Genetic characterization of Fasciola hepatica (Linnaeus, 1758) in cattle from Paraná, Brazil.

Fasciolosis is a foodborne anthropozoonotic disease caused by Fasciola spp. that affects multiple hosts worldwide. Genetic characterization studies have revealed considerable diversity within F. hepatica populations owing to human and animal migration and intermediate snail hosts. Molecular markers such as microsatellites and mitochondrial DNA sequences are useful tools for assessing parasite population dynamics and evolutionary history. In this study, 16 F. hepatica samples were analyzed using cytochrome c oxidase 1 (CO1) and nicotinamide dehydrogenase (NADH) genes. Parasites were collected from the livers of naturally infected cattle originating from 14 municipalities in Paraná, Brazil. Both CO1 and NADH sequences showed high homogeneity, with mean genetic distances <1% (0.0084 and 0.0092, respectively). Network analyses revealed seven CO1 haplotypes and four NADH haplotypes among the new Paraná samples. When compared with reference sequences available in GenBank from other Brazilian states (Rio Grande do Sul and São Paulo), the Paraná samples also displayed <1% genetic divergence. This high level of homogeneity suggests a common and stable origin, with limited gene flow across regions. The genetic information reported here can support the development of targeted interventions, such as vaccines and drugs, aimed at controlling similar F. hepatica genetic variants.