Abstract

Background:
Fascioliasis remains a significant neglected zoonotic infection affecting both livestock and humans worldwide, leading to considerable economic losses and public health concerns, particularly in endemic regions.

Aim:
This study aimed to determine the prevalence and molecular characterization of Fasciola spp. in livestock and humans and to identify the circulating species using molecular and phylogenetic analyses.

Methods:
Between 2024 and 2025, 364 fecal samples were collected from sheep (n = 120), goats (n = 56), cattle (n = 76), and humans (n = 112). Samples were initially screened for Fasciola eggs using microscopic examination, followed by molecular confirmation using 28S rRNA polymerase chain reaction and species differentiation using cox1-based primers. Positive isolates were sequenced and phylogenetically analyzed. Statistical associations between infection and host factors (species, age, and sex) were evaluated using Fisher’s exact test.

Results:
Microscopic examination revealed prevalence rates of 9.1%, 8.9%, 11.8%, and 11.6% in sheep, goats, cattle, and humans, respectively, with no significant difference among host species (p = 0.88). Infection was not significantly associated with age or sex among animals (n = 252). The age-specific prevalence in animals was 9.3% in those 3 years (p = 0.897), whereas the sex-related prevalence was 5.7% in males and 13.1% in females (p = 0.061). Molecular analysis confirmed that 38 positive samples produced the expected 618-bp amplicon, including 11 sheep, 5 goats, 9 cattle, and 13 human samples. Species identification using cox1 primers detected five Fasciola hepatica isolates, while no amplification was obtained for Fasciola gigantica. Sequence analysis (GenBank accession numbers: PX529836 and PX530408–PX530411) revealed 99%–99.5% similarity with global F. hepatica 28S rRNA sequences. Phylogenetic analysis clustered the isolates within F. hepatica lineage I and showed close relationships with isolates from Iran and Chile.

Conclusion:
The findings confirm that F. hepatica is the predominant species infecting both livestock and humans, with low genetic diversity suggesting common environmental transmission pathways between animals and humans.

Key words: Fasciola hepatica; Iraq; Molecular epidemiology; One Health.