Background Epidemics of sexually transmitted infections (STIs) among men who have sex with men (MSM) are major global public health concerns. This study aimed to examine the prevalence of syphilis and chlamydia trachomatis (CT) infection and associated factors among MSM in Jiangsu province, China, hoping to provide updated data for the formulation of relevant policies. Methods A cross-sectional survey was conducted among MSM from April to July 2021 in four cities in the province. Socio-demographic characteristics and behavioral information were collected through a face-to-face questionnaire interview. Venous blood specimens were collected for HIV, hepatitis C (HCV), and syphilis testing using serological testing methods. First-void urine specimens were collected for CT and Neisseria gonorrhoeae (NG) testing using nucleic acid amplification testing (NAAT) methods. Chi-square tests were used to compare differences in syphilis and CT infection between subgroups of variables. Multivariate logistic regression analysis was used to identify factors associated with syphilis and CT infection. Results A total of 1,087 participants were enrolled. The prevalence of HIV, HCV, syphilis, CT and NG infection were 6.6, 0.4, 6.3, 4.2, and 0.4%, respectively. MSM recruited online [adjusted odds ratio (aOR) = 2.189, P = 0.020], diagnosed with an STI in the past 12 months (aOR = 3.304, P < 0.001), and living with HIV (aOR = 4.721, P < 0.001) were more likely to have syphilis infection. MSM who were younger than 25 years (aOR = 4.286, P = 0.020), had senior high school level education (aOR = 2.521, P = 0.038), and were recruited via VCT clinics (aOR = 3.455, P = 0.001) were more likely to have CT infection. Conclusions Our study showed a high prevalence of syphilis and chlamydia among MSM in Jiangsu province, China. STI screening, diagnosis, and treatment services promotion should be a top priority on the prevention agenda.

The prevalence and incidence of human immunodeficiency virus type 1 (HIV-1) among men who have sex with men (MSM) are on the rise throughout China. With a large population of MSM, Jiangsu Province is facing an escalating HIV-1 epidemic. The aim of this study was to explore the phylogenetic and temporal dynamics of HIV-1 CRF01_AE and CRF07_BC among antiretroviral therapy (ART)-naive MSM recently infected with HIV-1 in Jiangsu Province. We recruited MSM in Jiangsu Province (Suzhou, Wuxi, Nantong, Taizhou and Yancheng) 2012 to 2015. We collected information on demographics and sexual behaviors and a blood sample for HIV genome RNA extraction, RT-PCR amplification, and DNA sequencing. Multiple alignments were made using Gene Cutter, with the selected reference sequences of various subtypes/recombinants from the Los Alamos HIV-1 database. Phylogenetic and Bayesian evolutionary analysis was performed by MEGA version 6.0, Fasttree v2.1.7. and BEAST v1.6.2. Categorical variables were analyzed using chi(2) test (or Fisher exact test where necessary). chi(2) test with trend was used to assess the evolution of HIV-1 subtype distribution over time. All data were analyzed using SPSS20.0 software package (IBM Company, New York, NY). HIV-1 phylogenetic analysis revealed a broad viral diversity including CRF01_AE (60.06%), CRF07_BC (22.29%), subtype B (5.88%), CRF67_01B (5.26%), CRF68_01B (2.79%), CRF55_01B (1.55%), CRF59_01B (0.93%), and CRF08_BC (0.62%). Two unique recombination forms (URFs) (0.62%) were also detected. Four epidemic clusters and 1 major cluster in CRF01_AE and CRF07_BC were identified. The introduction of CRF01_AE strain (2001) was earlier than CRF07_BC strain (2004) into MSM resided in Jiangsu based on the time of the most recent common ancestor. Our study demonstrated HIV-1 subtype diversity among ART-naive MSM recently infected with HIV-1 in Jiangsu. We first depicted the spatiotemporal dynamics, traced the dates of origin for the HIV-1 CRF01_AE/07_BC strains and made inference for the effective population size among newly infected ART-naive MSM in Jiangsu from 2012 to 2015. A real-time surveillance of HIV-1 viral diversity and phylodynamics of epidemic cluster would be of great value to the monitoring of the epidemic and control of transmission, improvement of antiretroviral therapy strategies, and design of vaccines.

The HIV epidemic among men who have sex with men (MSM) in China is severe. Peer can induce risky and preventive behaviors among MSM. We interviewed 220 MSM who had at least one significant other who was a peer MSM (SOPM). Interviews were conducted at two gay venues in Suzhou, China, which reported five HIV-related outcomes: HIV (8.2 %), syphilis (16.4 %), self-reported sexually transmitted infection symptoms (14.6 %), unprotected anal intercourse (UAI; 58.6 %) and having had taken up HIV testing (40.4 %). Adjusting for significant background variables, participants' perceived characteristics of the social network of SOPM, such as practicing risk behavior (e.g. UAI) or preventive behaviors (e.g. HIV antibody testing), or possessing HIV-related perceptions (e.g. dislike in condom use), were significantly associated with some of the five aforementioned outcomes (p < 0.05). Peer education and peer-based interventions involving significant others are hence potentially important in HIV prevention targeting MSM. Future pilot intervention studies are warranted.

目的探讨影响男男性行为人群HIV传播的危险因素。方法采用时间序列病例对照研究的研究方法，病例为江苏省2008年5—7月在南京、苏州、扬州市同时开展的针对男男性行为者（MSM）调查中发现的所有HIV感染者，对照为按照地区的入组时间进行1：4匹配的非感染者。调查问卷以2008年国家男男性行为人群综合防治试点工作问卷为核心并根据当地情况增加一些变量；采用拟合条件logistic回归模型对数据进行单因素和多因素分析。结果调查中共发现62例阳性感染者，对照组匹配248名非感染者。单因素分析显示从未使用安全套、梅毒、性病相关症状及无保护性肛交为HIV感染的危险因素，其OR值分别为5．56（95％CI：1．82～16．96）、2．19（95％CI：1．18～4．05）、2．50（95％CI：1．13～5．50）和3．13（95％CI：1．64～5．98）；通过互联网寻找性伴及性角色为0是感染HIV的保护性因素，其OR值分别为0．47（95％CI：0．22～0．998）和0．67（95％CI：0．23～1．97）。多因素分析显示患梅毒、无保护性肛交、首次性行为年龄大是感染HIV的独立危险因素，其OR值分别为2．28（95％CI：1．05～4．94）、4，16（95％CI：1．63～10．66）、1．11（95％CI：1．04～1．18）；而双性恋为感染HIV的保护性因素（OR=0．41，95％CI：0．18～0．97）。结论梅毒、无保护性肛交、首次发生男男性行为的年龄较大等因素是感染HIV的危险因素，性取向为双性是感染HIV的保护性因素。