Distribution and phylogenetic analysis of Blastocystis sp. subtypes isolated from IBD patients and healthy individuals in Iran

An Update on Blastocystis: Possible Mechanisms of Blastocystis-Mediated Colorectal Cancer

Blastocystis is an anaerobic parasite that colonizes the intestinal tract of humans and animals. When it was first discovered, Blastocystis was considered to be a normal flora with beneficial effects on human health, such as maintaining gut hemostasis and improving intestinal barrier integrity. Later, with increasing research on Blastocystis, reports showed that Blastocystis sp. is associated with gastrointestinal disorders, colorectal cancer (CRC), and neurological disorders. The association between Blastocystis sp. and CRC has been confirmed in several countries. Blastocystis sp. can mediate CRC via similar mechanisms to CRC-associated bacteria, including infection-mediated inflammation, increased oxidative stress, induced gut dysbiosis, and damage to intestinal integrity, leading to a leaky gut. IL-8 is the main inflammatory cytokine released from epithelial cells and can promote CRC development. The causal association of Blastocystis sp. with other diseases needs further investigation. In this review, we have provided an update on Blastocystis sp. and summarized the debate about the beneficial and harmful effects of this parasite. We have also highlighted the possible mechanisms of Blastocystis-mediated CRC.

Detection of Blastocystis sp. and Dientamoeba fragilis using conventional and molecular methods in patients with celiac disease

Blastocystis sp. and Dientamoeba fragilis are intestinal protists, which are common worldwide, but the pathogenic role of these organisms in gastrointestinal diseases is still controversial. This study aimed to investigate the frequency of Blastocystis sp. and D. fragilis in stool samples from adult patients with celiac disease (CD) by using conventional and molecular methods. A total of 75 patients with CD and 75 healthy individuals were included in this study. Fresh stool specimens collected from each individual were analyzed by conventional and molecular methods. The overall prevalence of Blastocystis sp. and D. fragilis was 41.3% (31/75) and 24% (18/75) in patients with CD, and 46.7% (35/75) and 13.3% (10/75) in healthy controls, respectively. There was no statistically significant difference in the prevalence of Blastocystis sp. and D. fragilis between CD patients and healthy individuals. Blastocystis sp. subtypes were identified in 20 CD and 16 control patients and the overall subtype distribution was observed as ST1 13.9%, ST2 30.6%, and ST3 55.6%. The prevalence of Blastocystis sp. and D. fragilis in adults with CD is similar to the prevalence of protozoa in healthy adults. In this study, the most prevalent Blastocystis subtype was ST3 and the most frequent allele was a34 in both CD patients and healthy individuals. No significant difference was found between the two groups in terms of the detection rates of Blastocystis sp. and D. fragilis, and it is thought that both protists may be colonisers of the intestinal microbiome.

Predominance of the Blastocystis subtype ST5 among free-living sympatric rodents within pig farms in China suggests a novel transmission route from farms

Blastocystis is a parasitic protist that can infect humans and various domestic and wild animals. However, there is limited research on the prevalence of this parasite among rodents, particularly those living in pig farm settings. Therefore, to investigate the occurrence, molecular characterization, and zoonotic potential of Blastocystis among rodents within pig farm environments, we conducted an investigation of 227 rodents and shrews from 34 pig farms located in Henan, Shaanxi, and Shanxi provinces of China using nested PCR of the SSU rRNA gene of Blastocystis. The potential transmission and public health implications were also assessed from a One Health perspective. Blastocystis was detected in 86 (37.9%) fecal samples. The highest infection rate was observed among Ruttus norvegicus (73.7%, 42/58), followed by Ruttus tanezumi (30.1%, 41/136), and Mus musculus (12.0%, 3/25). However, it was not detected among individuals with Apodemus agrarius (n = 1) and Crocidura shantungensis (n = 7). Five known zoonotic Blastocystis subtypes (ST1-ST5) were identified, with ST4 (51.2%, 44/86) and ST5 (40.7%, 35/86) being the predominant ones, followed by ST1 (3.5%, 3/86), ST3 (3.5%, 3/86), and ST2 (1.2%, 1/86). ST4 was prevalent among R. norvegicus (83.3%, 35/42), while ST5 dominated R. tanezumi (70.7%, 29/41). Furthermore, ST5 exhibited the widest distribution at pig farm level, accounting for 65.0% (13/20) of Blastocystis-positive pig farms. This investigation presents the first documented Blastocystis infection in R. tanezumi and M. musculus, highlighting the predominant presence of the zoonotic ST5 subtype in rodents for the first time. The results demonstrate that sympatric rodents can serve as natural reservoirs for Blastocystis and play a role in its transmission. These findings provide information on the dynamics of rodent transmission and emphasize the potential public health threat posed by zoonotic Blastocystis subtypes spillover from pig farms.

Prevalence of intestinal parasitic infections in patients with diabetes: a systematic review and meta-analysis

Patients with diabetes are at an increased risk of intestinal parasitic infections (IPIs). We evaluated the pooled prevalence and OR of IPIs in patients with diabetes through a systematic review and meta-analysis. A systematic search was performed using the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) protocol for studies reporting IPIs in patients with diabetes through 1 August 2022. The collected data were analyzed using comprehensive meta-analysis software version 2. Thirteen case-control studies and nine cross-sectional studies were included in this study. The overall prevalence of IPIs in patients with diabetes was calculated to be 24.4% (95% CI 18.8 to 31%). Considering the case-control design, the prevalence of IPIs in case (25.7%; 95% CI 18.4 to 34.5%) was higher than controls (15.5%; 95% CI 8.4 to 26.9%) and a significant correlation was observed (OR, 1.80; 95% CI 1.08 to 2.97%). Moreover, a significant correlation was seen in the prevalence of Cryptosporidium spp. (OR, 3.30%; 95% CI 1.86 to 5.86%), Blastocystis sp. (OR, 1.57%; 95% CI 1.11 to 2.22%) and hookworm (OR, 6.09%; 95% CI 1.11 to 33.41%) in the cases group. The present results revealed a higher prevalence of IPIs in patients with diabetes than in controls. Therefore, the results of this study suggest a proper health education program to preventing measures for the acquisition of IPIs in patients with diabetes.

Molecular epidemiology and subtyping of Blastocystis sp. and its subtypes in celiac patients; a case control study

Blastocystis sp. is a common intestinal protist, reported from symptomatic and asymptomatic subjects. Blastocystis sp. has been reported from a broad spectrum of gastrointestinal disorders. Celiac disease (CD) is an autoimmune disorder of the small intestine, which leads to the lack of tolerance against gluten. Long-term following of gluten-free diet in CD patients decreases the gut microbiota restoration and probably decreases the chance of Blastocystis sp. colonization. The current study aimed to investigate the prevalence of Blastocystis sp. and its subtypes in CD patients in comparison to healthy subjects. Stool samples were collected from 238 participants including 92 confirmed CD patients and 146 healthy subjects. upon DNA extraction, the presence of Blastocystis sp. was evaluated using amplification of discriminative regions of the small ribosomal RNA (ssu rRNA) gene. To characterize subtypes and alleles, amplified fragments were sequenced. Phylogenetic trees were constructed to visualize subtype correlation. Our findings showed that 21% (50) of samples including 16.3% (15/92) and 23.97% (35/146) were positive for Blastocystis sp. in CD patients and healthy controls, respectively. Except family relationship, other variables were not statistical correlated with the presence of Blastocystis sp.. Totally, 25 samples were successfully sequenced. Accordingly, ST1, ST2, and ST3 were present in 8 (32%), 9 (36%), and 8 (32%) of the samples, respectively. Allele discrimination showed that all ST1 were allele 4; alleles 11, 9, and 12 were retrieved from ST2, and alleles 34, 36, and 38 were observed in ST3. The relationship between colonization of Blastocystis sp. and alteration in the gut microbiota composition is indeterminate, however, this hypothesis that lower prevalence of Blastocystis sp. in CD patients who follow a gluten-free diet affect the colonization of Blastocystis sp. via alteration in the gut microbiota composition could be interesting for further investigations.

Detection of Blastocystis sp. in ulcerative colitis, Crohn's and chronic diarrheal patients by microscopy, culture and real-time polymerase chain reaction

Blastocystis sp. is a zoonotic parasite that is common in humans and animals and settles in the large intestine. The parasite can cause various gastrointestinal system complaints such as indigestion, diarrhea, abdominal pain, bloating, nausea and vomiting. The aim of this study is to determine the distribution of Blastocystis in patients diagnosed with ulcerative colitis, Crohn's and diarrhea from the gastroenterology outpatient clinic and to compare the diagnostic value of the most preferred methods. A total of 100 patients, 47 men and 53 women, were included in the study. Of the cases, 61 had diarrhea, 35 had ulcerative colitis (UC) and four had Crohn's disease. Stool samples of the patients were analyzed by as direct microscopic examination (DM), culture and real-time polymerase chain reaction (qPCR). A total of 42% positivity was detected, 29% positivity in DM and trichrome staining, 28% in culture and 41% in qPCR. 40.4% (20/47) of men and 37.7% (22/53) of women were found to be infected. Blastocystis sp. was found in 75% of Crohn's, 42.6% of diarrheal and 37.1% of UC patients. Diarrhea cases are more common with UC and there is a close relationship between Crohn's and Blastocystis positivity. While DM and trichrome staining showed a sensitivity of 69%, PCR test was found to be the most sensitive diagnostic method with approximately 98%. Diarrhea and UC are often seen together. A close relationship was detected between Crohn's disease and Blastocystis. High prevalence of Blastocystis in cases with clinical symptoms reveals the importance of the parasite. There is a need for studies on the pathogenicity of Blastocystis sp. in various gastrointestinal cases, and it is thought that molecular techniques should be used since PCR is seen to be a much more sensitive.

Frequency, subtypes distribution, and risk factors of Blastocystis spp. in COVID-19 patients in Tehran, capital of Iran: A case-control study

Background

Recent theories on the possible interactions between the intestinal parasites and COVID-19 have stated that these co-infections may cause immune imbalance and further complications in the affected patients. Until now, there is no data about Blastocystis subtypes as an intestinal parasite in COVID-19 patients. Therefore, the present work was done to evaluate the molecular prevalence of Blastocystis spp. and related risk factors in Iranian patients with COVID-19.

Method

Stool samples were gathered from 200 COVID-19 patients and 200 control, being matched regarding age, gender and residence. Then, stool samples were surveyed by parasitological methods, including direct slide smear and formalin-ether concentration. In the following, PCR and sequencing were used to detect Blastocystis spp. and their subtypes.

Results

The frequency of Blastocystis spp. in patients with COVID-19 (7.5%; 15/200 by molecular method vs. 6%; 12/200 by microscopy method) was slightly higher than in individuals without COVID-19 (4.5%; 9/200 by molecular method vs. 4%; 8/200 by microscopy method), this difference was not statistically significant (P value = 0.57 for molecular method vs. P value = 0.81 for microscopy method). Regarding associated factors for Blastocystis spp., we found significant differences regarding the residence (rural), loose and watery stool with diarrhea, and duration of treatment (6 weeks <) in the COVID-19 group. Blastocystis ST3 was the most common subtype in the patients with COVID-19 and control group.

Conclusions

Based on this results, health education, improved sanitation and good personal hygiene are highly recommended to prevent Blastocystis in COVID-19 patients.

Subtypes and phylogenetic analysis of Blastocystis sp. isolates from West Ismailia, Egypt

In Egypt, Blastocystis sp. is not yet on the diagnostic list of parasitology reports, and information about its subtypes (STs) is scarce. This study investigated its prevalence and its STs/alleles, performed phylogenetic analysis, and considered the distribution of risk factors associated with Blastocystis sp. infections in West Ismailia, Ismailia governorate. Sociodemographic data, exposure factors, and previous parasitic infection status were recorded for symptomatic and asymptomatic individuals. Microscopy, polymerase chain reaction, sequencing, and phylogenetic analysis for Blastocystis sp. isolated from fecal samples were performed. Eighty Blastocystis sp.-infected individuals (15.3%) were examined. The age of the individuals ranged between 0.60 and 85.0 (mean 17.10 ± 15.70), the male/female ratio was 33/47, and the asymptomatic/symptomatic ratio was 55/25. The findings demonstrate clear evidence of direct contact with animals, poor water quality, and previous parasitic infections. Eleven samples yielded three Blastocystis STs (ST1: allele 4, ST2: alleles 9 and 12, and ST3: allele 34), with ST3 (45.5%) representing the most common subtype. Phylogenetic analysis with a robust bootstrap revealed three distinct clades for isolates of each subtype. This study updates the epidemiological knowledge of the distribution of Blastocystis sp. STs in Egypt and expands the current understanding of the prevalence, risk factor frequencies, and genetic diversity of this protist in the studied area.

Molecular Epidemiology of Blastocystis in Confined Slow Lorises, Macaques, and Gibbons

Blastocystis sp. is a common intestinal anaerobic parasite infecting non-human primates and many other animals. This taxon threatens the health of NHPs due to its high genetic diversity, impeding efforts to improve confined management and subsequent conservation practices. This study collected 100 and 154 fecal samples from captive macaques, gibbons, and slow lorises in the summer and winter, respectively. The Blastocystis infection, its gene subtypes, and its zoonotic potential based on small subunit ribosomal RNA (SSU rRNA) were analyzed. The prevalence of Blastocystis in the three primate genera was 57.79% (89/154) in the summer (2021) and 29.00% (29/100) in the winter (2020). Four zoonotic subtypes-ST1, ST2, ST3, and ST4-were identified. ST2 was the most prevalent subtype, suggesting that these animals may serve as reservoirs for pathogens of human Blastocystis infections. The macaques showed a more significant variation in Blastocystis infection between seasons than gibbons and slow lorises. The slow lorises in small cages and enclosure areas were potentially more infected by Blastocystis in the summer, indicating that inappropriate captive management may have detrimental effects on their health.

Investigation of Dientamoeba fragilis and Blastocystis in patients from Turkey with ulcerative colitis and irritable bowel syndrome: Any relation with genotypes?

Blastocystis sp. and Dientamoeba fragilis are two most common protists worldwide, whose pathogenic potentials are a matter of debate since their discovery. This study aims to investigate the relationship between the activation of ulcerative colitis (UC) and irritable bowel syndrome (IBS) with these protists. A total of 100 patients (35 IBS, 35 active UC, and 30 remittent UC), diagnosed at Hacettepe University Adult Hospital (Ankara, Turkey), were screened for D. fragilis and Blastocystis sp. with microscopic examination using the methods of wet mount, trichrome staining, conventional PCR, nested PCR, real-time PCR and genotyping. Eight patients (4 IBS, 2 active, and 2 remittent UC patients) were found to be D. fragilis positive. 18S rRNA region of the parasite was amplified in four of the patients, whereas cathepsin L-like cysteine peptidase; clan Sc, family S9, serine peptidase; and clan MH, family M20 metallopeptidase in six different patients. All isolates were Genotype 1. Sequence results showed very limited diversity. A total of nine patients (3 IBS, 5 active UC, 1 remittent UC) were found to be positive for Blastocystis sp., all of which were Subtype 3. One active UC and one IBS patient were found to be positive for both parasites. No statistically significant difference was detected between the patient groups in means of parasite detection. D. fragilis was found to be related to older age (p=0,045). In our study, no significant correlation was identified between D. fragilis and Blastocystis sp., and the activation of UC and IBS. More studies are needed on the host-parasite relationship, including the role of gut microbiota, together with transcriptomic and metabolomic assessments to unveil the pathogenicity of both protists.

Gut Microbiota Shifting in Irritable Bowel Syndrome: The Mysterious Role of Blastocystis sp

Irritable bowel syndrome (IBS) is a chronic disorder, which its causative agent is not completely clear; however, the interaction between microorganisms and gastrointestinal (GI) epithelial cells plays a critical role in the development of IBS and presenting symptoms. During recent decades, many studies have highlighted the high prevalence of Blastocystis sp. in patients with IBS and suggested a probable role for this protist in this disease. Recent studies have documented changes in the gut microbiota composition in patients with IBS regarding the presence of Blastocystis sp., but it is not clear that either disturbance of the gut during GI disorders is a favorable condition for Blastocystis sp. colonization or the presence of this protist may lead to alteration in the gut microbiota in IBS patients. In this review, we comprehensively gather and discuss scientific findings covering the role of Blastocystis sp. in IBS via gut microbiota shifting.

Rare Occurrence of Blastocystis in Pet Animals and Their Owners in the Pomeranian Voivodeship in Poland in the Light of Literature Data

Blastocystis is an intestinal microeukaryote with ambiguous pathogenicity, commonly detected in human feces worldwide. It comprises at least 28 genetically diverse subtypes (STs), 12 of which also occur in a wide range of animal species, giving rise to suspicion of zoonotic transmission. To investigate this, we conducted a molecular study of 145 stool samples of pet animals, and 67 of their owners, living in an urban area in Poland. Blastocystis was detected in only three (2.1%) animal samples (of two bearded agamas and a leopard gecko), while all dogs, cats, and pet rodents were Blastocystis-negative. Blastocystis was also present in three (4.5%) owners of animals, but they were cat owners, not reptile owners, and the subtypes identified in them differed significantly from those of reptiles. Additionally, the frequency of Blastocystis in different groups of dogs (depending on how they were kept) was analyzed. This work is the first to find Blastocystis in pet reptiles, and we encourage further investigation of Blastocystis in this poorly examined group of animals, as well as continued study on the transmission of this microorganism between humans and animals.

Modulation of microRNAs and claudin-7 in Caco-2 cell line treated with Blastocystis sp., subtype 3 soluble total antigen

Background

Blastocystis sp., is a eukaryote of the large intestine, which is reported from almost all countries. The pathogenesis of this protist is not clear. The current study aimed to analyze the effects of Blastocystis sp., ST3 soluble total antigen (B3STA) on the microRNAs (miRNAs) involved in the gut permeability and also pro-inflammatory cytokines, occludin, and claudin-7.

Methods

Blastocystis sp., ST3 isolated from stool sample was purified, and its soluble total antigen was extracted using freeze and thawing. The Caco-2 cell line was treated with B3STA for 24 h and the expression levels of mir-16, mir-21, mir-29a, mir-223, and mir-874 were analyzed. In addition, the expression levels of il-8, il-15, occludin, and claudin-7 genes were assessed.

Results

B3STA significantly upregulated the expression of mir-223, and mir-874, and downregulated mir-29a. The expression of mir-16 and mir-21 was not significant. In addition, the expression of il-8 and il-15 was not significant. B3STA significantly decreased the expression level of claudin-7 (P-value < 0.0001), but the expression of occludin was not significant. Our results showed significant correlation between all studied miRNAs, except mir-29a, with downregulation of claudin-7.

Conclusions

This is the first study investigating the effects of Blastocystis sp., ST3 isolated from symptomatic subjects on the expression levels of miRNAs involved in the gut permeability. Our results demonstrated that B3STA may change miRNA expression, which are involved in the gut barrier integrity, and downregulates claudin-7, which is known as sealing factor.

Occurrence and subtyping of Blastocystis in coypus (Myocastor coypus) in China

BACKGROUND

Blastocystis is an anaerobic unicellular protist frequently detected in the gastrointestinal tracts of humans and animals worldwide. However, the prevalence and subtype distribution of Blastocystis in the coypu (Myocastor coypus) population have not been reported so far. The aim of this study was to determine the prevalence, genetic characteristics, and zoonotic potential of Blastocystis isolates detected in coypus in China.

RESULTS

A total of 308 fecal samples were collected from coypus in seven regions across China and subsequently examined. Blastocystis was detected in 44 (14.3%) specimens by nested PCR amplification of the small subunit ribosomal rRNA (SSU rRNA) gene. Further DNA sequencing and phylogenetic analyses resulted in the identification of two zoonotic known subtypes, ST4 and ST5, and an unknown subtype. ST4 was the most predominant subtype observed in the samples. ST5 infections were only observed in three coypus. Factors that were associated with prevalence of Blastocystis included age, geographical region and subtype. Interestingly, this is the first report about a potentially novel subtype infecting coypus.

CONCLUSIONS

This is the first comprehensive report of Blastocystis in M. coypus across a wide geographic range of China. A moderate degree of genetic divergence was observed. The presence of zoonotic subtypes in farmed M. coypus suggests that these animals have the potential to transmit blastocystosis to both humans and domestic animals. These findings provide a better understanding of the genetic diversity of Blastocystis in rodents and contribute towards the establishment of efficient blastocystosis control strategies in the investigated areas.

Blastocystis One Health Approach in a Rural Community of Northern Thailand: Prevalence, Subtypes and Novel Transmission Routes

Blastocystis is the most commonly found eukaryote in the gut of humans and other animals. This protist is extremely heterogeneous genetically and is classified into 28 subtypes (STs) based on the small subunit ribosomal RNA (SSU rRNA) gene. Numerous studies exist on prevalence of the organism, which usually focus on either humans or animals or the environment, while only a handful investigates all three sources simultaneously. Consequently, understanding of Blastocystis transmission dynamics remains inadequate. Our aim was to explore Blastocystis under the One Health perspective using a rural community in northern Thailand as our study area. We surveyed human, other animal and environmental samples using both morphological and molecular approaches. Prevalence rates of Blastocystis were 73% in human hosts (n = 45), 100% in non-human hosts (n = 44) and 91% in environmental samples (n = 35). Overall, ten subtypes were identified (ST1, ST2, ST3, ST4 ST5, ST6, ST7, ST10, ST23, and ST26), eight of which were detected in humans (ST1, ST2, ST3, ST4, ST5, ST7, ST10, and ST23), three in other animals (ST6, ST7, and ST23), while seven (ST1, ST3, ST6, ST7, ST10, ST23, and ST26) were found in the environment. In our investigation of transmission dynamics, we assessed various groupings both at the household and community level. Given the overall high prevalence rate, transmission amongst humans and between animals and humans are not as frequent as expected with only two subtypes being shared. This raises questions on the role of the environment on transmission of Blastocystis. Water and soil comprise the main reservoirs of the various subtypes in this community. Five subtypes are shared between humans and the environment, while three overlap between the latter and animal hosts. We propose soil as a novel route of transmission, which should be considered in future investigations. This study provides a thorough One Health perspective on Blastocystis. Using this type of approach advances our understanding on occurrence, diversity, ecology and transmission dynamics of this poorly understood, yet frequent gut resident.

Prevalence of Intestinal Protozoan Infection in Patients with Ulcerative Colitis (UC) in Isfahan, Iran

Background:

Determination of the prevalence of intestinal protozoan infection is a fundamental step to set up an effective control program to improve the health status of society and to establish efficient strategies. Intestinal pathogen and even non-pathogen protozoa consider as major causes of disease in patients with gastrointestinal problems. The objective of this study is to determine the prevalence of intestinal protozoan infection in patients with ulcerative colitis (UC) in Isfahan, Iran.

Methods:

The descriptive cross-sectional study carried out from 2013 to 2018 in Isfahan, Iran. One thousand nine hundred and sixty-five samples of feces from patients with UC collected and each sample examined using direct wet mounting with normal saline and iodine and sedimentation tests such as formol-ethyl acetate concentration and trichrome-staining methods.

Results:

From 655 patients, 185 (28.2%) infected with Giardia lamblia followed by Blastocystis hominis (27.3%), Endolimax nana (14.4%), Entamoeba coli (11.5%), Iodamoba butschlii (4.7%), Entamoeba histolytica (1.4%), and Chilomastix mesnili (0.6%).

Conclusions:

This study revealed a high prevalence of infection with at least one or six non-pathogenic and pathogenic intestinal protozoa in UC patients in the Isfahan region. Intestinal protozoa are a challenging public health problem wherever health care is limited in the area. The emergence of UC in the world results in the need to study etiologic factors. In order to obtain further information about the etiology of disease, we investigated the prevalence of intestinal protozoan infection in patients with UC in Isfahan, Iran.

Molecular prevalence and subtype distribution of Blastocystis sp. in Asia and in Australia

Blastocystis is a prevalent protozoan parasite reported in humans, animals, and environmental samples. Over the past decade, numerous studies have investigated the prevalence and subtype distribution of Blastocystis sp. alongside with its genetic and biochemical features. However, studies on subtype distribution of this protozoan in humans, animals, and environmental samples represent the potential transmission routes. In this review, we evaluated studies performed in Asian countries and in Australia to provide an overview of environmental factors on the prevalence and subtype distribution of Blastocystis sp. among humans, animals, and the environment.

The Coexistence of Blastocystis spp. in Humans, Animals and Environmental Sources from 2010-2021 in Asia

Blastocystis spp. are controversial unicellular protists that inhabit the gastrointestinal tract of humans and a wide range of animals worldwide. This review provides an overview of the prevalence and distribution of Blastocystis spp. and their subtypes throughout Asia. Research articles reporting on the presence of Blastocystis spp. in locations within Asia, between 1 January 2010, and 10 May 2021, were obtained from Scopus, PubMed, and Google Scholar. In 427 articles, the prevalence of Blastocystis spp. in 31 countries within the last decade was revealed. Isolates were found in humans, various mammals, birds, reptiles, insects, water sources, vegetables, and ambient air. Prevalence of Blastocystis spp. varied widely across host categories. Subtypes identified throughout Asia were STs 1-14, and ST18-22 (novel subtypes). ST1, ST2, ST3, ST4 were the most frequently isolated in humans; ST5 in pigs; ST10 and ST14 in goats, sheep, and cattle; and ST6 and ST7 in chickens. ST1 and ST3 were most common in water samples. ST1, ST2, ST3, ST4, ST5 and ST6 were shared by humans, animals, and water sources. There is a growing interest in the study of Blastocystis spp. and their subtypes in Asia. Due to the isolation of Blastocystis spp. from biotic and abiotic sources in Asia, the application of the One Health (OH) approach to the study of Blastocystis spp. is proposed for improved perception of this organism.

Prevalence and associated risk factors of intestinal parasitic infections among Egyptian patients with inflammatory bowel disease

The global prevalence of inflammatory bowel disease (IBD) is continuously rising, however, a little is known concerning intestinal parasitic infections (IPIs) and (IBD). We aimed to evaluate the prevalence of IPIs among IBD patients, through a case-control study and also, to correlate the positive cases to the socio-demographic risk factors of IPIs among the study groups. A 1-year case-control study included patients with IBD (n=125) and healthy controls (n=125). The fecal samples were examined with the classical parasitological methods for intestinal parasites. Also, in-vitro culture (for Blastocystis sp.) and Immuno-chromatography technique (for Cryptosporidium / Giardia /Entamoeba) were done. IBD patients had significant higher positivity rate of IPIs compared to healthy controls (Adjusted OR= 9.60, 95% CI: 4.51-20.41, P = 0.0001), with Blastocystis sp., Entamoeba dispar/ histolytica and Cryptosporidium sp. being highly significant in IBD patients. In addition to IBD, living in rural area, with low socio-economic stander, and consumed raw/contaminated food and age group > 50 years old were significant risk factors for IPIs. In conclusion, our results support a possible link between IPIs and IBD.

Comparative molecular prevalence and subtypes distribution of Blastocystis sp. a potentially zoonotic infection isolated from symptomatic and asymptomatic patients in Iran: A systematic review and meta-analysis

PURPOSE

The present systematic review and meta-analysis was aimed to assess the weighted molecular prevalence of Blastocystis sp. in humans along with the comparative molecular prevalence and subtypes distribution of Blastocystis isolated from symptomatic and asymptomatic patients in Iran.

METHODS

International electronic databases including Medline/PubMed, ProQuest, Scopus, Embase, and Google Scholar were explored until 4th October 2020. Heterogeneity index was evaluated among studies using Cochran's Q test and I² index. Finally, 23 eligible studies were qualified to be included in this review.

RESULTS

The pooled molecular prevalence of Blastocystis sp. in Iran was reported 15.2% (95% CI 11.5-19.7). In addition, the molecular prevalence based on PCR-sequencing and STS primers was reported 12.5% (95% CI 8.6-17.7) and 19.8% (95% CI 13.1-28.8), respectively. Interestingly, there was a considerably higher prevalence among asymptomatic patients [25.1% (95% CI 20.8-30.0)] in comparison to symptomatic ones [21.0% (95% CI 15.9-27.2)]. In addition, the frequency of Blastocystis ST1, ST2, and ST3 from positive samples in symptomatic patients was 19.7%, 35.1%, and 47.4%, respectively. In addition, the prevalence of Blastocystis ST1, ST2, and ST3 from positive samples in asymptomatic patients was 27.1%, 26.8%, and 37.8%, respectively. The results obtained in Iran showed that Blastocystis is more common in asymptomatic patients compared to patients having clinical symptoms. Of note, ST3, as the most common subtype causing clinical symptoms, was the most prevalent reported subtype among both symptomatic and asymptomatic patients in the country.

CONCLUSIONS

Hence, the pathogenicity of the Blastocystis parasite is not subtype-specific and appears to be related to a variety of risk factors. Still the Blastocystis epidemiology is open to question and more large-scale studies should be performed on this aspect.

Genetic characterization of Blastocystis from poultry, livestock animals and humans in the southwest region of Iran-Zoonotic implications

Blastocystis is the most common intestinal parasite found in epidemiological studies in Iran. The genus Blastocystis comprises multiple subtypes (ST), evincing the existence of extensive intrageneric diversity. Meanwhile, information on Blastocystis STs in domestic animals in Iran is limited. This study was designed to identify the prevalence and subtype distribution of Blastocystis in domestic animals and to evaluate the extent of zoonotic origin of human Blastocystis carriage. A total of 395 faecal samples from farm animals (220 from poultry, 100 from sheep and 75 from cattle) and 23 Blastocystis positive samples from humans (available from the previous report of this study and included for reference) from the Khuzestan province, southwestern Iran, were analysed. Standard parasitological methods and PCR-based analysis of the SSU-rRNA gene were used. Overall, 115 (29.1%; 95% CI, 26.5%-31.6%) of the animals were positive for Blastocystis sp. by parasitological methods. The highest colonization rate was found in cattle (50.6%, 38/75), followed by sheep (32.0%, 32/100) and poultry (20.4%, 45/220). Eight Blastocystis STs were identified among 55 sequenced isolates from animals (n = 32) and humans (n = 23): ST3 (27.3%), ST14 (25.4%), ST1 (12.7%), ST7 (12.7%), ST2 (9.1%), ST6 (7.3%), ST5 (3.6%) and ST10 (1.8%). Blastocystis ST1 and ST3 were found in both human and non-human hosts, and examples of shared alleles (strains) were observed. Meanwhile, ST2 was observed only in humans, ST5 only in sheep, ST6 only in poultry and ST10 in only cattle. This is the most comprehensive report of Blastocystis STs in farm animals in Iran.

Gut mycobiome: The probable determinative role of fungi in IBD patients

Inflammatory bowel disease (IBD) is a multi-factorial autoimmune disorder that its causative agents are unknown. The gut microbiota comprises of bacteria, viruses, fungi and protozoa that its role in IBD has remained controversially. Bacteria constitute more than 99% of the gut microbiota composition, and the main core of the gut microbiota is composed from Bacteroidetes and Firmicutes. The gut microbiota plays an important role in training, development and haemostasis of the immune responses during the life. Fungi compose a very small portion of gut microbiota, but play determinative roles in homeostasis of the gut bacterial composition and the mucosal immune responses. An interkingdom correlation between bacteria and fungi has been suggested. For example, the presence of Salmonella enterica serovar Typhimurium reduces the viability and colonisation of C albicans. Alterations in the composition and function of the gut microbiota, which is known as dysbiosis, are a usual event in patients who suffer from IBD. Although the main reason for this alteration is not clear, the interaction between gut bacteria and gut fungi seems to be an important subject in IBD patients. This review covers new findings on the interaction between fungi and bacteria and the role of fungi in the pathophysiology of IBD.

Intestinal protozoa and helminths in ulcerative colitis and the influence of anti-parasitic therapy on the course of the disease

PURPOSE

The aim of this study is to determine the prevalence of intestinal helminths and protozoa in patients with ulcerative colitis (UC) and to estimate the influence of the anti-parasitic therapy on the course of the disease.

METHODS

The study was conducted at the Research Institute of Epidemiology, Microbiology and Infectious Diseases and Coloproctology Department of the Republic Clinical Hospital №1 of the Ministry of Health of the Republic of Uzbekistan. One hundred UC patients and 200 healthy individuals were examined by triple coproscopy. Additionally, 20, 25 and 22 UC patients with Blastocystis infection were treated with nitazoxanide (1.0 g/day), mesalazine (1.5-2 g/day) or a combination of nitazoxanide (1.0 g/day) and mesalazine (≥1.5-2 g/day) for 14 consecutive days, respectively. Parasitological, clinical and endoscopic examinations were conducted before therapy, immediately after and 6 and 12 weeks after therapy completion.

RESULTS

The overall prevalence of helminths in UC patients and control individuals was not significantly different: 14±3.4% and 8.5±1.9%, respectively (OR: 1.7524; 95% CI: 0.8258 to 3.7186; P=0.1). Giardia lamblia was the most prevalent parasite in both groups, but the difference compared to the control was insignificant (OR: 0.4565; 95% CI: 0.2020 to 1.0318; P=0.05). A significantly higher prevalence of Blastocystis sp., Chilomastix mesnili and Iodamoeba butschlii in UC patients compared to control individuals was found (P<0.0005): 65.0%, 14.0% and 22.0%, respectively. During all follow-up periods, the clinical response and clinical remission were not statistically different between the groups (P>0.05). Mucosal healing immediately and 6 weeks after therapy with a combination of nitazoxanide with mesalazine was significantly better than with a monotherapy of nitazoxanide, respectively (P<0.05). UC patients treated with a combination of nitazoxanide with mesalazine showed better mucosal healing than in patients treated with a monotherapy of mesalazine (P>0.05).

CONCLUSIONS

Diagnosis of Blastocystis sp. should be introduced in the complex examination of UC patients. Further clinical studies are necessary for assessment of the efficiency of anti-Blastocystis therapy in UC patients.

Comparative genotyping of Blastocystis infecting cattle and human in the south of Iran

BACKGROUND

Blastocystis is a unicellular protozoan and one of the most common parasites found in humans and many animals' intestinal tract. The present study aimed to compare the genotypes of Blastocystis infecting cattle and humans in the south of Iran.

METHODS

A total of 100 human stool samples and 75 cattle stool samples were microscopically examined for Blastocystis infection. DNA was extracted from thirty-eight microscopically positive samples (13 humans and 25 cattle). PCR was performed on positive samples targeting the Blastocystis-specific SSU rDNA gene. PCR products of eight humans and eleven cattle samples were sequenced and compared with available reference sequences in GenBank by BLAST queries. Genetic diversity was measured for Blastocystis subtypes in human and cattle, based on haplotype and nucleotide diversities.

RESULTS

The PCR detected Blastocystis in ten humans and twenty-four cattle samples. Blastocystis subtypes 1, 2, and 6 were found in humans whereas subtypes 5 and 10 were found in cattle. Subtype (ST) 2 was the most predominant subtypes in humans whereas, in cattle specimens, the ST5 was the most dominant subtype. Based on the Blastocystis sequences of SSU rDNA, 68 sites were polymorphic and 49 sites were parsimony informative, resulting in the identification of 15 haplotypes, 10 haplotypes in the cattle and 5 in humans. No haplotype was shared between cattle and human parasites.

CONCLUSION

Human-derived Blastocystis subtypes were different from cattle subtypes in southern Iran. Nevertheless, subtype 5 in cattle can be a risk factor for human infection.

Association between Blastocystis and body mass index in healthy subjects; a theoretical pilot study

BACKGROUND

Blastocystis is a prevalent protozoan of the gut lumen with worldwide distribution. Recent studies showed that this microorganism may alter both richness and diversity of the gut microbiota. In the current study we assessed the dietary intakes in two Blastocystis-positive and Blastocystis-negative groups to evaluate the impact of this protozoan on the body mass index (BMI) and the dietary intakes.

METHODS

In total, ninety-three participants consisted of 17 and 76 Blastocystis-positive and Blastocystis-negative subjects, respectively, were included in this study. Positive cases of Blastocystis had been confirmed by microscopy and culture medium. Moreover, a standard FFQ was filled out for all participants and independent t-test was employed to evaluate the correlation between Blastocystis and the dietary intakes.

RESULTS

From participants, 21/93 (22.58%) and 72/93 (77.42%) were male and female, respectively. The mean age ± SD among Blastocystis-positive and Blastocystis-negative individuals was 39.41 ± 14.60 years and 37.37 ± 13.16 years, respectively. Furthermore, Blastocystis-positive participants had lower weight (67.84 ± 12.29 kg) in comparison to Blastocystis-negative individuals (69.80 ± 14.99 kg). Indeed, BMI of Blastocystis-positive subjects was 25.46 ± 4.66 and lower than Blastocystis-negative subjects 25.89 ± 5.01; (P value = 0.745).

CONCLUSIONS

Our findings showed that BMI in Blastocystis-positive subjects was lower than Blastocystis-negative persons. Blastocystis probably affects the dietary intakes and energy metabolism.

Gut Microbiota beyond Bacteria-Mycobiome, Virome, Archaeome, and Eukaryotic Parasites in IBD

The human microbiota is a diverse microbial ecosystem associated with many beneficial physiological functions as well as numerous disease etiologies. Dominated by bacteria, the microbiota also includes commensal populations of fungi, viruses, archaea, and protists. Unlike bacterial microbiota, which was extensively studied in the past two decades, these non-bacterial microorganisms, their functional roles, and their interaction with one another or with host immune system have not been as widely explored. This review covers the recent findings on the non-bacterial communities of the human gastrointestinal microbiota and their involvement in health and disease, with particular focus on the pathophysiology of inflammatory bowel disease.

Prevalence and Molecular Subtyping of Blastocystis from Patients with Irritable Bowel Syndrome, Inflammatory Bowel Disease and Chronic Urticaria in Iran

BACKGROUND

Blastocystis is a parasite that colonizes in the human intestine. Its clinical features include diarrhea, abdominal pain, or urticarial and irritable bowel syndrome (IBS). Spite of being significant genetic diversity and numerous subtypes within the genus there were no associations between its subtypes and symptomatology.

MATERIALS AND METHODS

Aim of this project was subtyping of the protozoa in 184 Iranian people with history of IBS/IBD (n = 74) or chronic urticaria (n = 59) and individuals referred to general clinic (n = 51). Microscopic and molecular examinations used for identifying and subtyping of Blastocystis.

RESULTS

Overall, frequency of the parasite was 24.46% while, 29.41% of people who referred to general clinic, 20.27%, and 25.42% of IBS/IBD and urticarial cases were infected, respectively. Subtyping result showed that 28.89% of all people were infected with Blastocystis sp. while the prevalence of ST3, ST2 and ST1 were 22.22%, 22.22%, and 17.78%, respectively. Blastocystis sp., was identified in most IBS/IBD cases (46.7%) followed with ST2 and ST3 (13.3 and 13.3, respectively). Whereas, in chronic urticaria group ST2(33.3%) was the major subtype and most individuals in control group were infected with ST3 (33.3%). Pearson's Chi Square test showed no significant differences between the parasite or subtype prevalence and diseases (p > 0.05).

CONCLUSION

Given significant factors have effect on clinical signs including host or parasite genetics, microbiota, as well as environmental factors, it seems that further studies are needed to find out different markers of host susceptibility to diverse parasite genotypes in patients with irritable bowel syndrome or urticaria.

Development and evaluation of high-resolution melting curve analysis for rapid detection and subtyping of Blastocystis and comparison the results with sequencing

Blastocystis is a prevalent parasite that has a wide distribution. In order to design HRM real-time PCR, primers were selected from SSU rRNA gene to amplify specific fragment with different melting temperatures for each subtype of Blastocystis. Subsequently, HRM real-time PCR was performed and melting curve analysis was done by Rotor-Gene Q software. The results of HRM real-time PCR was then compared with sequence results of "barcoding region" of SSU rRNA gene of Blastocystis. To evaluate sensitivity of test, 10-fold serial dilutions of the parasite were prepared from ~ 10⁶ to 1 parasite per mL of stool sample and were investigated by HRM real-time PCR. In order to determine specificity of method, HRM real-time PCR was done for some microorganisms and Blastocystis-negative stool samples. In silico analysis showed that all seventeen subtypes of Blastocystis were distinguish. In vitro analysis revealed that the test discriminated subtypes with specific melting temperatures.

Molecular analysis of Blastocystis sp. and its subtypes from treated wastewater routinely used for irrigation of vegetable farmlands in Iran

Treated wastewater samples were collected, filtered using sterile 47-mm cellulose nitrate membrane and DNA extracted from the filtered materials. The presence of Blastocystis sp. was confirmed via polymerase chain reaction (PCR) targeting the SSU rRNA gene of Blastocystis sp. in 5/12 of samples. Based on the subtype analysis after sequencing, 2, 2 and 1 of ST2, ST6 and ST8 were detected among the isolates, respectively. Furthermore, both ST6s were allele 139, alleles 11 and 138 were identified in ST2 and the only ST8 was allele 95. The phylogenetic tree showed that one of ST2 was clustered together with those ST2 that were already reported from humans and animals. The presence of Blastocystis sp. in treated wastewater can indicate the potential role of this type of water for irrigation in the transmission of pathogenic microorganisms to downstream farmlands.

First record of Leptospira and Blastocystis infections in captive flying squirrels (Trogopterus xanthipes) from Enshi County, China

In traditional Chinese medicine, the feces of flying squirrels have long been used to promote blood circulation and relieve bodily stasis. However, the excrement of flying squirrels may harbor zoonotic agents that could be hazardous to public health. To understand the occurrence of bacterial and parasitic infections in this species, we investigated selected zoonotic pathogens including Leptospira and Blastocystis in the urine and feces of flying squirrels in China. Urine and fecal samples from flying squirrels were collected from a family-owned flying squirrel farm located in Enshi County, Hubei Province in China. Leptospira and Blastocystis DNA was extracted from the urine and feces of flying squirrels, and used as targets for PCR amplification, using different specific primers. PCR amplification and DNA sequencing showed that 4.4% (3/69) of flying squirrels were positive for Leptospira, while 30.4% (21/69) of the animals were positive for Blastocystis. Notably, 1.4% (1/69) of flying squirrels were found to be co-infected with Leptospira and Blastocystis. Sequence analyses allowed for the detection of 3 Blastocystis subtypes (ST1, ST3 and ST13), and mixed infections of Blastocystis subtype 1 and subtype 3 were found in 4.4% (3/69) of flying squirrels. Phylogenetic analysis of the 16S ribosomal RNA gene (rrs2), the flagellin B gene (flaB), and outer membrane lipoprotein lipL32 gene (LipL32) sequences indicated that the Leptospira species detected in the study was L. interrogans. We concluded that flying squirrels from central China were infected with Leptospira and Blastocystis, suggesting that these animals can be a source of infection for their owners, and using fresh excrement from this animal as traditional medicine could be risky to human health. To the best of our knowledge, this is the first report of Leptospira and Blastocystis infection in flying squirrels from Enshi County, China. Our findings provide new data on the epidemiology of these pathogens in this region.

Blastocystis subtype 1 (allele 4); Predominant subtype among tuberculosis patients in Iran

BACKGROUND

Blastocystis and tuberculosis are two public health issues that are frequently reported in regions with low level of hygiene. Therefore, the current study aimed to investigate Blastocystis subtype and allele distribution in TB patients.

METHODS

Totally, 161 stool samples were taken from TB patients who were undergoing anti-MTB treatment. Stool samples were concentrated using conventional formalin-ether technique and examined using Lugol's iodine staining under light microscopy. DNA extraction was carried out and discriminative fragment was amplified and sequenced. With comparison in GenBank database, relevant subtypes and alleles were characterized and phylogenetically analyzed using MEGA v.7 and Tamura 3-parameter model.

RESULTS

In total, from 161 stool samples, 19 samples were suspected to be Blastocystis-positive. The expected fragment was amplified in 13 (8.07%) of samples. Accordingly, 11/13 (84.62%) of Blastocystis cases settled in urban and 2/13 (15.38%) were villagers. Close-contact with animals was also seen among 7/13 (53.84%) of samples. Subtype 1 (7/13; 53.84%) was the most prevalent followed by subtype 2 (5/13; 38.46%) and subtype 3 (1/13, 7.69%). All ST1 were allele 4, while alleles 9, 11 and 12 were seen in ST2 and allele 34 was the only allele observed in ST3. All three subtypes were clearly separated, while there was no separation between sequences from TB and non-TB patients.

CONCLUSION

Blastocystis ST1 was the most prevalent subtype in TB patients and there was no difference between Blastocystis isolates from TB and non-TB human subjects.

Pinning down the role of common luminal intestinal parasitic protists in human health and disease - status and challenges

While some single-celled intestinal parasites are direct causes of diarrhoea and other types of intestinal pathology, the impact of other gut micro-eukaryotes on human health remains elusive. The fact that some common luminal intestinal parasitic protists (CLIPPs) have lately been found more often in healthy than in diseased individuals has fuelled the hypothesis that some parasites might in fact be protective against disease. To this end, the use of new DNA technologies has helped us investigate trans-kingdom relationships in the gut. However, research into these relationships is currently hampered by the limited data available on the genetic diversity within the CLIPPs genera, which results in limited efficacy of publicly available DNA sequence databases for taxonomic annotation of sequences belonging to the eukaryotic component of the gut microbiota. In this paper, I give a brief overview of the status on CLIPPs in human health and disease and challenges related to the mapping of intestinal eukaryotic diversity of the human gut.

Impacts of human development index and climate conditions on prevalence of Blastocystis: A systematic review and meta-analysis

Blastocystis is a prevalent eukaryotic microorganism that has been frequently reported from the stool samples of human and animals, all over the world. The prevalence of this parasite has close correlation with the climate and hygiene situation of studied populations. For the current study, English and Persian databases were searched for the following terms: "Blastocystis hominis", "Blastocystis sp.", "Intestinal Parasites", "Prevalence" and "Iran". In order to data analysis and assess the possibility of publication bias, STATA v11 and Begg's Funnel plot were employed respectively. From 605 searched cases, 86 publications met our criteria for the analysis. The pooled prevalence of Blastocystis was 9.1% (95%CI: 8.2%, 10.1%). The results represented that the prevalence of the parasite using molecular techniques or cultivation followed by molecular techniques (20.89%) was higher than only microscopical examination (8.96%). The prevalence rate of Blastocystis according to human development index was 7.6%, 7.2%, 11.9%, 13.4%, and 3.3% for ranks 1 to 5, respectively. This is the first study signifying the prevalence of Blastocystis regarding the human development index and climate conditions. The findings represented that although human development index, low levels of socioeconomic situations together with appropriate climate such as sufficient humidity and high temperature increase the chance of transmission of Blastocystis in a society.

Genetic diversity analysis of Blastocystis subtypes from both symptomatic and asymptomatic subjects using a barcoding region from the 18S rRNA gene

Blastocystis is the most prevalent protozoa found in human stool samples. This study aimed to evaluate genetic diversity among Blastocystis subtypes isolated from both symptomatic and asymptomatic subjects as well as the potential correlation between subtypes and symptoms. A total of 55 Blastocystis-positive isolates were included in this study. A barcoding region of the small subunit rDNA was amplified and genetically assessed using MEGA6 and DnaSP regarding the presence of symptoms. BLAST analyses revealed the presence of 5 different subtypes (ST1, ST2, ST3, ST6 and ST7) among the samples. ST3 was the most prevalent subtype (25/55, 45%) while only one ST7 isolate was detected. Moreover, alleles 4 and 86 for ST1; alleles 9, 11 and 12 for ST2; alleles 31, 34, 36, 37 and 52 for ST3; allele 122 for ST6 and allele 137 for ST7 were detected. No statistically significant association was found between gender and symptoms with certain subtypes. Analysis of the intra-subtype variability in both symptomatic and asymptomatic subjects revealed highest similarity among ST1 isolates while lowest similarity was seen among ST3 isolates. Neutrality indices, Tajima's D and Fu's Fs, were negative but only statistically significant for ST3. Furthermore, highest values of Hd, π and S were observed among ST1, ST2 and ST3 isolated from symptomatic patients indicating high level of diversity among isolates obtained from these subjects. In addition, inter-subtype analysis showed the highest similarity between ST1 and ST2 isolates and the lowest similarity between ST2 and ST7 isolates. This is the first study revealing the presence of both ST6 and ST7 isolates in human from Iran. Phylogenetic analysis did not suggest any significant correlation between clinical manifestations and certain subtypes although genetic analysis showed highest value of diversity and significant neutrality indices among ST3 isolates obtained from symptomatic patients.