Causative organism Treponema pallidum spp pallidum
Incubation period 9-90 days (mean 30) to primary syphilis; 30-150 days to secondary syphilis; 5-35 years to tertiary syphilis.
How far back to trace According to sexual history and clinical stage of infection: Primary syphilis — 3 months plus duration of symptoms; Secondary syphilis — 6 months plus duration of symptoms; Early latent syphilis — 12 months.
Usual testing method Serology for syphilis. Ulcer swab can be tested by nucleic acid amplification
Common symptoms

Anogenital or oral ulcers


Early infection commonly asymptomatic

Likelihood of transmission per act of unprotected intercourse

Early syphilis (primary, secondary, early latent): >20 % Late latent and tertiary: usually not infectious
Likelihood of long-term sexual partner being infected

Up to 50% if early syphilis;

<1% if no contact during infectious period

Protective effect of condoms High if lesions covered by condoms
Transmission by oral sex  Probably common
Duration of potential infectivity Up to 24 months (rare after 12 months)
Important sequelae Neurosyphilis, cardiovascular syphilis, and congenital infection. Enhanced HIV transmission and incidence, so a diagnosis of syphilis is an indication for HIV pre-exposure prophylaxis (PrEP) in gay men
Direct benefit of detection and treatment of contacts Cure, and prevention of transmission
Usual management of contacts

Consultation with sexual health physician in all cases is suggested

  1. Presumptively treat all sexual contacts of patients with primary or secondary syphilis regardless of serology. Contacts of early latent syphilis can also be treated presumptively, but if the contact was greater than 3 months previous, treatment can be given according to serology result.
  2. If the exposure was greater than 12 months ago and the patient has positive serology, treat as for late infection:
  3. If the contact is penicillin allergic or needle-phobic check the STI Guidelines
Contact tracing priority  High
Notification Notifiable by doctors in all Australian states and territories, and in New Zealand; as well as laboratories in some Australian states and territories