en عمومى General پژوهشي Research Article <span style="font-size:12pt"><span style="line-height:16.0pt"><span new="" roman="" style="font-family:" times=""><b><i><span style="font-size:9.0pt">Background & Aims</span></i></b><b><span style="font-size:9.0pt">:</span></b><i> </i><i><span style="font-size:9.0pt">Blastocystis</span></i><span style="font-size:9.0pt"> sp. is a common parasite of humans with a vast variety of nonhuman hosts and global distribution. Based on molecular methods, distinct subtypes are isolated from different hosts. In this study, we detected human-isolated <i>Blastocystis</i> subtypes in the northwestern of Iran. </span></span></span></span><br> <span style="font-size:12pt"><span style="line-height:16.0pt"><span new="" roman="" style="font-family:" times=""><b><i><span style="font-size:9.0pt">Materials & Methods</span></i></b><b><span style="font-size:9.0pt">:</span></b><span style="font-size:9.0pt"> A total of 600 stool samples referred to health centers in Urmia and Maragheh cities in the northwest of Iran was randomly collected and examined using direct wet mount, formalin-ether concentration, a modified version of the Ziehl&ndash;Neelsen staining technique for the detection of parasitological items<i> </i>and using barcoding method (18S rRNA gene) for the molecular survey. </span></span></span></span><br> <span style="font-size:12pt"><span style="line-height:16.0pt"><span new="" roman="" style="font-family:" times=""><b><i><span style="font-size:9.0pt">Results</span></i></b><b><span style="font-size:9.0pt">:</span></b><span style="font-size:9.0pt"> From 600 samples studied, 496 (82.7%) and 104 (17.3%) were male and female, respectively. Three subtypes, including ST₁, ST₂ and ST₃, were identified from collected samples, and the frequent subtypes were ST₃, ST_1, and ST₂, respectively.</span></span></span></span><br> <span style="font-size:12pt"><span style="line-height:16.0pt"><span new="" roman="" style="font-family:" times=""><b><i><span style="font-size:9.0pt">Conclusion</span></i></b><b><span style="font-size:9.0pt">:</span></b><span style="font-size:9.0pt"> While genetic similarity of <i>Blastocystis</i> isolated from human and animal did not show in this region, the zoonotic cycle of this parasite, probably by fecal contamination, exists in the study area. By identifying <i>Blastocystis</i> subtypes, it is possible to prevent the transmission and related complications. </span></span></span></span> Blastocystis sp., 18S rRNA, Northwestern of Iran 109 115 http://hsm.umsu.ac.ir/browse.php?a_code=A-10-111-1&slc_lang=en&sid=1 Mehrdad Rostami m.rostami9675@gmail.com 10031947532846001520 1111-1111-1111-1111 No Department of Hematology and Blood Bank, Mashhad University of Medical Sciences, Mashhad, Iran Arezoo Bozorgomid arezoobozorgomid@yahoo.com 10031947532846001521 10031947532846001521 No Infectious Diseases Research Center, Kermanshah University of Medical Sciences, Kermanshah, Iran Hadi Mirahmadi hmirahmadi59@gmail.com 10031947532846001522 10031947532846001522 No Infectious Diseases and Tropical Medicine Research Center, Zahedan University of Medical Sciences, Zahedan, Iran AND Dept. of Parasitology, Mycology and Entomology, Faculty of Medicine, Zahedan University of Medical Sciences, Zahedan, Iran Saber Raeghi saberraeghi@gmail.com 10031947532846001523 10031947532846001523 Yes Department of Laboratory Sciences, Maragheh University of Medical Sciences, Maragheh, Iran