Diagnostic sensitivity of enzyme-linked immunosorbent assay for IgG in hydatid disease

Hydatid disease in humans is most commonly caused by Echinococcus granulosus and results in development of cysts in various organs of body. The diagnosis is made by serology i.e. by estimation of antibody levels or on imaging studies. Enzyme-linked immunosorbent assay (ELISA) is widely used for serological confirmation of the disease.

To study the sensitivity of ELISA for IgG antibodies against E. granulosus in detecting hydatid disease of liver or lung.

A retrospective study of serology of all surgically confirmed cases of hydatid cysts of liver or lung in a tertiary level hospital.

The levels of IgG antibodies against Echinococcus, measured by ELISA, in patients of cystic lesions of liver or lung, who underwent surgery for the same and confirmed as having hydatid disease, during surgery or on histopathological examination after surgery, were recorded and analysed. There were 28 such patients from January 2001 to 2007. Twenty-three patients with hydatid cysts in liver and 4 in lung were included. One patient with hydatid liver was excluded from the study due to heavily calcified cyst.

Two types of kits were used; one using crude antigen and other using purified antigens. Among 23 patients with hydatid cysts of liver, 8 had positive serology while 15 had either equivocal or negative results. All 4 patients with hydatid of lung had positive serology.

ELISA test is not sensitive enough to be relied upon for confirmation of hydatid disease and considering its high cost, an alternative more specific, sensitive, cheaper and easily available test needs to be evaluated for confirming hydatid disease.