Syphilis tests: what to take and how to read the result

When syphilis tests are taken

The reasons fall into two groups. Mandatory: pregnancy (three times during the term), hospital admission and surgery, health certificates for some professions, blood donation, the army medical board. Personal: unprotected sex with a new partner, a painless sore on the genitals or in the mouth (hard chancre), an unexplained rash on the palms and soles, testing “as a couple” before a relationship. Syphilis is insidious because it can stay hidden for a long time — a test is the only way to find it at an early, fully curable stage.

Two classes of tests: screening and confirmation

Non-treponemal tests (the microprecipitation reaction — RW/RMP, RPR) detect antibodies to cardiolipin, a substance released when cells are damaged by Treponema pallidum. They are cheap and fast but not specific: the same response occurs in pregnancy, respiratory infections and autoimmune diseases. Their strength is the quantitative titre, which is used to track how well treatment works. Treponemal tests (CLIA/ELISA, TPHA, FTA) detect antibodies to the treponeme itself: they are specific and confirm that an encounter with the pathogen really took place. The diagnostic standard is a positive result in both classes.

The window period after exposure

Antibodies do not appear instantly: the tests become positive 3–6 weeks after infection, usually at the same time as the hard chancre appears. Testing the day after exposure is pointless — the result will be negative whether or not infection occurred. The scheme after a risky contact: the first test at 4–6 weeks; if negative and you are still worried, a follow-up at 3 months. It also makes sense to take an HIV test and hepatitis tests — they have their own windows, so an “STI screening” panel is repeated according to the longest window.

How testing works: paid and free

In Russia, syphilis tests are done free of charge at dermatovenerology dispensaries (KVD) and with a referral at a polyclinic — and if the infection is confirmed, it is treated there under OMS, anonymously and without being “registered” in the old sense. Privately, any laboratory chain will do it: venous blood, result the same or next day; strict fasting is not required, but fatty food the evening before can interfere with the test (lipaemia), so a morning draw is preferable. No referral is needed. For an occupational health record, a certificate is obtained from a KVD or an accredited laboratory — check your employer's requirements in advance.

Reading the report: four typical situations

Both tests negative outside the window period — no infection. Non-treponemal positive, treponemal negative — a false-positive screening test: retest in 2–4 weeks and look for other causes (pregnancy, autoimmunity). Both positive for the first time — active syphilis: see a dermatovenereologist urgently; at an early stage the disease is fully cured with a single course. Treponemal positive with a negative non-treponemal test — either previously treated syphilis (antibody memory) or a very early stage: the doctor decides based on the history and, if needed, FTA/immunoblot. This is exactly why interpreting one of the two tests on your own is almost always wrong.

After treatment: follow-up and the antibody “tail”

Treatment success is tracked by the titre of the non-treponemal test: it should fall at least fourfold within 6–12 months, and in most people the test eventually becomes negative. Treponemal antibodies (CLIA) stay positive for life in many people — this is not “incomplete treatment” but immunological memory; it is important to keep the certificate of treated syphilis so that future positive CLIA results are not mistaken for a new infection. The follow-up schedule is set by the doctor: tests are usually repeated every 3 months in the first year.

Syphilis and pregnancy: why the test is taken three times

Treponema pallidum crosses the placenta, and untreated syphilis in the mother puts the baby at risk of severe congenital damage. That is why the test is part of mandatory screening: at registration, in the third trimester and on admission to the maternity hospital. The three-step scheme is needed to catch an infection acquired during the pregnancy. If the test is positive, penicillin treatment is safe for the foetus and, started early, fully prevents congenital syphilis. A false-positive RW in pregnancy is common; a treponemal test resolves it, and it is not a reason for alarm until confirmed.

Partners and everyday contact: what you need to know

When syphilis is confirmed, all sexual partners from the last 3–12 months (depending on the stage) are examined and treated if necessary. Household transmission — via dishes, towels, bedding — is theoretically possible when there is fresh discharge from syphilitic lesions, but in reality it is extremely rare: the treponeme dies quickly outside the body. There is no vaccine against syphilis; the only prevention is condoms and testing of new partners. Successful treatment does not create immunity — you can be reinfected, so protected sex continues to make sense.

Frequently asked questions

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