in the MSW population, and their current status of HIV/STI infection, risk factor persistence and variations in China are unclear.
To address this question, we investigated HIV infection, together with syphilis epidemic, as an example to indicate STIs among MSW in MSM in Hangzhou, China. Specifically, we sampled the participants in the year 2011. We believe our findings will be helpful in elucidating the current risk factors for HIV/syphilis infection in the MSW MSM population of China, which may be useful to direct further health education and behavioural interventions.
Methods
Subjects
This study was designed as a cross-sectional survey on MSW who provided commercial sex services (including anal and oral sex) to men from May 2011 to December 2011 in Hangzhou, China. The inclusion criteria were: (1) age ≥18 years; (2) engaging in sex with men in the previous year and (3) willing to cooperate in the implementation of the study. The original protocol was required to be sampled by a respondent-driven sampling (RDS) method. Since investigators were unable to obtain large enough sample sizes using RDS, all sampling was changed to the snowball methods and outreach convenience sampling (provision of outreach service on-site, such as in bath-houses and clubs) in the early phase of the study. Overall, 87% of participants were recruited by the snowball method, 10% by the RDS method and 3% by the outreach convenience sampling method.
Signed informed consent was acquired from each participant. Participants were anonymised by assigning unique identification numbers.
Measures
The survey questionnaire was based on that used in the national sentinel surveillance programme since 1995, which included demographics, knowledge levels, HIV/STI relevant behaviours, drug consumption and HIV and syphilis infection status. Information was obtained via one-on-one interviews by qualified investigators. The Center for Disease Control and Prevention staff who conducted the survey by interview were given intensive training and a detailed protocol. Interview settings had at least one private interview/counselling room, a testing room and a waiting room.
Peripheral blood samples were collected from each participant, followed by the ELISA test for HIV-1p24antibody. The ELISA-positive participants were verified by western blotting on HIV-1 gp120. In addition, the rapid plasma regain test was used to identify the syphilis antibody in serum, and the spirochete antibody haemagglutination (Treponema pallidum haemagglutination) test was adopted for confirmation. Participants were assigned to the HIV/syphilis group (including HIV infection, syphilis infection and HIV/syphilis co-infection) and the control group according to their HIV and syphilis status.
Statistical analysis
The required sample size was calculated to provide estimates of the prevalence of HIV and syphilis co-infection among men MSM in MSW. On the basis of our previous pilot study, we estimated the prevalence of HIV/syphilis co-infection among men MSM in MSW in Hangzhou, China, to be approximately 30%. A minimum of 233 participants was required to obtain 80% power with a two-sided significance level of α=0.05. Data were analysed using SPSS V.15.0 (SPSS Inc, Chicago, Illinois, USA). Statistical significance was accepted when p<0.05. The data were presented as the mean±SD for continuous variables and as the frequency (%) for categorical variables. Logistic regression analysis was performed with HIV/syphilis infection as a dependent variable. Participants were categorised into two groups: control (non-HIV/syphilis) and cases (infected with HIV/syphilis). The selection of independent variables was primarily based on the results from the univariate analyses as shown in tables 1–4.
Table 1.
Sociodemographic characteristics of participants (n=259)
| Variable | HIV/syphilis group (n=60, %) | Control group (n=199, %) | Total (%) | p Value* |
|---|---|---|---|---|
| Age (years) | ||||
| Mean±SD | 22.2±3.3 | 21.8±3.4 | 21.9±3.3 | 0.448 |
| Minimum–maximum | 19–34 | 19–39 | 19–39 | |
| Age group (years) | ||||
| 19 | 8 (13.3) | 49 (24.6) | 57 (22.0) | 0.085 |
| 21 | 49 (81.7) | 144 (72.4) | 193 (74.5) | |
| >30 | 3 (5.0) | 6 (3.0) | 9 (3.5) | |
| Education | ||||
| Primary | 1 (1.7) | 8 (4.0) | 9 (3.5) | 0.207 |
| Secondary | 46 (76.7) | 165 (82.9) | 211 (81.5) | |
| University | 13 (21.7) | 26 (13.1) | 39 (15.1) | |
| Marital status | ||||
| Married | 2 (3.3) | 10 (5.0) | 12 (4.6) | 0.498 |
| Unmarried | 58 (96.7) | 186 (93.5) | 244 (94.2) | |
| Others | 0 (0) | 3 (1.5) | 3 (1.2) | |
| Resident duration in Hangzhou (months) | ||||
| <3 | 37 (61.7) | 136 (68.3) | 173 (66.8) | 0.643 |
| 3–12 | 11 (18.3) | 28 (14.1) | 39 (15.1) | |
| ≥12 | 12 (20.0) | 35 (17.6) | 47 (18.1) | |
| Employment status as MB | ||||
| Full time | 31 (51.7) | 109 (54.8) | 140 (54.1) | <0.001 |
| Part time | 29 (48.3) | 90 (45.2) | 119 (45.9) | |
| Self-identified sexual orientation | ||||
| Homosexuality | 30 (50.0) | 60 (30.2) | 90 (34.7) | 0.024 |
| Heterosexuality | 3 (5.0) | 25 (12.6) | 28 (10.8) | |
| Bisexuality | 20 (33.3) | 92 (46.2) | 112 (43.2) | |
| Unsure | 7 (11.7) | 22 (11.1) | 29 (11.2) | |
| Occupation of part-time MB† | ||||
| Student | 5 (8.8) | 24 (12.1) | 29 (11.2) | <0.001 |
| Office worker | 14 (23.5) | 79 (39.6) | 91 (35.2) | |
| Waiter in entertainment venues | 25 (41.2) | 50 (25.3) | 77 (29.6) | |
| Others | 16 (26.5) | 46 (23.1) | 62 (24.0) | |
*χ2 Test.
†119 Part-time MBs.
MB, money boy.
Table 2.
Participants’ knowledge and attitude on HIV/AIDS
| HIV/syphilis group (n=60, %) | Control group (n=199, %) | Total (%) | p Value* | |
|---|---|---|---|---|
| Knowledge on HIV/AIDS (correct answers to questions) | ||||
| Will a person be infected by sharing needles with HIV carriers or patients? | 57 (95.0) | 192 (96.5) | 249 (96.1) | <0.001 |
| Will a person be infected by inputting blood or blood products with HIV? | 54 (90.0) | 190 (95.5) | 244 (94.2) | 0.191 |
| Can a person reduce the risk of HIV transmission by using condoms correctly in every sexual behaviour? | 55 (91.7) | 189 (95.0) | 244 (94.2) | 0.568 |
| May an infected pregnant woman transmit the AIDS virus to her child? | 50 (83.3) | 187 (94.0) | 237 (91.5) | 0.025 |
| Can a person reduce the risk of HIV transmission by maintaining an uninfected partner? | 50 (78.3) | 160 (80.4) | 207 (79.9) | 0.862 |
| Will a person get infected by having dinner with carriers or patients of HIV? | 48 (80.0) | 158 (79.4) | 206 (79.5) | 1.000 |
| May a seemingly healthy person carry HIV? | 42 (70.0) | 141 (70.9) | 183 (70.7) | 1.000 |
| Will mosquito bites spread HIV? | 37 (61.7) | 108 (54.3) | 145 (56.0) | 0.316 |
| Proportion (%) of correct answers to questions on HIV/AIDS knowledge (mean±SD) | 68.5±1.9 | 73.4±1.4 | 72.2±1.6 | 0.536 |
| Attitude on HIV/AIDS | ||||
| The risk you think you get HIV infection | 31 (51.7) | 76 (38.2) | 107 (41.3) | 0.064 |
| The effect of condom usage in HIV prevention | 45 (75.0) | 144 (72.4) | 189 (73.0) | 0.749 |
*χ2 Test.
Table 3.
Sexual behaviour of participants (n=259)
| HIV/syphilis group (n=60, %) | Control group (n=199, %) | Total (%) | p Value* | |
|---|---|---|---|---|
| First time sexual behaviour | ||||
| Age of the first sexual behaviour (years) | ||||
| Mean±SD | 19.2±3.3 | 18.6±2.2 | 18.7±2.5 | 0.091 |
| Minimum–maximum | 13–32 | 10–26 | 10–32 | |
| Age of the first sexual behaviour with a man (years) | ||||
| Mean±SD | 20.7±3.5 | 20.4±2.5 | 20.4±2.7 | 0.548 |
| Minimum–maximum | 14–32 | 10–26 | 10–32 | |
| Gender of the first sexual partner | ||||
| Male | 26 (43.3) | 78 (39.2) | 104 (40.2) | 0.652 |
| Female | 34 (56.7) | 121 (60.8) | 155 (59.9) | |
| Sexual behaviour in the past 6 months | ||||
| Selling sex to males | ||||
| Yes | 60 (100) | 191 (96.0) | 251 (96.9) | 0.204 |
| Number of selling-sex male partners | ||||
| 0 | 0 | 8 (4.0) | 8 (3.1) | 0.181 |
| 1 | 2 (3.3) | 10 (5.0) | 12 (4.6) | |
| 2–9 | 15 (25.0) | 41 (20.6) | 56 (21.6) | |
| ≥10 | 43 (71.7) | 140 (70.4) | 183 (70.7) | |
| Buying sex from males | ||||
| Yes | 3 (5.0) | 20 (10.1) | 23 (8.9) | 0.778 |
| Number of buying-sex male partners | ||||
| 0 | 57 (95.0) | 179 (89.9) | 236 (91.1) | 0.148 |
| 1 | 0 | 5 (2.5) | 5 (1.9) | |
| ≥2 | 3 (5.0) | 15 (7.5) | 18 (6.9) | |
| Selling sex to females | ||||
| Yes | 9 (15.0) | 31 (15.6) | 40 (15.4) | 1.000 |
| Number of selling-sex female partners | ||||
| 0 | 51 (85.0) | 168 (84.4) | 219 (84.6) | 0.861 |
| 1 | 3 (5.0) | 7 (3.5) | 10 (3.9) | |
| ≥2 | 6 (10.0) | 24 (12.1) | 30 (11.6) | |
| Non-commercial anal intercourse behaviour with males | ||||
| Yes | 36 (60.0) | 91 (45.7) | 127 (49.0) | <0.001 |
| Number of non-commercial male sex partners | ||||
| 0 | 24 (40.0) | 108 (54.3) | 132 (51.0) | 0.087 |
| 1 | 11 (18.3) | 17 (8.5) | 28 (10.8) | |
| 2–9 | 11 (18.3) | 42 (21.1) | 53 (20.5) | |
| ≥10 | 14 (23.3) | 32 (16.1) | 46 (17.8) | |
| Non-commercial sexual behaviour with females | ||||
| Yes | 10 (16.7) | 53 (26.6) | 63 (24.3) | 1.000 |
| Number of non-commercial female sex partners | ||||
| 0 | 50 (83.3) | 146 (73.4) | 196 (75.7) | 0.233 |
| 1 | 6 (10.0) | 32 (16.1) | 38 (14.7) | |
| ≥2 | 4 (6.7) | 21 (10.6) | 25 (9.7) | |
*χ2 Test.
Table 4.
Usage of condoms on sexual service in the past 6 months
| HIV/syphilis group (%) | Control group (%) | Total (%) | p Value* | |
|---|---|---|---|---|
| With males | ||||
| Consistent condom use when selling anal sex (n=251) | ||||
| Yes | 50 (83.3) | 168 (88.0) | 218 (86.9) | 0.355 |
| No | 10 (16.7) | 23 (12.0) | 33 (13.1) | |
| Consistent condom use when selling oral sex (n=244) | ||||
| Yes | 29 (50.0) | 106 (57.0) | 135 (55.3) | 0.350 |
| No | 29 (50.9) | 80 (43.0) | 109 (44.7) | |
| Consistent condom use when buying oral sex (n=23) | ||||
| Yes | 3 (100.0) | 18 (94.7) | 21 (95.5) | 1.000 |
| No | 0 | 1 (5.3) | 1 (4.5) | |
| Consistent condom use in non-commercial anal sex (n=127) | ||||
| Yes | 29 (80.6) | 69 (75.8) | 98 (77.2) | 0.567 |
| No | 7 (19.4) | 22 (24.2) | 29 (22.8) | |
| With females | ||||
| Consistent condom use in commercial sex (n=40) | ||||
| Yes | 9 (81.8) | 22 (75.9) | 31 (77.5) | 1.000 |
| No | 2 (18.2) | 7 (24.1) | 9 (22.5) | |
| Consistent condom use in non-commercial sex (n=63) | ||||
| Yes | 7 (58.3) | 24 (47.1) | 31 (49.2) | 0.482 |
| No | 5 (41.7) | 27 (52.9) | 32 (50.8) | |
*χ2 Test.
Results
Participant characteristics
With an overall response rate of 79.3%, the final sample size reached 259 participants. Among the 259 MSW, the population age ranged from 19 to 39 years, with a mean of 21.9±3.3 years. Among them, 61.4% were educated to secondary level, 94.2% were unmarried, 54.1% were full-time MB, 43.2% were bisexual and 66.8% had been living in Hangzhou for less than 3 months (table 1). In addition, 60 (23.2%) were infected with HIV and/or syphilis. Among them, 23 (8.9%) were infected only with HIV, 33 (12.7%) only with syphilis and 4 (1.5%) with HIV and syphilis.
HIV/AIDS-related knowledge
Only 35.5% of participants correctly answered all of the items pertaining to HIV/AIDS relevant knowledge. More than 90% participants knew that a person could be infected by sharing needles with HIV carriers or patients with AIDS; a person could be infected by fusion blood or blood products with HIV; a person could reduce the risk of HIV transmission by using condoms correctly in every sexual behaviour; and an infected pregnant woman may transmit HIV to her child (or children). Only 56% of participants knew that mosquito bites could not spread HIV. The difference in knowledge on HIV/AIDS in the item ‘Will a person be infected by sharing needles with HIV carriers or patients?’ was statistically significant between the HIV/syphilis group and the control group (p<0.05). The proportion of correct answers to questions on HIV/AIDS knowledge, regarding needle sharing and mother-to-child transmission, was significantly higher in the control group than in the HIV/syphilis group (table 2).
HIV/AIDS-related attitudes
Among the participants, 41.3% considered that they may be at risk of getting HIV infection, and 73% acknowledge the effect of condom use in HIV prevention. There was no statistical difference in HIV/AIDS-related attitudes between the HIV/syphilis group and the control group (table 2).
Sexual behaviour
Table 3 details the participants’ sexual behaviours at the first encounter and during the past 6 months. Among these participants, the mean age of the first sexual encounter was 18.7±2.5 years and the mean age of the first sexual encounter with a male was 20.4±2.7 years; of these, 40.2% revealed that their first sexual partner was male.
In the past 6 months, 96.9% of the participants sold sex to males and 70.7% of them had more than 10 male partners to whom they sold sex. In addition, 8.9% had bought sex from other MSW; 6.9% had more than two male partners from whom they bought sex; 15.4% sold sex to females and 11.6% had more than two female partners to whom they sold sex. Meanwhile, 49% participants had conducted non-commercial anal intercourse with males and 24.3% had non-commercial sexual behaviour with at least one female partner.
Compared with the control group, the HIV/syphilis group had a significantly higher rate of having non-commercial anal intercourse with males (p<0.05), but there was no significant difference in other sexual behaviours between the two groups (table 3).
Condom use
Table 4 details the participants’ condom use during the past 6 months. Among the 251 participants who offered commercial sex services to males, 86.9% used condoms every time when selling anal sex to males. Among the 244 participants who sold oral sex to males, only 53.8% used condoms during this practice. Among the 23 participants who bought oral sex from males, 95.5% used condoms every time; among the 127 participants who had non-commercial anal intercourse with males, 77.2% used condoms every time.
Among the 40 participants who sold sex to females, 77.5% used condoms every time. Regarding the 63 participants who had non-commercial sexual behaviour with females, only 49.2% used condoms every time. There was no significant difference in sexual behaviour with females between the HIV/syphilis group and the control group.
Multivariate logistic regression analysis of factors associated with HIV/syphilis infection
The logistic regression models with HIV/syphilis as the dependent variable demonstrated that age (>30 years; OR, 1.055; 95% CI 1.015 to 1.095) and non-commercial male sex partners (n≥10; OR, 1.573; 95% CI 1.018 to 2.452) are significantly associated with HIV/syphilis infection, while heterosexuality was significantly associated with a lower HIV/syphilis infection rate (OR, 0.238; 95% CI 0.066 to 0.855; table 5). These results have been adjusted for age, frequency of condom use for commercial sex during the past 6 months and employment status as an MB (table 5).
Table 5.
Multivariable logistic regression of explanatory variables against HIV/syphilis
| OR | 95% CI | p Value | |
|---|---|---|---|
| Age group | |||
| <20 | 1.000 | ||
| 20–30 | 1.038 | 0.503 to 2.140 | 0.920 |
| >30 | 1.055 | 1.015 to 1.095 | 0.006 |
| Employment status as money boy | |||
| Full time | 1.000 | ||
| Part time | 1.033 | 0.564 to 1.891 | 0.916 |
| Sex orientation | |||
| Homosexuality | 1.000 | ||
| Heterosexuality | 0.238 | 0.066 to 0.855 | 0.028 |
| Bisexuality | 0.647 | 0.245 to 1.710 | 0.379 |
| Unsure | 0.638 | 0.245 to 1.666 | 0.359 |
| Non-commercial anal intercourse behaviour with males | |||
| No | 1.000 | ||
| Yes | 1.576 | 0.704 to 3.527 | 0.269 |
| Number of non-commercial male sexual partners | |||
| 0 | 1.000 | ||
| 1 | 1.378 | 0.490 to 3.877 | 0.543 |
| 2–9 | 0.611 | 0.234 to 1.590 | 0.312 |
| ≥10 | 1.573 | 1.018 to 2.452 | 0.046 |
Discussion
We demonstrated here that the MSW in MSM in Hangzhou, 2011, had high HIV and syphilis infection rates and a low condom use rate. Furthermore, older and frequent non-commercial male sex activity with different partners was associated with increased probability of contracting HIV or syphilis. In contrast, heterosexuality was associated with less risk of being infected with HIV/syphilis.
Our results on the rate of HIV and/or syphilis infection (23.2%), HIV infection (8.9%), syphilis infection (12.7%) and HIV and syphilis infection (1.5%) in MSW in MSM are comparable with studies from others on MSW only. Cuypers et al11 found that 45.5% of MSW were diagnosed with at least one STI and that the HIV infection rate was 11.1% in the cohorts of the Netherlands and other Western countries. Song et al12 surveyed 80 MSWs in Beijing and observed that the infection rate of HIV and syphilis was 11.3% and 16.3%, respectively. Huan et al13 studied 328 MSWs and reported the prevalence of syphilis to be 13% in Jiangsu province. In this study, the HIV and syphilis infection rates were higher than the overall prevalence (HIV 4.9%, syphilis 11.8%) among MSM in a large national survey across 61 cities14 and similar to the prevalence among MSM in Chengdu, China (HIV 13.3%, syphilis 15.9%)15 and reports from South and South east Asia (range: 14–18%).16 The Ministry of Health of the People's Republic of China estimated that HIV prevalence among China's MSM population was approximately 6.3% in 2011, which suggests that the HIV epidemic is still expanding in this population.17–19 Our findings emphasise that MSM in MSW are more vulnerable to HIV/syphilis infection compared with the general MSM population. The results in our survey showed that the participants were generally young, educated to a higher level, unmarried and highly migratory. Most part-time MBs were office workers and waiters in entertainment venues. These data are in-line with the findings of other studies.11 14
Regarding the basic knowledge of HIV/AIDS, more than 90% of MSW in MSM maintained accurate knowledge on some aspects of HIV transmission, but there were some false beliefs, such as that of HIV/AIDS being transmitted by mosquito bites or when people dine together. This corroborates similar findings of other studies in China, and warrants further educational interventions.20 We found that up to 94.2% of the 259 MSW knew that using condoms correctly in every sexual behaviour could reduce the risk of HIV transmission; however, only 53.8% used them every time when having oral sex during the past 6 months. Meanwhile, there were also low condom use rates when having commercial or non-commercial sex with females. In fact, the lowest rate of consistent condom use in this study was in the context of MSW in MSM having sex with female partners and selling oral sex. In addition, only 41.6% of the participants in this study revealed that they consider themselves at high risk of HIV infection. These results highlight the poorly perceived risks of HIV and suggest that when MSW encounter different types of sexual partners, their consideration of the risk of non-protective sexual behaviour was different. Specifically, they may consider that casual sexual partners with mutually friendly emotions between each other are safer, which leads to reduced disease prevention and less condom use frequency.
The mean age of the first sexual behaviour among the MSW in MSM was relatively young, and generally they had multiple sexual partners. The risk factors identified for having HIV and syphilis infections are not unexpected and the results are consistent with other reports.14 15 These results indicate that the HIV/syphilis group was more likely to have non-commercial anal intercourse behaviour with males. Therefore, the necessity of education and behavioural intervention to target more MSW, especially MSW in MSM, in the AIDS voluntary consultation is an important issue so that risky sexual behaviour can be reduced through ‘peer education’.
In this study, only 34.7% of MSW in MSM self-identified as gay; most of them (54%) were either bisexual or heterosexual men engaging in sex with men and women concurrently, and had complicated sexual relationships with their partners. These observations on the bisexual or heterosexual proportion are consistent with the findings of other studies in China9 21 22 but higher than those reported in other countries.23 A higher HIV/syphilis infection rate was found in those who self-identified as homosexual or bisexual, compared with those who self-identified as heterosexual; indeed, heterosexual participants were associated with a 4.17-fold decrease in the risk for HIV/syphilis infection. This finding is consistent with the conclusion from China14 and other countries.16 In fact, bisexual MSW have a higher rate of engagement in commercial sex and a lower rate of condom use, and have the least HIV knowledge. The low rate of consistent condom use found in this study was in the context of MSW having sex with female partners.24 It has been a long-existing concern that HIV/syphilis infection could be spread through risky man-to-man sex into heterosexual networks.25 In this regard, MSW should be the target of specific preventive activities, given their particular vulnerability and because infections are likely to disseminate into the general population given the high proportion of bisexual activity and marriage.
We also noted some possible limitations in the study. First, selection bias may exist, due to the RDS sampling method and outreach site service, which might restrict the representativeness of the study. Second, it is unavoidable that the participants may not provide honest responses to the sensitive questions covered in the questionnaire, though this may have been ameliorated by using self-administered questionnaires and the established good relations between data collectors and MSWs.
Conclusions
This study showed that the MSW in MSM population in Hangzhou in 2011 had a high prevalence of HIV/syphilis infection, relatively good knowledge on HIV/AIDS, poor perceived risks of HIV and more engagement in unsafe sex with their clients and partners, along with a low rate of condom use. These factors may account for the relatively high infection rate of HIV/syphilis in this subgroup. Specific and comprehensive prevention and treatment engagements require to be implemented urgently.
Acknowledgments
The authors would like to thank Dr Sun Qing of Shangcheng Center for Disease Prevention and Control and Dr Shengjun Xi of Xiacheng Center for Disease Prevention and Control for their kind assistance.
Footnotes
Contributors: All authors contributed to the drafting and revision of this manuscript for intellectual content. YL directed the study implementation, including quality assurance and control. SC designed the study's analytic strategy and helped conduct the literature review. CZ analysed and interpreted the data and drafted the article. QG designed the study and reviewed the article. RF helped to supervise the field activities and prepared the discussion sections of the text. XL, KX, JC and JD carried out acquisition of data and helped conduct the literature review.
Funding: This work was supported by the Medical Science Research Fund of Zhejiang Province (2008B158) and the Health science and technology plan Fund of Hangzhou (2008A030).
Competing interests: None declared.
Patient consent: Obtained.
Ethics approval: This study was reviewed and approved by the Institutional Review Board of the National Center for AIDS/STD Control and Prevention, China.
Provenance and peer review: Not commissioned; externally peer reviewed.
Data sharing statement: No additional data are available.
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