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Open Access Technical advance

The development and validation of dried blood spots for external quality assurance of syphilis serology

Pieter W Smit12*, Thomas van der Vlis1, David Mabey2, John Changalucha3, Julius Mngara3, Benjamin D Clark23, Aura Andreasen24, Jim Todd23, Mark Urassa3, Basia Zaba2 and Rosanna W Peeling2

Author Affiliations

1 Leiden Cytology and Pathology Laboratory, Leiden, The Netherlands

2 London School of Hygiene & Tropical Medicine, Keppel Street, London, WC1E 7HT, UK

3 National Institute for Medical Research, NIMR, Mwanza, Tanzania

4 Mwanza Intervention Trials Unit, Mwanza, Tanzania

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BMC Infectious Diseases 2013, 13:102  doi:10.1186/1471-2334-13-102

Published: 26 February 2013

Abstract

Background

Syphilis causes up to 1,500,000 congenital syphilis cases annually. These could be prevented if all pregnant women were screened, and those with syphilis treated with a single dose of penicillin before 28 weeks gestation. In recent years, rapid point-of-care tests have allowed greater access to syphilis screening, especially in rural or remote areas, but the lack of quality assurance of rapid testing has been a concern. We determined the feasibility of using dried blood spots (DBS) as specimens for quality assurance of syphilis serological assays.

Methods

We developed DBS extraction protocols for use with Treponema pallidum particle agglutination assay (TPPA), Treponema pallidum haemagglutination assay (TPHA) and an enzyme immunoassay (EIA) and compared the results with those using matching plasma samples from the same patient.

Results

Since DBS samples showed poor performance with TPHA and EIA (TPHA sensitivity was 50.5% (95% confidence interval: 39.9–61.2%) and EIA specificity was 50.4% (95% CI: 43.7–57.1%), only the DBS TPPA was used in the final evaluation. DBS TPPA showed an sensitivity of 95.5% (95% CI: 91.3–98.0%) and a specificity of 99.0% (95% CI: 98.1–99.5%) compared to TPPA using plasma samples as a reference.

Conclusion

DBS samples can be recommended for use with TPPA, and may be of value for external quality assurance of point-of-care syphilis testing.

Keywords:
Dried blood spots; Syphilis; Treponema pallidum; DBS; Sensitivity; Evaluation