Discussion. The epidemic of HIV/STD among MSM is severe, and the prevalence of risk sexual behaviors was at a high level among MSM in China. The risk factors for HIV/STD and factors associated with DAI reported in this study give some insights towards designing relevant prevention programs. The simplicity and feasibility of our effective intervention, enhanced VCT, makes it possible for this to be incorporated into standard VCT procedures. Further translational research is needed to investigate its effectiveness in the real-world setting. / Introduction. Men who have sex with men (MSM) have become the main group for HIV transmission in China in 2009. There have been many epidemiological cross-sectional studies targeting MSM in China in recent years. These provide limited data compared with cohort studies, which can describe the rate at which HIV/STD are spreading in a target population. Moreover, there is a dearth of intervention studies which are theory-based with rigorous research methodology in China. Last but not least, research is needed on sexual behaviors and their determinants, including cognitions from health behavioral theories, event-specific factors, etc. / Objectives. This study investigated the prevalence and incidence of HIV/STD, as well as their associated risk factors among MSM in Nanjing, China. It also explored the prevalence of unprotected anal sex (UAI) and the associated factors, including cognitions from health behavioral theories and event-specific factors. In addition, this is also one of the first studies to examine the efficacy of a randomized control trial (RCT) designed intervention, to use enhanced voluntary counseling and testing (VCT) to reduce UAI among MSM in China. / Results. The RDS-adjusted HIV, syphilis and HCV prevalence were respectively 7.3%, 14.4% and 0.2% at baseline. Of the 397 MSM who were found to be HIV seronegative at baseline, 286 (72.0%) retested at Month 6. HIV, syphilis and HCV incidence were respectively 5.12, 7.58 and 0 per 100 person-years (PY). Recruiting male sex partners mostly at saunas was the risk factor associated with being HIV seropositive at baseline (OR=3.84) and undergoing HIV/syphilis seroconversion at Month 6 (RR=2.351RR=6.72). In the RCT study, participants in the Intervention Group reported significantly less risk than those in the Control Group (UAI with any male sex partners: 48.4% vs. 66.7%;UAI with regular male sex partners: 52.2% vs. 68.9%) at Month 6. Furthermore, Perceived Behavior Control showed a significant association with DAI with both regular (AOR=0.42) and casual partners (AOR=O.73). / Subjects and Methods. A cohort study and randomized control trial were conducted. Out of 416 MSM approached by respondent driven sampling (RDS), 397 HIV negative participants were recruited to the HIV/syphilis/HCV cohort, and they were invited to return for a follow-up visit at Month 6. A subsample from the baseline cohort consisting of 307 MSM, was randomly assigned to either the Intervention Group (enhanced VCT) or the Control Group (standard VCT). Evaluation was conducted at Month 6. Both baseline and Month 6 visits consisted of VCT service and interviewing. Statistical methods such as Chi-square test, logistic regression and Poisson regression were used in this study. / Hao, Chun. / Adviser: Joseph TF Lan. / Source: Dissertation Abstracts International, Volume: 73-04, Section: B, page: . / Thesis (Ph.D.)--Chinese University of Hong Kong, 2011. / Includes bibliographical references (leaves 166-179). / Electronic reproduction. Hong Kong : Chinese University of Hong Kong, [2012] System requirements: Adobe Acrobat Reader. Available via World Wide Web. / Electronic reproduction. [Ann Arbor, MI] : ProQuest Information and Learning, [201-] System requirements: Adobe Acrobat Reader. Available via World Wide Web. / Abstract and appendixes I-II also in Chinese.

Background A dramatic increasing trend of HIV prevalence among men who have sex with men (MSM) was observed in China from 2000. Most previous investigations were based on convenience sampling and none of them differentiated money boys (MB) from other MSMs. The objectives of this study was to determine the prevalence of HIV infection and its risk factors among MSMs in Shenzhen, China, using approximate probability sampling methods; and to interpret HIV transmission pattern among MSMs with both phylogenetical and epidemiological information. / Conclusions The prevalence of MV infection in Shenzhen MSMs was similar to the national rate in MSMs. HIV infection and related characteristics in Mf3s and other MSMs were different, indicating that a separate analysis was necessary. TLS could provide information on venue comparisons for venue-based MSMs and RDS could recruit more hidden subjects. Results from this study suggest that venue-specific intervention approaches should be developed and provided to different venues. / Results HIV prevalence was 5.5% among MSMs in Shenzhen. A significantly lower HIV infection was observed in MBs (4.5%) compared with other MSMs (7.0%). The HIV infection rate among MSMs was 5.7% by TLS and 4.6% by RDS, which were not significantly different. Factors related to HIV infection in MSMs included syphilis infection, occupation, sexual orientation, venue for recruitment and hometown HIV prevalence. HIV rate and social-behavioral characteristics were found to vary with venues, with significantly higher rates in family clubs, parks and saunas, than entertainment venue. Molecular phylogenetical analysis showed that genetic clusters were related to receptive anal intercourse, short stay in Shenzhen, early age of first sex, and high hometown HIV prevalence. Venue-specific transmission chains were observed in 60% of the subjects. / Subjects and Methods A total of 2143 MSMs were recruited in Shenzhen from 2008 to 2009, including 1651 persons from time-location sampling (TLS) and 492 from respondent-driven sampling (RDS). A separate recruitment of MBs and other MSMs was applied in TLS surveys and a mixed sample of MSMs was applied in RDS. All subjects were interviewed and had blood tests for HIV and syphilis. HIV positive samples were further used for phylogenetic analysis. / Zhao, Jin / Adviser: Mingliang He. / Source: Dissertation Abstracts International, Volume: 73-02, Section: B, page: . / Thesis (Ph.D.)--Chinese University of Hong Kong, 2010. / Includes bibliographical references (leaves 161-177). / Electronic reproduction. Hong Kong : Chinese University of Hong Kong, [2012] System requirements: Adobe Acrobat Reader. Available via World Wide Web. / Electronic reproduction. [Ann Arbor, MI] : ProQuest Information and Learning, [201-] System requirements: Adobe Acrobat Reader. Available via World Wide Web. / Abstract also in Chinese.

In the past decade, the rising incidence of human immunodeficiency virus (HIV) in men who have sex with men (MSM) calls for targeted epidemiological investigations. However, the approach of most current epidemiological studies might be inadequate for characterising transmission risks of MSM, as they focus largely on the practice of risk behaviours in population context and have assumed a homogeneous distribution of such behaviours and their resultant risks in HIV transmission. A study investigating the networking pattern of MSM, in addition to their sexual behaviour, was therefore proposed to re-examine HIV epidemiology in Hong Kong and model HIV transmission dynamics. / Following literature review on network analyses conducted in MSM, it was found that the use of two-mode network data for constructing sexual affiliation network had not been widely applied. Such two-mode network approach could be more feasible in describing sexual structure of MSM, who are connected by their preferred social venues. To adopt this approach, a two-part study, composing a field survey and a modelling study, was performed. A cross-sectional questionnaire survey was conducted between January and April 2013 to obtain data about sex-networking venues and associated behavioural profiles of MSM in Hong Kong. Comparisons of networking patterns, risk behaviour and demographics between MSM in different networks, delineated by two-mode network analysis, were made. Based on the survey data and assumptions derived from other network-based and behavioural studies, HIV transmission dynamics was simulated by building a stochastic agent-based model. / In the field survey, a total of 932 respondents were recruited from physical venues (n=625), including nine bars and six saunas, and the Internet (n=307). The proportion of MSM using condom for every anal sex with casual partners met in physical venues was 66.6% (225/338), while that for partners met in the Internet was 62.6% (139/222). Only 51.5% (204/396) MSM always used condom while having anal sex with regular partners. Community detection by networks of social venues identified nine clusters of MSM from three network bases. The simulation model gave a median number of new HIV infections over a 5-year period at 83 per 1000 MSM. The median numbers of annual infections ranged between 14 and 20. In over 30% of MSM networked through the Internet, having regular sex partners or practising receptive anal sex, more than 50 infections out of 500 iterations could occur in the model simulation, suggesting their higher risk of HIV infection. / In conclusion, the modelling results suggested that HIV transmission in Hong Kong might have occurred largely between regular partners. The potential impact of local sex-networking pattern through social venues with casual partners on HIV transmission is relatively little and indirect. To prevent HIV from spreading into new networks, intervention shall be targeted at MSM having unprotected anal sex with regular partners and seeking casual partners in social venues, especially through the Internet. Network approach in HIV epidemiology, such as collection of network-based data from HIV-infected MSM as part of surveillance, and assessing the network configuration from time to time, shall also be considered. / 過去十年間，透過同性性行為感染愛滋病病毒的個案持續上升，令針對男男性接觸者的流行病學研究顯得重要。現時大部分相關研究都假設所涉行為和相應的傳染風險是平均分佈於研究人群中，採用這研究方法去了解男男性接觸者間的病毒傳播風險明顯有所不足。有鑑於此，本研究透過了解男男性接觸者的社交網絡模式及其風險行為，重新審視本地愛滋病病毒感染的流行病學狀況及設計相關模型，用以了解病毒的傳播及流行規律。 / 探討過往文獻發現，雖然二模網絡能勾劃出男男性接觸者與其結識性伴侶的社交場所間的關係，卻未被廣泛應用於流行病學研究。本研究採納二模網絡的分析方法，並分兩部分進行。實地調查部分於二零一三年一月至四月期間進行，透過問卷收集本港男男性接觸者結交性伴侶的場所及相關性行為等資料，並比較其網絡模式、風險行為及人口特徵。建模研究部分則是利用調查所得之數據及參考其他研究去建立模型，用以模擬愛滋病病毒的傳播規律。 / 問卷調查從九間酒吧、六間桑拿及互聯網中，招募了九百三十二位受訪者參與研究。受訪者中，每次肛交均使用安全套的比率因性伴侶的種類而異，比率介乎百分之五十二至六十七。透過分析三種社交場所的網絡結構，本港男男性接觸者社群共可分為九個群組。由模擬模型得知，五年間新增的愛滋病病毒感染個案為八十三宗（每千人計），而相應的年度感染數字則介乎十四至二十宗。從五百次模擬運算中，發現超過三成透過互聯網結識性伴侶或擁有固定性伴侶的男男性接觸者與及受體肛交者的感染次數多於五十次，顯示其較高的愛滋病病毒感染風險。 / 總括而言，研究發現本港愛滋病病毒的傳播多於固定性伴侶間發生。相反，透過本地社交場所結識非固定性伴侶的網絡模式只間接影響本港愛滋病病毒的散播。為有效預防愛滋病病毒散播，干預措施應針對有與固定伴侶進行不安全性行為及透過互聯網結識性伴侶的男男性接觸者，同時衛生部門亦可考慮將感染愛滋病病毒的男男性接觸者的網絡數據納入恆常監測及不時評估同志社群間的網絡結構。 / Poon, Chin Man. / Thesis Ph.D. Chinese University of Hong Kong 2015. / Includes bibliographical references (leaves 112-121). / Abstracts and appendix B also in Chinese. / Title from PDF title page (viewed on 07, October, 2016). / Detailed summary in vernacular field only. / Detailed summary in vernacular field only. / Detailed summary in vernacular field only. / Detailed summary in vernacular field only.