Introduction Congenital syphilis is responsible for over 500,000 adverse pregnancy outcomes globally every year, including stillbirth, fetal loss, neonatal death, low birth weight, preterm birth and syphilis infection in the infant. In Haiti, 90% of pregnant women report at least one antenatal visit. We evaluated the field performance of the SD BIOLINE HIV/Syphilis Duo test in a high-risk setting in Port-au-Prince, Haiti using whole blood fingerprick specimens.
Methods GHESKIO (Haitian Study Group for Kaposi’s sarcoma and Opportunistic Infections) clinic attendees 18 years of age or older were invited to participate. Venipuncture blood specimens were used for reference testing: for HIV, Murex HIV-1.2.0 (DiaSorin S.p. A.) or Determine HIV-1/2 (Alere Inc). Positive results were confirmed with the HIV(1+2) Rapid Test Strip (KHB Shanghai Kehua Bioengineering Co. Ltd). For Treponema pallidum (Tp) antibody comparison, Treponema Pallidum Hemagglutination Assay (TPHA) (Human Gesellschaft fur Biochemica und Diagnostica mbH) was used. For 21 TPHA indeterminate results, specimens were retested using a Tp enzyme-linked immunosorbent assay test (ELISA) (Architect Syphilis Tp, Abbott Laboratories). Sensitivity and specificity were calculated and the exact binomial method was used to determine 95% confidence intervals (CI).
Results Of 298 study participants, 61 (20.5%) were male. Of 237 females, 49 (20.7%) were pregnant. For the HIV component, sensitivity and specificity were 99.2% (95% CI: 95.8%, 100%) and 97.0% (95% CI: 93.2%, 99.0%), respectively. All 21 TPHA indeterminate results were Tp ELISA reactive. For the Tp component, sensitivity and specificity were 96.5% (95% CI: 91.2%, 99.0%) and 90.8% (95% CI: 85.7%, 94.6%), respectively. In pregnant women, the HIV component sensitivity and specificity were 93.3% (95% CI: 68.0%, 99.8%) and 94.1% (95% CI: 80.3%, 99.3%), respectively; and for the Tp component were 100% (95% CI: 81.5%, 100%) and 96.8% (83.3%, 99.9%), respectively.
Conclusion The HIV antibody component of the Duo test shows excellent performance. The Treponema pallidum antibody component showed high sensitivity, and slightly lower specificity. Amongst pregnant women the test performed very well.
Disclosure of interest statement The study was supported in part by Standard Diagnostics.
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