​​​​​​​​​​​​​​​​ Diagnosis of Treponema pallidum, the causative agent of syphilis, relies on a combination of serologic assays that detect treponemal and nontreponemal antibodies. Treponemal assays either directly detect the pathogen (darkfield microscopy, PCR and DFA) or antibodies to the pathoge​n. Nontreponemal assays detect the body’s antibody response to the release of cardiolipin, which is elevated in numerous chronic conditions including syphilis.

Consultation on Laboratory Diagnosis of Syphilis

APHL hosted an expert consultation in November 2017 in partnership with the Centers for Disease Control and Prevention's Division of Sexually Transmitted Diseases Prevention (DSTDP) to develop expert recommendations on the laboratory diagnosis of syphilis. The consultation occurred after a months long process of key question development and comprehensive literature review by key subject matter experts. The final meeting report is available for your review and has been submitted to CDC for the development of official recommendations.

Suggested Reporting Language for Syphilis Serology Testing

The APHL STD Subcommittee and associated workgroup created the Suggested Reporting Language for Syphilis Serology Testing to aid laboratory professionals, clinicians, healthcare workers, epidemiologists and program staff in the interpretation of the two most commonly used syphilis serologic testing algorithms. The reporting guidance in this document is only suggestive and may need to be adapted or modified depending on factors such as jurisdictional requirements or advances in diagnostic technology.