Prevalence and Molecular Study of Fasciola species in slaughtered cattle in Mosul, Iraq

Fasciola species cause a parasitic disease that poses a significant threat to the health and economic productivity of livestock worldwide, including in Iraq. This study aimed to investigate fascioliasis and assess its prevalence in cattle slaughtered at Mosul abattoirs from August 2024 to the end of February 2025. Flukes were collected from infected livers for morphological examination and molecular analysis, based on gene amplification, sequencing, and subsequent phylogenetic analysis. Out of 200 liver samples examined, an overall infection rate was 9.5%, which was higher in females with no significant difference. The highest prevalence was observed in cattle over two years of age, with a statistically significant difference. The greatest monthly infection rates were recorded in October and September; differences were not statistically significant. Morphological evaluation using carmine staining confirmed the presence of two species: Fasciola gigantica and Fasciola hepatica. Moreover, the combined analysis of the 28S rRNA and 16S rRNA genes, along with morphological features proved effective in accurately identifying the species using conventional PCR. This approach revealed three specific fragments: 377 bp and 529 bp, indicative of F. gigantica, and 618 bp, characteristic of F. hepatica. Molecular analysis showed 98–100% sequence similarity with known Fasciola species. Phylogenetic analysis revealed clear genetic differentiation between F. gigantica and F. hepatica and significant genetic diversity within F. gigantica populations, including newly classified Iraqi isolates (PV344638 and PV290745–PV290747). Additionally, two isolates from this study (PV335564 and PV335557) were closely related to known F. hepatica populations.