title: Prevalence of HIV and syphilis co-infection and associated factors among non-commercial men who have sex with men attending a sexually transmitted disease clinic in Shenzhen, China.
abstract: Although HIV and syphilis co-infection has been frequently observed in men who have sex with men (MSM), only few studies have focused on it. Different subgroups of MSM might exhibit heterogeneous HIV and syphilis risk profiles, indicating that interventions for HIV and HIV-related co-infections may vary with different subgroups of MSM. However, no previous study has investigated HIV and syphilis co-infection among non-commercial MSM (ncMSM) attending a sexually transmitted disease (STD) clinic. Therefore, this study aimed to explore the prevalence of HIV and syphilis co-infection and associated factors among ncMSM attending an STD clinic in Shenzhen, China.
  
  
  
  NcMSM attending the STD clinic of Shenzhen Center for Chronic Disease Control were recruited in this cross-sectional study every Monday between March 2013 and August 2015 using a site based convenience sampling method. An anonymous questionnaire was used to collect data regarding socio-demographic characteristics, risky sexual behaviors and HIV-related knowledge. Blood samples were collected to perform HIV and syphilis tests.
  
  
  
  Totally 533 participants were enrolled in this study and the prevalence of HIV and syphilis co-infection among them was 13.13%. Multivariable analyses indicated that having lived in Shenzhen for less than one year (aOR = 2.80, 95% CI = 1.30-6.05), having first anal sexual intercourse before the age of 18 (aOR = 2.78, 95% CI = 1.29-5.89), having 3 to 5 anal sexual partners in the past six months (aOR = 2.54, 95% CI = 1.19-5.40), playing exclusively receptive (aOR = 6.87, 95% CI = 3.02-15.61) or both insertive and receptive (aOR = 3.65, 95% CI = 1.64-8.09) roles in anal sexual intercourse and not always using condom in anal sexual intercourse (aOR = 2.13, 95% CI = 1.08-4.19) were associated risk factors for HIV and syphilis co-infection, relative to the non-infected ncMSM. Compared with the mono-infected ncMSM, associated risk factors for the co-infection were being unmarried (aOR = 2.47, 95% CI = 1.03-5.89) and playing exclusively receptive role (aOR = 2.44, 95% CI = 1.04-5.73) in anal sexual intercourse.
  
  
  
  HIV and syphilis co-infection is quite prevalent among the study participants in Shenzhen. Integrated and intensified intervention strategies, specifically targeting at the non-infected and mono-infected ncMSM attending the STD clinic, are needed to reduce HIV and syphilis co-infection. Most importantly, non-infected and mono-infected ncMSM attending the STD clinic with the aforementioned associated risk factors should be given special concern.
authors.affiliation: Department of Epidemiology and Health Statistics, Xiangya School of Public Health, Central South University, Changsha, Hunan, China.|Shenzhen Center for Chronic Disease Control, Shenzhen, Guangdong, China.
authors.forename: Wenjie
authors.initials: W
authors.lastname: Dai
authors.affiliation: Department of Epidemiology and Health Statistics, Xiangya School of Public Health, Central South University, Changsha, Hunan, China.|Shenzhen Center for Chronic Disease Control, Shenzhen, Guangdong, China.|Shenzhen Nanshan Center for Chronic Disease Control, Shenzhen, Guangdong, China.
authors.forename: Zhenzhou
authors.initials: Z
authors.lastname: Luo
authors.affiliation: Department of Epidemiology and Health Statistics, Xiangya School of Public Health, Central South University, Changsha, Hunan, China.|Shenzhen Center for Chronic Disease Control, Shenzhen, Guangdong, China.
authors.forename: Ruiwei
authors.initials: R
authors.lastname: Xu
authors.affiliation: Shenzhen Center for Chronic Disease Control, Shenzhen, Guangdong, China.
authors.forename: Guanglu
authors.initials: G
authors.lastname: Zhao
authors.affiliation: Graduate School, Shenzhen University, Shenzhen, Guangdong, China.
authors.forename: Dan
authors.initials: D
authors.lastname: Tu
authors.affiliation: Department of Epidemiology and Health Statistics, Xiangya School of Public Health, Central South University, Changsha, Hunan, China.|Shenzhen Center for Chronic Disease Control, Shenzhen, Guangdong, China.
authors.forename: Lin
authors.initials: L
authors.lastname: Yang
authors.affiliation: Shenzhen Center for Chronic Disease Control, Shenzhen, Guangdong, China.
authors.forename: Feng
authors.initials: F
authors.lastname: Wang
authors.affiliation: Shenzhen Center for Chronic Disease Control, Shenzhen, Guangdong, China.
authors.forename: Yumao
authors.initials: Y
authors.lastname: Cai
authors.affiliation: Shenzhen Center for Chronic Disease Control, Shenzhen, Guangdong, China.
authors.forename: Lina
authors.initials: L
authors.lastname: Lan
authors.affiliation: Shenzhen Center for Chronic Disease Control, Shenzhen, Guangdong, China.
authors.forename: Fuchang
authors.initials: F
authors.lastname: Hong
authors.affiliation: Department of Epidemiology and Health Statistics, Xiangya School of Public Health, Central South University, Changsha, Hunan, China.
authors.forename: Tubao
authors.initials: T
authors.lastname: Yang
authors.affiliation: Shenzhen Center for Chronic Disease Control, Shenzhen, Guangdong, China. fengtiej@126.com.
authors.forename: Tiejian
authors.initials: T
authors.lastname: Feng
mesh_terms: D000328:Adult; D002681:China / Q000453:epidemiology; D060085:Coinfection / Q000453:epidemiology*; D017280:Condoms / Q000706:statistics & numerical data*; D003430:Cross-Sectional Studies; D015658:HIV Infections / Q000453:epidemiology*; D018451:Homosexuality, Male / Q000706:statistics & numerical data*; D006801:Humans; D008297:Male; D015995:Prevalence; D012307:Risk Factors; D012309:Risk-Taking; D012725:Sexual Behavior / Q000706:statistics & numerical data*; D012747:Sexual Partners; D011795:Surveys and Questionnaires; D013587:Syphilis / Q000453:epidemiology*; D013588:Syphilis Serodiagnosis; D055815:Young Adult
keywords: Co-infection; HIV; Non-commercial men who have sex with men; Sexually transmitted disease clinic; Syphilis