title: Will changes in gay men's sexual behavior reduce syphilis rates?
abstract: BACKGROUND
  Reducing rates of partner change and increasing condom usage among gay men are obvious targets for potentially reducing syphilis transmission among gay men.
  
  
  METHODS
  We developed an agent-based stochastic model to examine syphilis transmission among a population of gay men, representative of gay men in Australia. This model was used to explore the potential impact of changes in sexual behavior over 1 month, 3 month, and indefinite time frames on syphilis epidemics.
  
  
  RESULTS
  Simulations of interventions showed that short-term reductions in rates of partner change and increased condom use would have negligible impact on the long-term trends of syphilis epidemics. If no interventions are introduced, then the model forecasts that the syphilis prevalence in the population could continue to rise, with an increase of 80% in the number of men infected with syphilis during the next decade. However, if changes in sexual behavior are maintained in the long-term, then syphilis epidemics can be mitigated. If condom use is sustained at 80% in partnerships that are HIV discordant or of unknown status, then the prevalence of syphilis is estimated to decrease by 9% over 10 years. Similarly, if partner acquisition rates decrease by 25%, then there will be a 22% reduction in syphilis prevalence.
  
  
  CONCLUSIONS
  Interventions promoting partner reduction or increased condom use would be ineffective in the short-term, and would have limited prospects for success in the long-term unless very large changes in behavior are sustained. Complementary social research indicates that such long-term changes in behavior are unlikely to be adopted, and therefore other intervention strategies need to be developed to reduce syphilis among gay men.
authors.affiliation: Kirby Institute for Immunity Infection and Society, 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: Pol Dominic
authors.initials: PD
authors.lastname: McCann
authors.forename: Jack
authors.initials: J
authors.lastname: Bradley
authors.forename: Ian
authors.initials: I
authors.lastname: Down
authors.forename: Basil
authors.initials: B
authors.lastname: Donovan
authors.forename: Garrett
authors.initials: G
authors.lastname: Prestage
authors.forename: David P
authors.initials: DP
authors.lastname: Wilson
mesh_terms: D000293:Adolescent; D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D001315:Australia / Q000453:epidemiology; D058872:Epidemics / Q000517:prevention & control*; D015658:HIV Infections / Q000453:epidemiology / Q000635:transmission; D018451:Homosexuality, Male / Q000523:psychology*; D006801:Humans; D008137:Longitudinal Studies; D008297:Male; D008875:Middle Aged; D015995:Prevalence; D021841:Safe Sex; D012725:Sexual Behavior / Q000706:statistics & numerical data*; D012747:Sexual Partners; D013587:Syphilis / Q000453:epidemiology* / Q000635:transmission; D055815:Young Adult