Field evaluation of urine antigen detection for diagnosis of Taenia solium cysticercosis

Abstract

(Neuro)cysticercosis is an important zoonotic disease caused by infection with Taenia solium metacestode larvae. Existing immunodiagnostic techniques detect antibodies and circulating antigens (Ag) in serum and cerebrospinal fluid (CSF). Blood/CSF collection is an invasive procedure associated with blood-borne infections and is often not well accepted by communities. Detection of circulating Ag in urine has been suggested as an alternative, however this has been evaluated in clinical settings only. The aim of the present study was to evaluate the performance of a urine Ag-ELISA under field conditions. Paired serum and urine samples were obtained from participants in endemic areas of Ecuador (n=748) and Zambia (n=690) and were subjected to a monoclonal antibody-based Ag-ELISA. Calculation of positive and negative agreement indices (AI) showed better agreement in the negative direction both for Ecuadorian and Zambian samples (AI of 93.1 and 86.8, respectively). Using a Bayesian approach to determine the test characteristics, similar sensitivities were obtained for serum and urine Ag detection, whereas a decreased specificity was determined for the urine Ag-ELISA with a lower specificity (78.6%) for Zambian samples than for Ecuadorian samples (88.4%). This study indicates a higher specificity for the serum test under field conditions and promotes further research to improve the urine test.