[Sensitivity and specificity of new commercial tests for the detection of specific Echinococcus antibodies]

Cystic echinococcosis (CE), caused by Echinococcus granulosus, and alveolar echinococcosis (AE), caused by E. multilocularis belong to the most serious parasitic diseases. Both forms of echinococcosis occur in Austria; in addition, imported cases are diagnosed and treated regularly in Austria. Diagnosis of echinococcosis is based on clinical symptoms, imaging techniques and particularly on the detection of specific antibodies in serum specimens of patients. For decades several companies have been providing commercial Echinococcus antigens and echinococcosis tests based on different methods, i.e. complement fixation test (CFT) and electrophoretic methods (CIEP, IEP) in the past and enzyme-linked immunosorbent assays (ELISA), western blot assays (WB) and indirect haemagglutination assays (IHA) in recent years. During the last years two studies have been carried out in our laboratory in order to evaluate the sensitivity and specificity of two commercial E. granulosus antigens (the synthetic p176 antigen, arc 5 antigen) and three commercial testkits (IHA from Dade Behring, IHA from Fumouze, ELISA from Novagnost-Dade Behring). Sera of patients with histologically and/or molecular biologically confirmed cystic or alveolar echinococcosis, of patients with other parasitic infections and of healthy people were tested comparatively for specific Echinococcus antibodies. The synthetic p176 antigen proved to be a highly specific but a insensitive antigen, whereas both the indirect haemagglutination assay as well as the Novagnost-ELISA showed a much higher sensitivity but only moderate specificity. Our studies demonstrated that neither the commercial antigens nor the test kits tested should be used as a primary test in a routine laboratory for the diagnosis of cystic echinococcosis or of alveolar echinococcosis.