Parasite serology: Echinococcus – hydatid

Hydatid (Echinococcus granulosus) - UKAS accredited test         

Samples are screened with commercial ELISA.  IHA is performed on ELISA positive samples.

Amongst proven cases of hydatid disease, 92% show a positive ELISA test.  Sensitivity depends on cyst site:  Liver 96%, pulmonary 76%, skeletal 60%, other sites vary.  Brain hydatid rarely shows positive serology. Serological cross-reactions, giving rise to false positives, can occur with other parasitic infections, particularly larval cestodes, and filarial worms and with some neoplasms.  Less than 3% of non-infected controls are positive.

False negatives may occur (about 8%) and are more common in patients with extra-hepatic cysts.  False negatives can be due to calcified cysts.  Patients with cysts occurring in the brain are usually serologically negative.

Antibody levels are detected at variable timescales post-infection due to the nature of the disease.

Antibody levels may remain positive for life post successful treatment/surgery.

IHA is performed on all samples with positive hydatid ELISA serology.




ELISA (in house verification)



IHA (manufacturers analysis)



The sensitivity of the ELISA is estimated to be 97%, the cases with negative serology but subsequently proven hydatid disease have mainly been those patients with extra-hepatic lesions.

Samples found equivocal by ELISA are re-tested by IHA. We consider the results significant if both tests are positive. If the sample shows equivocal results, we would suggest repeating serology in 1 months’ time.

ELISA utilises Echinococcus species antigen and detects IgG antibodies.

IHA uses Echinococcus granulosis antigen.