TPHA antitreponemal test

TPHA is a blood test for syphilis. It shows whether your body has ever produced antibodies against the bacterium Treponema pallidum, which causes this sexually transmitted infection. Syphilis responds well to antibiotics, and the test can provide reassurance after a risky contact, before a new relationship or during pregnancy.

Who the test is intended for

• you have had unprotected sex (vaginal, anal or oral) with a new or casual partner;
• your partner has been diagnosed with syphilis or another sexually transmitted infection;
• you have noticed a painless sore on the genitals, around the anus or in the mouth, or a rash, particularly on the palms and soles;
• you are pregnant or planning a pregnancy: syphilis testing is part of pregnancy investigations because the disease can be passed to the baby;
• your VDRL test is positive and needs confirmation;
• you have HIV or another sexually transmitted infection, so the doctor also requests a syphilis check.

What the test reveals

TPHA (haemagglutination test for Treponema pallidum) looks for antibodies directed specifically against the bacterium. It therefore reliably shows whether a person has been infected. After infection, antibodies usually remain in the blood for years, often for life, even after successful treatment.

TPHA is therefore combined with the VDRLtest. VDRL shows whether the disease is active and gradually weakens after successful treatment, so the doctor uses it to monitor treatment success. Together, they provide a fuller picture than either test alone.

What the test involves and how to prepare

A blood sample is taken from a vein, and collection takes a few minutes. You do not need to fast, and no special preparation is required.

Antibodies do not appear immediately after infection, but usually after several weeks, and in some people only within three months. If little time has passed since the risky contact, the doctor may recommend repeating the test. For a genital sore, the doctor may also request PCR detection of Treponema pallidum. PCR detects the presence of the bacterium itself.

What your result means

The result is reported as positive or negative. A doctor interprets it alongside your symptoms, the timing of possible contact and the VDRL result.

• Negative: antibodies were not found. If less than three months have passed since the risky contact, it is advisable to repeat the test.
• Positive TPHA and positive VDRL: support syphilis, most often active or recently treated. The doctor determines the disease stage and the need for treatment, and partners should also be tested.
• Positive TPHA with negative VDRL: most often previously treated syphilis, but it may also be a very early or longstanding untreated infection. A doctor assesses it, with additional tests if necessary.
• Unexpectedly positive: false-positive results are rare, but possible in some other diseases, so the doctor confirms them with another test.

How to arrange testing

You can have blood collected without an appointment or referral at one of our branches across Croatia (listed on the Contact). Prices for all tests and panels are available in the price list. If you also want to check for other sexually transmitted infections, see the Sexually transmitted infection testing.

Frequently asked questions

What is the difference between the TPHA and VDRL tests?

TPHA shows whether a person has ever been infected and usually remains positive for life. VDRL shows disease activity and falls after treatment. They are therefore most often performed together.

Does TPHA remain positive after treatment?

Usually yes. A positive TPHA after treatment does not mean that treatment failed. Success is monitored using VDRL, according to a schedule set by the doctor.

When should I be tested after a risky sexual contact?

You can take the test immediately, but a negative result in the first few weeks does not rule out infection. It is therefore usually recommended to repeat it around three months after contact. If you have a sore or rash, consult a doctor immediately.

Can syphilis be treated?

Yes. Syphilis is treated with antibiotics, most often penicillin, and treatment is managed by a doctor, usually a dermatovenereologist or infectious disease specialist. Untreated syphilis can progress silently for years and damage the heart, nerves and other organs, so timely testing is important.