The STI from the Middle Ages that won’t go away

6 min

While most young Aussies are aware of syphilis, our knowledge of it doesn’t match that of other common sexually transmitted infections (STIs) like chlamydia and gonorrhoea. Given the rates of syphilis have tripled in Australia in the past decade and the STI can have a serious impact on your health (plus that of your sexual partner or unborn child if you’re trying to conceive) it’s critical we get up to speed. Here’s what you need to know about syphilis, how to detect it as soon as possible and why STI tests are as shame-free as checking your blood pressure.

What is syphilis?

Syphilis is a sexually transmitted bacterial infection that’s spread through skin-to-skin contact during vaginal, anal or oral sex.

When syphilis is caught early, it can be cured easily. Syphilis is diagnosed with a blood test and, in its early stages, can be treated with a single shot of long-acting penicillin, a commonly used antibiotic. 

Syphilis can also be passed to an unborn child during pregnancy. This is called congenital syphilis, and it can cause miscarriage, stillbirth, premature birth, low birth weight, death shortly after birth or permanent disability.

What are the symptoms of syphilis?

Around 50% of infected people don’t have any symptoms of syphilis, which is why it’s important to get tested regularly. Symptoms of syphilis occur over four stages and begin to present around 10 to 90 days after infection.

You might notice one or more sores at the location where syphilis bacterium enters the body, often around the genitals, anus or mouth. These sores are usually firm and painless, and represent the primary phase of the infection. 

If syphilis continues to go untreated, you may develop symptoms of the second phase, which include fever, headache, fatigue, swollen lymph nodes, rashes, hair loss and muscle and joint aches, changes to your vision, tinnitus (ringing in your ears), deafness or meningitis (inflammation of the membrane that surrounds your brain and spinal cord). Importantly, you can be infected with syphilis and fail to have any visible symptoms; this is called the latent phase of the disease. Syphilis is easily transmitted during the first two years of latency. 

One in three infected people will go on to develop tertiary syphilis years after infection, which can cause serious health issues including blindness, brain infections, dementia, lung and heart failure, mental illness and even death.

Who’s at risk?

Anyone. Forget stigmatising assumptions about STIs that might make you think you’re untouchable. STIs and syphilis can affect anyone. 

“Everybody who’s sexually active is at risk, you may only have one partner, but you could still be at risk,” says Professor David Lewis, Professor in Sexual Health at the University of Sydney. “That’s why we’re always encouraging people to go and get tested wherever possible.”

Rates of syphilis are higher among men who have sex with men and Aboriginal and/or Torres Strait Islander people living in remote places. However, there’s increasing prevalence in the general population, especially in men and women of reproductive age. 

“There were just over 6,000 cases of infectious syphilis in Australia in 2022, of which 82% were in men,” Professor Lewis says. “Seventy-seven per cent of all infectious syphilis was amongst people who resided in major cities and over half, 53%, within younger people aged between 25 and 39 years.”

Many people who are infected don’t have symptoms and could pass it on to others without realising. 

“It’s important to think about your partner, especially in the context of a heterosexual relationship if you’re planning on having children, making sure that there is no syphilis in yourself or your female partner,” Professor Lewis says. “Unfortunately, there were 15 congenital syphilis cases in 2022, and five of those [babies with] congenital syphilis actually died through stillbirth or shortly after birth.”

Testing and using protection are the most important ways to reduce your risk of getting and passing on syphilis.

How to reduce your risk 

Always use a condom, correctly

That means putting them on before your genitals touch, using the correct size to prevent slippage or leakage, and a water-based lubricant to help prevent breakage. Using condoms regularly substantially reduces your risk of acquiring STIs but oral sex may also provide another route for transmission.

“It’s really important to understand a lot of the transmissions are actually occurring from the mouth,” Professor Lewis says. “So, having oral sex, which people correctly regard as negligible risk for HIV infection, [can spread] infections like syphilis, as well as other bacterial STIs like gonorrhoea, and condoms generally are not used in that sort of setting.”

You can use condoms or dental dams to reduce your risk of sharing STIs during oral sex. 


If you think you may have syphilis, see your doctor as soon as possible.



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