Authors

M Komal²; K Afshan²; S Firasat²; JE Hodgkinson¹; K Cwiklinski¹;  ¹ University of Liverpool, UK;  ² Quaid-i-Azam University Islamabad, Pakistan

Discussion

The helminth parasites, Fasciola hepatica and Fasciola gigantica, are the causative agents of fasciolosis, an economically important disease of people and their livestock worldwide. Molecular analyses of geographically dispersed Fasciola spp. isolates has revealed high levels of genetic diversity within liver fluke populations. These population genetic analyses allow the origins of Fasciola spp. isolates to be delineated and are vital for furthering our understanding of how drug resistance genes spread throughout liver fluke populations. Several molecular markers have been developed for analyses of Fasciola spp., based on ribosomal, mitochondrial and nuclear regions of the liver fluke genomes. In this study we compared four molecular markers (fatty acid binding protein, fabp; phosphoenolpyruvate carboxykinase, pepck; NADH dehydrogenase, nad1; RAPD) to investigate the F. gigantica population substructure across Pakistan. Adult parasites (n=595) were collected from buffalo and cattle across four provinces in Pakistan (Baluchistan, Gilgit and Skardu, Khyber Pakhtunkhwa, Punjab). The four molecular markers confirmed the species classification of all 595 parasites as F. gigantica, except for the fabp marker which could not be amplified in 274 parasites (46%), indicating genetic variation within the fabp gene sequence. These 274 samples were collected from across the four provinces, indicating the genetic diversity observed within the fabp gene was not specific to a geographical location. Sequence analysis of the mitochondrial nad1 gene revealed a predominance for single haplotypes within liver fluke parasites infecting individual animals, consistent with other Fasciola spp. genetic studies in Pakistan. This study verifies the high level of genetic diversity observed in F. gigantica parasites in Pakistan. It highlights the inconsistencies that can be observed between the Fasciola spp. molecular markers, indicating that robust analyses of genetic diversity in liver fluke populations requires multi-locus markers.