In shortA syphilis test is always paired: a non-treponemal test (RPR — process activity) plus a treponemal one (TPHA/ELISA — confirmation). A positive pair means syphilis (current or past); mismatched results require retesting. Earlier than 3–6 weeks after contact the test can be falsely negative.
About the infection
Syphilis is caused by Treponema pallidum. Tests come in two groups: non-treponemal (RPR) — react to the active process and fall after treatment, and treponemal (TPHA, ELISA) — specific confirmatory tests that stay positive for years, often lifelong.
So one result without the other means little: screening starts with one test, and any positive is confirmed with one from the other group.
Diagnostic methods
| Method | What it shows | When it is used |
|---|---|---|
| Non-treponemal: RPR | Process activity; the titer falls after treatment | Screening and treatment-efficacy control |
| Treponemal: TPHA, ELISA | Specific antibodies to Treponema pallidum | Diagnosis confirmation; stays “+” for years |
| ELISA total antibodies (screening) | A sensitive first test | Mass screening, pregnancy, donors |
Window period: when the test becomes reliable
The incubation period of syphilis averages 3–4 weeks (10 to 90 days). A test earlier than 3–6 weeks after a possible contact can be falsely negative: with high risk it is repeated at 6 weeks and 3 months.
How to prepare
Venous blood, fasting or 4 hours after a meal. No special preparation. In pregnancy the test is done three times — per the observation calendar.
Reading the result
| Result | What it means |
|---|---|
| Both tests negative | No syphilis (if more than 6 weeks since contact) |
| Both tests positive | Syphilis, current or past — a dermatologist-venereologist judges by titer and history |
| Treponemal “+”, non-treponemal “−” | Past/treated syphilis, late stage or a false reaction — further workup |
| Non-treponemal “+”, treponemal “−” | Often a false-positive reaction (pregnancy, autoimmune disease, infections) — retest |
When a retest makes sense
After a risky contact — at 6 weeks and 3 months if the first result is negative. After treatment the non-treponemal titer is followed on the doctor’s schedule, usually every 3 months in the first year.
Which specialist to see
A positive or doubtful result is reviewed by: Dermatologist-venereologist. Note the date of the first test and the possible contact — the retesting plan depends on it.
Several markers on your report?
The app reads your whole report — this marker together with its neighbors, not one by one.
Frequently asked questions
RPR positive, TPHA negative — is it syphilis?
Mostly not: an isolated positive non-treponemal reaction can be false in pregnancy, autoimmune disease, recent infections and in the elderly. A repeat workup by a dermatologist-venereologist gives the answer.
I had syphilis treated 10 years ago — will tests be positive?
Treponemal tests (TPHA, ELISA) often stay positive for life; that does not mean active disease. Activity is judged by the non-treponemal test and its titer.
When to test for syphilis after a contact?
Not earlier than 3–6 weeks: before that the test can be negative even after infection. Optimally at 6 weeks; if very anxious, repeat at 3 months.
Sources
- WHO — Guidelines for the treatment of Treponema pallidum (syphilis) — WHO, 2016 (iris.who.int). Accessed: September 17, 2026.
- MSD Manuals — Helminths — MSD Manuals (msdmanuals.com). Accessed: September 17, 2026.