Outcomes of Mathematical Modelling for the National Gay Men’s Syphilis Action Plan. Presentation given by David Wilson at the AFAO National Syphilis Forum, 23 October 2009.

1. Outcomes of Mathematical Modelling for the National Gay Men’s Syphilis Action Plan Associate Professor David Wilson National Centre in HIV Epidemiology and Clinical Research Sydney, Australia [email_address]

4. Included HIV infection and possible syphilis coinfection Uninfected Primary HIV Primary HIV Chronic HIV Chronic HIV AIDS / Late stage infection AIDS / Late stage infection 1 st Line Treatment Treatment Failure 2 nd Line Treatment Undiagnosed Infection Diagnosis

10. Simulating the sexual network

11. Reproducing the past epidemic Syphilis HIV Prevalence of syphilis in HIV+ and HIV- men in agreement with available data

13. Increased condom use Partnership status Currently Intervention HIV Concordant 10% 10% Unknown 40% 80% / 100% HIV Discordant ~69% 80% / 100%

14. Increased condom use Intervention for one month, three months, or indefinitely Long term

15. Reduction in partner numbers 25% decrease 50% decrease

16. Mass treatment Rollout 3 months > 10 partners Rollout 1 month > 25 partners Rollout 1 month >10 partners

19. Targeted screening at population groups

20. Targeting risk behaviour groups (increased frequency) 2 tests per year 4 tests per year

22. Partner notification

23. Follow-up testing

24. Efficiency of interventions Intervention Infections averted (10 years) Total tests (10 years) Tests per infection averted 85% coverage 6524 83004 13 Frequency 2 tests/yr 16466 239369 15 Frequency 4 tests/yr 20506 548767 27 Diagnosed HIV+ 6 tests/yr 6678 84535 13 >10 partners, 2 tests/yr 12865 83929 7 >20 partners, 2 tests/yr 12254 45329 4 >50 partners, 2 tests/yr 3003 8539 3 Follow up 75% every 3 months 2385 5036 2 Contact tracing 75% regular, 5% casual 8903 6199 0.7