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Treponema Pallidum Particle Agglutination Assay (TPPA)

Published: July 27, 2026Updated: August 25, 2026

The TPPA test measures antibodies against the bacterium Treponema pallidum, which causes syphilis, to aid in the diagnosis of this infectious disease.

Quick summary

TPPA detects antibodies for diagnosing syphilis infection.

Medically reviewed by WellAlly Editorial TeamLast reviewed August 25, 2026Editorial policy

Key facts at a glance

Units
titer
Clinical utility
diagnostic
Result kind
qualitative
FDA-cleared
Roche TPPA, Fujirebio TPPA, Serodia TPPA
interpretation: {"text":"A titer within this range may indicate the presence of antibodies against T. pallidum. Clinical correlation is required for interpretation.","label":"0–80 titer"}; {"text":"A titer above 80 is considered a strong positive result, indicating a high likelihood of current or past syphilis infection.","label":">80 titer"}

The TPPA is a serological test used to confirm the presence of antibodies against the bacterium Treponema pallidum, which is responsible for syphilis. It is often used as a confirmatory test following a positive screening test such as the Rapid Plasma Reagin (RPR) or Venereal Disease Research Laboratory (VDRL) test.

The TPPA test involves the agglutination of colored particles coated with T. pallidum antigens when mixed with a patient's serum containing antibodies. The titer, or dilution level at which agglutination is still visible, is reported to indicate the concentration of antibodies present.

A positive TPPA test typically indicates current or past infection with syphilis. However, it does not differentiate between active and past infections, and further clinical evaluation is necessary for confirmation and treatment decisions.

Frequently asked questions

What does a positive TPPA test mean?
A positive TPPA test indicates the presence of antibodies against Treponema pallidum, suggesting current or past syphilis infection.
Can TPPA differentiate between active and past syphilis infections?
No, TPPA cannot differentiate between active and past infections. Additional tests and clinical evaluation are needed for this purpose.
  1. 1
    Treponema pallidum particle agglutination assay (TPPA)Source
  2. 2
    Syphilis Testing: Serologic Testing for SyphilisSource

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This information is for educational purposes only and is not a substitute for professional medical advice, diagnosis, or treatment.

Medical Disclaimer

This content is for general informational and educational purposes only and is not a substitute for professional medical advice, diagnosis, or treatment. Always seek the guidance of a qualified healthcare provider with any questions you have about a medical condition, and never disregard professional medical advice or delay seeking it because of something you read here.

If you think you may have a medical emergency, call your local emergency number or go to the nearest emergency department immediately.

Medically reviewed by WellAlly Editorial Team Last reviewed August 25, 2026. · Read our editorial policy