Efforts in blood safety: Integrated approach for serological diagnosis of syphilis

Advancements in the development of nucleic acid vaccines for syphilis prevention and control

Syphilis, a chronic systemic sexually transmitted disease, is caused by the bacterium Treponema pallidum (T. pallidum). Currently, syphilis remains a widespread infectious disease with significant disease burden in many countries. Despite the absence of identified penicillin-resistant strains, challenges in syphilis treatment persist due to penicillin allergies, supply issues, and the emergence of macrolide-resistant strains. Vaccines represent the most cost-effective strategy to prevent and control the syphilis epidemic. In light of the ongoing global coronavirus disease 2019 (COVID-19) pandemic, nucleic acid vaccines have gained prominence in the field of vaccine research and development, owing to their superior efficiency compared to traditional vaccines. This review summarizes the current state of the syphilis epidemic and the preliminary findings in T. pallidum nucleic acid vaccine research, discusses the challenges associated with the development of T. pallidum nucleic acid vaccines, and proposes strategies and measures for future T. pallidum vaccine development.

The impact of antenatal syphilis point of care testing on pregnancy outcomes: A systematic review

Background

Mother-to-child transmission of syphilis remains a leading cause of neonatal death and stillbirth, disproportionally affecting women in low-resource settings where syphilis prevalence rates are high and testing rates low. Recently developed syphilis point-of-care tests (POCTs) are promising alternatives to conventional laboratory screening in low-resource settings as they do not require a laboratory setting, intensive technical training and yield results in 10–15 minutes thereby enabling both diagnosis and treatment in a single visit. Aim of this review was to provide clarity on the benefits of different POCTs and assess whether the implementation of syphilis POCTs is associated with decreased numbers of syphilis-related adverse pregnancy outcomes.

Methods

Following the PRISMA guidelines, three electronic databases (PubMed, Medline (Ovid), Cochrane) were systematically searched for intervention studies and cost-effectiveness analyses investigating the association between antenatal syphilis POCT and pregnancy outcomes such as congenital syphilis, low birth weight, prematurity, miscarriage, stillbirth as well as perinatal, fetal or infant death.

Results

Nine out of 278 initially identified articles were included, consisting of two clinical studies and seven modelling studies. Studies compared the effect on pregnancy outcomes of treponemal POCT, non-treponemal POCT and dual POCT to laboratory screening and no screening program. Based on the clinical studies, significantly higher testing and treatment rates, as well as a significant reduction (93%) in adverse pregnancy outcomes was reported for treponemal POCT compared to laboratory screening. Compared to no screening and laboratory screening, modelling studies assumed higher treatment rates for POCT and predicted the most prevented adverse pregnancy outcomes for treponemal POCT, followed by a dual treponemal and non-treponemal POCT strategy.

Conclusion

Implementation of treponemal POCT in low-resource settings increases syphilis testing and treatment rates and prevents the most syphilis-related adverse pregnancy outcomes compared to no screening, laboratory screening, non-treponemal POCT and dual POCT. Regarding the benefits of dual POCT, more research is needed. Overall, this review provides evidence on the contribution of treponemal POCT to healthier pregnancies and contributes greater clarity on the impact of diverse diagnostic methods available for the detection of syphilis.

The evaluation of the reverse algorithm for syphilis screening in blood donors

Background: In Turkey, prior to transfusion and apheresis, it is mandatory to screen blood for HBsAg, anti-HCV, anti-HIV 1/2, and syphilis. In recent years, efforts have been made to create effective diagnostic algorithms for screening, and as a screening strategy, many countries have switched from traditional algorithms to reverse algorithms. This study was carried out to evaluate the results we obtained after changing to chemiluminescence immunoassay (CLIA) based reverse algorithm, which is more sensitive and specific than the traditional algorithm and VDRL test we currently use for syphilis screening.

Methods: The screening algorithm was initiated with the treponemal CLIA method. The reactive samples were tested using a nontreponemal test VDRL and a second treponemal test TPHA. In the descriptive analyses, the averages, numbers, and percentage distributions were calculated. The group comparisons were undertaken with the chi-square test, accepting p < 0.05 as statistically significant.

Results: Of the 5,053 samples that were tested with CLIA syphilis TPA assay 5,043 were negative (99.802%) and 10 were positive reactive (0.198%), and the difference between the two was statistically significant (p < 0.001). Ten samples that were recurrently reactive were analyzed by VDRL and TPHA tests simultaneously. VDRL was negative in all 10 samples, whereas TPHA was negative in one sample, but positive in nine samples at a titer of ≥1/160.

Conclusion: Based on the results of this study, we decided to use the CLIA method and reverse algorithm instead of using the traditional algorithm and VDRL as the initial screening method.

Syphilis detection: evaluation of serological screening and pilot reverse confirmatory assay algorithm in blood donors

Serological assays are still considered the most useful tests in the diagnosis of syphilis. Since no single serological assay is able to provide a satisfactory result, in our laboratory we have evaluated the usefulness of a commercially-available immunoblot to diagnose syphilis infection among blood donors. From October 2012 to June 2013, 4572 blood donors were screened for syphilis with an automated chemiluminescent microparticle immunoassay (CMIA). To confirm the presence of treponemal antibodies, CMIA-reactive sera were tested by standard Treponema pallidum haemagglutination assay (TPHA). In addition, an alternative confirmatory test - the immunoblot INNO-LIA assay was introduced in our laboratory. Since two additional positives among CMIA-reactive-TPHA-negative samples were found, we concluded that the INNO-LIA immunoblot allowed a better detection of syphilis compared to TPHA. A confirmatory strategy based on the use of two treponemal assays could meet the screening requirements for blood donors as well as in our centre.