Australia’s Latest STI Data: What the 2026 Report Means for You

Every September, the Kirby Institute at UNSW Sydney publishes Australia’s national report on sexually transmissible infections. The latest release, in September 2026, covers diagnoses made in 2025. The headline is simple: STIs are still common in Australia, and two of them have risen sharply over the past decade.

Here’s what the numbers show, what’s behind them, and what they mean if you’re deciding whether to get tested.

The 2025 numbers at a glance

• Chlamydia: 94,184 diagnoses. Still Australia’s most common notifiable STI, and down on 2024.
• Gonorrhoea: 42,393 diagnoses, slightly down on the 2024 peak but far above a decade ago.
• Infectious syphilis: 5,986 diagnoses, up a little on 2024.
• Congenital syphilis (passed from mother to baby during pregnancy): 14 cases. Over the past decade there have been 113 cases, and 40 of those babies died.

Gonorrhoea and syphilis: up by more than three-quarters in a decade

Compared with 2016, gonorrhoea diagnoses are up 78% and infectious syphilis diagnoses up 77%. Both dipped during 2020 and 2021, when COVID-19 lockdowns meant fewer new partners and fewer tests, then climbed again from 2022.

Chlamydia tells a different story. It has gone up and down but ended 2025 almost exactly where it was in 2016, and it fell by about 7% in the past year.

Some of the rise reflects more testing, which is a good thing: infections that would once have gone unnoticed are now being found and treated. But testing alone doesn’t explain the size of the increase in syphilis and gonorrhoea.

Syphilis is rising fastest in women

Most syphilis diagnoses are still in men (78% in 2025). But over the past decade, syphilis in women rose by 167%, compared with 39% in men.

That matters because syphilis in pregnancy can be passed to the baby, causing miscarriage, stillbirth or serious illness. Congenital syphilis is almost entirely preventable with testing and treatment during pregnancy, which is why health authorities describe each case as a missed opportunity. Syphilis testing is part of routine pregnancy care, and in some parts of Australia it’s repeated later in pregnancy. If you’re pregnant or planning a pregnancy, ask your doctor or midwife about it.

Syphilis is often called “the great imitator” because its symptoms, such as a painless sore or a rash, are easy to miss or mistake for something else. Read more in the return of syphilis in Australia.

Some good news: prevention is working in some groups

Among gay, bisexual and other men who have sex with men attending sexual health clinics, infectious syphilis fell by around 30–37% and chlamydia by around 26–31% over the past three years. The Kirby Institute links this to regular testing and the growing use of Doxy-PEP, an antibiotic taken after sex to lower the risk of syphilis and chlamydia for people at higher risk. Gonorrhoea in this group has stayed fairly stable.

It’s a useful reminder that STI rates aren’t fixed. Testing, treatment and prevention tools change the numbers.

Young adults carry most of the burden

• Around half of all chlamydia diagnoses are in people aged 20 to 29.
• Gonorrhoea rates are highest in people aged 25 to 29.
• Syphilis rates are highest in people aged 25 to 34.

Many of these infections cause no symptoms at all. Around 1 in 9 chlamydia tests among 15–34 year olds came back positive in 2024. That’s why regular testing matters more than waiting for symptoms. See the rise of silent STIs.

Where you live makes a difference

STI rates vary a lot across Australia. The latest state-by-state rates (for 2024) show:

Diagnoses per 100,000 people, 2024. Source: Kirby Institute, Annual Surveillance Report 2025.

The Northern Territory’s rates are several times the national average, and Queensland has the highest syphilis rate of the larger states. Remote and regional communities, and Aboriginal and Torres Strait Islander people, face much higher rates. Researchers link this to unequal access to culturally safe, local sexual health services. First Nations people had more than six times the rate of syphilis of non-Indigenous Australians in 2025, and 6 of the 14 babies with congenital syphilis were First Nations infants.

Wherever you are, you can see a doctor by phone or video and test at a local collection centre. Find your city on our locations page.

What this means for you

The numbers point to a few practical steps:

• Test regularly, not just when you have symptoms. Most chlamydia and gonorrhoea, and early syphilis, can go unnoticed.
• Ask for a syphilis test. It’s a simple blood test and is often included in a standard STI check, but it’s worth making sure.
• Test between partners, and after a new partner. See how long after unprotected sex to test.
• If you’re at higher risk, ask whether Doxy-PEP or PrEP suits you.
• If you might have been exposed to HIV in the last 72 hours, speak to a doctor about PEP straight away.

Chlamydia, gonorrhoea and syphilis are all curable. Finding them early is the best way to avoid complications and stop them spreading.

Frequently asked questions

What is the most common STI in Australia?

Chlamydia, with 94,184 diagnoses in 2025. Around half were in people aged 20 to 29.

Are STIs increasing in Australia?

Gonorrhoea and syphilis have increased by more than three-quarters since 2016. Chlamydia is at about the same level as in 2016. Some groups, such as gay and bisexual men attending sexual health clinics, have seen recent declines in syphilis and chlamydia.

Why is syphilis increasing in women?

The report doesn’t point to a single cause. Syphilis often has mild or no noticeable symptoms, so it can pass between partners unnoticed. Regular testing, including during pregnancy, is the main way to find and treat it early.

How often should I get an STI test?

It depends on your situation. Many sexually active people under 30 test once a year, and people with new or multiple partners may test every 3 to 6 months. A doctor can suggest what suits you.

Book an STI check

Speak to an Australian doctor by phone or video, usually the same day, 7 days a week. Consults and standard tests are bulk-billed for eligible Medicare card holders. Start your online STI test.

Sources: Kirby Institute: STI rates remain high in Australia’s latest sexual health data (September 2026); Kirby Institute: Annual Surveillance Report 2025; Data @ Kirby Institute. Figures for 2016–2024 are from the 2025 report and may be revised slightly in later reports. This article is general information, not personal medical advice.