Performance of Echinococcosis Serology is Associated with Disease Endemicity, Hydatid Cyst Location, Eosinophilia, Imaging Finding, and Treatment.

BACKGROUND

We aimed to assess echinococcosis serology performance for diagnosing cystic echinococcosis (CE) in children living in CE-endemic vs. non-endemic populations, and in different clinical settings.

METHODS

A retrospective cohort study, assessing children with ELISA test for echinococcosis, 2005-2021. Sensitivity, specificity, positive and negative predictive values (PPV and NPV) were calculated comparing CE-endemic vs. non-endemic populations, cases with/without eosinophilia, and cases with/without CE-suggestive imaging findings. Additionally, we examined the association between serology titers/levels (values) and clinical characteristics.

RESULTS

Of 273 cases, 66 (24%) were confirmed as CE. Overall, 97% of CE were in Bedouin children, and the pre-test probability was 28% vs. 9% (p < 0.001) in CE-endemic vs. non-endemic population, respectively. Sensitivity was higher in hepatic than extra-hepatic CE (74% vs. 47%). Overall specificity was 86%. PPVs were higher in CE-endemic population compared to non-endemic (66% vs. 22%), while NPVs were higher in non-endemic population (100% vs. 87%). Eosinophilia was associated with lower specificity (73% vs. 94%) and PPV (47% vs. 78%). Typical imaging was associated with higher specificity (94% vs. 82%) and PPV (91% vs. 11%), while NPVs were lower in typical imaging cases (77% vs. 98%). Higher titer levels (above median) were associated with typical imaging (76% vs. 49%), higher PPV (79% vs. 43%), albendazole treatment (100% vs. 56%), surgery (60% vs. 19%), and new imaging finding (75% vs. 0%).

CONCLUSIONS

Echinococcosis serology performance was impacted by disease endemicity, and by various clinical characteristics. These findings may assist physicians in the interpretation of echinococcosis serology results.