A disease from the history books has become a threat in modern Australia
Updated . First published
Syphilis has been linked to the deaths of kings and gangsters, with recorded cases dating as far back as the 15th century; now the old-world disease is making a deadly comeback in modern-day Australia.
What started as an uptick in cases more than a decade ago has snowballed into a nationwide outbreak which the Australian Centre for Disease Control (CDC) declared a Communicable Disease Incident of National Significance in 2025.
Syphilis is a highly contagious and potentially deadly STI caused by the Treponema pallidum bacterium. AP
Annual syphilis case numbers have almost doubled over the last decade and congenital syphilis has killed dozens of infants in the same period.
More than 2470 cases of infectious syphilis have been reported already in 2026, compared to 3380 cases in all of 2016, and just 2203 in 2006.
It’s a difficult disease to spot, too, even for healthcare professionals.
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“Often in medicine, we refer to syphilis as the ‘great mimicker’ because it can cause all kinds of symptoms that can mimic other diseases,” sexual health physician Dr Arthur Wong told nine.com.au.
“So if it’s not something that a patient or a nurse or a doctor has at the forefront of their mind, it can be missed.”
Syphilis infections can also be asymptomatic for years, so many patients go undiagnosed until it’s in the later stages.
All of this to say syphilis is having a resurgence in Australia, and it’s putting some of the nation’s most vulnerable populations at risk of serious long-term health concerns, disabilities and even death.
How an old-world disease came back to life
Syphilis is a highly contagious sexually transmissible infection (STI) caused by bacteria called Treponema pallidum, which is most commonly spread through unprotected vaginal, anal or oral sex.
Its origins are hotly contested, though the first reported outbreak was in Europe in the late 1400s.
“We hear that a lot from patients who, when they’re diagnosed with syphilis, go ‘I thought that was a disease you read about in history books,’” Wong said.
But a fresh Australian syphilis outbreak was identified in Queensland in 2011 and the disease has been spreading ever since.
Now it’s in almost every part of Australia and epidemiologists like Dr Skye McGregor at the Kirby Institute are working overtime to contain the spread.
“Initially, the outbreak was among First Nations populations and gay and bisexual men,” she told nine.com.au.
The disease spread especially quickly among groups facing specific inequities and inadequate access to healthcare, especially culturally appropriate healthcare.
“Now we see broader increases,” McGregor said.
“Among women we’ve seen a tripling of cases in 10 years, and of course, associated with that is congenital syphilis cases.”
Congenital syphilis occurs when syphilis spreads from a pregnant woman to her unborn child and can cause severe health issues or death for the baby.
At least 34 infant deaths have been attributed to congenital syphilis in the past decade and nine cases have already been reported in 2026.
McGregor called it “the worst of the outcomes” from the ongoing outbreak.
Despite being preventable and treatable, syphilis remains a major concern nationally more than a decade after case numbers started rising.
Syphilis symptoms vary depending on the stage and can go unnoticed. Some patients experience mouth sores and rash in the first months after infection. Michael Moloney
An ‘incident of national significance’
The CDC declared syphilis a Communicable Disease Incident of National Significance in August last year, but work was being done behind the scenes to tackle the outbreak for years beforehand.
Though there’s no vaccine for syphilis, it can be diagnosed with a blood test and effectively treated with penicillin injections (other options are available for patients with a penicillin allergy).
An enhanced syphilis response began in 2017 and is now being led by the National Aboriginal Community Controlled Health Organisation (NACCHO).
Doxy-PEP, a post-exposure prevention medication, has been available since early 2023.
More recently, the national guidelines for syphilis testing during pregnancy were changed to recommend testing a minimum of three times.
These and other measures have already had an impact and syphilis case numbers as of June 2026 are lower than the same period last year and in 2024, but the figures remain worryingly high.
Syphilis cases increased in 2021, after having fallen between 2019 and 2020. AP
“The personal health burdens are significant, and there is also a burden on health care systems,” a CDC spokesperson told nine.com.au.
Since 2024, the federal government has allocated $132.5 million to support targeted programs aimed at reducing rates of syphilis and other STIs.
Funding has gone towards community-controlled services, antenatal care initiatives, and health workforce syphilis awareness and training, to name a few.
“We conduct national surveillance, analyse trends, identify populations and settings at higher risk, and support coordinated, evidence-based responses across the health system,” the CDC spokesperson said.
“This helps to ensure programs are targeted to the areas of greatest need.”
The CDC, federal government, and state and territory governments are also undertaking coordinated action to tackle the syphilis outbreak under the National Syphilis Response Plan 2023 to 2030.
Stopping the spread
Testing for and treating syphilis is only one part of the puzzle.
Experts say that if Australia really wants to reduce numbers and one day eradicate this disease, we need a different approach to sexual health across the board.
Individuals must be encouraged to speak to GPs and other healthcare providers about sexual health, undergo regular and comprehensive STI screening, and have honest discussions with new sexual partners.
Healthcare providers need more comprehensive education on and awareness of syphilis to better serve patients and broader communities.
“We really need to change the conversation to remove the shame and stigma that we attach to having an STI diagnosis,” Wong said.
“We should frame [STI testing] as a normal part of healthcare, like just getting your normal health checks.”
He fears that without broader change in communities and the healthcare industry, syphilis case numbers will remain high, especially in areas and among populations with limited access to safe, good quality sexual healthcare.
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