The Return of Syphilis in Australia: Why You Can’t Ignore the “Great Imitator”

For decades, syphilis was thought of as an infection of the past. It isn’t any more. Australia recorded 5,986 infectious syphilis diagnoses in 2025, about 77% more than in 2016, and cases are no longer concentrated in one group. Most are still in men, but over the past decade syphilis in women has risen by 167%.

Syphilis is called “the great imitator” because its symptoms are easy to miss or mistake for something else. Here’s how to recognise it at each stage, how it’s tested and treated in Australia, and what to do after a diagnosis.

Medically reviewed by Dr Vafa Derakshan (MBBS, FRACGP). Last reviewed 2 October 2026. Checked against the Australian STI Management Guidelines (updated 7 September 2026) and Kirby Institute data released September 2026.

The short version

• The first sign is usually a single painless sore, around 3 weeks after infection, which heals by itself while the infection continues.
• A rash, often on the palms or soles, can follow weeks later. Then the infection can go quiet for years.
• Changes in vision or hearing can happen at any stage and need urgent care.
• It’s diagnosed with a blood test (reliable from about 6 weeks, repeated at 12 weeks) and a swab of any sore.
• Syphilis is curable with antibiotic injections given in person. Follow-up blood tests and partner notification are part of treatment.

What is syphilis and how does it spread?

Syphilis is a bacterial infection caused by Treponema pallidum. It spreads through skin-to-skin contact with a syphilis sore or rash during vaginal, anal or oral sex. Because a sore can sit outside the area a condom covers, condoms reduce the risk but don’t remove it. Syphilis can also pass from a pregnant person to their baby.

The stages, and how to spot them

1. Primary syphilis

A sore (called a chancre) appears where the bacteria entered, usually about 3 weeks after infection, but anywhere from 10 to 90 days. It’s typically single, firm and painless, on the genitals, anus or mouth. Because it doesn’t hurt and may be hidden inside the vagina, rectum or throat, it’s often missed. It heals by itself within a few weeks, but the infection remains.

2. Secondary syphilis

Usually more than 6 weeks after infection, the bacteria spread through the body. Symptoms can include:

• A rash, often on the palms of the hands and soles of the feet, that usually isn’t itchy.
• Fever, swollen glands, tiredness, muscle aches and a sore throat.
• Patchy hair loss.
• Flat, wart-like growths around the genitals or anus.

These symptoms also fade without treatment, which is why secondary syphilis is often mistaken for a virus or an allergy.

3. Latent syphilis

There are no symptoms, but the infection is still there and only shows up on a blood test. It’s called early latent syphilis in the first 2 years, when it can still relapse and be passed on (including to a baby in pregnancy), and late latent after that.

4. Tertiary (late) syphilis

Years later, untreated syphilis can damage the heart, blood vessels, brain, nerves and other organs. This is now rare in Australia because most infections are found and treated earlier.

A warning sign at any stage: eyes and ears

Syphilis can affect the eyes, ears and nervous system early in the infection, not just after years. Blurred or changed vision, eye pain or redness, ringing in the ears, sudden hearing loss, a severe headache or facial weakness after a possible exposure need urgent medical care, at an emergency department if necessary. These complications are treated differently, in hospital.

How syphilis is tested

Syphilis is diagnosed with a blood test. Antibodies can take time to show up, so the test is reliable from about 6 weeks after exposure, and a repeat at 12 weeks is recommended if the first is negative and the exposure was recent. If you have a sore, a swab of it can detect syphilis before the blood test turns positive.

Syphilis is part of a standard STI check for most people. If you’re not sure it was included in your last test, ask. See what a full STI check includes and how long after sex to test.

How syphilis is treated

Syphilis is curable with antibiotics, usually given as injections:

• Early syphilis (primary, secondary or early latent): treatment given at a single visit.
• Late latent syphilis: weekly treatment for 3 weeks.
• Eye, ear or nervous system involvement: intravenous treatment in hospital.

The injections are given in person, at a GP, sexual health clinic or hospital. An online doctor can assess you, arrange the tests, explain your results and organise where you’ll be treated.

After treatment

1. No sex for 7 days after treatment, and until any sores or rash have fully healed.
2. Follow-up blood tests at 3, 6 and sometimes 12 months to confirm the treatment has worked. Some antibody tests stay positive for life, so the follow-up test measures whether levels are falling.
3. Tell partners so they can be tested and treated. How far back depends on the stage: for primary syphilis, about 3 months plus how long you had symptoms; for secondary, 6 months plus how long you had symptoms; and for early latent, 12 months, or back to your last negative test. Let Them Know can send an anonymous message for you.

Being treated once doesn’t make you immune. You can catch syphilis again.

Syphilis in pregnancy

Syphilis in pregnancy can cause miscarriage, stillbirth or serious illness in the baby. Australia recorded 14 cases of congenital syphilis in 2025, and 113 over the past decade, 40 of which ended in the baby’s death. Almost all are preventable with testing and treatment during pregnancy.

healthdirect advises syphilis testing at the first antenatal visit, again at 28–32 weeks and at 36 weeks. If you’re pregnant or planning a pregnancy, ask your doctor or midwife about it, and get tested if you or a partner may have been exposed.

Who should test, and how often?

• Anyone with a new partner, as part of a routine STI check.
• Gay and bisexual men with multiple partners, and anyone on PrEP: every 3 months.
• Anyone with a painless sore, an unexplained rash, or whose partner has been diagnosed.
• Anyone who is pregnant or planning a pregnancy.

For some gay and bisexual men and trans women at higher risk, Doxy-PEP (an antibiotic taken after sex, ideally within 24 hours and no later than 72) lowers the risk of syphilis. Among gay and bisexual men attending sexual health clinics, infectious syphilis has fallen by 30–37% over the past three years, which the Kirby Institute links to the growing use of Doxy-PEP.

Frequently asked questions

Can syphilis go away on its own?

The symptoms do, but the infection doesn’t. Without treatment, it moves into a hidden stage and can cause serious damage years later.

How soon after sex can I test for syphilis?

The blood test is reliable from about 6 weeks, with a repeat at 12 weeks after a recent exposure. If you have a sore, see a doctor straight away, as a swab can detect it sooner.

Can you get syphilis from oral sex?

Yes. A sore in or around the mouth, or on the genitals of a partner, can pass syphilis on during oral sex.

Is syphilis curable?

Yes. Antibiotic treatment cures syphilis, although damage from late-stage infection may not be reversible. That’s why early testing matters.

Can I get syphilis treatment online?

An online doctor can assess you, order tests and arrange your treatment, but the injections need to be given in person. Your doctor will tell you where to go.

Get tested for syphilis

Speak to an Australian doctor by phone or video, usually the same day, 7 days from 9am to 7pm Sydney time. Book a syphilis test: consults are bulk billed for eligible Medicare card holders, and standard tests are usually covered by Medicare at the collection centre. Without Medicare, see our fees.

Related guides: syphilis testing online; STI window periods; Doxy-PEP; and Australia’s latest STI data.

Sources: Australian STI Management Guidelines, syphilis (updated 7 September 2026); Kirby Institute, STI rates remain high in Australia’s latest sexual health data (September 2026); healthdirect, syphilis; Let Them Know. This article is general information, not personal medical advice.