Causative organism Treponema pallidum spp pallidum
Incubation period

9-90 days (mean 30) to primary syphilis;

30-150 days to secondary syphilis;

early latent presents post-secondary syphilis less than 2 years post last negative test; late latent presents more than 2 years post last negative test;

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 or last negative test;
  • Secondary syphilis — 6 months plus duration of symptoms or last negative test;
  • Early latent syphilis — 12 months or most recent negative test
  • Late latent/tertiary syphilis: Test current partner/s. If any doubt as to whether the patient has early latent or late latent syphilis, contact trace as for early latent syphilis.

If the stage of syphilis is unclear, contact your local specialist service for advice

Usual testing method Serology for syphilis. PCR can be done from ulcers/rash or other lesions
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. However, close sexual contact and oral sex are modes of transmission
Transmission by oral sex  Probably common
Duration of potential infectivity Up to 24 months (rare after 12 months). Late latent/tertiary syphilis are usually not infectious
Important sequelae

Congenital infections in pregnancy

Neurosyphilis, cardiovascular syphilis, enhanced HIV transmission 

Direct benefit of detection and treatment of contacts Cure, and prevention of transmission and congenital syphilis
Contact tracing considerations

Ensure window period follow-up testing occurs where the person is not offered presumptive treatment, is pregnant or intending to become pregnant, or is the sexual partner of a pregnant person. This will decrease the risk of a missed diagnosis, reinfection and/or congenital syphilis.

Seek specialist advice if there is a concern for older children of a person newly diagnosed with syphilis during pregnancy.

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. Ensure additional serology such as (HIV, syphilis, Hepatitis A, B and C) is collected as appropriate, plus a screen for chlamydia and gonorrhoea. Informed consent must be obtained before testing or treating.
  2. Contacts of early latent syphilis can also be treated

    presumptively, but if the contact was greater than 3 months previous, treatment delayed until serology is available and then given according to serology result. If the exposure was greater than 12 months ago and the patient has positive serology, treat as for late infection.

  3. If the contact ispenicillin allergic [1] or needle-phobic check the STI Guidelines for alternative treatment or discuss treatment options with your local specialist service. If obtaining benzathine penicillin is difficult, do not substitute with a different treatment and consult with your local specialist service.
Contact tracing priority  High

Notifiable by doctors in all Australian states and territories, and in New Zealand; as well as laboratories in some Australian states and territories

Where a syphilis register exists in your State, Territory or region, ensure you promptly report the required details. Where there are any concerns or ambiguity contact your local public health service for additional support.


NPS Medcinewise, Devchand M; Trubiano JA; Penicillin allergy: a practical approach to assessment and prescribing Australian Prescriber 2 December 2019 Available online at:



Page last updated September 2022