title: Prevalence of syphilis infection in different tiers of female sex workers in China: implications for surveillance and interventions.
abstract: BACKGROUND
  Syphilis has made a dramatic resurgence in China during the past two decades and become the third most prevalent notifiable infectious disease in China. Female sex workers (FSWs) have become one of key populations for the epidemic. In order to investigate syphilis infection among different tiers of FSWs, a cross-sectional study was conducted in 8 sites in China.
  
  
  METHODS
  Serum specimens (n = 7,118) were collected to test for syphilis and questionnaire interviews were conducted to obtain socio-demographic and behavioral information among FSWs recruited from different types of venues. FSWs were categorized into three tiers (high-, middle- and low-tier FSWs) based on the venues where they solicited clients. Serum specimens were screened with enzyme-linked immunosorbent assay (ELISA) for treponemal antibody followed by confirmation with non-treponemal toluidine red unheated serum test (TRUST) for positive ELISA specimens to determine syphilis infection. A logistic regression model was used to determine factors associated with syphilis infection.
  
  
  RESULTS
  Overall syphilis prevalence was 5.0% (95%CI, 4.5-5.5%). Low-tier FSWs had the highest prevalence (9.7%; 95%CI, 8.3-11.1%), followed by middle-tier (4.3%; 95%CI, 3.6-5.0%, P < 0.001) and high-tier FSWs (2.2%; 95%CI, 1.6-2.9%, P < 0.001). Factors independently associated with syphilis infection included older age, lower education level, geographic location, lower tier of typology, and injection drug use.
  
  
  CONCLUSIONS
  This multi-site survey showed a high prevalence of syphilis infection among FSWs and substantial disparities in syphilis prevalence by the tier of FSWs. The difference in syphilis prevalence is substantial between different tiers of FSWs, with the highest rate among low-tier FSWs. Thus, current surveillance and intervention activities, which have low coverage in low-tier FSWs in China, should be further examined.
authors.affiliation: National Center for STD Control, Chinese Academy of Medical Sciences and Peking Union Medical College Institute of Dermatology, 12 Jiangwangmiao Street, Nanjing 210042, China. chenxs@ncstdlc.org
authors.forename: Xiang-Sheng
authors.initials: XS
authors.lastname: Chen
authors.forename: Qian-Qiu
authors.initials: QQ
authors.lastname: Wang
authors.forename: Yue-Ping
authors.initials: YP
authors.lastname: Yin
authors.forename: Guo-Jun
authors.initials: GJ
authors.lastname: Liang
authors.forename: Ning
authors.initials: N
authors.lastname: Jiang
authors.forename: Li-Gang
authors.initials: LG
authors.lastname: Yang
authors.forename: Qiao
authors.initials: Q
authors.lastname: Liu
authors.forename: Yu-Jiao
authors.initials: YJ
authors.lastname: Zhou
authors.forename: Xi-Ping
authors.initials: XP
authors.lastname: Huan
authors.forename: Wan-Hui
authors.initials: WH
authors.lastname: Wei
authors.forename: Baoxi
authors.initials: B
authors.lastname: Wang
mesh_terms: D000293:Adolescent; D000328:Adult; D000907:Antibodies, Bacterial / Q000097:blood; D002681:China / Q000453:epidemiology; D003430:Cross-Sectional Studies; D004797:Enzyme-Linked Immunosorbent Assay; D005260:Female; D006801:Humans; D016036:Seroepidemiologic Studies; D060386:Sex Workers; D012959:Socioeconomic Factors; D011795:Surveys and Questionnaires; D013587:Syphilis / Q000453:epidemiology*; D055815:Young Adult
chemical_list: D000907:Antibodies, Bacterial