Human hydatidosis: evaluation of three serodiagnostic methods, the principal subclass of specific immunoglobulin and the detection of circulating immune complexes.

Three serological methods were examined for the diagnosis of hydatid disease: indirect haemagglutination, immuno-electrodiffusion and radioimmunoassay. The sensitivity of the three methods was similar. The principal subclass of specific anti-hydatid immunoglobulin was IgG and high levels of specific anti-IgE were found in two out of the five patients studied. The hypothesis that false negative reactions seen in patients with clinically confirmed hydatidosis may be due to the presence of circulating immune complexes was explored. Immune complexes were demonstrated in only two out of 13 patients studied and these patients did not have negative sera. It is concluded that for a satisfactory serodiagnosis of hydatid disease the radioimmunoassay and immuno-electrodiffusion should both be used and that further work should be done on the purification of hydatid antigens to improve the sensitivity of the radioimmunoassay without loss of specificity.