Infectious syphilis under two years’ duration is a surveillance classification encompassing primary, secondary and early latent syphilis [1]. The duration boundary is used for reporting and does not imply that the date of infection is known precisely in every case [1]. Syphilis is a bacterial sexually transmitted infection caused by Treponema pallidum [2][3].
Disease overview
Bacterial Evidence-backed information EN 6/7 applicable sections · ZH 6/7 applicable sections Updated Oct 23, 2026
This category covers infectious syphilis of less than two years’ duration, including primary, secondary and early latent syphilis, within the Australian national surveillance framework [1]. Confirmed and probable cases meeting the surveillance definition are nationally reportable [1].
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Classification may incorporate compatible clinical findings, including a primary chancre or signs of secondary syphilis, together with specified laboratory evidence [1]. Laboratory pathways include recent seroconversion and qualifying changes in non-treponemal antibody titres with treponemal confirmation [1].
Infectious syphilis is widely recognized as a common sexually transmitted infection. Public health tracking consistently documents its sustained prevalence across diverse demographic groups. Standardized monitoring frameworks capture its ongoing distribution to support community-level intervention planning [4].
Syphilis can be transmitted through sexual contact with infectious lesions during vaginal, anal or oral sex, through blood transfusion, and from a pregnant woman to her fetus [2][3]. Transmission may occur through exposed lesions or body areas not covered by a condom [2].
Correct and consistent condom use reduces the likelihood of sexual transmission, although it does not eliminate risk when infectious lesions are outside the covered area [2][5]. People at higher risk should undergo regular testing, and pregnant women should be tested at the first prenatal care visit; people diagnosed with syphilis should notify sexual partners [2].
Confirmed and probable cases that meet the national definition are reportable [1]. Interpretation of trends should retain the applicable definition version, the confirmed-versus-probable scope, and jurisdictional notification practices [1].
- 1 Australian Government Department of Health and Aged Care. Syphilis (less than 2 years duration) – surveillance case definition [Internet]. cited 11 Aug 2026. Available from: https://www.health.gov.au/sites/default/files/documents/2022/06/syphilis-less-than-2-years-duration-surveillance-case-definition.pdf
- 2 World Health Organization. Syphilis [Internet]. cited 20 May 2026. Available from: https://www.who.int/news-room/fact-sheets/detail/syphilis
- 3 World Health Organization. Syphilis -- Global [Internet]. cited 20 May 2026. Available from: https://www.who.int/health-topics/syphilis
- 4 US Centers for Disease Control and Prevention. About Syphilis | Syphilis | CDC [Internet]. cited 3 Sept 2026. Available from: https://www.cdc.gov/syphilis/about/
- 5 Wikipedia contributors. Syphilis - Wikipedia [Internet]. Wikipedia. cited 20 May 2026. Available from: https://en.wikipedia.org/wiki/Syphilis
- 6 Chevalier FJ et al. Syphilis: A Review. JAMA. 2025 Dec 2. PMID: 41100079. doi: 10.1001/jama.2025.17362. PubMed: https://pubmed.ncbi.nlm.nih.gov/41100079/
- A51
- 1A70
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