First morphometric and molecular characterization of Fasciola spp. in Northwest Tunisia

The aim of this study was to characterize the Tunisian Fasciola spp. flukes by morphometric and molecular analyses. Flukes were collected from livers of sheep slaughtered in Sejnane slaughterhouses (Bizerte gouvernorate, Northwest Tunisia) between January and March 2021.Five morphometric parameters were determined for all the liver flukes, as follows: (i) total body length (BL), (ii) distance between ventral sucker and the tail (VS-T), (iii) distance between oral sucker and ventral sucker (OS-VS), (iv) abdomen diameter (AD), (v) tail diameter (TD) and the body length to width ratio (BL/BW). Molecular identification of the fluke specimens was carried out by polymerase chain reaction, restriction fragment polymorphism (PCR-RFLP) of a 680 bp sequence of the internal transcribes spacer 1 (ITS1) gene and by amplification, sequencing, and phylogenetic analysis of a 500 bp sequence of the ITS2 gene. Morphometric measurements showed that the mean of the total body length of the adult flukes was 21.1 ± 2.7 mm with minimum and maximum lengths of 13 and 31 mm, respectively. The PCR-RFLP analysis revealed a single profile consisting of three bands of approximately 370, 100, and 60 bp. Fasciola sequences described in the present study (GenBank numbers: OQ457027 and OQ457028) showed 99.58-100% identity to Fasciola hepatica. In conclusion, the results of this study show that molecular and phylogenetic analyses confirm the presence of a single species of F. hepatica in the Sejnane region Northwest of Tunisia. However, further studies are needed to identify the occurrence of Fasciola species in other Tunisian regions.

Genetic variation and population structure of Fasciola hepatica: an in silico analysis

Fasciola hepatica is a trematode leading to heavy economic setbacks to the livestock sector globally. The population's genetic information and intimate kinship level are frequently assessed using analysis of mitochondrial DNA. In this analysis, we retrieved cox1 (n = 247) and nad1 (n = 357) sequences of F. hepatica from the NCBI GenBank database and aligned the sequences with the respective reference sequences using MEGA software. The median joining network was drawn using PopArt software while neutrality and diversity indices were estimated with the help of DnaSp software. Neighbor-joining phylogenetic tree was constructed using the MEGA software package. A total of 46 and 98 distinctive haplotypes were observed for cox1 and nad1 genes, respectively. Diversity indices indicated high haplotype and nucleotide diversities in both genes. Positive Tajima's D and Fu's Fs values were found for the entire population of both the genes under study. The cox1 and nad1 gene segments in this study showed high Tajima's D values, suggesting a low likelihood of future population growth. The Tajima's D value of the nad1 gene sequence is lower (2.14910) than that of the cox1 gene sequence (3.40314), which suggests that the former is growing at a slower rate. However, the region-wise analysis revealed that both the cox1 and nad1 genes showed deviation from neutrality suggesting a recent population expansion as a result of an excess of low-frequency polymorphism. Furthermore, the overall host-wise analysis showed positive and significant Tajima's D values for the cox1 and nad1 gene sequences. To the best of our knowledge, this is the first attempt to provide insights into genetic variations and population structure of F. hepatica at a global scale using cox1 and nad1 genes. Our findings suggest the existence of specific variants of F. hepatica in different parts of the world and provide information on the molecular ecology of F. hepatica. The results of this study also mark a critical development in upcoming epidemiological investigations on F. hepatica and will also contribute to understanding the global molecular epidemiology and population structure of F. hepatica.

Multiplex PCR and Sequence Analysis to Investigate Genetic Diversity of Fasciola Isolates from Cattle and Sheep in Turkey

Fasciolosis is a highly prevalent helminthic infection caused by Fasciola hepatica and F. gigantica. With the aim of identifying hybrid Fasciola flukes, multiplex PCR was performed to amplify the pepck gene. Furthermore, to determine Fasciola haplotypes, mitochondrial nad1 gene was amplified and sequenced, and phylogenetic analyses were performed. Adult Fasciola isolates were collected from 51 cattle and 51 sheep, genomic DNA was isolated, and one-step multiplex PCR was subsequently performed to amplify pepck. Isolates that generated a 510 bp band were identified as F. gigantica, those that generated a 241 bp band were identified as F. hepatica, and those that generated both bands were identified as hybrid (aspermic) flukes. Multiplex PCR data identified four isolates as F. gigantica and 84 as F. hepatica. Fourteen hybrid isolates (five cattle and nine sheep) were identified. On unidirectional DNA sequence analysis of nad1 PCR products, three sequences were identified as F. gigantica and 99 as F. hepatica. In addition, only 4 of 87 haplotypes detected for F. hepatica nad1 sequences were found to be previously reported, while the remaining 83 are unique to this study. To summarize, this study is the first to report the existence of hybrid Fasciola flukes and 83 unique haplotypes of F. hepatica in Turkey.

Phylogenetic Characteristics of Fasciola hepatica Isolated from a Korean Patient

Fascioliasis is a parasitic infection caused by liver flukes. Although several cases have been reported in Korea, phylogenetic analysis of isolates is lacking. In this study, a 66-year-old woman with right upper quadrant (RUQ) abdominal pain was diagnosed as fascioliasis involving abdominal muscle by imaging study. She received praziquantel treatment, but symptoms were not improved. Lateral movement of the abscess lesion was followed. Trematode parasite was surgically removed from the patient’s rectus abdominis muscle. The fluke was identified as Fasciola hepatica based on sequence analysis of 18S rDNA. To determine the phylogenetic position of this Fasciola strain (named Korean Fasciola 1; KF1), the cox1 gene (273 bp) was analyzed and compared with the genes of 17 F. hepatica strains isolated from cows, sheep, goats, and humans from various countries. Phylogenetic analysis showed that KF1 was closely related with the isolates from China goat.

DNA barcoding of Iranian radicine freshwater snails begins to untangle the taxonomy and phylogeography of intermediate hosts of schistosomiasis and fasciolosis from the Middle East and across Central Asia

In the Middle East radicine snails are of considerable medical and veterinary importance acting as vectors of trematodes. In Iran, such snails are responsible for the transmission of the zoonotic trematodes Schistosoma turkestanicum and Fasciola gigantica. Historically, Radix gedrosiana has been incriminated as an important intermediate host for both trematodes, however, controversy remains over the snail's true taxonomic status. This species has been determined using morphological characters that has resulted in erroneous identification of species, affecting understanding of population biology, and ultimately affecting vector incrimination. In this current study DNA barcoding using cox1 and phylogenetic analyses revealed that snails identified as R. gedrosiana from Iran split into two separate species, Radix euphratica and Ampullaceana sp. The cox1 also provided useful insights into the evolutionary history of R. euphratica populations. Phylogeographic analyses indicated that R. euphratica had an Iraqi/Iranian origin approximately 3.3 MYA and exists as a large stable population across the Middle East and Central Asia, and a lack of genetic differentiation between geographical isolates. Such molecular barcoding techniques are crucial for the identification of radicine snails of Iran being invaluable for the monitoring of zoonotic flukes, understanding the distribution of infection and the accurate incrimination of snail vectors.

Molecular analysis reveals expansion of Fasciola hepatica distribution from Afghanistan to China

Recently, phosphoenol pyruvate carboxykinase (pepck) and DNA polymerase delta (pold) were established as reliable nuclear markers for species identification of Fasciola spp. in multiplex polymerase chain reaction (PCR) and PCR-restriction fragment length polymorphism-based assays, respectively. Currently, little is known about Fasciola species distribution in Central Asia. Therefore, the objective of the present study was to perform precise molecular species identification of liver flukes from Afghanistan and to reveal their dispersal route(s) via phylogenetic analysis based on mitochondrial nad1 haplotypes. Ninety-two Fasciolaflukes collected from sheep in Kabul, Afghanistan, were identified as F. hepatica based on pepck and pold screening. Although the pepck fragment pattern obtained via multiplex PCR analysis could not distinguish the species of the seven Fasciola flukes, the pepck nucleotide sequence data confirmed that they were F. hepatica.The 20 nad1 haplotypes detected among the Afghani liver flukes were closely related to those from China and Egypt, with the F_STvalue (-0.003, P = .41) between the F. hepatica populations from Afghanistan and China confirming a very close relationship. Nucleotide diversity was greater in the population from Afghanistan compared with that from China, indicating that the Afghani population was older, and that the dispersal direction of F. hepatica was from Afghanistan to China. The results of the present study contribute to our understanding of the dispersal of F. hepatica from its predicted origin, the Fertile Crescent.