title: Sexual networks, surveillance, and geographical space during syphilis outbreaks in rural North Carolina.
abstract: BACKGROUND
  Sexually transmitted infections (STIs) spread along sexual networks whose structural characteristics promote transmission that routine surveillance may not capture. Cases who have partners from multiple localities may operate as spatial network bridges, thereby facilitating geographical dissemination. We investigated how surveillance, sexual networks, and spatial bridges relate to each other for syphilis outbreaks in rural counties of North Carolina.
  
  
  METHODS
  We selected from the state health department's surveillance database cases diagnosed with primary, secondary, or early latent syphilis during October 1998 to December 2002 and who resided in central and southeastern North Carolina, along with their sex partners and their social contacts irrespective of infection status. We applied matching algorithms to eliminate duplicate names and create a unique roster of partnerships from which networks were compiled and graphed. Network members were differentiated by disease status and county of residence.
  
  
  RESULTS
  In the county most affected by the outbreak, densely connected networks indicative of STI outbreaks were consistent with increased incidence and a large case load. In other counties, the case loads were low with fluctuating incidence, but network structures suggested the presence of outbreaks. In a county with stable, low incidence and a high number of cases, the networks were sparse and dendritic, indicative of endemic spread. Outbreak counties exhibited densely connected networks within well-defined geographic boundaries and low connectivity between counties; spatial bridges did not seem to facilitate transmission.
  
  
  CONCLUSIONS
  Simple visualization of sexual networks can provide key information to identify communities most in need of resources for outbreak investigation and disease control.
authors.affiliation: School of Medicine, University of North Carolina at Chapel Hill, Chapel Hill, NC, USA. doherty@med.unc.edu
authors.forename: Irene A
authors.initials: IA
authors.lastname: Doherty
authors.forename: Marc L
authors.initials: ML
authors.lastname: Serre
authors.forename: Dionne
authors.initials: D
authors.lastname: Gesink
authors.forename: Adaora A
authors.initials: AA
authors.lastname: Adimora
authors.forename: Stephen Q
authors.initials: SQ
authors.lastname: Muth
authors.forename: Peter A
authors.initials: PA
authors.lastname: Leone
authors.forename: William C
authors.initials: WC
authors.lastname: Miller
mesh_terms: D000328:Adult; D017677:Age Distribution; D001727:Bisexuality / Q000706:statistics & numerical data; D004196:Disease Outbreaks / Q000706:statistics & numerical data*; D005260:Female; D020010:Heterosexuality / Q000706:statistics & numerical data; D006716:Homosexuality / Q000706:statistics & numerical data; D006801:Humans; D015994:Incidence; D008297:Male; D009657:North Carolina / Q000453:epidemiology; D011159:Population Surveillance; D015995:Prevalence; D012189:Retrospective Studies; D012424:Rural Population / Q000706:statistics & numerical data*; D017678:Sex Distribution; D012737:Sex Factors; D012725:Sexual Behavior; D012747:Sexual Partners; D060756:Social Networking; D013587:Syphilis / Q000453:epidemiology*