Researchers from Monash University and Alfred Health’s Melbourne Sexual Health Centre are calling for increased use of rapid diagnostic tests (RDTs) for syphilis, particularly among pregnant women and men who have sex with men (MSM). This advocacy comes as global and domestic syphilis cases surge, prompting a national health alert in Australia.
The study, published in The Lancet Infectious Diseases, highlights the economic and health benefits of RDTs, which provide same-day diagnosis and treatment. In contrast, traditional lab-based tests, despite their accuracy, can delay results for days or even weeks. This delay can be critical, especially in cases involving pregnant women where timely intervention is crucial.
Economic and Health Implications of Rapid Testing
According to the research, led by Ying Zhang from the Monash University School of Translational Medicine and the Melbourne Sexual Health Centre, rapid testing is both cost-effective and beneficial in health outcomes. The study evaluated three rapid testing algorithms based on the two main types of rapid tests available, considering factors such as cost, the number of active cases missed, and instances of overtreatment.
“The first rapid test for syphilis alone was approved in 2020, so this work is filling a knowledge gap about what works best for different groups,” said Ms. Zhang. “Confirming an active syphilis case can be difficult – especially when we don’t have a patient’s medical history – and tests don’t tell the whole story.”
The simplest and cheapest test, T-RTD, was found to be most effective for pregnant women, despite its inability to distinguish between old and new infections. The potential harm of missing a syphilis case in pregnancy outweighs the risk of overtreatment.
Tailoring Testing Approaches to Different Populations
For populations with higher prevalence, such as MSM in urban areas, a modified version of the dual T/NT-RTD test showed superior cost-effectiveness and health outcomes. This algorithm significantly reduced missed cases by more than 90% and minimized overtreatment risks.
“Urban clinics tend to have better triage and follow-up care, so they can more easily mitigate the impact of overtreatment,” Ms. Zhang explained. “You can get syphilis more than once, so we want to avoid overuse of antibiotics, which of course contributes to resistance.”
Professor Jason Ong, the senior author and Director of the Melbourne Sexual Health Centre, emphasized the need for tailored testing strategies. “In pregnancy, a simpler test that may treat a few extra people unnecessarily is better than missing an infection that could harm a baby. But for men at higher risk, using a test that’s more precise helps avoid unnecessary treatment while still finding most cases,” he stated.
Addressing the Rising Tide of Infections
The call for increased use of RDTs is timely, given the recent declaration by Chief Medical Officer Professor Michael Kidd, who classified syphilis as a Communicable Disease Incident of National Significance. In Australia, congenital syphilis has led to numerous newborn deaths, with surviving infants often suffering from impaired brain development, hearing, and vision.
“The next step is making sure these tests are available where they’re most needed – especially in antenatal care and for communities with higher infection burden – so we can save lives and stop the rise in cases,” Professor Ong added.
While lab tests remain the gold standard, the urgency of syphilis testing, particularly for pregnant women, necessitates the use of rapid tests as a first-line option in settings with limited access to labs and healthcare.
The research underscores the importance of adapting syphilis testing strategies to the specific needs of different populations, aiming to curb the spread of the disease and mitigate its severe consequences.
For further details, the full research paper can be accessed at The Lancet Infectious Diseases.
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