Morphometric and Molecular Study of Fasciola Isolates from Ruminants in Iran.

Objective: The purpose of the present study was morphometric and molecular characterization of Fasciola isolates from ruminants in Iran.

Methods: Flukes were collected from the livers of 54 naturally infected sheep and cattle. The proportion of body length to width (L/W) of each fresh fluke was measured using a digital caliper. We employed receiver operating characteristic (ROC) curve analysis to explore the reliability of L/W for differentiating the two species. Polymerase chain reaction (PCR)-sequencing was performed on ribosomal Internal Transcribed Spacers (ITS) and mitochondrial cytochrome c oxidase subunit 1 (cox1) genes. The sequences were then analyzed and phylogenetic relationships were investigated.

Result: Forty-eight out of 54 isolates (88.9%) were identified as F. hepatica and four isolates (7.4%) as F. gigantica. All the sheep isolates were F. hepatica, while 4 out of 10 cattle were infected with F. gigantica. The morphometric study revealed an L/W ratio of 1.2 to 6.5 in Fasciola isolates with significantly higher L/W ratio in F. gigantica (p<0.00). According to the ROC curve analysis, the L/W value of 3.55 was regarded as the critical value to discriminate between the two species.

Conclusions: Findings of the present study indicate the presence of both Fasciola species in southeastern Iran. The phylogenetic analysis revealed two different clades representing F. hepatica and F. gigantica. The two isolates in this study were described as Fasciola sp. The mitochondrial DNA of these isolates were similar to F. hepatica, while their ITS fragments were identical to F. gigantica.