title: A case-control study evaluating the role of internet meet-up sites and mobile telephone applications in influencing a syphilis outbreak: Multnomah County, Oregon, USA 2014.
abstract: Early syphilis in Multnomah County, Oregon, USA, increased 16-fold during 2007-2013. Cases predominantly occurred among men who have sex with men (MSM); 55% were HIV coinfected. We conducted a case-control study to evaluate the association between meeting sex partners online and early syphilis.
  
  
  
  Cases subjects (cases) were Multnomah County resident, English speaking, MSM, aged ≥18 years with laboratory-confirmed early syphilis reported 1 January to 31 December 2013. We recruited two MSM controls subjects (controls) per case, frequency matched by HIV status and age. Participants completed self-administered questionnaires. We performed multivariable logistic regression.
  
  
  
  Seventy per cent (40/57) of cases and 42% (50/119) of controls met partners online (p<0.001). Cases more frequently met partners online (adjusted OR (aOR)=3.0; 95% CI 1.2 to 6.7), controlling for presumptive confounders. Cases reported more partners than controls (medians 5, 2; p<0.001). When including number of partners, aOR decreased to 1.4 (95% CI 0.5 to 3.9).
  
  
  
  Early syphilis was associated with meeting partners online. We believe this association may be related to number of sex partners acting as an intermediate variable between use of online resources to meet sex partners and early syphilis. Online meet-up sites might represent areas for public health interventions targeting at-risk individuals.
authors.affiliation: Epidemic Intelligence Service, Division of Scientific Education and Professional Development, Center for Surveillance, Epidemiology, and Laboratory Services, CDC, Atlanta, Georgia, USA.
authors.forename: Malini
authors.initials: M
authors.lastname: DeSilva
authors.affiliation: Oregon Health Authority, Portland, Oregon, USA.
authors.forename: Katrina
authors.initials: K
authors.lastname: Hedberg
authors.affiliation: Epidemiology Workforce Branch, Division of Scientific Education and Professional Development, Center for Surveillance, Epidemiology, and Laboratory Services, CDC, Atlanta, Georgia, USA.
authors.forename: Byron
authors.initials: B
authors.lastname: Robinson
authors.affiliation: Adolescent Health Promotion and STD/HIV/HCV Programs, Multnomah County Health Department, Portland, Oregon, USA.
authors.forename: Kim
authors.initials: K
authors.lastname: Toevs
authors.affiliation: Epidemiology and Surveillance Branch, Division of STD Prevention, National Center for HIV/AIDS, Viral Hepatitis, STD, and TB Prevention, CDC, Atlanta, Georgia, USA.
authors.forename: Robyn
authors.initials: R
authors.lastname: Neblett-Fanfair
authors.affiliation: Epidemiology and Surveillance Branch, Division of STD Prevention, National Center for HIV/AIDS, Viral Hepatitis, STD, and TB Prevention, CDC, Atlanta, Georgia, USA.
authors.forename: Emiko
authors.identifier: 0000-0001-5194-0121
authors.initials: E
authors.lastname: Petrosky
authors.affiliation: Epidemiology and Surveillance Branch, Division of STD Prevention, National Center for HIV/AIDS, Viral Hepatitis, STD, and TB Prevention, CDC, Atlanta, Georgia, USA.
authors.forename: Susan
authors.initials: S
authors.lastname: Hariri
authors.affiliation: Oregon Health Authority, Portland, Oregon, USA.
authors.forename: Sean
authors.initials: S
authors.lastname: Schafer
mesh_terms: D000293:Adolescent; D000328:Adult; D001727:Bisexuality / Q000706:statistics & numerical data; D016022:Case-Control Studies; D004196:Disease Outbreaks / Q000706:statistics & numerical data*; D018451:Homosexuality, Male / Q000706:statistics & numerical data; D006801:Humans; D020407:Internet / Q000706:statistics & numerical data*; D008297:Male; D008875:Middle Aged; D063731:Mobile Applications / Q000706:statistics & numerical data*; D009922:Oregon / Q000453:epidemiology; D011159:Population Surveillance; D012307:Risk Factors; D012725:Sexual Behavior / Q000706:statistics & numerical data*; D012747:Sexual Partners / Q000523:psychology*; D011795:Surveys and Questionnaires; D013587:Syphilis / Q000453:epidemiology*; D055815:Young Adult
keywords: GAY MEN; PUBLIC HEALTH; SYPHILIS