Most STI diagnoses in England fell between 2023 and 2024 — gonorrhoea dropped 16%, from 85,370 to 71,802 cases. Syphilis went the other way. UKHSA reported 9,535 diagnoses of early-stage syphilis in 2024, up 2% on the previous year, with the overall syphilis figure including late-stage and complicated infection rising 5% to 13,030.
An infection that was close to eliminated in the UK within living memory is now at levels not seen for decades.
Why It Is Missed
Syphilis progresses in stages, and the early ones are easy to dismiss.
Primary
A single painless sore — a chancre — at the site of infection, appearing typically two to three weeks after exposure. It is painless, which is exactly why it gets ignored, and it may be somewhere you cannot see. It heals on its own within a few weeks, which feels like recovery and is not.
Secondary
Weeks to months later: a rash often involving the palms and soles, flu-like symptoms, swollen glands, patchy hair loss, mouth ulcers. It also resolves without treatment.
Latent
No symptoms at all, potentially for years, while the infection persists.
Tertiary
Years later, serious damage to the heart, brain, nerves or other organs. Neurological and eye involvement can occur at any stage.
The pattern is the danger: symptoms that resolve on their own convince people nothing is wrong, and the infection continues.
How Testing Works
Syphilis is diagnosed with a blood test — a screening test followed by confirmatory testing if positive. It is included as standard in a full sexual health screen, along with HIV, and it is often the test people do not realise they have had.
Home testing kits that include syphilis use a blood sample, usually a finger-prick, posted to a laboratory. Kits that only test for chlamydia and gonorrhoea — a large share of the cheaper ones — do not detect syphilis at all. When comparing test kits on price, check what is actually in the panel, because that is where the difference usually is.
The Window Period
Antibody tests need time to become positive. Testing too early gives a false reassurance. Guidance generally suggests a test at around 12 weeks after exposure is definitive, with earlier testing useful but potentially needing repeating. A sexual health service will advise on timing for your circumstances.
Treatment
Syphilis is treated with antibiotics — usually injected penicillin — and treatment is highly effective. Earlier treatment means simpler treatment and no lasting damage. Late-stage complications, once established, may not be reversible even after the infection is cured.
Partner notification matters here more than almost anywhere, because of how long the infection can be carried without symptoms.
Pregnancy
Syphilis in pregnancy can be passed to the baby with serious consequences, which is why antenatal screening is offered to all pregnant women in the UK. Rising syphilis rates in the general population make that screening more important, not less.
Who Should Test
Anyone having a sexual health screen should have syphilis included. Test if you have any of the symptoms described above, if a partner has been diagnosed, or if you have had condomless sex with a new partner. Regular screening is recommended for those at higher ongoing risk.
Given how quietly this infection behaves, testing is what finds it — waiting for a symptom that convinces you is not a strategy.