Publications & Reports

Will changes in gay men's sexual behavior reduce syphilis rates?

Richard T Gray, Alexander Hoare, Pol Dominic McCann, Jack Bradley, Ian Down, Basil Donovan, Garrett Prestage, David P Wilson
Kirby Institute for Immunity Infection and Society, University of New South Wales, Sydney, Australia.


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.


  • Journal: Sexually Transmitted Diseases
  • Published: 01/12/2011
  • Volume: 38
  • Issue: 12
  • Pagination: 1151-1158