About Our Syphilis, T Pallidum Test

Purpose of the test

This test checks whether you’ve been infected with Treponema pallidum, either now or in the past. Syphilis moves through four stages: primary, secondary, latent, and tertiary. Symptoms can be mild, easy to miss, or disappear between stages. Testing is the only reliable way to know your status.

Untreated syphilis can damage the brain, heart, eyes, and bones over time, as described by the CDC’s syphilis disease education resource. It can pass to an unborn baby during pregnancy, causing miscarriage, stillbirth, or severe complications (congenital syphilis). Open sores from syphilis raise the risk of getting or passing HIV.

This test doesn’t tell you which stage you’re in. It doesn’t replace an RPR or VDRL (venereal disease research laboratory) test for tracking treatment response. Those are different tests with a different job.

Screening: The CDC recommends routine syphilis screening for sexually active people at higher risk, including all pregnant people at their first prenatal visit.
Diagnosis: Consider this test when you have symptoms, a known exposure, or a positive non-treponemal result that needs treponemal confirmation.
Monitoring: This test isn’t used to track treatment response. An RPR or VDRL is the right tool for that.

What does our Syphilis, T Pallidum Test measure?

Several types of treponemal tests detect Treponema pallidum antibodies. The method your lab uses depends on its equipment and the clinical context.

Enzyme immunoassay (EIA) / chemiluminescent immunoassay (CIA): The most common method in CLIA-certified labs today. Detects both IgG and IgM antibodies. Many labs now run EIA/CIA first in what’s called the reverse sequence algorithm: treponemal test first, then RPR if reactive. IgM may point to a more recent infection; IgG stays in your blood for life.
Fluorescent treponemal antibody absorption test (FTA-ABS): An older confirmatory method. Some labs still use it for follow-up testing.
Treponema pallidum particle agglutination assay (TPPA): A widely used confirmatory test. Red blood cells coated with T. pallidum antigens clump together when antibodies are present. Highly specific.
Treponema pallidum hemagglutination assay (TPHA / MHA-TP): An older agglutination method similar to TPPA. Some labs still use it; results are read the same way.
Non-treponemal tests (RPR / VDRL): what this test is NOT. RPR and VDRL detect a different antibody called reagin. They’re used for screening and tracking treatment response. They aren’t the same as the treponemal test described here.

The CDC’s 2024 laboratory recommendations for syphilis testing describe how labs using the reverse sequence algorithm run a treponemal test first, then confirm with RPR if reactive. Your report may show both a treponemal result and an RPR titer. That’s expected. The two results together help your provider figure out whether infection is active, past, or needs more evaluation.

When should I get a Syphilis, T Pallidum Test?

Consider testing if any of these apply:

A possible exposure to syphilis through sexual contact
A partner recently diagnosed with syphilis or another STI
A painless sore on the genitals, anus, or mouth
A positive RPR or VDRL that needs treponemal confirmation
A current pregnancy, at any stage
An HIV diagnosis or current PrEP (pre-exposure prophylaxis) use
A skin rash on the palms or soles, or a widespread body rash

For routine screening, the CDC’s STI screening recommendations advise syphilis testing for:

Women at increased risk (history of incarceration, transactional sex work, geography, or other personal risk factors): screening is recommended; routine age-based annual screening is not recommended for all women
Pregnant people: at the first prenatal visit; rescreen at 28 weeks gestation and at delivery if at increased risk due to geography (living in a high syphilis prevalence) or personal risk factors (such as substance use, STIs during pregnancy, multiple partners, a new partner, or a partner with STIs)
Gay, bisexual, and other men who have sex with men (MSM): at least annually; every three to six months if at higher risk
Anyone diagnosed with HIV: at the first HIV evaluation and annually after; more often if at higher risk
People taking PrEP: at each follow-up visit, usually every three months.

The U.S. Preventive Services Task Force also issues preventive screening recommendations and is a useful reference for understanding which populations are prioritized for routine syphilis screening.

How It Works

How to get tested

You can order this test through Testing.com without a provider visit. We work with CLIA-certified labs including LabCorp and Quest Diagnostics. After you order, visit a nearby patient service center for a blood draw. Results land in your secure online account, and you’ll get an email when they’re ready.

You can compare tests by cost, turnaround time, and privacy before ordering.

Prefer to test privately from home with an at-home syphilis test? Syphilis is included in our at-home STD test, which screens for chlamydia, gonorrhea, syphilis, HIV, herpes, hepatitis B, and trichomoniasis from a self-collected sample.

Before the test

No fasting required. There are no dietary restrictions, and you don’t need to abstain from sex before testing. Because this is a blood test, the behavioral prep rules for urine-based STI tests don’t apply here.

Tell the lab about any medications you take, especially immunosuppressants. In rare cases, these can affect antibody levels.

If you have an active sore (chancre), mention it before your visit. A swab or darkfield microscopy may be recommended alongside the blood draw.

Bring a record of any prior syphilis diagnoses or treatments. Treponemal antibodies stay in your blood for life after any syphilis infection, even after a full cure. If you were treated years ago, your result will still be reactive. Knowing your treatment history helps your provider read that result correctly.

During the test

A technician cleans a spot on your inner arm and draws a small blood sample from a vein. The draw takes about two to three minutes.

You’ll feel a brief pinch when the needle goes in. Some people notice mild bruising or soreness afterward. That’s normal.

A small bandage covers the site. Keep it on for at least 15 minutes. Avoid heavy lifting with that arm for a few hours.

Call your provider if you notice lasting pain, swelling that doesn’t go down, or redness spreading from the draw site.

After the test

Results are ready in one to three business days after the lab receives your sample. Through Testing.com, results appear in your secure online account with an email notification.

If the initial treponemal result is reactive, the lab may automatically run a follow-up RPR or VDRL on the same sample. This is the reverse sequence algorithm at work. Both results may show up together on your report, which is why you might see two syphilis-related values when you were only expecting one.

What do my results mean?

Treponemal syphilis test results are reported as reactive or non-reactive, not positive or negative. “Reactive” means antibodies were detected, but it doesn’t tell you whether the infection is active or past. That distinction requires more context.

If your lab uses the reverse sequence algorithm, your report may include both a treponemal result and an RPR titer. These two results together help your provider figure out whether infection is active, past, or needs further evaluation.

If your results are non-reactive

No treponemal antibodies were found. There’s no evidence of current or past syphilis infection.

If exposure was within the last few weeks, antibodies may not yet be detectable. A non-reactive result in that window doesn’t rule out infection. Retest after the window closes if you know exposure occurred.

Talk with your provider about retesting if symptoms persist or a known exposure happened.

If your results are reactive

Treponemal antibodies were detected. This may indicate two things: a current active infection, or a past infection that was successfully treated.

Treponemal antibodies stay in your blood for life, even after a full cure. If you were treated for syphilis years ago and get tested today, a reactive result is expected. It doesn’t automatically mean you’re infected now.

Your provider will look at your RPR or VDRL result to figure out what’s happening. A high RPR titer may point to active infection. A low or absent RPR in someone with a prior treatment history suggests past infection.

If this is a new reactive result with no prior syphilis history: syphilis is curable with antibiotics, most often penicillin. Treatment works best when started early. Notify recent sexual partners so they can get tested too.

False positives on treponemal tests are rare. According to the Cleveland Clinic’s syphilis overview, false reactives can occur with certain autoimmune conditions like lupus or Lyme disease. If you have no known exposure and get a reactive result, ask your provider about confirmatory testing.

FAQs

Is the treponema pallidum test the same as an RPR test?

No. Treponemal tests detect antibodies specific to T. pallidum and stay reactive for life, even after successful treatment. RPR detects a different antibody called reagin and is used for screening and tracking treatment response. Both are syphilis tests, but they serve different purposes.

What does a treponema pallidum antibodies test actually detect?

It detects antibodies your immune system made in response to Treponema pallidum. Depending on the method your lab uses (EIA, CIA, TPPA, or FTA-ABS), the test may detect IgG antibodies, IgM antibodies, or both. IgM may indicate a more recent infection; IgG persists for life.

I was treated for syphilis years ago. Why is my test still reactive?

This is expected. Treponemal antibodies stay in your blood for life, even after a full cure. A reactive result in someone with a prior treated infection doesn’t mean the infection is active. Your provider will use an RPR or VDRL to check current activity.

Can I have syphilis if my treponemal test is non-reactive?

A non-reactive result means no antibodies were found at the time of testing. If exposure was very recent, antibodies may not yet be detectable. Retest after the window closes if you know exposure occurred.

Can I get syphilis again after treatment?

Yes. Syphilis doesn’t create immunity. Anyone successfully treated may become reinfected through new exposure to the bacteria. Regular testing is the only way to know your status after new exposures.

Should I test for syphilis during pregnancy?

Yes. The CDC recommends testing at the first prenatal visit. Untreated syphilis during pregnancy can cause miscarriage, stillbirth, or severe health problems for the baby (congenital syphilis). Rescreening at 28 weeks gestation and at delivery is recommended for those at increased risk due to geography or personal risk factors.

Can other conditions cause a false reactive result?

Treponemal tests have a very low false-positive rate, but false reactives can happen with certain autoimmune conditions like lupus or Lyme disease. If you have no known syphilis exposure and get a reactive result, ask your provider about confirmatory testing.