Background Due to the similarity of Strongyloides stercoralis with free-living nematodes of Rhabditis species they might be miss-diagnosed with each other in microscopical examination of stool samples. The aim of this study was molecular characterization and differentiation of human derived isolates of S. stercoralis and Rhabditis species based on the mitochondrial gene of cytochrome c oxidase subunit 1 ( cox1 ) amplification. Methods Using parasitological methods, ten isolates of S. stercoralis and three isolates of Rhabditis spp. were obtained from fresh stool samples of patients and the genomic DNA of the samples were extracted. PCR amplification of cox1 gene was carried out for all the isolates and the products were sequenced. Results The phylogenetic analysis illustrated that S. stercoralis and Rhabditis spp. isolates were placed in two distinguishable separate clades. Inter-species genetic variation between isolates of S. stercoralis and Rhabditis spp . were ranged from 13.5 to 14.5%. Conclusions Cox1 gene was a suitable marker for discrimination of S. stercoralis from Rhabditis spp. retrieved from human in the current study. The availability of gene sequence information will be helpful in the future development and validation of discriminatory PCR-based assays of these nematodes.

Background: In microscopical examinations of stool samples, S. stercoralis may be miss-diagnosed with other nematodes infecting human digestive system, especially Rhabditis species that release larvae in stool samples. The aim of this study was molecular characterization and differentiation of human derived isolates of S. stercoralis and Rhabditis species based on the mitochondrial gene of cytochrome c oxidase subunit 1 (cox1) amplification. Methods: Using parasitological methods, ten isolates of S. stercoralis and three isolates of Rhabditis spp. were obtained from fresh stool samples of patients and the genomic DNA of the samples were extracted. PCR amplification of cox1 gene was carried out for all the isolates and the products were sequenced. Results: The phylogenetic analysis illustrated that S. stercoralis and Rhabditis spp. isolates were placed in two distinguishable separate clades. Inter-species genetic variation between isolates of S. stercoralis and Rhabditis spp. were ranged from 13.5 to 14.5%. Conclusions: Cox1 gene was a suitable marker for discrimination of S. stercoralis from Rhabditis spp. retrieved from human in the current study.

Background: We aimed to detect the genetic diversity of samples identified morphologically as Fasciola spp. from sheep, cattle and goat from Lorestan Province, western Iran using PCR-RFLP method. Besides, we evaluated the genetic diversity indices, sequencing and phylogenetic analysis using mitochondrial gene (ND1 and CO1). Methods: PCR-RFLP analysis of ribosomal ITS1 fragment by RsaI restriction enzyme to investigate the genetic characteristics of Fasciola species obtained from different hosts (18 sheep, 21 cattle, and 17goats) was conducted.  The samples were sequenced. Sequences were evaluated using BLAST software and the parasite species were identified with similarity percentage and overlap with the species registered in the gene bank. Then similarity and diversity of intra-species and intra-species diversity of Fasciola species were calculated. Results: In Lorestan, based on RFLP pattern, 93% (52) of the Fasciola spp. isolates had a RFLP pattern related to F. hepatica and 7% (4) were F. gigantica. No hybrid forms were detected. The CO1 gene could clarify 19 haplotypes against ND1 gene that found 22 haplotypes among livestock. Sequencing results of the mtDNA showed intra-species identity 98. 5%-100% and Intra-species-diversity: 0-1.5% compared to the GenBank sequences. Conclusion: Using PCR-RFLP method, two species of F. hepatica and F. gigantica, were present in Lorestan Province, but F. hepatica was more prevalent. Mitochondrial genes could better test variability indices in different hosts than ribosomal genes, consequently among mitochondrial genes, the ND1 gene could better examine differences and similarities than CO1.

Background: Due to the similarity of Strongyloides stercoralis with free-living nematodes of Rhabditis species they might be miss-diagnosed with each other in microscopical examination of stool samples. The aim of this study was molecular characterization and differentiation of human derived isolates of S. stercoralis and Rhabditis species based on the mitochondrial gene of cytochrome c oxidase subunit 1 ( cox1 ) amplification. Methods: Using parasitological methods, ten isolates of S. stercoralis and three isolates of Rhabditis spp. were obtained from fresh stool samples of patients and the genomic DNA of the samples were extracted. PCR amplification of cox1 gene was carried out for all the isolates and the products were sequenced. Results: The phylogenetic analysis illustrated that S. stercoralis and Rhabditis spp. isolates were placed in two distinguishable separate clades. Inter-species genetic variation between isolates of S. stercoralis and Rhabditis spp . were ranged from 13.5 to 14.5%. Conclusions: Cox1 gene was a suitable marker for discrimination of S. stercoralis from Rhabditis spp. retrieved from human in the current study. The availability of gene sequence information will be helpful in the future development and validation of discriminatory PCR-based assays of these nematodes.

Background: Due to the similarity of Strongyloides stercoralis with free-living nematodes of Rhabditis species they might be miss-diagnosed with each other in microscopical examination of stool samples. The aim of this study was molecular characterization and differentiation of human derived isolates of S. stercoralis and Rhabditis species based on the mitochondrial gene of cytochrome c oxidase subunit 1 ( cox1 ) amplification. Methods: Using parasitological methods, ten isolates of S. stercoralis and three isolates of Rhabditis spp. were obtained from fresh stool samples of patients and the genomic DNA of the samples were extracted. PCR amplification of cox1 gene was carried out for all the isolates and the products were sequenced. Results: The phylogenetic analysis illustrated that S. stercoralis and Rhabditis spp. isolates were placed in two distinguishable separate clades. Interspecies genetic variation between isolates of S. stercoralis and Rhabditis spp . were ranged from 13.5 to 14.5%. Conclusions: Cox1 gene was a suitable marker for discrimination of S. stercoralis from Rhabditis spp. retrieved from human in the current study. The availability of gene sequence information will be helpful in the future development and validation of discriminatory PCR-based assays of these nematodes.