eWe assessed the laboratory performance of the Chembio dual-path platform HIV-syphilis rapid immunodiagnostic test and electronic reader for detection of HIV and Treponema pallidum antibodies in 450 previously characterized serum specimens. For visual or electronic reader HIV antibody detection, the sensitivity was 100% and the specificity was 98.7%. For visual T. pallidum antibody detection, the test sensitivity was 94.7% and the specificity was 100.0%; with the electronic reader, the sensitivity was 94.7% and the specificity was 99.7%.
Rapid multiplex point-of-care tests are increasingly available means to screen for syphilis and HIV infections (1-4). Dual screening tests for antibodies to HIV and Treponema pallidum have been evaluated in serum and venipuncture whole-blood samples, showing excellent sensitivity and specificity (5-7). We assessed the laboratory performance of the Chembio dual-path platform (DPP) HIV-syphilis rapid test and the Chembio digital electronic reader with stored serum samples collected from a cohort of men who have sex with men (MSM) and transwomen at high risk for HIV and syphilis infections.Serum specimens were collected between 2013 and 2014 from MSM and transwomen who had been recruited into an ongoing cohort study in Lima, Peru, and the specimens were stored at Ϫ20°C (8). HIV positivity was determined with the Genscreen Ultra HIV Ag-Ab test (Bio-Rad, Hercules, CA), a novel enzyme immunoassay (EIA) which detects HIV p24 antigen (Ag) and HIV antibodies in the same test (9). Positive EIA results were confirmed by Western blotting (New Lav Blot I; Bio-Rad). Specimens also underwent rapid plasma reagin (RPR) testing, using the BD Macro-Vue RPR card test kit (BD, Franklin Lakes, NJ), and Treponema pallidum particle agglutination (TPPA) testing (Serodia; Fujirebio Diagnostics Inc., Tokyo, Japan). All tests were used according to the manufacturers' instructions.The Chembio DPP HIV-syphilis test is a single-use, visual and qualitative immunochromatographic, dual rapid test for the detection of antibodies to HIV types 1 and 2 and Treponema pallidum in human serum, plasma, or venous or fingerprick wholeblood samples (10). A red control line confirms test validity. Visual observation of a red line in the HIV and/or syphilis detection zone is interpreted as a reactive result (10).Immediately after visual interpretation, tests were analyzed using the small, battery-powered, Chembio electronic reader, which was designed specifically to complement the Chembio DPP technology. The electronic reader scans the DPP test cartridge and displays a numerical value based on the test line intensity. If the electronic reader value is higher than the set cutoff value, then the result for the sample is reported as positive; the test result is reported as negative if the measured value is lower than the cutoff value.We estimated the sensitivity, specificity, and 95% confidence intervals (CIs) using the exact binomial method, and we calculated the concordance between the visual results of the Chembio DPP HIV-sy...