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NACCHO and ASHM

How to Test

Treponemal syphilis testing

Last Updated: June 2026

Treponemal tests detect specific treponemal antibodies and are used as a screening test to identify whether someone has ever been infected with syphilis. Most laboratories currently use a treponemal test that is reported as reactive or non-reactive.

  • treponemal tests have a small false positive rate, therefore, a second reactive treponemal test is required to confirm a true positive result
  • if a non-reactive test result occurs after exposure to infection was within three weeks, the treponemal test should be repeated
  • following exposure to syphilis, treponemal tests will become reactive by three months if infected

Most people will have a positive antibody test by two to four weeks post exposure. However, some people can take up to three months for treponemal tests to be reactive after infection. This is called the window period and shows the importance of regular testing as people may be falsely negative if tested in the window period

Screening treponemal tests include:

  • enzyme immunoassay (EIA)
  • immunoglobulin M (IgM) and immunoglobulin G (IgG)
  • Point-of-Care tests (PoCT)

Positive treponemal screening tests are confirmed by a confirmatory treponemal test such as:

  • treponema pallidum particle agglutination assay (TPPA)
  • treponema pallidum haemagglutination assay (TPHA)

References