Background and purpose: Fasciola hepatica is highly prevalent in the northern regions of Iran, and if not treated promptly, it can impose a significant burden on the healthcare system. Additionally, infection with various parasites can present as eosinophilia. Therefore, the aim of this study was to investigate the seroepidemiology of fascioliasis in individuals with and without eosinophilia in Sari, Iran between 2022 and 2023.
Materials and methods:  A total of 200 serum samples from eosinophilic individuals and 200 control samples from individuals without eosinophilia were included in the study. Both groups were tested for serum levels of anti-Fasciola IgG using the ELISA method to assess seropositivity.
Results: The prevalence of anti-Fasciola IgG in eosinophilic individuals was 1%. Affected individuals were primarily farmers and homemakers, aged over 20 years, reported consuming aquatic plants, and had eosinophilia levels greater than 15%.
Conclusion: The findings of this study suggest that in cases of high eosinophilia, individuals should be further investigated for parasitic infections, particularly fascioliasis. Monitoring eosinophil levels and conducting serological tests for Fasciola infection may serve as a useful diagnostic approach in regions with high endemicity.