An enzyme-linked immunosorbent assay using an arc 5 antigen for the diagnosis of cystic hydatid disease.

We report on an easily standardized enzyme-linked immunosorbent assay (ELISA) for the diagnosis of cystic hydatid disease. The antigen used is commercially available, and purified to elicit an arc 5 precipitation line by immunoelectrophoresis (IEP) with sera of patients harbouring hydatid cysts. The IgG-ELISA was highly sensitive and specific, and of diagnostic value compared to total Ig-ELISA, IgM-ELISA or IgA-ELISA. When compared to the indirect hemagglutination test and to counterimmunoelectrophoresis using an arc 5 antigen, minimal cross-reactions were observed in sera of patients with a presumptive diagnosis of hydatidosis but none were observed in those harbouring intestinal helminths, schistosomes or filarial parasites. The assay is of low cost, simple to perform, and highly reproducible. The IgG-ELISA provides an unequivocal laboratory diagnosis of hydatidosis. It is eminently suited for accurate and early identification of hydatid disease patients, for instance in mass surveys, who may benefit immediately from currently available anthelmintics, thereby obviating the need for surgery later.