Treponema pallidium hemagglutination assay (tpha) Test

TPHA positive indicates presence of antibodies to Treponema pallidum, confirming exposure to syphilis. It cannot distinguish active, latent, or previously treated infection. Interpretation requires clinical assessment and a non-treponemal test (VDRL/RPR) to assess activity and monitor treatment response. A positive result prompts further evaluation, appropriate antibiotic treatment if active, and partner notification and testing.

The TPHA (Treponema pallidum hemagglutination) test is a treponemal serologic assay that detects antibodies against Treponema pallidum. Patient serum is mixed with red blood cells coated with T. pallidum antigen; visible agglutination indicates a positive result. It’s sensitive and specific for syphilis but often remains positive after treatment, so it can’t distinguish active from past infection and is used with non-treponemal tests.

TPHA (Treponema pallidum hemagglutination assay) is a blood test that detects antibodies to Treponema pallidum, the bacterium that causes syphilis. It’s used to confirm infection after a screening test or to support diagnosis. TPHA indicates past or present exposure but cannot reliably distinguish active infection from treated disease, so results are interpreted with clinical findings and non‑treponemal tests.

TPHA is highly accurate for detecting treponemal antibodies, with sensitivity typically around 85–100% and specificity about 98–100% once antibodies develop. It reliably confirms past or current syphilis but can be negative in very early (window period) infection and usually remains positive for life, so it cannot distinguish active from treated disease; non‑treponemal tests (VDRL/RPR) assess activity.

Yes—TPHA (a treponemal antibody test) usually remains positive for life after infection, even after successful treatment. A positive TPHA indicates past or present syphilis but cannot distinguish active disease. Non-treponemal tests (RPR/VDRL) and clinical assessment are used to monitor treatment response. Rare seroreversion can occur, especially after very early treatment or in infants, so consult a clinician.

The normal TPHA result is non-reactive (negative), meaning no Treponema pallidum antibodies are detected. A reactive (positive) TPHA indicates current or past syphilis exposure and usually requires confirmatory or activity testing (for example, a non-treponemal test). Clinical correlation and additional testing (e.g., RPR/VDRL) are needed to determine active disease and guide treatment.