Abstract
BackgroundIn Egypt, liver flukes, Fasciola spp. (Digenea: Fasciolidae), have a serious impact on the farming industry and public health. Both Fasciola hepatica and Fasciola gigantica are known to occur in cattle, providing the opportunity for genetic recombination. Little is known on the identity and genetic variability of Fasciola populations in sheep.MethodsThis study was performed to determine the prevalence of liver flukes in sheep in Menofia Province as a representative area of the delta region in Egypt, as measured by postmortem examination of slaughtered animals at three abattoirs. The identity and genetic variability of Fasciola spp. in slaughtered animals were determined by PCR-sequence analysis of the nuclear ribosomal internal transcribed spacer 1 (ITS1) and the mitochondrial NADH dehydrogenase subunit 1 (nad1) genes.ResultsPhysical inspection of the liver indicated that 302 of 2058 (14.7%) slaughtered sheep were infected with Fasciola spp. Sequence analysis of the ITS1 and nad1 genes of liver flukes from 17 animals revealed that 11 animals were infected with F. hepatica, four with F. gigantica, and two with both species. Seventy eight of 103 flukes genetically characterized from these animals were F. hepatica, 23 were F. gigantica, and two had ITS1 sequences identical to F. hepatica but nad1 sequences identical to F. gigantica. nad1 sequences of Egyptian isolates of F. gigantica showed pronounced differences from those in the GenBank database. Egyptian F. gigantica haplotypes formed haplogroup D, which clustered in a sister clade with haplogroups A, B and C circulating in Asia, indicating the existence of geographic isolation in the species.ConclusionsBoth F. hepatica and F. gigantica are prevalent in sheep in Egypt and an introgressed form of the two occurs as the result of genetic recombination. In addition, a geographically isolated F. gigantica population is present in the country. The importance of these observations in epidemiology of fascioliasis needs to be examined in future studies.
Highlights
In Egypt, liver flukes, Fasciola spp. (Digenea: Fasciolidae), have a serious impact on the farming industry and public health
Occurrence of liver flukes Postmortem examinations of slaughtered sheep indicated that 302 of 2058 (14.7%) animals had Fasciola flukes in the bile duct
Fasciola species at nuclear internal transcribed spacer 1 (ITS1) locus Sequences of ~ 639 bp containing the complete ITS1 sequence and partial 18S and 5.8S rRNA gene sequences were generated from 103 Egyptian flukes
Summary
In Egypt, liver flukes, Fasciola spp. (Digenea: Fasciolidae), have a serious impact on the farming industry and public health. (Digenea: Fasciolidae), have a serious impact on the farming industry and public health Both Fasciola hepatica and Fasciola gigantica are known to occur in cattle, providing the opportunity for genetic recombination. Liver flukes reside in the bile duct of the definitive hosts, resulting in sever hepatic damage and associated health consequences [3]. In developing countries such as African nations, Fasciola infections have been recognized as a major constraint to animal farming [1, 4], Fasciola hepatica (Linnaeus, 1758) and Fasciola gigantica (Cobbold, 1856) are the causative agents of the disease in both humans and animals. Fasciola flukes of abnormal ploidy (triploid and mixoploid) have been reported; they are parthenogenetic with no evidence of sperm production [14, 16, 17]
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