Sexually transmitted infection (STI) rates in the US may finally be trending downward, but one vulnerable population continues to face a growing threat: newborns.
Cases of congenital syphilis have increased steadily for more than a decade, putting infants at risk of developmental delays, neurological damage, organ abnormalities, and even death. Despite being both detectable and treatable, the disease continues to affect thousands of babies each year.
Here, Lily Li, Medical Safety Officer and Senior Director of Medical and Scientific Affairs at QuidelOrtho, discusses why congenital syphilis cases remain high and how improved testing strategies could help protect mothers and infants.
How serious is the situation with congenital syphilis rates in the US?
Back in the early 2000s, syphilis rates had fallen to historic lows in the US. As a result, people stopped talking about it, and awareness of the disease reduced.
However, in more recent years, syphilis incidence has been on the rise, peaking in 2023 with over 200,000 reported cases.
Since then, we have seen some modest downward trending in cases, according to Centers for Disease Control and Prevention (CDC) data, indicating some degree of success in public health campaigns about syphilis.
What is worrying is that downward trend is not observed in cases of congenital syphilis. That is where the disease is passed from mother to child during pregnancy or delivery – with very serious health consequences for the infant.
In 2024, nearly 4,000 congenital syphilis cases were reported in the US. I would go as far as to say that we have congenital syphilis crisis in this country.
What is the current standard of care for syphilis diagnosis?
The standard diagnosis for syphilis is based on serological tests using blood samples.
Nontreponemal tests detect antibodies that are not specific to Treponema pallidum, the bacterium that causes syphilis. These tests help determine disease activity and stage. Treponemal tests detect antibodies specific to T. pallidum and are used to detect current or past infection. Both test types are needed for an accurate diagnosis, following either the traditional or reverse algorithm recommended by CDC.
QuidelOrtho has developed an automated treponemal test, alongside other companies who supply automated tests as in vitro diagnostics, targeting high-throughput labs. These tests are widely available, meaning every patient, particularly pregnant women, in the US should have access to syphilis testing.
With such well-established diagnostics in place, why are congenital cases still rising?
The heartbreaking reality is that most congenital syphilis cases are preventable.
The problem is a cascade of missed opportunities: missed testing, gaps in prenatal care, and delays in treatment.
Looking closer at CDC data, we find that in 40 percent of congenital syphilis cases, the mother didn't receive any prenatal care. Without that, those mothers missed out on screening tests for syphilis and several other diseases.
There are a number of socioeconomic reasons for that failure of care. In some cases, the patient might have no access to facilities. Or, in certain locations, there may be a lack of awareness of syphilis and sexually transmitted infections (STIs).
Another concerning statistic is that in around 50 percent of cases, the mother did receive testing but then experienced delayed, inadequate, or missed treatment. Treatment of syphilis is very effective using penicillin G benzathine, so these gaps are frustrating.
The reasons could be structural – a breakdown in the link between the test result and treatment, incorrect interpretation of the test result, or lack of knowledge about treatment regimes. There could be compliance issues resulting in missing doses of penicillin, or a lack of patient follow-up from the care provider.
There is also the challenge of delivering treatment within the recommended window during the pregnancy, up to 30 days before delivery.
What factors could facilitate earlier detection of syphilis in pregnant mothers?
Syphilis, in most cases, is a silent disease. Many patients don't know they have it, especially during the latent stage. And if a mother with the disease is not adequately treated, regardless of the disease stage – latent, primary, secondary, or tertiary – she remains contagious, and the disease can be passed to the unborn child.
Therefore, testing is key.
Previous testing recommendations included only high-risk patients. However, updated guidance from the American College of Obstetricians and Gynecologists recommends testing all pregnant women for syphilis as early as possible – ideally during their first prenatal visit. Testing should be repeated during the third trimester and again at delivery. That is important because research suggests that women receiving treatment for syphilis are still in danger of reinfection during pregnancy.
Strict adherence to these guidelines is critical to reducing the risk of congenital transmission.
We're also seeing growing interest in point-of-care syphilis testing. Some can be used by the patient in their own home, which is ideal for expectant mothers who can't access healthcare facilities.
What are the practical strategies that health systems can implement to improve syphilis detection in pregnant patients?
Awareness comes first and foremost. Many people – including healthcare providers – still believe that syphilis is an historic disease and have no knowledge of its current prevalence.
There is also a retraining aspect to be addressed for those involved in syphilis testing. It's essential that they are aware of the tests and algorithms recommended by CDC, and how to interpret test results. That’s important because the antibody profile can vary according to the four disease stages of syphilis.
Another important strategy is to improve access to care. If you look at syphilis rates on a map of the US, it's apparent that certain regions have elevated rates. We need to focus on improving access to both prenatal care and syphilis testing in those regions.
Finally, from a policy perspective, we need to establish syphilis testing as a universal screening test in pregnant mothers. Testing is the only way to rule out the disease, even in low-risk populations, due to multiple transmission routes and the absence of symptoms.
Tackling this problem requires a multifactor approach, with many different stakeholders working together to control the situation and reverse the rising trend in congenital syphilis.
What is your message to healthcare providers on addressing this issue?
This is a serious public health problem. Four thousand cases of congenital syphilis in one year is a large number, and we don't yet know if the number of cases has peaked. But we do know that if we do nothing, the numbers could continue to rise.
Given the narrow window for treatment during pregnancy, it's imperative that the healthcare provider explains the benefits of testing in the context of the risks of congenital syphilis to the baby, to discourage opt-outs.
We also need to remove the stigma surrounding syphilis. Because it's classified as an STI, some women may hesitate to be tested. We need to reframe the conversation and emphasize that syphilis screening is fundamentally about protecting babies, mothers, and families.
When testing and treatment are available, every missed opportunity matters.
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