Syphilis
A sexually transmitted infection caused by the bacterium Treponema pallidum. It progresses through stages — starting with a painless sore, then a body rash, then, if untreated for years, serious damage to the heart, brain and nerves. It is fully curable with antibiotics when caught, and blood tests screen for it.
What it is
Syphilis is an infection caused by the bacterium Treponema pallidum, passed on mainly through sexual contact and, in pregnancy, from mother to baby. Untreated, it moves through recognised stages. The primary stage brings a single, usually painless sore (a chancre) at the site of infection, which heals on its own — so it is easily missed. Weeks later, the secondary stage causes a widespread rash, classically including the palms and soles, with flu-like symptoms and swollen glands; these too settle without treatment. The infection then becomes latent — silent, with no symptoms but detectable on blood tests — sometimes for many years. In a proportion of untreated people, the late (tertiary) stage eventually causes serious damage to the heart and large blood vessels, or to the brain and nerves (neurosyphilis), which can occur at any stage. Because its symptoms come and go and mimic other conditions, syphilis is called 'the great imitator', and it is usually diagnosed through blood tests rather than symptoms alone. The great news is that syphilis is fully curable with antibiotics (usually penicillin) at any stage, though later damage may not reverse. This is why screening — routinely in pregnancy and sexual-health checks — matters so much.
Key lab markers
- Syphilis RPR/VDRL — the non-treponemal screening test; reactive in infection, with a titre that falls after treatment.
- Treponemal tests (TPPA, treponemal antibody) — specific confirmatory tests for the bacterium.
- HIV test — always offered, as sexually transmitted infections often travel together.
- Screening for other STIs — chlamydia, gonorrhoea, hepatitis.
- CSF (spinal fluid) tests — if neurosyphilis is suspected.
Symptoms
- A single, usually painless sore (chancre), often on the genitals, mouth or anus (primary stage)
- A widespread rash, classically on the palms and soles (secondary stage)
- Flu-like symptoms, swollen lymph nodes, patchy hair loss, mouth sores
- Often no symptoms at all during the latent stage
- In late untreated disease: heart, brain or nerve problems
- Frequently silent, detected only on screening blood tests
Related symptoms
When to discuss with a doctor
Syphilis is important to catch because it is fully curable when treated but can cause serious harm if left, and it can be passed to a baby in pregnancy. A reactive syphilis screening test needs a confirmatory treponemal test and, if positive, antibiotic treatment (usually penicillin), testing for HIV and other sexually transmitted infections, and notification and testing of sexual partners. A new painless genital, oral or anal sore, or an unexplained rash on the palms and soles, should prompt a sexual-health assessment even though these signs may fade on their own. Routine screening in pregnancy and as part of sexual-health checks is the main way silent infection is found. Mediora.AI can highlight a reactive syphilis screen and its titre alongside related tests, but diagnosis, confirmation and treatment belong with your doctor or a sexual-health service, where partner care and follow-up are arranged.