DNA Multi-Marker Genotyping and CIAS Morphometric Phenotyping of Fasciola gigantica-Sized Flukes from Ecuador, with an Analysis of the Radix Absence in the New World and the Evolutionary Lymnaeid Snail Vector Filter

Abstract

Fascioliasis is a disease caused by Fasciola hepatica worldwide transmitted by lymnaeid snails mainly of the Galba/Fossaria group and F. gigantica restricted to parts of Africa and Asia and transmitted by Radix lymnaeids. Concern has recently risen regarding the high pathogenicity and human infection capacity of F. gigantica. Abnormally big-sized fasciolids were found infecting sheep in Ecuador, the only South American country where F. gigantica has been reported. Their phenotypic comparison with F. hepatica infecting sheep from Peru, Bolivia and Spain, and F. gigantica from Egypt and Vietnam demonstrated the Ecuadorian fasciolids to have size-linked parameters of F. gigantica. Genotyping of these big-sized fasciolids by rDNA ITS-2 and ITS-1 and mtDNA cox1 and nad1 and their comparison with other countries proved the big-sized fasciolids to belong to F. hepatica. Neither heterozygotic ITS position differentiated the two species, and no introgressed fragments and heteroplasmic positions in mtDNA were found. The haplotype diversity indicates introductions mainly from other South American countries, Europe and North America. Big-sized fasciolids from Ecuador and USA are considered to be consequences of F.gigantica introductions by past livestock importations. The vector specificity filter due to Radix absence should act as driving force in the evolution in such lineages.

The Differences in the Susceptibility Patterns to Triclabendazole Sulfoxide in Field Isolates of Fasciola hepatica Are Associated with Geographic, Seasonal, and Morphometric Variations

“…The morphometric characteristics of F. hepatica have been shown to vary significantly within and between parasite clones [45]. The geographic distribution of the parasites does not seem to play a role in these differences [48]. We used adult F. hepatica body length as a representative morphometric characteristic and determined that smaller parasites were more likely to be susceptible to TCBZ.SO than larger parasites.…”

Paleobiogeographical origins of Fasciola hepatica and F. gigantica in light of new DNA sequence characteristics of F. nyanzae from hippopotamus

“…. regional levels (24,25) and in worldwide analyses, including the assessment of the spreading routes (1). Only adult flukes collected from livers of the respective hosts were used for the sequences obtained in the present study.…”

“…For DNA extraction, a small part of the anterior body region of fasciolids was individually processed (24,25,37). Materials were suspended in 400 µl of lysis buffer (10 mM Tris-HCl, pH 8.0, 100 mM EDTA, 100 mM NaCl, 1% sodium dodecyl sulfate SDS) containing 500 µg/ml Proteinase K (Promega, Madison, WI, USA).…”

One Health Action against Human Fascioliasis in the Bolivian Altiplano: Food, Water, Housing, Behavioural Traditions, Social Aspects, and Livestock Management Linked to Disease Transmission and Infection Sources

“…Fasciola gigantica is more pathogenic [8], although restricted to warm regions of only Africa and Asia, where it is transmitted by usually bigger, more aquatic lymnaeid species of the Radix group [9]. Thus, the absence of Radix throughout the Americas has recently been argued to constitute an insurmountable filter for the introduction of F. gigantica into the New World [10].…”