Syphilis transmission: what you need to know

Syphilis spreads when the bacterium Treponema pallidum moves from an infected person to someone else. The most common route is sexual contact — vaginal, anal, or oral — when a sore (chancre) or rash is present. You don’t need intercourse for transmission: direct skin-to-skin contact with an infectious lesion is enough.

Symptoms aren’t always obvious. A painless sore can appear about three weeks after exposure (range 10–90 days). If untreated, the infection can move into a stage with a rash, fever, and swollen glands. People can pass syphilis during the primary and secondary stages, and sometimes even if they don’t notice symptoms at all.

Concrete ways syphilis spreads

Here are specific transmission routes to watch for:

• Sexual contact: Direct contact with a chancre during vaginal, anal, or oral sex.
• Mother to baby: Pregnant people with untreated syphilis can pass it to the fetus at any stage, causing miscarriage, stillbirth, or serious newborn illness.
• Blood exposure: Transmission via blood transfusion is rare now because of screening, but possible if screening fails. Sharing needles is an uncommon route but still risky if blood is exchanged.

Condoms lower risk but don’t block contact with sores outside the covered area. That’s why visual checks and honest talk with partners matter.

Testing, treatment, and prevention — simple steps

Testing is straightforward. Doctors use blood tests (screening tests like RPR/VDRL and confirmatory treponemal tests) and visual exams for sores. If you think you were exposed or have symptoms, get tested quickly — early detection avoids complications.

Treatment is usually a single injection of benzathine penicillin G for early-stage syphilis. Later stages or different situations may need longer courses. Pregnant people should always receive penicillin; alternatives aren’t safe in pregnancy. If you’re allergic to penicillin, talk to a clinician about safe options and desensitization when needed.

To prevent spread: use condoms, avoid sex if you or your partner have sores, get tested regularly if sexually active with new or multiple partners, and ensure prenatal screening in pregnancy. If diagnosed, avoid sex until treatment is complete and partners have been notified and tested.

Final practical note: syphilis is treatable, and early care stops it from causing long-term harm. If you’re unsure about symptoms or exposure, contact a clinic or your healthcare provider — prompt testing and treatment protect you and others.