Introduction In resource-limited settings, syphilis rapid diagnostic tests (RDTs) aide in the prevention of congenital syphilis. However, most syphilis RDTs detect only treponemal antibodies which persist after treatment. Consequently, treatment may be provided unnecessarily to pregnant women with past infection. We estimated the potential reduction of over-treatment by comparing a new RDT detecting both treponemal and non-treponemal antibodies, with a treponemal RDT (T-RDT).
Methods A prospective descriptive study among pregnant women in antenatal care was conducted in Déou, Burkina Faso. The women were included if they were eligible for routine syphilis screening and provided informed consent. DPP Screen and Confirm assay (Chembio) and T-RDT (SD Bioline) were performed on whole blood specimens by a trained laboratory technician. Plasma was tested in an international reference laboratory by T. Pallidum Particle Agglutination (TPPA) and quantitative Rapid Plasma Reagin, (RPR). Presumptive active syphilis was defined as both TPPA and RPR were reactive.
Results A total of 242 pregnant women were included: 91 (37.6%) had a presumptive active syphilis and one-in-five (19.8%) had high RPR titres ≥1:8. The DPP did not reduce the number of incorrectly treated cases (over-treatment) compared to the T-RDT (0.0% vs. 2.5%; p = 0.218). In addition, the DPP led to a higher proportion of under-treatment compared to the T-RDT (18.2% vs. 0.8%; p < 0.001). Therefore, 48.4% of women requiring treatment (including 16% with high RPR titres) would not have been treated using DPP against 2.2% using T-RDT.
Conclusion This study was the first evaluation of DPP in pregnant women. DPP showed no added value in reducing the proportion of women unnecessarily treated. Conversely, it underestimated women needing treatment. Our study population may not have been representative as the surprising high seroprevalence may suggest presence of other treponemal infections in the area. Accordingly, additional studies are required to evaluate the potential benefits of DPP.
Disclosure of interest statement Médecins Sans Frontières funded this study. Epicentre receives core funding from Médecins Sans Frontières. No pharmaceutical grants were received in the development of this study. The authors have declared that no competing interests exist.
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