Fig. 2. Performance of recombinant Ov-CB-1 as a serodiagnostic antigen. Panel A: receiver operating characteristic (ROC) curve of recombinant cathepsin B from Opisthorchis viverrini
(rOv-CB-1) employed as the antigen in an indirect ELISA, calculated from optical density (OD) at 492 nm values for sera from parasitologically negative and positive opisthorchiasis
individuals. The curve was plotted between true positivity rate (sensitivity) and false-positivity rate (100-specificity) for different cut-off points of OD. Each point on the ROC plot
represents a sensitivity/specificity pair corresponding to a particular decision threshold. The curve represents the suitable cut-off point at OD 0.7637 and showed that the area under
the curve (AUC) was 0.63 (95% confidence interval 0.463 to 0.777). Panel B: serodiagnosis of O. viverrini infection among different infection intensity groups using the rOv-CB-1 ELISA.