Tehran University of Medical Sciences Iranian Journal of Parasitology 1735-7020 17 3 2022 09 05 296 305 Ayşe Gureser Department of Medical Microbiology, Faculty of Medicine, Hitit University, Corum, Turkey Atakan Comba Department of Pediatrics, Faculty of Medicine, Hitit University, Corum, Turkey Djursun Karasartova Department of Medical Microbiology, Faculty of Medicine, Hitit University, Corum, Turkey Nezahat Koşar Department of Medical Microbiology, Faculty of Medicine, Hitit University, Corum, Turkey Adem Keskin Department of Biology, Faculty of Science and Art, Tokat Gaziosmanpaşa University, Tokat, Turkey Christen Stensvold Department of Bacteria, Parasites and Fungi, Infectious Disease Preparedness, Statens Serum Institut, Copenhagen, Denmark Ayşegül Taylan-Ozkan 1. Department of Medical Microbiology, Faculty of Medicine, Hitit University, Corum, Turkey 2. Department of Medical Microbiology, Faculty of Medicine, University of Economics and Technology University, TOBB, Ankara, Turkey 2021 04 18 2021 10 13 Background: Blastocystis has been associated with various symptoms of the gastrointestinal tract. We aimed to investigate the prevalence of Blastocystis in children with celiac disease (CeD) or functional abdominal pain (FAP) and to evaluate its subtypes (STs) with respect to demographic, socioeconomic and epidemiological factors. Methods: Overall, 161 fecal samples were collected from healthy children and patients with FAP or CeD in Hitit University Erol Olçok Research and Training Hospital, Corum, Turkey  between 2016-2018. Samples were examined using both native-Lugol (NL) and trichrome-stained (TS) smears, and further analyses by PCR and Sanger sequencing were performed. A standard questionnaire was applied to obtain demographic, socioeconomic, epidemiological data. Results: Blastocystis was found in 10.6% of the total study population. Neither bacteria nor any other parasites were found, except for one Giardia (0.6%) in the CeD group. The presence/absence of the parasite was not found to be associated with demographic, socioeconomic and epidemiological factors. Blastocysis was detected in 11.5% (6/52) of the CeD, 7.7% (4/52) of the FAP, and 12.3% (7/57) of the healthy group. Diagnostic methods were similar in terms of Blastocystis detection (P= 0.671), and there was fair agreement between the NL, TS and PCR (Fleiss' Kappa=0.847, P=0.001). ST2 (42.8%) and ST3 (35.7%) were the predominant STs followed by ST1 (21.4%). Conclusion: We observed no difference between study groups in terms of Blastocystis prevalence. ST1, ST2 and ST3 subtypes were detected. Blastocystis prevalence and STs were not related to any of the demographic, socioeconomic and epidemiological factors. https://ijpa.tums.ac.ir/index.php/ijpa/article/view/3322 https://ijpa.tums.ac.ir/index.php/ijpa/article/download/3322/1224