The rapid syphilis test: is it useful for syphilis diagnosis among HIV-vulnerable groups? The Argentinean experience.

DURAN A; GALLO VAULET L; RODRIGUEZ FERMEPÍN M; CASCO R; ROSSI D; MARONE R; ORELLANO G; ROMERO M; PETRACCA C; BENEDETTI E; AVILA MM; SALOMON H; PANDO MA

Vancuver

Conferencia; 8th IAS Conference on HIV Pathogenesis, Treatment and Prevention; 2015

IAS

 Background: InArgentina, syphilis, caused by infection with Treponema pallidum, subsp.pallidum, has been reported in high prevalence in HIV-vulnerable groups. Anew syphilis-rapid test (RT) has recently been approved in the country. Inorder to evaluate this RT, it was included in the syphilis diagnoses algorithmduring a cross sectional prevalence study among vulnerable groups.  Methods:  A cross-sectional syphilis and HIV prevalence studywas conducted at different settings (non-governmental organizations, hospitalsand field visits) (September 2013-May 2014). Men who have sex with men (MSM),female transgender/travesties, drug users (DU) and female sex workers (FSW) wereincluded. Syphilis diagnosis was done using: AlereDetermine Syphilis TP, VDRL, TPHA and FTA. HIVdiagnosis was also done (Allere Determine HIV-1/2, Genscreen Ultra HIVAg&Ab, bDNA Versant HIV RNA).  Results: 1517 individuals were tested. Comparison of syphilis-RT with standardlaboratory diagnosis showed that 53 samples non-reactive for syphilis-RT werepositive for syphilis according to other laboratory tests. Among these, 16 hadreactive TPHA, 5 had reactive VDRL/FTA and 31 had both. Seventeen samples thatwere reactive for syphilis-RT were confirmed as negative by standardlaboratory. Sensitivity and specificity for syphilis RT was 81.3% and 98.8%respectively (PPV: 93.1%, NPV: 96.4%). Prevalence of syphilis was 17.7% (179/1014,95% CI 15.2-20.0) for MSM, 47.3% (78/165, 95% CI 39.3-55.2) for transgender/travesties, 7.7% (20/259, 95% CI 4.3-11.2)for DU and 14.1% (11/78, 95% CI 5.7-22.5) for FSW. Co-infection with HIV wasdetected among 17,0% transgender/travesties, 4.2% MSM and 0.8% DU.  In few patients clinical data were obtained: 78.2%(43/55) with reactive RT and 90% (10/11) with no-reactive RT (but reactive bylaboratory assays) presented clinical manifestations that justified penicillin treatment.   Conclusions: Early detection and treatment of syphilis is critical in preventingsevere long-term complications, co-infection with agents like HIV and transmissionto sexual partners. Syphilis-RT implementation could aid early diagnosis. Sincetreponemal RT cannot distinguish betweenactive and past infection, treatment of all RT-positive individuals willresult in over-treatment. However, given the high prevalence of infection invulnerable groups and the serious consequences of missed treatment, thebenefits of syphilis-RT implementation should be considered in some settings.