Comparative Prevalence of Blastocystis in Patients with the Irritable Bowel Syndrome and Healthy Individuals: A Case Control Study

Abstract

Background: Blastocystis is one of the most common anaerobic protozoa found in the intestinal tract of humans and various animals, with a worldwide distribution. The parasite has been linked to the pathogenesis of the irritable bowel syndrome (IBS), previously. Objectives: The aim of this study was to evaluate the prevalence of Blastocystis in IBS patients compared to healthy individuals. Methods: The collected feces from 152 patients with Gastrointestinal (GI) symptoms, and 130 healthy volunteers from Ahvaz, southwest Iran, were examined using the direct saline smear, Lugol's iodine staining, and inoculated in a Jones' medium for Blastocystis detection. The DNA was extracted from all culture-positive samples, and then the polymerase chain reaction (PCR) was performed by the SSU-rDNA gene. Results: Blastocystis was identified in 18 (6.4%) samples, including two (1.3%) of the IBS patients and 16 (12.3%) of the control group by microscopy. Stool culture was positive in 15 with IBS, one without IBS, and 40 control samples. From these, the expected 600 bp fragments of the SSU-rDNA gene were identified in 15 (27.3%) cases and 40 (72.7%) controls. Subtypes (STs) 1, 2, and 3 were identified from the 54 successfully sequenced samples. Subtype 3 was the most common ST with the frequency of 46.3%, followed by ST2, 37% and ST1, 16.7% in the case and control groups. The highest frequency of Blastocystis STs (27.8%) was identified in the age group of 31-40 years and the lowest was found in the age groups of under 10 years and over 81 years. Conclusions:The findings of the current study showed that Blastocystis was more common in the control group compared to the IBS patients. Therefore, our findings highlight the contrast between Blastocystis infection and GI disorders. Furthermore, these results support the hypothesis that Blastocystis could be a GI health marker.

Parasitic infections in irritable bowel syndrome patients: evidence to propose a possible link, based on a case–control study in the south of Iran

“…In another study by Khademvatan et al [12] in Khuzestan, south of Iran, 122 patients with IBS and 122 healthy individuals were evaluated for Blastocystis infection where no statistically significant difference was found between the two groups. In another study in Iran, Beiromvand et al [21] demonstrated that Blastocystis spp. was more prevalent in the control group in comparison with the patients with IBS.…”

Molecular prevalence and subtype distribution ofBlastocystissp. in Asia and in Australia

“…in humans in Iran and molecular epidemiology studies estimated the prevalence rate as 27%. Based on the consensus terminology, six subtypes ST1 (32.01%), ST2 (21.9%), ST3 (36.7%), ST5 (0.3%), ST6 (2.43%), and ST7 (5.03%) together with unknown subtypes (1.52%) have been reported (Motazedian et al 2008;Moosavi et al 2012;Badparva et al 2014;Azizian et al 2016;Beiromvand et al 2017;Jalallou et al 2017;Khademvatan et al 2017Khademvatan et al , 2018Mirjalali et al 2017;Rezaei Riabi et al 2017Salehi et al 2017;Piranshahi et al 2018;Mardani Kataki et al 2019;Taghipour et al 2019). The subtype distribution in Iran shows that ST1-3 were the most prevalent subtypes (Alinaghizade et al 2017).…”

Molecular Detection of Blastocystis Subtypes in Domestic Pigeons and Their Owners in Tafresh City

“…The prevalence of this parasite in humans is estimated to be 27% based on molecular epidemiological studies. So far, six known subgroups, including ST1 (32.01%), ST2 (21.9%), ST3 (36.7%), ST5 (0.3%), ST6 (2.43%), and ST7 (5.03%), and some unknown subgroups (1.52%) have been reported in humans [23][24][25][26][27][28][29][30][31][32][33][34][35][36][37] . According to these reports, the most common subtypes isolated from humans are subtypes 1 to 3 [38] .…”