Depending on cyst location, individuals may not develop high enough antibody titers to be detectable by serologic assays, leading to false-negative results. Cysts localized to the lungs, central nervous system or spleen, or cysts that are senescent, calcified, or dead are associated with lower serologic reactivity.
False-positive results may occur in patients with other helminth infections, including with Taenia species, Schistosoma species, and Strongyloides. Careful correlation with imaging findings and exposure history is required.
This assay may not detect antibodies to other species of Echinococcus, including Echinococcus vogeli and Echinococcus oligarthrus, both fairly uncommon causes of hydatid disease in humans.
Mayo Clinic Laboratories
Negative: the absence of antibodies to Echinococcus species suggests that the individual has not been exposed to this cestode. A single negative result should not be used to rule-out infection (see Cautions).
Equivocal: consider repeat testing on a new serum sample in 1 to 2 weeks.
Positive: results suggest infection with Echinococcus. False positive results may occur in settings of infection with other helminths, or in patients with chronic immune disorders. Results should be considered alongside other clinical findings and exposure history.