title: Frequent testing of highly sexually active gay men is required to control syphilis.
abstract: BACKGROUND
  The incidence of syphilis infections has been substantially increasing in gay men in the developed world.
  
  
  METHODS
  We developed an individual-based mathematical model describing syphilis transmission within a gay male population: we used the model to simulate the expected relative impact of numerous screening and treatment interventions, targeting different at-risk groups with various coverage and frequency rates and follow-up schedules.
  
  
  RESULTS
  The model predicts that increasing the proportion of gay men tested each year would have a relatively modest impact on syphilis incidence. However, increasing the frequency of testing can have a large impact, with the prevalence of syphilis reduced substantially if individuals are tested every 3 months. Targeting frequent screening at gay men who have large numbers of partners or who engage in group sex is a more efficient way of reducing syphilis epidemics. Contact tracing the regular partners of infected individuals is the most efficient intervention and can have a significant epidemiological impact with relatively high coverage rates.
  
  
  CONCLUSIONS
  Increasing the frequency of testing and treatment are required to mitigate syphilis epidemics. Notifying and testing partners of infected men should occur where possible but the high rates required to reverse epidemic trends are likely to be infeasible. Contact tracing should be a secondary priority that is coupled with increases in the frequency of testing in the population. Encouraging testing among men not previously tested for syphilis is also recommended.
authors.affiliation: National Centre in HIV Epidemiology and Clinical Research, The University of New South Wales, Sydney, Australia.
authors.forename: Richard T
authors.initials: RT
authors.lastname: Gray
authors.forename: Alexander
authors.initials: A
authors.lastname: Hoare
authors.forename: Garrett P
authors.initials: GP
authors.lastname: Prestage
authors.forename: Basil
authors.initials: B
authors.lastname: Donovan
authors.forename: John M
authors.initials: JM
authors.lastname: Kaldor
authors.forename: David P
authors.initials: DP
authors.lastname: Wilson
mesh_terms: D001315:Australia; D016358:Contact Tracing; D004196:Disease Outbreaks / Q000517:prevention & control; D018562:Disease Transmission, Infectious / Q000706:statistics & numerical data*; D018451:Homosexuality, Male / Q000706:statistics & numerical data*; D006801:Humans; D008297:Male; D008403:Mass Screening; D015233:Models, Statistical; D011159:Population Surveillance; D012747:Sexual Partners; D013587:Syphilis / Q000175:diagnosis / Q000453:epidemiology / Q000517:prevention & control* / Q000635:transmission; D047568:Unsafe Sex / Q000706:statistics & numerical data*