High prevalence of human hydatid disease (echinococcosis) in communities in northern Israel: epidemiologic studies in the town of Yirka.

The resurgence of hydatid disease in communities in northern Israel led to epidemiologic studies in 1988 in the town of Yirka, a semirural Druze community of 8200 persons. In domestic animal surveys, 8% of 63 dogs tested after an arecoline purge and 10% of 255 sheep at the abattoir were found to be infected. In a randomized serosurvey of 758 persons using the indirect hemagglutination test (positive titer greater than or equal to 1:512), 9% (68) had a titer greater than or equal to 1:64, 2.2% had a titer greater than or equal to 1:256 and 0.9% had a titer greater than or equal to 1:512. Of those with titers greater than or equal to 1:64, 59 were evaluated by abdominal sonography and chest x-ray: 6 of the 59 were found to be persons who previously had had a liver or a lung hydatid cyst surgically removed; 6 other persons (5 with negative indirect hemagglutination titers) were found to have a newly detected asymptomatic cyst. Of the latter group, hydatid confirmation was subsequently obtained by surgery for 2 persons and by arc 5 and/or immunoblot assay for 4 persons. Thus, the cumulative percentage of confirmed present or recent past hydatid infections was 12/758 (1.6%) leading to an extrapolated rate of 1583/100,000 persons. This ranks Yirka among the highly endemic areas for hydatidosis worldwide. The study also showed that imaging methods were more sensitive than the indirect hemagglutination serologic test for conducting a prevalence survey.