Echinococcus granulosus: a seroepidemiological survey in northern Israel using an enzyme-linked immunosorbent assay

Following an intensive health education programme, 8651 finger-prick blood samples, 4122 from a predominantly adult group attending a primary care clinic and 4529 from schoolchildren, were collected in Tamra, northern Israel. An enzyme-linked immunosorbent assay (ELISA) for immunoglobulin G (IgG) was used to detect anti-Echinococcus granulosus antibodies, using both crude and purified antigens. The seroprevalence in the adult group was 0.48% (20/4122); optical density values were 0.1-0.14 in 10 subjects, 0.15-0.19 in 9, and greater than or equal to 0.2 in one; prevalences did not differ significantly between males and females or among age groups. Twenty-six of the schoolchildren (0.57%) were seropositive, 23 with optical densities of 0.1-0.14, one of 0.15-0.19, and 2 greater than or equal to 0.2. A high correlation was observed between ELISA positivity and both positivity in the are 5 immunoelectrophoresis test and the presence of a high titre in the indirect immunofluorescence assay. Cross reactivity was observed with sera from schistosomiasis and ancylostomiasis patients, using both crude and purified echinococcal antigens. The results indicated that the IgG ELISA, using both crude and purified antigens, was very useful for seroepidemiological screening for echinococcosis, and that this condition is an emerging disease in northern Israel.