High prevalence of syphilis in Australia: test, treat and trace

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Hi, and welcome to this Australian Prescriber Podcast on syphilis and syphilis testing. I'm Dr Justin Coleman. I'm a GP at Inala Indigenous Health in Brisbane and have spent a lot of my career, 7 years of it, in remote Northern Territory Aboriginal communities.

So I've probably treated and am more familiar with treating syphilis than most GPs. But I'm no expert, which is why I have with me Manoji Gunathilake. Manoji is head of the Sexual Health Unit and Blood Borne Virus Unit at CDC [Centre for Disease Control] for the Northern Territory. Welcome to the podcast.

Thank you, Justin. Thanks for having me.

You wrote a wonderful article in Australian Prescriber, 'High Prevalence of Syphilis in Australia: Test, Treat and Trace.' So we're going to go through those 3 things about testing, treating and tracing. And this article is here because unfortunately we have seen a resurgence in syphilis.

Your article mentions over the last 15 years, and certainly even more so probably over the last 7 or 8 years, to the point now that whereas it used to be well-known to us remote area practitioners, now it really unfortunately has to become more familiar for practitioners all around the nation.

And in fact, we've seen not only a resurgence, but cases of congenital syphilis, which I think should ideally in Australia never occur. Can you talk us through the resurgence of syphilis over the last 15 years, Manoji?

Yeah. Unfortunately, syphilis resurgence is mostly seen in men who have sex with men. In other words, they are disproportionately affected, mostly in urban areas, but also heterosexual Aboriginal and Torres Strait Islander people in Northern Australia also have seen a resurgence with very high case numbers. The notification rates are going very high across Australia, and with that, cases of congenital syphilis started appearing all over as well.

I noticed there were tragically 11 cases of congenital syphilis in 2025, the first 9 months, and 4 infant deaths as a result. So very important that we think about it. Manoji, could you take us through the basics of the transmission of syphilis?

Syphilis is mostly transmitted through direct sexual contact or vertically from an untreated mother to the unborn baby through transplacental passage of the bacterium Treponema pallidum. The untreated syphilis is infectious to sexual partners during the early stages that we call primary, secondary, or early latent.

After some time, especially after 2 years of untreated syphilis, people go into a late or late latent disease, which is usually not infectious to sexual partners, but mother to child transmission can still occur.

It's a little bit back to med school, but if we briefly outline, you mentioned primary, secondary, latent, and then tertiary. So the primary, we're talking essentially about a syphilitic ulcer, which is called a chancre, and that's often 3 weeks or so, although 9 to 90 days after the start of the infection.

And that's the time when certainly we should be looking at testing and swabbing if such an ulcer occurs. And then the secondary phase is 6 to 8 weeks after the syphilitic ulcer. What do we look out for in the secondary phase?

During the secondary syphilis stage, mostly people have nonspecific symptoms, including rashes, which are more common. It could be any rash, to be honest. However, we are generally looking for maculopapular rash. Most people have a maculopapular rash or ulceronodular in some people. And usually rash can involve palms and soles as well. So it's really important to look at palms and soles in a person who comes with rash.

But other multiple nonspecific symptoms might include oral lesions, we call them snail track ulcers, or some patchy areas on the tongue or in the mouth, and they can present with alopecia, especially patchy alopecia. They can also present with lymph node enlargement, generalised usually with some kind of hepatitis-like features. And not to forget that secondary syphilis can lead to some visual symptoms and auditory symptoms as well.

Physicians used to call it the great imitator because it's so widespread, the potential skin and other organ manifestations that it can imitate so many other diseases. We won't go much into latent and tertiary, but early latent and latent, that's defined as to whether it's more or less than 2 years after exposure, and tertiary is 1 year after exposure to really pretty much the end of life.

And you've listed in your article up to 46 years later. Moving from the clinical manifestations, the main point of this article and podcast is we have to be thinking now about testing. So let's look at the populations where we should be doing syphilis testing. Can you run us through those?

Yes. Anyone with signs and symptoms of syphilis need testing or the people attending for sexually transmitted infection check-ups or STI checks, and pregnant people during their first antenatal visit as well as around 26 to 28 weeks and 36 weeks or at birth. That is really, really important they get couple more syphilis tests during pregnancy.

But if they are at higher risk of syphilis, they need more testing. In this part of Australia, we generally recommend testing 5 times during the period of pregnancy and immediately postpartum. Also, there are several priority populations who are at increased risk of infection.

They include Aboriginal and Torres Strait Islander people, gay, bisexual and other men who have sex with men, people who can become pregnant and people experiencing socioeconomic disadvantage or barriers to health care access. Also, very important to test people who are attending for pre- and post-exposure prophylaxis for HIV [human immunodeficiency virus].

Thank you. So a fairly comprehensive list and including importantly the pregnancy and also the STI checks. When the tests come back, it can be confusing. It's not quite as straightforward tests as many other infectious diseases we test for. So HIV tends to be a positive or negative. Syphilis is a bit more complex.

There are direct tests if you take a swab, so if you're worried about an ulcer. And then there's serological tests which are divided into treponemal tests and non-treponemal tests. Could you help clarify for us what we're going to be looking at on a pathology result?

Yeah. So it's really important that all of us are well aware of direct detection methods. So we can simply do a swab, the dry swab from the ulcer or lesion and ask for syphilis testing. Generally, during that test, they test for Treponema pallidum DNA, just ask for syphilis PCR [polymerase chain reaction] test. So it's a dry swab. It is not the MC&S [microscopy, culture and sensitivity] swab. And when it comes to the blood test, the serological tests, the labs usually do an initial screening serology.

We call it treponemal-specific antibody test. If that test is positive, the lab goes on to do further testing with another treponemal-specific test as well as a non-treponemal test. We generally call it RPR [rapid plasma reagin]. Also, it is important to remember that treponemal tests initially, even with the genital ulcer, can be negative. So if you are suspecting syphilis in a person with a lesion, always important to do the swab and repeat the testing after 1 or 2 weeks' time where you will see the serological response.

Okay. So watching out for that false negative period very early on in the infection. But if it's not early on in the infection and you're doing, say, just an STI screening check, the treponemal test comes back negative and they're fine.

If it does come back positive, then it's a bit more complex and that's when many listeners, I'm sure, would be seeking some advice. But that is where the RPR, Rapid Plasma Reagin, comes in and that is that test which tends to double and double and double again. And it's a rise and a fall in titre that matters.

In very early disease or initial stages of the ulcer, the RPR test may be non-reactive, but in late disease, again, it can be non-reactive as well. In between, from primary to secondary, with time, RPR [titre] goes up and it can be 1 in 2 at the stage of primary syphilis and it will go up to 1 in 64 during secondary syphilis when a person present with a rash.

With RPR, we get an idea about the response to treatment as well. When we treat a person for syphilis, after about 3 months, RPR titre come down. For example, 4-fold decrease of RPR would be in a person who had RPR of 1 in 64, coming down to 1 in 16 after treatment. And in many people it can go further down to even non-reactive levels after several months. In comparison, treponemal-specific tests such as TPPA [Treponema pallidum particle agglutination] or EIA [enzyme immunoassay] tests, they remain positive for life in majority of individuals.

Thank you. For interested listeners, there's a wonderful figure in Manoji's article, a guide to interpretation of syphilis serology. And of course, by that stage, most of us would also be in contact with our public health unit or obstetrician if it's during pregnancy or whoever is the relevant expert for treating in that scenario.

Moving on to treatment now, Manoji, having given a lot of painful L-A Bicillin [long-acting benzathine benzylpenicillin] injections, I think that is the mainstay of treatment. So we are looking at benzathine benzylpenicillin, which is a thick white substance, which hurts a bit when you put it in intramuscularly.

And for someone who definitely has early syphilis and it's their first infection, I think we use it once. And for those in other circumstances, we use it 3 times, 1 week apart. What do we need to know about treating syphilis?

Yeah, penicillin is very effective as the treatment for syphilis. So it's really important that people are offered the long-acting penicillin, benzathine penicillin. Majority of people with early and late disease can be treated with that. And there are occasionally people with neurosyphilis or ocular syphilis where we have to give intravenous penicillin for a longer duration.

And during pregnancy, we also treat the same way?

Yes. So during pregnancy, penicillin is the treatment of choice and also the only treatment we can give to a pregnant individual. The other alternative treatment, doxycycline, is not suitable during pregnancy as doxycycline is contraindicated.

Wonderful. Thank you. So we've covered testing, the concept being test more than you used to, I think is a take-home message. And if someone has syphilis, you're treating them and usually you would be in contact with the public health unit, because it is a notifiable disease and it will be notified by the laboratory and also important for clinicians to contact their public health unit. And then finally, there'll be contact tracing and potential treatment of contacts. And hopefully that would be also under advice from the public health unit. Is that what usually happens?

There is a lot of guidance available in our guidelines as well as in the article and the ASHM website, Australasian Society for Sexual Health, HIV and Viral Hepatitis. It is really important to talk to the patient about the necessity of treatment for their partner or their contacts and also to avoid sexual exposures with their contacts until they are treated. So we have given the durations we need to look into in the article.

Manoji Gunathilake, it has been a pleasure talking to you about a disease which sadly is emerging again. But with good public health measures, good clinician activity and access to treatments, hopefully we will together knock syphilis on the head again and decrease its prevalence. Thank you so much for helping be a part of that happening.

Thank you very much, Justin.

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My guests' views are their own and don't represent Australian Prescriber, and my views are certainly all mine.

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