Background Human immunodeficiency virus (HIV) and Treponema pallidum share modes of transmission. Congenital syphilis is a significant cause of stillbirth, prenatal death and serious neonatal infections. We sought to evaluate rapid test kit for HIV-syphilis dual detection to improve diagnosis and enable accurate management towards achieving the renewed zeal of eradicating syphilis and congenital syphilis.
Methods Six hundred and eighty serum specimens from HIV discordant couples in a clinical trial, tested for syphilis infection by RPR with reactive specimens confirmed by TPHA, were used for this evaluation. HIV status was determined by Uni-Gold™ and Determine™ HIV rapid kits and all positive samples confirmed by two HIV Enzyme immunoassay test. These specimens were blindly retested using the HIV-Syphilis Duo kit.
Results Of 698 samples evaluated 139 (20%) were RPR positive and 346 (50%) were HIV positive. Among the RPR positive, 85 (61%) were TPHA positive. None of 559 RPR negative samples tested syphilis positive on HIV-Syphilis Duo kits. Of the 85 RPR positive-TPHA positive samples, none tested syphilis negative on the HIV-Syphilis Duo kit. All RPR positive-TPHA negative samples tested syphilis negative on the HIV-Syphilis Duo kit. Sensitivity and specificity was: both 100% for syphilis detection and; 99.71% and 100% respectively for HIV detection. On this sample set the Sensitivity of Determine™ and Uni-Gold™ was 96.82% and 98.27% respectively while the Specificity was 93.75% and 99.43% respectively. HIV-Syphilis Duo kit detected 5 early HIV infections that were missed out by Determine™ and Uni-Gold™ at least one month prior to a seroconversion visit.
Conclusion HIV-Syphilis DUO test kit performed better compared to RPR for syphilis and Determine™ for HIV detection. It was equivalent to TPHA for syphilis and Uni-Gold™ for HIV detection. Its implementation in antenatal clinics/VCTs will present an added opportunity for simultaneous diagnosis of HIV and syphilis.