Molecular evidence shows that the liver fluke Fasciola gigantica is the predominant Fasciola species in ruminants from Pakistan

Fascioliasis is an important disease affecting livestock, with great costs to producers worldwide. It has also become a serious issue for human populations in some endemic areas as an emerging zoonotic infection. There are two Fasciola species of liver fluke responsible for this disease, which occur worldwide, Fasciola hepatica and Fasciola gigantica. Identifying these two species on the basis of adult or egg morphology requires specialist knowledge due to the similarity of characters, and may misidentify putative intermediate or hybrid forms. In this study we sequenced the internal transcribed spacer 2 (ITS-2) rDNA of liver flukes collected from multiple species of hosts from seven localities in the Punjab and Baluchistan provinces of Pakistan, to determine the distribution of these two species. All 46 flukes processed in this study, collected from seven sites, showed the rDNA ITS-2 genotype corresponding to F. gigantica, contradicting previous reports, based on adult and egg morphology, that both species are present in Pakistan, with F. hepatica being the more common.