title: Spatial epidemiology of the syphilis epidemic in Toronto, Canada.
abstract: BACKGROUND
  Urban centers across Canada and the United States have battled syphilis epidemics with high rates of human immunodeficiency virus (HIV) coinfection for over a decade. We examined the spatial epidemiology of syphilis over time for Toronto (Canada) with the intention of forming new insights and strategies for restoring low syphilis rates.
  
  
  METHODS
  Syphilis incidence rates, HIV-syphilis coinfection, and sexual risk behavior prevalences were estimated and mapped from primary, secondary, early latent syphilis cases reported to Toronto Public Health between January 1, 2006, and December 31, 2010, using ArcGIS 9.0. Geographic clusters of significantly elevated syphilis incidence rates were identified using SaTScan 9.0. The relationship between syphilis incidence rates and sociocultural factors was modeled using the Besag, York, and Mollie model.
  
  
  RESULTS
  Between 2006 and 2010, syphilis incidence rates were high in Toronto's downtown core area, intensified, and spread outward initiating 3 independent outbreak areas. HIV coinfection was high (47%); however, no spatial clustering was identified. Syphilis incidence rates, HIV coinfection, and behavioral risk factors promoting sexually transmitted infection transmission were high outside the core area, suggesting that peripheral sexual networks may be influencing high syphilis infection rates both inside and outside the core.
  
  
  CONCLUSIONS
  Toronto's syphilis epidemic is mature. Response, resources, and intervention activities should target core and noncore areas.
authors.affiliation: From the *Dalla Lana School of Public Health, University of Toronto, Toronto, Ontario, Canada; †Cancer Care Ontario, Toronto, Ontario, Canada; ‡Public Health Agency of Canada, Toronto, Ontario, Canada; and §Toronto Public Health, Toronto, Ontario, Canada.
authors.forename: Dionne
authors.initials: D
authors.lastname: Gesink
authors.forename: Susan
authors.initials: S
authors.lastname: Wang
authors.forename: Todd
authors.initials: T
authors.lastname: Norwood
authors.forename: Ashleigh
authors.initials: A
authors.lastname: Sullivan
authors.forename: Dana
authors.initials: D
authors.lastname: Al-Bargash
authors.forename: Rita
authors.initials: R
authors.lastname: Shahin
mesh_terms: D002170:Canada / Q000453:epidemiology; D016000:Cluster Analysis; D060085:Coinfection / Q000453:epidemiology*; D016358:Contact Tracing / Q000706:statistics & numerical data*; D058872:Epidemics; D005260:Female; D015658:HIV Infections / Q000453:epidemiology* / Q000517:prevention & control; D007722:Health Knowledge, Attitudes, Practice; D006291:Health Policy; D006801:Humans; D015994:Incidence; D008297:Male; D011634:Public Health; D012307:Risk Factors; D012309:Risk-Taking; D012725:Sexual Behavior / Q000706:statistics & numerical data*; D012959:Socioeconomic Factors; D062211:Spatio-Temporal Analysis; D013587:Syphilis / Q000453:epidemiology* / Q000517:prevention & control