Live stock is a vital industry because of its commercial worth. But; live stock farmers have to cope with a lot of diseases and Fascioliasis is one of them caused by the Fasciola species which are found in ruminants and may infrequently affect humans. According to a report; economic losses are more than two billion US dollars per annum. Moreover; human infection because of this parasitic disease is prevailing globally and almost 180 million people are at risk of infection worldwide in endemic areas1. Fasciola hepatica “the common liver fluke” or “the sheep liver fluke.” and Fasciola gigantic cause this threatening disease. Fasciola hepatica is circulated worldwide, while F. gigantica is limited to tropical areas and reported in Africa and South and Southeast Asia2. According to some investigations; Iran ruminant’s fascioliasis chiefly in cattle and buffaloes based on geography and climate variability3,4.
These two parasites can be differentiated on the basis of morphological characters including body size, ratio of body length to width and shape; but, this technique is not always trustworthy because of the morphological variety within the species5. Identification of F. gigantic and F. gigantica can be done through nucleotide sequences of the nuclear ribosomal internal transcribed spacer 1 (ITS1) and 2 (ITS2)6,7. Furthermore, DNA sequences of mitochondrial nicotinamide adenine dinucleotide dehydrogenase subunit I (ND1) and cytochrome c oxidase subunit I (CO1) genes have also been utilized to study intraspecific phylogenetic relations of Fasciola spp8,9.
Accordingly, Soheila Rouhani, Saber Raeghi and Adel Spotin conducted a research to analyze these two species by employing nuclear and mitochondrial markers (ITS1, ND1 and CO1) and to investigate the intraspecific phylogenetic associations of Fasciola spp. In this experiment, scientists collected almost 150 Fasciola specimens in 7 different geographical territories in the North West of Iran (Azerbaijan) from January-September, 2015 and then stained with haematoxylin-carmine dye. These specimens were examined under an optical microscope to evaluate the presence of sperm. The ITS1 marker was utilized to recognize different Fasciola and phylogenetic analysis based on ND1 and CO1 sequence data; conducted by maximum likelihood algorithm.
Scientists separated the Fasciola samples into 2 groups. It was noted that approximately all specimens had many sperms in the seminal vesicle (spermic fluke) while on the other hand one fluke did not contain any sperm in the seminal vesicle. The aspermic sample had F. gigantica RFLP pattern with ITS1 gene. Phylogenetic analysis based on NDI and COI sequence data exhibited parallel topology of the trees obtained mainly for F. hepatica and F. gigantica. Conclusively; this investigation helped to reveal that aspermic Fasciola found in the specific region has same genetic structures through the spermic F. gigantica populations in accordance to phylogenetic tree.
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17 November, 2019