Close Relationship Between Clinical Regression and Specific Serology in the Follow-up of Patients with Alveolar Echinococcosis in Different Clinical Stages

We compared four enzyme-linked immunosorbent assays (ELISAs) with 172 serum samples from 28 patients with alveolar echinococcosis in different clinical stages according to the World Health Organization-PNM (P = parasitic mass in the liver, N = involvement of neighboring organs, M = metastasis) staging system. The sequential antibody responses against Em (2plus), Em10, and Em18 antigens, and a crude antigen extract were measured in cohorts with resected and unresected lesions. Antibody levels in all assays correlated with the PNM stage before treatment, and the highest correlation was shown for the Em18 assay. The PNM stage did not influence the antibody kinetics, but changes in antibody levels depended on the treatment. In patients after curative surgery, seroreversion in the Em (2plus) ELISA indicated successful resection of lesions in more patients than any other assay, irrespective of the clinical stage. There were no significant differences in the time before assays that use recombinant or purified antigens became unreactive. Antibodies directed against crude antigens were detectable longer than other antibodies in all patient cohorts and stages.