Enzyme Immunoassays Employed to Diagnose Neurocysticercosis

All of the five commercial tests compared were enzyme immunoassays for the qualitative determination of the immunoglobulin G (IgG) class of antibodies against Taenia solium, the causative agent of neurocysticercosis, in human serum or plasma.

A team of investigators working at the Institut Pasteur de Madagascar (Antananarivo, Madagascar) tested a collection of reference serum samples which included 14 defined cysticercosis serum samples, 100 serum samples positive for T. solium antibodies, 99 negative samples, and 60 sera from patients with other parasitic infections. All sera were tested both by enzyme-linked immunosorbent assays (ELISA) and by an immunoblot method, the enzyme-linked immunoelectrotransfer blot (EITB). The ELISA tests compared in the study were the DRG T. solium IgG (Cysticercosis); RIDASCREEN T. solium IgG; NOVATECH NovaLisa T. solium IgG; CYPRESS Cysticercosis Ab (T. solium); and the IVD Cysticercosis (T. solium) Microwell Serum ELISA.

The Ridascreen test (R-Biopharm; Darmstadt, Germany) had the best positive EITB concordance rate of between 85.1%-91.2%, followed by the Cypress test (Cypress; Langdorp, Belgium) with results between 71.0%-77.2%. The NovaLisa test (NovaTec Immunodiagnostica; Dietzenback, Germany) showed the optimal negative concordance rate of between 93.7%-95.6% when compared with the EITB, as did the DRG Diagnostics test (DRG International; Mountainside, NJ, USA) at 93.7%. All tests had a sensitivity under 72% and if equivocal specimens are considered negative, four of the tests, DRG, NOVALISA, CYPRESS, and IVD (IVD Research; Carlsbad, CA, USA) display a sensitivity under 50%.

Cross-reactivity with non-neurocysticercosis sera was observed for all tests for all the sera positive for Echinococcus granulosis antibodies. E. multilocularis–positive sera gave false-positive reactions for most of the tests. Except for these common cross-reactions, very few other cross-reactions were encountered with the DRG Diagnostics test and the NovaLisa test. The authors concluded that for the commercial assays they evaluated, the most appropriate ELISA test for screening might be the Ridascreen assay. However, antibody detection seems to be not appropriate for the diagnosis of neurocysticercosis because of its overall lack of sensitivity. The study was published in the January issue of the journal Diagnostic Microbiology and Infectious Disease.

Related Links:
Institut Pasteur de Madagascar
R-Biopharm
Cypress