Syphilis Screening in Pregnancy: A complex diagnostic landscape

Syphilis Screening in Pregnancy: Are Current Rapid Tests Missing the Mark?

Mira Elwood in Health & Wellness August 2025 • 4 min read.

"A new study reveals the limitations of dual screening tests in detecting active syphilis in pregnant women, especially in regions where non-venereal treponematoses are common."

Syphilis screening during antenatal care (ANC) is a crucial strategy for preventing congenital syphilis, a serious condition that can occur when an infected mother transmits the disease to her unborn child. The World Health Organization (WHO) has recommended syphilis screening during ANC since 2006, emphasizing its role in enabling infected mothers to receive timely treatment and prevent transmission.

In resource-limited settings, rapid diagnostic tests (RDTs) are commonly used for syphilis screening due to their simplicity and ability to provide same-day results, facilitating prompt treatment. However, most syphilis RDTs detect only treponemal antibodies, which can lead to overtreatment in women who have been previously treated for syphilis or have non-venereal treponematoses, a group of related infections that elicit a similar antibody response. This is particularly problematic in regions where both venereal and non-venereal treponematoses are endemic.

A study conducted in Burkina Faso evaluated the effectiveness of a newer rapid test, the Dual Path Platform (DPP) Screen and Confirm Assay, which detects both treponemal and non-treponemal antibodies, in reducing overtreatment compared to traditional treponemal RDTs. The findings revealed that the DPP assay did not reduce overtreatment and, surprisingly, had a higher rate of underdiagnosis, raising concerns about its suitability in this specific context.

The Challenge of Syphilis Diagnosis in Endemic Regions

Syphilis Screening in Pregnancy: A complex diagnostic landscape

The study, conducted in Déou, Burkina Faso, involved 242 pregnant women attending antenatal care. Researchers compared the performance of the DPP assay to a traditional treponemal RDT (SD Bioline) and reference laboratory tests, including Treponema pallidum passive particle agglutination (TPPA) and quantitative rapid plasma reagin (RPR).

The results indicated that 37.6% of the women had presumptive active syphilis, defined as a reactive TPPA and RPR result. Notably, 19.0% had high RPR titres (≥8), suggesting a significant proportion of active infections. The DPP assay did not reduce the number of women who would have been overtreated compared to the traditional T-RDT (0.0% vs 2.5%; p=0.218) and resulted in a higher proportion of underdiagnosis (48.4% vs 2.2%; p<0.001).

Overtreatment Concerns: Traditional syphilis RDTs often detect antibodies from past infections, leading to unnecessary treatment.
DPP Assay Performance: The Dual Path Platform assay, designed to improve accuracy, did not reduce overtreatment in the study.
Underdiagnosis Risk: The DPP assay showed a higher rate of underdiagnosis compared to traditional tests, potentially leaving active infections untreated.
Regional Factors: High seroprevalence in the area suggests the presence of non-venereal treponemal infections, complicating accurate diagnosis.

The study highlights the complexities of syphilis screening in regions where non-venereal treponematoses are prevalent. The high seroprevalence in the study population may indicate the presence of other treponemal infections, such as bejel or yaws, which can lead to false-positive results with traditional syphilis tests. This underscores the need for accurate and context-specific diagnostic strategies to ensure appropriate treatment and prevent overtreatment.

Rethinking Syphilis Screening Strategies

The findings suggest that a nuanced approach to syphilis screening is necessary, taking into account the local epidemiology and the potential for non-venereal treponematoses. Further research is needed to determine the optimal screening strategies in different contexts, considering the trade-offs between overtreatment and underdiagnosis. Additionally, efforts to control non-venereal treponematoses through mass treatment with azithromycin may help reduce the burden of these infections and improve the accuracy of syphilis screening in pregnant women.

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This article was crafted using a human-AI hybrid and collaborative approach. AI assisted our team with initial drafting, research insights, identifying key questions, and image generation. Our human editors guided topic selection, defined the angle, structured the content, ensured factual accuracy and relevance, refined the tone, and conducted thorough editing to deliver helpful, high-quality information.See our About page for more information.

This article is based on research published under:

DOI-LINK: 10.1136/sextrans-2018-053722, Alternate LINK

Title: Dual Screen And Confirm Rapid Test Does Not Reduce Overtreatment Of Syphilis In Pregnant Women Living In A Non-Venereal Treponematoses Endemic Region: A Field Evaluation Among Antenatal Care Attendees In Burkina Faso

Subject: Infectious Diseases

Journal: Sexually Transmitted Infections

Publisher: BMJ

Authors: Céline Langendorf, Céline Lastrucci, Isabelle Sanou-Bicaba, Kara Blackburn, Marie-Hortense Koudika, Tania Crucitti

Published: 2018-12-22

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Everything You Need To Know

1

Why is syphilis screening during antenatal care (ANC) so important?

Syphilis screening during antenatal care (ANC) is crucial to prevent congenital syphilis. This serious condition occurs when an infected mother transmits the disease to her unborn child. Timely screening allows for the infected mothers to receive treatment and prevent the transmission of the disease to the baby, safeguarding the health of both mother and child.

2

What are the limitations of using rapid diagnostic tests (RDTs) for syphilis screening, especially in resource-limited settings?

While rapid diagnostic tests (RDTs) are convenient for syphilis screening in resource-limited settings due to their simplicity and rapid results, most detect only treponemal antibodies. This can lead to overtreatment in women who have been previously treated for syphilis or have non-venereal treponematoses. The latter elicit a similar antibody response, complicating accurate diagnosis, especially in regions where both venereal and non-venereal treponematoses are endemic.

3

How did the Dual Path Platform (DPP) Screen and Confirm Assay perform compared to traditional treponemal RDTs in the study conducted in Burkina Faso?

The study in Burkina Faso compared the Dual Path Platform (DPP) Screen and Confirm Assay with a traditional treponemal RDT (SD Bioline). Surprisingly, the DPP assay did not reduce overtreatment compared to the traditional T-RDT. The DPP assay also showed a higher rate of underdiagnosis. This indicates that the newer test did not improve accuracy in this specific context and raised concerns about its suitability.

4

What are the implications of non-venereal treponematoses on the accuracy of syphilis screening?

Non-venereal treponematoses, such as bejel or yaws, can lead to false-positive results with traditional syphilis tests because they elicit a similar antibody response. In regions where these infections are prevalent, the high seroprevalence complicates accurate diagnosis. This underscores the need for context-specific diagnostic strategies to ensure appropriate treatment and prevent both overtreatment and underdiagnosis.

5

What alternative strategies are suggested to improve syphilis screening and treatment in pregnant women?

The findings suggest a nuanced approach to syphilis screening. This means taking into account the local epidemiology and the potential for non-venereal treponematoses. Further research is needed to determine optimal screening strategies in different contexts. In addition, controlling non-venereal treponematoses through mass treatment with azithromycin may help improve the accuracy of syphilis screening in pregnant women, reducing the burden of these infections, and improving treatment outcomes.