Serological differentiation betweenEchinococcus granulosus andE. multilocularis infections in man

An enzyme-linked immunosorbent assay (ELISA) was adapted for the serological differential diagnosis of cystic or alveolar echinococcosis in man caused byEchinococcus granulosus orE. multilocularis respectively. By affinity chromatography using rabbit anti hydatid fluid IgG coupled covalently to CNBr-Sepharose 4B a protein fraction (Em 1) containing shared antigens of both parasites could be isolated from an extract ofE. multilocularis metacestode tissue. From the same source another antigen fraction (Em 2) with a high degree of specificity forE. multilocularis was prepared by immunosorption. Antigen Em 1 was equally sensitive for the detection of antibodies againstE. granulosus andE. multilocularis, whereas antigen fraction Em 2 appeared to be more specific forE. multilocularis. A correct serological differential diagnosis was achieved in 95% of 57 confirmed cases of human cystic or alveolar echinococcosis by the simultaneous use of both antigen fractions in the ELISA and by comparison of their reactivities.