The usefulness of a point-of-care immunochromatographic dual test for the simultaneous detection of both nontreponemal and Treponema pallidum-specific antibodies (Chembio Diagnostics Systems Inc., Medford, NY, USA) was assessed in various situations related to syphilis, by reference to conventional syphilis serology. Thawed sera were obtained from 100 adults including 36 primary syphilis, 6 secondary syphilis, 6 re-infection, 9 recently-treated syphilis, and 43 old syphilis. Doubtful reactivities for the treponemal line were considered positive; doubtful reactivities for the nontreponemal line were considered positive only when the treponemal line was present. The sensitivity, the specificity, and its concordance to gold standard serology of treponemal line were high, around 90%. The sensitivity of nontreponemal line was 96.3%, its specificity 76.7%, and its concordance 83.4%. In conclusion, the dual rapid test from Chembio Diagnostics Systems Inc. is useful for rapid point-of-care diagnosis in the various situations encountered with patients suffering from syphilis.
Keywords: Syphilis; Treponema pallidum; Treponema pallidum-specific antibodies; diagnosis; nontreponemal antibodies; point-of-care; rapid test; sensitivity; specificity.