title: Sexual bridging socially and over time: a simulation model exploring the relative effects of mixing and concurrency on viral sexually transmitted infection transmission.
abstract: BACKGROUND
  Sexual partnerships between people at higher and lower risk for sexually transmitted infections (STIs) (i.e., bridging) occur through dissortative mixing and concurrent partnerships, yet the relative effects of these network patterns on population STI spread are poorly understood.
  
  
  OBJECTIVE
  Using a stochastic model, the authors investigated the impact of mixing and concurrency on the spread of a persistent viral STI.
  
  
  METHODS
  A total of 1,050 populations were simulated of 1,000 subjects over 400 weeks with varied concurrency levels and mixing patterns. STI prevalence and the average number of secondary transmissions per subject were analyzed with regression.
  
  
  RESULTS
  Mixing had a greater impact on prevalence for all groups, whereas concurrency was significant for only the lowest activity group. Mixing patterns moderated the magnitude of concurrency's impact on secondary transmissions.
  
  
  CONCLUSIONS
  Through connecting subgroups of differential risk, sexual mixing facilitates dissemination of STIs throughout a population. Concurrency expedites transmission by shortening the time between sexual contacts among infected and susceptible persons, particularly during the highly infectious period.
authors.affiliation: School of Medicine, University of North Carolina, Chapel Hill, 27599-7030, USA. Doherty@med.unc.edu
authors.forename: Irene A
authors.initials: IA
authors.lastname: Doherty
authors.forename: Stephen
authors.initials: S
authors.lastname: Shiboski
authors.forename: Jonathan M
authors.initials: JM
authors.lastname: Ellen
authors.forename: Adaora A
authors.initials: AA
authors.lastname: Adimora
authors.forename: Nancy S
authors.initials: NS
authors.lastname: Padian
mesh_terms: D003198:Computer Simulation; D018562:Disease Transmission, Infectious; D006801:Humans; D015233:Models, Statistical; D012725:Sexual Behavior; D015229:Sexually Transmitted Diseases, Viral / Q000635:transmission*; D013269:Stochastic Processes; D013997:Time Factors