Evaluation of a new immunochromatographic test using recombinant antigen B8/1 for diagnosis of cystic echinococcosis

Diagnosis of cystic echinococcosis (CE) is based on the identification of the cyst(s) by imaging, using immunodiagnostic tests mainly as complementary tools in clinical settings. Among the antigens used for immunodiagnosis, previous studies described a good performance of the recombinant antigen B8/1 (rAgB) in an enzyme-linked immunosorbent assay (ELISA) format; however, in remote parts of areas where the disease is endemic, the implementation of an ELISA is difficult, so a more simple, rapid, and reliable method such as the immunochromatographic test (ICT) is required. In this study, using a set of 50 serum samples from patients with surgically confirmed CE, we compared the performance of an ICT and that of an ELISA using the rAgB. The overall sensitivities of ICT and ELISA were not statistically different (78% versus 72%; P=0.36). The overall agreement between both tests was moderate (κ=0.41; P<0.01). Concordance between ICT and ELISA was substantial or almost perfect for patients with liver involvement (κ=0.65; P<0.001) and patients with more than one hydatid cyst (κ=0.82; P<0.001), respectively. Moreover, specificity analysis using a total of 88 serum samples from healthy individuals (n=20) and patients (n=68) with other parasitic infections revealed that ICT had a specificity of 89.8%. ICT and ELISA had similar performance for the detection of specific antibodies to E. granulosus, and ICT had a high specificity, opening the possibility of using ICT as a screening tool in rural settings.