i 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 ( ؍ 0.41; P < 0.01). Concordance between ICT and ELISA was substantial or almost perfect for patients with liver involvement ( ؍ 0.65; P < 0.001) and patients with more than one hydatid cyst ( ؍ 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.
Cystic echinococcosis (CE) is a zoonotic disease caused by the larval stage of the dog tapeworm Echinococcus granulosus. This zoonosis has a worldwide distribution, being considered a public health problem in areas dedicated to the raising of livestock where CE is endemic (1). In these areas, risk factors such as access of dogs to contaminated viscera and close contact between infected dogs and humans facilitate and maintain the transmission of the disease (2, 3). Humans are infected by the accidental ingestion of the tapeworm eggs, which can develop to the larval stage (hydatid cyst) in any internal organ after several years. The organs more frequently involved are the liver and the lungs, representing ϳ70% and ϳ20% of cases, respectively (4). Diagnosis of CE is based on the identification of the hydatid cyst(s) by imaging methods (e.g., abdominal ultrasound, chest X ray, or computed tomography) (5). Immunodiagnostic tools are of use in clinical settings as a complementary diagnostic tool and have quite variable performance, which depends on the antigen or technique used and is affected by certain disease characteristics, such as cyst location and presence of cyst rupture or aggregated bacterial infection (6-9).Among the antigens used for immunodiagnostic, hydatid cyst fluid (HCF) has been the one most widely used. Antibody-detecting assays using HCF report sensitivities between 75% and 95% with poor specificity and frequent cross-reactions (5, 9-11). More recently, synthetic peptides or recombi...