Irritable bowel syndrome: is it associated with genotypes of Blastocystis hominis

Prevalence and subtyping of Blastocystis sp. in ruminants in Southwestern, Iran

Blastocystis is the most common gastrointestinal protozoan parasite of humans and many vertebrates. This study was carried out to investigate the prevalence and determination subtype (ST) of Blastocystis in domestic ruminants of Shahrekord County, southwestern Iran. In this descriptive cross-sectional study, 330 ruminant fecal samples (107 cows, 115 sheep, and 108 goats) were evaluated by parasitological methods (direct wet mount microscopic examination and formalin-ether concentration), Giemsa staining, In vitro xenic culture (The modified Dobell and Laidlaw culture method), polymerase chain reaction, and sequencing from 2018 to 2019, then data were analyzed using SPSS software version 21. The overall Blastocystis positive in ruminants was 14.2% and the frequency of Blastocystis sp. in cattle, sheep, and goats were 0.93%, 17.4%, and 24.1% respectively. Molecular diagnosis techniques revealed that ruminants were infected with four STs (genotypes) of Blastocystis including ST5(21.3%), ST7(2.1%), ST10(17.1%) and ST14(57.4%). Also, the STs identified in cows were ST10, and the observed STs in sheep were ST5 (40%), ST7 (3%), ST10 (5%), ST14 (45%), and one unknown subspecies. Goats were infected by ST5 (7.7%), ST10 (23.1%), and ST14 (69.2%). In this study, ST14 was identified as the most common subtype of Blastocystis sp. that was not common between humans and livestock, meanwhile, ST5 and ST7 are common between humans and animals accounted 21.3% and 2.1% of the positive cases, respectively, and reinforces the hypothesis that ruminants are reservoirs of blastocystosis in humans.

Unveiling Blastocystis epidemiology in Morocco: subtype diversity among clinical patients with and without gastrointestinal manifestations in the Meknes region

Blastocystis is an intestinal protist frequently identified in humans and other animals, though its clinical significance remains controversial. This study aimed to determine the prevalence and genetic diversity of Blastocystis in faecal samples from symptomatic (n = 55) and asymptomatic (n = 50) individuals seeking medical care in Meknes, Morocco. Detection of the protist was accomplished through coproparasitological examination and culture in Jones medium. Culture-positive samples were subjected to molecular analyses (PCR and Sanger sequencing) based on sequences of the small subunit ribosomal RNA gene. Epidemiological questionnaires on demographics and potential risk factors were collected from participating patients. The overall Blastocystis infection rate was 51.4% (54/105), with no differences between symptomatic (52.7%, 29/55) and asymptomatic (50.0%, 25/50) individuals. Sequence analyses identified three Blastocystis subtypes, with ST3 being the most prevalent (42.0%), followed by ST1 (34.0%), and ST2 (12.0%). Regarding intra-subtype diversity, allele 4 was found within ST1; alleles 11/12 and alleles 34/36 (alone or in combination) were identified within ST2 and ST3 respectively. Allele 34 in ST3 (40.8%) and allele 4 in ST1 (34.7%) were the most common genetic variants circulating in the surveyed clinical population. A statistically significant association between ST2 and the presence of flatulence was observed. This is the first study assessing the epidemiology and genetic diversity of Blastocystis sp. in the Meknes region, Morocco.

Irritable Bowel Syndrome Associated with Blastocystis hominis or Without Relationship to It? A Case-Control Study and Minireview

BACKGROUND

Blastocystis hominis (B. hominis) is a protozoan parasite that has a worldwide distribution. Some studies have suggested a link between B. hominis and the development of irritable bowel syndrome (IBS). The objective of this study was to determine the prevalence of B. hominis in patients with IBS compared to healthy individuals.

MATERIAL AND METHODS

A total of 65 stool samples from patients with IBS and 65 samples from healthy individuals in northern Iran were examined. The samples were tested using various methods including direct smear, formalin ether sedimentation and culture to detect the presence of B. hominis. Additionally, polymerase chain reaction (PCR) was performed on all culture-positive isolates to confirm the results and identify the genotype.

RESULTS

B. hominis was detected in 15.38% of IBS patients and 9.2% of the healthy group. The culture in RPMI1640 was found to be better than the formalin ether and direct smear methods. Positive samples were confirmed using the molecular method. No significant difference was observed in the order of B. hominis infection between the two groups.

CONCLUSIONS

The results of our study indicate that no significant difference was observed in the order of B. hominis infection between IBS patients and healthy groups. Therefore, further study is necessary to determine the potential pathogenic effects of this parasite and its role in causing IBS.

Detection and Molecular Characterization of Blastocystis Species in Polish Soldiers Stationed in the Republic of Kosovo

Blastocystis species (sp.) is one of the less well-understood water- and foodborne protozoa of medical and veterinary importance linked to different gastrointestinal disorders. Soldiers participating in military missions are particularly vulnerable to infection with this protozoa. The present study used molecular methods to detect, identify, and subtype (ST) Blastocystis sp. in Polish soldiers stationed in the Republic of Kosovo. Fecal samples were collected from 192 soldiers on arrival and after four months of stay. After DNA extraction, the barcoding region of the small subunit ribosomal RNA (SSU-rRNA) gene was amplified and sequenced. The DNA of Blastocystis sp. was detected in six (3.13%) and thirty (15.16%) samples in the first and second batch, respectively. Sequencing analysis revealed infections with ST 2, 3, 4, and 7. There was no statistical association between Blastocystis sp. infection and the parasite's ST or the age or rank of soldiers. The results indicate that the visit to a new environment and prolonged stay in the area of military operation in Kosovo resulted in a significant increase in both Blastocystis sp. infections and ST diversity among surveyed soldiers. This shows the need to undertake appropriate countermeasures to reduce Blastocystis infections in the military environment abroad.

Epidemiology of Blastocystis Infection: A Review of Data from Poland in Relation to Other Reports

Blastocystis is a common gut protist of humans and various animals worldwide, with a high level of genetic diversity. Neither its zoonotic potential and transmission routes nor its pathogenicity are fully known. This fact, and the fact that Blastocystis is the most abundant eukaryote in human faeces, raises the question of its relevance to public health. Here, we summarise (in relation to other reports) the results of studies on the prevalence and genotypic variation of Blastocystis, which were carried out in animals, humans, and in water environments in Poland. In humans, the prevalence ranged between 0.14 and 23.6%, in some animals reached 58.97%, and in water environments was 5.1%. Seven subtypes were identified in humans (ST1-ST4, ST6, ST7, and ST9), of which ST3 was the most common. Among animals (wild, livestock, and pet animals), eleven STs were identified, with differential host specificity. Humans and animals shared ST1, ST2, ST3, ST6, and ST7, while ST1 and ST3 were present in humans, animals, and water sources. These observations indicate the possibility of Blastocystis transmission between animals and humans. Further studies should be continued in search of the sources and transmission routes of Blastocystis in order to prevent the spread of infections among humans and animals.

Circulation and colonisation of Blastocystis subtypes in schoolchildren of various ethnicities in rural northern Thailand

Blastocystis is a protist of controversial pathogenicity inhabiting the gut of humans and other animals. Despite a century of intense study, understanding of the epidemiology of Blastocystis remains fragmentary. Here, we aimed to explore its prevalence, stability of colonisation and association with various factors in a rural elementary school in northern Thailand. One hundred and forty faecal samples were collected from 104 children at two time points (tp) 105 days apart. For tp2, samples were also obtained from 15 animals residing on campus and seven water locations. Prevalence in children was 67% at tp1 and 89% at tp2, 63% in chickens, 86% in pigs, and 57% in water. Ten STs were identified, two of which were shared between humans and animals, one between animals and water, and three between humans and water. Eighteen children (out of 36) carried the same ST over both time points, indicating stable colonisation. Presence of Blastocystis (or ST) was not associated with body mass index, ethnicity, birth delivery mode, or milk source as an infant. This study advances understanding of Blastocystis prevalence in an understudied age group, the role of the environment in transmission, and the ability of specific STs to stably colonise children.

Molecular characterization of Blastocystis subtypes in symptomatic patients from the southern region of Syria

Blastocystis sp. is an enteric protist found in humans and a wide range of animal hosts. Genetic variations were established among the 38 different subtypes detected so far, 14 of which are commonly found in human and animal hosts. The aim of the present study is to estimate the prevalence of the common Blastocystis subtypes and evaluate the possible correlation with several variables (gender, age, symptoms, domestic animals…), among patients from the southern region of Syria. Fecal samples were collected from individuals suffering from gastrointestinal complaints. Microscopic examination along with genotype analyses using seven pairs of subtype-specific primers was performed. Our results revealed the presence of Blastocystis sp. in 46 isolates out of the 60 samples microscopically studied (76.7%); single infection was detected in 24 isolates whereas co-infection with other protozoa was identified in 22 ones. Molecular detection targeting the SSU rRNA gene revealed a 100% positive presence of Blastocystis sp. in all the samples. Genotyping results detected the presence of five different subtypes (ST1-ST5) with varying proportions. However, ST1 was the dominant subtype observed (66.7%). Mixed subtype infections were found in 9 isolates (15%). Three samples remained undefined, nonetheless. Our statistical results showed no significant correlation between Blastocystis STs infection and the different studied variables. In conclusion, this study provides the first genetic characterization of Blastocystis subtypes prevalence in patients from the southern region of Syria. ST1 distribution was highly predominant. Further molecular studies are needed to estimate the prevalence of Blastocystis sp. infection in other regions in Syria and to understand the epidemiology and sources of transmission to humans.

Influence of Blastocystis hominis on the small intestine and lactase enzyme activity

Blastocystis hominis is a cosmopolitan protozoan that has been associated with several gastrointestinal disturbances involving lactose intolerance. However, the underlying pathogenic factors remain indistinct. 20 Swiss albino mice were utilized and assembled into four groups, each of five mice: group-I: received neither infection nor lactose (healthy control), group-II: received a single dose of 10,000 cysts of Blastocystis and lactose diets in a dose of 12.5 g/day/mouse for 7 consecutive days starting from day 14 p.i., group-III: non-infected mice with oral doses of lactose (12.5 g/day/mouse) for 7 consecutive days (positive control), group-IV: infected mice on lactose free diet (negative control). We investigated the histopathological changes using H&E stain.s Also, lactase enzyme activity was measured using spectrophotometry and the production of TNF-α and apoptotic events were explored via immunohistochemistry and compared in the small intestine of all groups. The active inflammatory changes in the infected animals were moderate in the form of loss of villous architecture, increased ILC (P-value > 0.001) besides scattered forms of the parasite as compared to non-infected mice. There was a reduction in lactase enzyme activity p.i. The TNF-α levels were induced p.i. as compared to non-infected mice (P-value > 0.001). The expression of Bax protein was upgraded, while Bcl-2 expression decreased significantly with a reverse in Bax/Bcl2 ratio in infected animals. Blastocystis infection appears to humble lactase enzyme activity via the induction of apoptosis in the epithelial cells of the small intestinal brush border in a TNF-α associative pathway.

Pre-and post-treatment evaluation of intestinal inflammation in Giardia and Blastocystis infected children: a community-based study

Giardia intestinalis and Blastocystis hominis cause frequent infections in children in developing countries. However, the role of intestinal inflammation in their pathogenesis is still poorly understood. Faecal calprotectin (FC) level is used as an indicator of intestinal inflammation and neutrophil migration in the intestinal tract. The present study aimed to evaluate intestinal inflammation by measuring FC level among children infected with either G. intestinalis or B. hominis before and after treatment. Stool samples were collected from 282 children inhabiting a rural area in Egypt and examined microscopically for intestinal parasites. FC level was estimated in a group of children infected with G. intestinalis (n = 12) or B. hominis (n = 12) before and 3 weeks after receiving nitazoxanide (200 mg twice daily for 3 days) and compared to a control group (n = 18) of parasite-free children. Cases of mixed infection were excluded. Nitazoxanide cure rate was 83% in both infections with a remarkable reduction of infection intensity in uncured children. The difference in FC levels between infected children and controls was not statistically significant. Also, the difference between the pre- and post-treatment estimations was not statistically significant. Elevated levels were observed before treatment in three children (two infected with G. intestinalis and one with B. hominis) who displayed normal post-treatment levels. Although G. intestinalis and B. hominis infections appear to cause no remarkable intestinal inflammation, they may induce abnormally elevated FC levels in a subset of children.

The neglected role of Blastocystis sp. and Giardia lamblia in development of irritable bowel syndrome: A systematic review and meta-analysis

The possible role of Blastocystis sp. and Giardia lamblia infections in the development of irritable bowel syndrome (IBS) has long been controversial. In this study, we conducted a systematic review and meta-analysis to investigate whether these protozoan infections are associated with IBS development. We systematically searched international databases for all studies that reported these protozoa in IBS patients published by May 10, 2021. Studies were included in the review if they were observational studies with confirmed patients with IBS (in case-control and cross-sectional studies) or parasitic infections (cohort studies) with an appropriate control group. Pooled odds ratios (ORs) and 95% confidence intervals were estimated using a random-effects meta-analysis model for included studies. A total of 32 papers (42 datasets), including 29 papers (31 datasets) for Blastocystis sp./IBS and 11 papers (11 datasets) for G. lamblia/IBS met the eligibility criteria. Our results indicated that the individuals with Blastocystis sp. infection were significantly at a higher risk of IBS development (OR, 1.78; 95%CI, 1.29-2.44). Moreover, cohort studies indicated a significant positive association between G. lamblia infection and IBS risk (OR, 5.47; 95%CI, 4.23-7.08); while an increasing but no statistically significant risk was observed in case-control studies (OR, 1.19; 95%CI, 0.75-1.87). Our findings suggested that Blastocystis sp. and G. lamblia infections are associated with the increased risk of developing IBS. Despite these results, further studies are needed to determine the effect of these protozoa on IBS development.

Epidemiology and subtype distribution of Blastocystis in humans: A review

Blastocystis is a commonly encountered gastrointestinal protozoan in humans and animals with uncertain pathogenicity. Despite its potential public health impact, epidemiological data regarding the prevalence and molecular subtype (ST) distribution of Blastocystis have been rarely reported. Among Blastocystis STs, ST1-ST4 are common in humans, including healthy and immunodeficient populations. According to the Chi-squared (χ²) association based on the data compiled for this cross-sectional study, the presence of ST1 is associated with asymptomatic infection, whereas the presence of ST4 is associated with symptomatic infection. However, cross-sectional studies cannot clarify the potential pathogenicity of Blastocystis, unlike in vivo and in vitro studies. Poor hygiene, poor sanitation and zoonotic transmission are possible factors associated with high Blastocystis prevalence, although this protozoan may be part of the normal healthy human gastrointestinal microbiota. This review covers the prevalence, STs and distribution of Blastocystis infection in humans. Thus, future epidemiological and subtyping studies could reveal new STs in humans as well as possible associations of STs with disease, drug resistance and related mechanisms such as protease activity. These associations with proper ST identification may facilitate the control of potential threats to host health, including the direct pathogenic effects of Blastocystis or alterations of the gastrointestinal microbiome.

Blastocystis Colonization Alters the Gut Microbiome and, in Some Cases, Promotes Faster Recovery From Induced Colitis

Protists are a normal component of mammalian intestinal ecosystems that live alongside, and interact with, bacterial microbiota. Blastocystis, one of the most common intestinal eukaryotes, is reported as a pathogen that causes inflammation and disease, though health consequences likely vary depending on host health, the gut ecosystem, and genetic diversity. Accumulating evidence suggests that Blastocystis is by and large commensal. Blastocystis is more common in healthy individuals than those with immune mediated diseases such as Inflammatory Bowel Diseases (IBD). Blastocystis presence is also associated with altered composition and higher richness of the bacterial gut microbiota. It is not clear whether Blastocystis directly promotes a healthy gut and microbiome or is more likely to colonize and persist in a healthy gut environment. We test this hypothesis by measuring the effect of Blastocystis ST3 colonization on the health and microbiota in a rat experimental model of intestinal inflammation using the haptenizing agent dinitrobenzene sulfonic acid (DNBS). We experimentally colonized rats with Blastocystis ST3 obtained from a healthy, asymptomatic human donor and then induced colitis after 3 weeks (short term exposure experiment) or after 13 weeks (long term exposure experiment) and compared these colonized rats to a colitis-only control group. Across experiments Blastocystis ST3 colonization alters microbiome composition, but not richness, and induces only mild gut inflammation but no clinical symptoms. Our results showed no effect of short-term exposure to Blastocystis ST3 on gut inflammation following colitis induction. In contrast, long-term Blastocystis exposure appears to promote a faster recovery from colitis. There was a significant reduction in inflammatory markers, pathology 2 days after colitis induction in the colonized group, and clinical scores also improved in this group. Blastocystis colonization resulted in a significant reduction in tumor necrosis factor alpha (TNFα) and IL-1β relative gene expression, while expression of IFNγ and IL17re/17C were elevated. We obtained similar results in a previous pilot study. We further found that bacterial richness rebounded in rats colonized by Blastocystis ST3. These results suggest that Blastocystis sp. may alter the gut ecosystem in a protective manner and promote faster recovery from disturbance.

Prevalence and Subtype Analysis of Blastocystis hominis Isolated from Patients in the Northeast of Iran

Blastocystis hominis is the most common intestinal parasite found in humans and many other hosts. Pathogenicity of Blastocystis spp. remains controversial, and it has been suggested that it may be associated with specific subtypes of the organism. This study identified the B. hominis subtypes and their prevalence rates in the northeast of Iran. A total of 1878 samples were collected from the northeast of Iran from January to December 2017. The patients' demographic details were recorded. Samples were examined by a wet mount, and genomic DNA was extracted from positive samples. Also, PCR was done on the positive samples, and sequencing and phylogenetic analysis were subsequently performed. From 1878 collected stool samples, 152 (8.1%) Blastocystis samples were detected by the microscopic method. Of the 152 samples, Blastocystis spp. were found in 53.6% of the men and 28.9% of the women who showed clinical gastrointestinal symptoms, and a significant relationship was observed between gender and clinical symptoms (P = 0.002). A meaningful relationship was found between the season and infection with this parasite (P value = 0.003). The results of the sequencing of 22 PCR products showed the dominance of ST3, which was isolated from 10 (45.45%) patients, while ST1, ST2, and ST7 were found in 4 (18.19%), 7 (31.81%), and 1 (4.55%) patients, respectively. In this study, ST7 had a low prevalence in the northeast of Iran, and similar to previous studies, ST3 was the dominant subtype.

Worldwide prevalence of emerging parasite Blastocystis in immunocompromised patients: A systematic review and meta-analysis

BACKGROUND

Blastocystis is one of the most common pathogens of the human intestine, caused by an emerging parasite, which can lead to severe symptoms and even death in immunocompromised patients. We aimed to determine the global prevalence of Blastocystosis infection in people with immunodeficiency. A systematic literature search was conducted on Web of Science, Scopus, Google scholar, Science Direct and MEDLINE databases to select all observational studies reporting the prevalence of Blastocystosis infection in Worldwide, based on different diagnostic methods in immunocompromised patients of any age and published from inception to February 2019. Pooled estimates and 95% confidence intervals (95% CIs) were calculated using random effects models and in addition, the I² statistic was calculated. The geographic distribution of studies was evaluated and the diagnosis of Blastocystis was compared by various techniques. Electronic databases were reviewed for Blastocystosis infection in HIV/AIDS, cancer and other immunocompromised patients, and meta-analyses were conducted to calculate the overall estimated prevalence. Total68 eligible studies were included. The estimated pooled prevalence rate of Blastocystosis infection in immunocompromised patients was overall 10% (95% CI, 7-13%; I² 96.04%) (P < 0.001), of whom 21% [18-25] were in Australia, 12% [4-24] in America, 11% [6-17] in Europe and 10% [5-15], 7% [3-13] in Asia and Africa, respectively. It was calculated that the estimated pooled prevalence rate of Blastocystosis infection in immunocompromised patients was overall 10% and the prevalence estimates ranged from 0.44 to 72.39. Also, overall the prevalence of parasites co-infection in immunocompromised patients was detected as 0.024%. Our finding showed that immunocompromised people show a high prevalence of Blastocystosis infection compared to the control population. Adequate information on the prevalence rate is still missing from many countries. However, current information underscore that Blastocystis should not be neglected.

Cockroach as a Vector of Blastocystis sp. is Risk for Golden Monkeys in Zoo

Blastocystis sp. is a kind of protozoa living in the intestinal tract of human and animals, which will cause intestinal diseases such as diarrhea, abdominal distension and vomiting. This paper was aimed to understand the infection of Blastocystis sp. In golden monkeys and the transmission path in North China. Thirty-seven feces samples from golden monkeys and 116 cockroach samples from Shijiazhuang Zoo were collected from July to October 2019 for PCR analysis of Blastocystis sp. Genetic diversity analysis was further conducted on the samples with positive PCR results. The results showed that the infection rate was 48.7% (18/37) in golden monkeys and 82.8% (96/116) in cockroaches, respectively. The genetic evolution analysis based on small subunit ribosomal RNA demonstrated that three subtypes (ST) of Blastocystis sp. including ST1, ST2, and ST3 existed in the intestinal tract of golden monkeys, while only ST2 was detected in the intestinal tract of cockroaches. This paper may provide supports for the quarantine and control of Blastocystis sp. for the zoo in Northern China.

Molecular Epidemiology and Risk Factors of Blastocystis sp. Infections Among General Populations in Yunnan Province, Southwestern China

BACKGROUND

Blastocystis is a common enteric parasite of controversial pathogenic roles in human diseases. Although the prevalence of Blastocystis infections has been investigated in a diverse range of populations, there is little knowledge on the molecular epidemiology and risk factors of Blastocystis infections among general populations in southeastern China.

MATERIALS AND METHODS

A total of 507 individuals were randomly selected in Yunnan province, China from July 2016 to March 2017. Stool specimens were sampled for detection of Blastocystis sp. using PCR assay, and the risk factors of Blastocystis infections were identified. Blastocystis isolates were subtyped, and the associations of Blastocystis infections and subtypes with clinical manifestations were examined.

RESULTS

The overall detection rate of Blastocystis sp. was 9.47% (95% CI: 7.13-12.44%). Toilet type (OR = 3.248, 95% CI: 1.245-8.473), anemia (OR = 2.601, 95% CI: 1.245-8.473) and type of daily drinking water (OR = 3.11, 95% CI: 1.557-6.213) were identified as risk factors of Blastocystis infections; however, Blastocystis infections showed no associations with clinical symptoms. Four subtypes (ST1 to ST4) were characterized in Blastocystis isolates, in which ST3 was predominant (4.73%, 95% CI: 3.2-6.94%), followed by ST1 (3.16%, 95% CI: 1.95-5.07%), ST4 (1.38%, 95% CI: 0.07-2.82%) and ST2 (0.2%, 95% CI: 0-1.11%). In addition, ST1 subtype infection was found to correlate with anemia (OR = 4.66, 95% CI: 1.631-14.314).

CONCLUSIONS

There is a high prevalence of Blastocystis infections among general populations in Yunnan province, southwestern China, and toilet type, anemia and type of daily drinking water are risk factors of Blastocystis infections. ST3 is the dominant subtype of Blastocystis sp. characterized, and ST1 correlates with anemia. Improving hygiene conditions, developing healthy lifestyles and intensifying health education programs are strongly recommended to reduce the prevalence and transmission potential of Blastocystis infections.

Distribution and molecular analysis of Blastocystis subtypes from gastrointestinal symptomatic and asymptomatic patients in Iran

INTRODUCTION

Blastocystis is a common intestinal parasite of human and animal hosts. The parasite has 17 subtypes, and among those at least nine subtypes (ST1-ST9) are found in human hosts.

OBJECTIVE

The aim of the present study was to investigate the presence of different subtypes of Blastocystis spp. among the patients referred to Velayat hospital of Qazvin province, Iran.

METHODS

Overall, 864 stool samples were examined by using formalin-ethyl acetate concentration method and Trichrome staining. All specimens were cultured in clotted fetal bovine medium. Later, DNA extraction and PCR amplification of 18S ribosomal RNA gene region was conducted and phylogenetic tree constructed.

RESULTS

The results revealed 7.9% (68/864) of the study population were infected with Blastocystis. Intestinal symptoms were observed in 61% (36/59) of individuals positive for Blastocystis, with abdominal pain in 58% (21/36) of cases which was more frequent than other intestinal signs. No significant relationship was observed among the study variables. By molecular and phylogenetic analysis, three subtypes ST1 (45%), ST2 (30%) and ST3 (23%) of parasite were identified.

CONCLUSION

This study showed ST1 subtype was the predominant subtype among the positive specimens, meanwhile the highest haplotype and nucleotide diversity were clarified in ST3 subtype.

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.

Anaemia in asymptomatic parasite carriers living in urban, rural and peri-urban settings of Gabon

Background

This cross-sectional study was carried out in different settlements of Gabon to determine the influence of single or multiple parasite carriage on haemoglobin (Hb) levels.

Methods

Between April 2015 and June 2016, healthy volunteers from urban, peri-urban and rural areas were screened for malaria, blood filariasis and intestinal parasitic infections using microscopic methods. Hb concentration was measured with a Hemocue analyser. The association between parasite carriage and anaemia was assessed.

Results

Among the 775 volunteers examined, 319 (41.2%) were from rural villages and 76.0% were adults. Filariasis, intestinal parasitic infections, Plasmodium falciparum and polyparasitism were detected in 15.6, 14.6, 9.5 and 6.8% of participants, respectively. Anaemia prevalence was 72.6%, with rates of mild, moderate and severe anaemia being 30.9, 61.1 and 8.0%, respectively. The median Hb level was lowest in the presence of hookworms (7.1 g/dl [interquartile range {IQR} 6.8–7.5]), Schistosoma intercalatum (6.9 g/dl), Trichuris trichiura (10.1 g/dl [IQR 8.9–11.5]) and Plasmodium falciparum (10.0 g/dl [IQR 9.1–11.2]) compared with filariaemia (12.1 g/dl [IQR 10.5–13.2]) (p=0.03). Moderate to severe anaemia predominated among those single-infected with P. falciparum (69.5%) or co-infected with intestinal parasitic infections and P. falciparum (76.2%), while it was found in only 23.2% of individuals with filariasis. All participants with soil-transmitted helminths and more than half with a Blastocystis sp. (68.8%) infection had moderate anaemia.

Conclusions

The prevalence of anaemia is high. Asymptomatic parasite carriage is associated with anaemia in this surveyed population in Gabon.

Molecular prevalence and subtypes of Blastocystis sp. in primates in northern China

Blastocystis sp. is a common enteric protist that colonizes humans and a wide range of animals. Although some studies have reported incidences of Blastocystis sp. in humans and animals in China, there are limited data available concerning the prevalence among people and non-human primates. The aims of the present study were to determine the prevalence, subtype distribution and genetic characteristics of Blastocystis sp. in primates, and to investigate the potential for zoonotic transmission between human and non-human primates. A total of 185 faecal samples from non-human primates and 1,118 samples from human volunteers were collected in Hebei province. The overall prevalence of Blastocystis sp. in non-human primates was 32.97% (61/185) based on polymerase chain reaction (PCR) amplification of the barcode region of the SSU rRNA gene. Rates of prevalence were highest among Cercopithecus neglectus (100%, 5/5) and were absent in Cebus apella and Colobus guereza. The prevalence of Blastocystis sp. in humans was 34.88% (390/1,118), and the highest rates were 41.24% in children three years of age. There was a higher detection rate in humans with diarrhoea (53.68%). Five potentially zoonotic subtypes (ST1, ST2, ST3, ST5 and ST9) were identified; among these, ST1 and ST2 were more prevalent than others in non-human primates. Similarly, two subtypes (ST2 and ST5) were detected in humans and ST2 was also the most prevalent. To the best of our knowledge, this is the first report of the prevalence and subtype composition of Blastocystis sp. in Hebei province, and the first study concerning the relationship of Blastocystis sp. among primates in China. The findings of the study will improve our understanding of the genetic diversity and public health potential of Blastocystis sp. enteric infections in addition to providing a profile of subtype characteristics of Blastocystis sp. in primates of northern China.

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

OBJECTIVES

The current study aimed to evaluate the prevalence of parasitic infections and their possible association with irritable bowel syndrome (IBS), through a case-control study. Stool samples were collected from patients with IBS and healthy subjects and were examined microscopically to detect intestinal parasites.

RESULTS

A total of 200 subjects were enrolled in the study including 100 patients with IBS and 100 healthy controls. The patients were selected based on the Rome III criteria. Of the 100 patients with IBS, 65 (65%) were female and 35 (35%) were male, with a mean age of 42.57 (± 4.07) years. Of these, 30 (30%) were infected with at least one intestinal parasite; the most common ones were Blastocystis hominis and Giardia lamblia. Of the control cases, 64 (64%) were female and 36 (36%) were male, with a mean age of 41.82 (± 11.75) years. Of these, 16 (16%) were infected with at least one intestinal parasite; the most common were B. hominis and Endolimax. There was a significant difference between the rate of parasitic infections between the patients with IBS and the control in particular, B. hominis and G. lamblia. The findings of the study support a possible link between parasitic infections and IBS.

Australian consensus statements for the regulation, production and use of faecal microbiota transplantation in clinical practice

OBJECTIVE

Faecal microbiota transplantation (FMT) has proved to be an extremely effective treatment for recurrent Clostridioides difficile infection, and there is interest in its potential application in other gastrointestinal and systemic diseases. However, the recent death and episode of septicaemia following FMT highlights the need for further appraisal and guidelines on donor evaluation, production standards, treatment facilities and acceptable clinical indications.

DESIGN

For these consensus statements, a 24-member multidisciplinary working group voted online and then convened in-person, using a modified Delphi approach to formulate and refine a series of recommendations based on best evidence and expert opinion. Invitations to participate were directed to Australian experts, with an international delegate assisting the development. The following issues regarding the use of FMT in clinical practice were addressed: donor selection and screening, clinical indications, requirements of FMT centres and future directions. Evidence was rated using the GRADE (Grading of Recommendations Assessment, Development and Evaluation) system.

RESULTS

Consensus was reached on 27 statements to provide guidance on best practice in FMT. These include: (1) minimum standards for donor screening with recommended clinical selection criteria, blood and stool testing; (2) accepted routes of administration; (3) clinical indications; (4) minimum standards for FMT production and requirements for treatment facilities acknowledging distinction between single-site centres (eg, hospital-based) and stool banks; and (5) recommendations on future research and product development.

CONCLUSIONS

These FMT consensus statements provide comprehensive recommendations around the production and use of FMT in clinical practice with relevance to clinicians, researchers and policy makers.

Prevalence and Subtypes of Blastocystis in Alpacas, Vicugna pacos in Shanxi Province, China

Blastocystis, an enteric protist, has been reported to be an important cause of protozoal gastrointestinal manifestations in humans and animals worldwide. Animals harboring certain Blastocystis subtypes (STs) may serve as a potential source of human infection. However, information about the prevalence and genetic diversity of Blastocystis in alpacas is limited. In the present study, a total of 366 fecal samples from alpacas in Shanxi Province, northern China, were examined for Blastocystis by PCR amplification of the small subunit rRNA gene, followed by sequencing and phylogenetic analysis. The prevalence of Blastocystis in alpacas was 23.8%, and gender difference in the prevalence of Blastocystiswas observed. The most predominant Blastocystis ST was ST10, followed by ST14 and ST5. The detection of ST5, a potentially zoonotic genotype, indicates that alpacas harboring ST5 could be a potential source of human infection with Blastocystis. These data provide new insight into the prevalence and genetic diversity of Blastocystis in alpacas.

In vitro toxicity evaluation of short cationic antimicrobial peptide (CM11) on Blastocystis sp

Blastocystis infection accounts for one of the causes of gastrointestinal problems with the prevalence rate of 3-100% worldwide. There is a wide range of drugs examined for the treatment of infected patients, among them metronidazole (MTZ) has been introduced as one of the efficient drugs. Besides to the suitable clinical effects, the administration of MTZ has some reported side-effects which emphasize on the identification of putative alternates. To this end, we aimed to evaluate the cytotoxicity effect of a newly-introduced synthetic antimicrobial peptide (AMP) named CM11 on in vitro cultured Blastocystis. Our results exhibited that CM11 treatment affected the viability of parasites in two cultural conditions including culturing alone and in co-culture with the Caco-2 cell line. The time- and dose-dependent effect of CM11 was consistent with the effect of MTZ which was used as control positive. The highest toxicity effect of CM11 was observed at the concentration of 24 μg/ml, leading to 28.7% and 25% viable parasites after 24 h and 48 h incubation times, respectively. Interestingly, the disruption of the Blastocystis cell membrane could be observed in the treated parasites. Therefore, CM11 can be suggested as a potential treatment for Blastocystis-infected patients after further in vitro and in vivo assessments.

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.

Prevalence of Intestinal Parasitic Infections among the Bulgarian Population Over a Three Year Period (2015 - 2017)

The aim of the present study is to perform a retrospective analysis of the prevalence of intestinal parasitic infections among the Bulgarian population over the period 2015 - 2017. The study involved all Bulgarians and foreign nationals residing in the country who had been tested for intestinal protozoa and helminths. A total of 23,785 infections have been revealed, of which 17,712 (74.47 %) were helminth and 6,073 (25.53 %) protozoan invasions. Enterobiasis was found to be the most prevalent among patients infected with intestinal helminths (81.75 %), while giardiasis (62.05 %) was the most common among those diagnosed with protozoan infections. In spite of improved living conditions and increasing public health awareness, parasitic diseases in general, and intestinal parasitic infections in particular, still represent a significant part of the overall morbidity in Bulgaria, thus posing a major issue for the public health care system.

Giardia intestinalis and Fructose Malabsorption: A Frequent Association

Nowadays, scientific studies are emerging on the possible etiological role of intestinal parasites in functional digestive disorders. Our study was carried out with healthy individuals (control group; n = 82) and symptomatic patients with lactose or fructose malabsorption, including positive (malabsorbers; n = 213) and negative (absorbers; n = 56) breath test, being analyzed for the presence of intestinal parasites. A high parasitic prevalence was observed in malabsorbers (41.8%), exclusively due to single-cell eukaryotes but not helminths. Giardia intestinalis was the predominant parasite in cases of abnormal absorption (26.5%), significantly associated with fructose malabsorption and doubling the probability of developing this pathology. Within controls, Blastocystis sp. (13.4%) was almost the only parasite, being the second among patients (12.6%), and Cryptosporidium parvum, the last species of clinical relevance, was detected exclusively in two malabsorbers (0.9%). The consumption of ecological food and professions with direct contact with humans arose as risk factors of parasitism. A diagnosis of carbohydrate malabsorption in adulthood is the starting point, making the search for the primary cause necessary. Accurate parasitological diagnosis should be considered another tool in the clinical routine for patients with recurrent symptoms, since their condition may be reversible with adequate therapeutic intervention.

Molecular epidemiology of Blastocystis spp. in children referred to Qods hospital in northwest of Iran

Blastocystis sp. is a polymorphic intestinal parasite in humans and animals. The parasite has a worldwide distribution, especially in developing countries with poor sanitation, exposure to animals, and improper disposal systems. The aim of this study was to identify the subtypes of Blastocystis sp. among children of Qazvin, northwest Iran. Totally, 864 stool samples were collected from the children referred to Qods hospital in Qazvin, Iran. Fecal specimens were investigated by formalin-ethyl acetate concentration method and trichrome staining as well as cultivation of all samples in clotted fetal bovine medium. DNA extraction of culture-positive specimens and PCR amplification of 18S ribosomal RNA gene region was performed. The sequences detected were compared with reference genes in the GenBank, and the sequences further deposited in the GenBank database. Data analysis was performed by Chi square test while a p value of < 0.05 was considered as significant. Of 864 isolates, 4.1% (36/864) were positive for Blastocystis sp. with infection rate insignificantly higher among the females than males. The highest infection rate was estimated at 6.8% in 6-9 years old age group with abdominal pain as the most common (33%) gastrointestinal sign. No statistically significant difference was found between the variables and Blastocystis infection. Molecular analysis clarified the presence of three subtypes of Blastocystis including ST1 (56%), ST2 (28%), and ST3 (16%) of among specimens with ST1 as the predominant subtype. A significant association between intestinal signs and the subtypes was not found. Considering ST1 as the predominant subtype, it seems that zoonotic transmission is a main route of human infections with Blastocystis sp. in the area studied.

Blastocystis subtypes isolated from travelers and non-travelers from the north of Poland - A single center study

Blastocystis is a common, enteric protist of humans and animals with a worldwide distribution and unclear clinical relevance. Nine out of 17 genetically diverse subtypes occur in humans. We analysed the distribution of Blastocystis subtypes and the intensity of invasion in relation to the gastrointestinal tract disorders and travels to different continents. 122 Blastocystis stool cultures were subtyped via polymerase chain reaction (PCR) with seven pairs of subtype-specific, sequence-tagged-site (STS) primers. Five subtypes of Blastocystis were detected: ST3 (59%), ST2 (19.7%), ST1 (13.1%), ST6 (3.3%), ST7 (3.3%), and two mixed infections with ST1/ST3 (1.6%). ST1 was detected exclusively in travelers to hot climate zones and ST2 was found more frequently in people visiting other continents compared to those who never left Poland. We found no correlation between gastrointestinal tract disorders, Blastocystis STs, and parasite load. There was no age predisposition to the Blastocystis infection. We established the distribution of Blastocystis STs among Poles traveling to different continents and never leaving Poland. Our study sheds more light on the problem of importing Blastocystis infection. It shows that certain subtypes detected in Europe can be imported due to travel or migration. Collecting data on the travel history of the surveyed persons is necessary to clarify this matter.

Blastocystis ST-1 is associated with Irritable Bowel Syndrome-diarrhoea (IBS-D) in Indonesian adolescences

Objective

IBS is a functional gastrointestinal disorder and commonly presents in children and adolescences, presented as diarrhoea, constipation or mixed type. Blastocystis is a common intestinal protozoa found worldwide, which pathogenicity is still controversial. This study aimed to identify the risk factors of IBS, the association between IBS types with Blastocystis subtypes and analyse Blastocystis pathogenicity.

Design

A comparative cross-sectional study was conducted among senior high school students. Rome III Criteria for IBS diagnosis, questionnaires on the risk factors of IBS and types of IBS were recorded. Students were further selected and classified into IBS and non-IBS groups to analyse the association between IBS, IBS types with Blastocystis infection and its subtypes. Direct microscopic stool examination to identify single Blastocystis infection was performed, followed by culture in Jones' medium, PCR, sequencing of 18S rRNA and phylogenetic analysis to determine Blastocystis subtype. Data was analysed using SPSS v22.0 and P value <0.05 was considered statistically significant (95% confidence intervals).

Results

IBS was found in 30.2% of 454 students, consisted of 33.3% IBS Diarrhoea, 27.7% IBS Mixed, 27.7% IBS Unclassified and 11.1% IBS Constipation. Major risk factors to IBS consisted of family history of recurrent abdominal pain, abuse, bullying and female gender in respective order (OR 3.6–2.1). Blastocystis ST-1 was significantly associated to IBS-D with 2.9 times risk factor.

Conclusions

Blastocystis infection is a risk factor to develop IBS-D type in adolescence; Blastocystis ST-1 can be regarded as a pathogenic subtype.

Can the pyruvate: ferredoxin oxidoreductase (PFOR) gene be used as an additional marker to discriminate among Blastocystis strains or subtypes?

BACKGROUND

Blastocystis spp. are the most prevalent intestinal eukaryotes identified in humans, with at least 17 genetic subtypes (ST) based on genes coding for the small-subunit ribosomal RNA (18S). It has been argued that the 18S gene should not be the marker of choice to discriminate between STs of these strains because this marker exhibits high intra-genomic polymorphism. By contrast, pyruvate:ferredoxin oxidoreductase (PFOR) is a relevant enzyme involved in the core energy metabolism of many anaerobic microorganisms such as Blastocystis, which, in other protozoa, shows more polymorphisms than the 18S gene and thus may offer finer discrimination when trying to identify Blastocystis ST. Therefore, the objective of the present study was to assess the suitability of the PFOR gene as an additional marker to discriminate among Blastocystis strains or subtypes from symptomatic carrier children.

METHODS

Faecal samples from 192 children with gastrointestinal symptoms from the State of Mexico were submitted for coprological study. Twenty-one of these samples were positive only for Blastocystis spp.; these samples were analysed by PCR sequencing of regions of the 18S and PFOR genes. The amplicons were purified and sequenced; afterwards, both markers were assessed for genetic diversity.

RESULTS

The 18S analysis showed the following frequencies of Blastocystis subtypes: ST3 = 43%; ST1 = 38%; ST2 = 14%; and ST7 = 5%. Additionally, using subtype-specific primer sets, two samples showed mixed Blastocystis ST1 and ST2 infection. For PFOR, Bayesian inference revealed the presence of three clades (I-III); two of them grouped different ST samples, and one grouped six samples of ST3 (III). Nucleotide diversity (π) and haplotype polymorphism (θ) for the 18S analysis were similar for ST1 and ST2 (π = ~0.025 and θ = ~0.036); remarkably, ST3 showed almost 10-fold lower values. For PFOR, a similar trend was found: clade I and II had π = ~0.05 and θ = ~0.05, whereas for clade III, the values were almost 6-fold lower.

CONCLUSIONS

Although the fragment of the PFOR gene analysed in the present study did not allow discrimination between Blastocystis STs, this marker grouped the samples in three clades with strengthened support, suggesting that PFOR may be under different selective pressures and evolutionary histories than the 18S gene. Interestingly, the ST3 sequences showed lower variability with probable purifying selection in both markers, meaning that evolutionary forces drive differential processes among Blastocystis STs.

Blastocystis subtypes and their association with Irritable Bowel Syndrome

Blastocystis spp. is a common intestinal protozoan that affects humans and animals. The role of this parasite as a pathogen is still controversial and it is suspected to be linked to Irritable Bowel Syndrome (IBS), a functional bowel disorder characterized by chronic or recurrent abdominal pain associated with altered intestinal habits. A broad search in electronic databases, libraries, portals of journals, etc. for reports on the association between the parasite and IBS without language restriction was performed. The selection was not restricted by date, but articles published in the last seven years were given preference. We investigated the evidence regarding Blastocystis and IBS coexistence as well as the implications of the parasite in pathogenesis and clinical manifestations. Only standardized parasitological tools, supplemented by epidemiological analysis, will be able to clarify whether parasite carriage could be connected to IBS and its status as a human pathogen. Although a variation in pathogenicity and virulence between subtypes has been confirmed, Blastocystis can only be considered an indicator of dysbiosis. Accurate diagnoses of this parasitic eukaryote, specifically at genotypic and phenotypic levels, as well as the complete analysis of the intestinal microbial communities, have to be included in the protocol of those patients with IBS.

Genetic Diversity and Distribution of Blastocystis Subtype 3 in Human Populations, with Special Reference to a Rural Population in Central Mexico

Blastocystis subtype 3 (ST3) is a parasitic protist found in the digestive tract of symptomatic and asymptomatic humans around the world. While this parasite exhibits a high prevalence in the human population, its true geographic distribution and global genetic diversity are still unknown. This gap in knowledge limits the understanding of the spread mechanisms, epidemiology, and impact that this parasite has on human populations. Herein, we provided new data on the geographical distribution and genetic diversity of Blastocystis ST3 from a rural human population in Mexico. To do so, we collected and targeted the SSU-rDNA region in fecal samples from this population and further compared its genetic diversity and structure with that previously observed in populations of Blastocystis ST3 from other regions of the planet. Our analyses reveled that diversity of Blastocystis ST3 showed a high haplotype diversity and genetic structure to the world level; however, they were low in the Morelos population. The haplotype network revealed a common widespread haplotype from which the others were generated recently. Finally, our results suggested a recent expansion of the diversity of Blastocystis ST3 worldwide.

A Mexican Honeymoon Marred by Gastrointestinal Upset: A Case of Dientamoeba fragilis Causing Post-infectious Irritable Bowel Syndrome

Dientamoeba fragilis (D. fragilis) is an anaerobic intestinal protozoan parasite that has been associated with irritable bowel syndrome (IBS)-like symptoms. We report a case of post-infectious IBS caused by D. fragilis treated successfully with metronidazole.

A 33-year-old African American male with an unremarkable past medical history was seen in the office with a three-month history of intermittent, generalized, crampy abdominal pain with bloating and flatulence without associated weight loss. He visited Mexico for his honeymoon four months ago. Initial lab work was normal. Dietary changes including fermentable oligosaccharides, disaccharides, monosaccharides, and polyols (FODMAP) diet and loperamide were prescribed with the presumptive diagnosis of IBS; however, his symptoms persisted. Three samples of stool for ova and parasites (O&P) were positive for D. fragilis. The patient was treated with metronidazole for 14 days. Repeat fecal O&P were negative. Upon follow-up, the patient’ symptoms substantially improved with a resolution of abdominal pain and flatulence.

Infection caused by D. fragilis may be symptomatic or asymptomatic. It is transmitted by the fecal-oral route. Symptoms include abdominal pain, bloating, and alteration of bowel movements, resembling IBS. The diagnosis is made via the detection of D. fragilis trophozoites in appropriately fixed and stained stool samples or by a polymerase chain reaction. Treatment options include tetracyclines, paromomycin, metronidazole, and Iodoquinol. Further epidemiologic studies may help in elucidating the association between D. fragilis and IBS.

Blastocystis subtypes isolated from irritable bowel syndrome patients and co-infection with Helicobacter pylori

Irritable bowel syndrome (IBS) is a chronic functional gastrointestinal disease presenting clinically by abdominal pain with alteration of bowel habits. Although IBS has uncertain etiology, chronic gut inflammation due to persistent exposure to an infectious agent including Blastocystis sp. was proposed. The aim of this study was to detect the prevalence of Blastocystis sp. subtype (ST) isolated from stool of IBS patients and to assess Blastocystis sp. and H. pylori co-infection in IBS patients from Beni-Suef Governorate, Egypt. Stool samples were collected from 115 IBS patients, following Rome III criteria. All stool samples were microscopically examined by wet mount and permanent trichrome stain, cultured on Jones' medium with further sequencing of positive Blastocystis isolates and screened for detection of H. pylori coproantigen. Blastocystis sp. was the predominant parasite in IBS patients; it had statistical significant association with both rural residence (OR = 10) and flatulence (OR = 8.2). There was a predominance of Blastocystis sp. ST3 (81%) followed by ST1 (19%). Blastocystis culture results (19.1%) were superior than microscopy (16.5%). The majority of Blastocystis-positive IBS patients (72.7%) were co-infected with H. pylori with statistical significance; however, H. pylori was higher in Blastocystis-negative IBS patients (47/64) than in Blastocystis-positive IBS patients (17/64). Interestingly, IBS is usually associated with gut dysbiosis, while the most prevalent parasite in our IBS patients was Blastocystis sp., which is frequently found in asymptomatic individuals. Whether Blastocystis sp. is a cause or a consequence of IBS still needs further investigation, with a particular focus on correlation of IBS with different Blastocystis sp. subtypes and gut microbiomes.

Blastocystis: how do specific diets and human gut microbiota affect its development and pathogenicity?

Blastocystis is an enteric parasite that inhabits the gastrointestinal tract of humans and many animals. This emerging parasite has a worldwide distribution. It is often identified as the most common eukaryotic organism reported in human fecal samples. This parasite is recognized and diagnosed more often than ever before. Furthermore, some strains develop resistance against currently recommended drugs, such as metronidazole; therefore, the use of natural remedies or special diets has many positive aspects that may address this problem. The goal of this review is to compare natural treatments and various diets against the efficacy of drugs, and describe their influence on the composition of the gut microbiota, which affects Blastocystis growth and the occurrence of symptoms. This article reviews important work in the literature, including the classification, life cycle, epidemiology, pathogenesis, pathogenicity, genetics, biology, and treatment of Blastocystis. It also includes a review of the current knowledge about human gut microbiota and various diets proposed for Blastocystis eradication. The literature has revealed that garlic, ginger, some medical plants, and many spices contain the most effective organic compounds for parasite eradication. They work by inhibiting parasitic enzymes and nucleic acids, as well as by inhibiting protein synthesis. The efficacy of any specific organic compound depends on the Blastocystis subtype, and, consequently, on its immunity to treatment. In conclusion, the article discusses the findings that human gut microbiota composition triggers important mechanisms at the molecular level, and, thus, has a crucial influence on the parasitic pathogenicity.

The role of Blastocystis sp. and Dientamoeba fragilis in irritable bowel syndrome: a systematic review and meta-analysis

Irritable bowel syndrome (IBS) is globally one of the most prevalent gastrointestinal disorders with a negative impact on quality of life and socio-economic status of patients. Recently, controversial evidences suggest that Blastocystis sp. and Dientamoeba fragilis infections may be implicated in the development of IBS. We performed a systematic review and meta-analysis to examine the possible association regarding this issue. PubMed, ScienceDirect, Scopus, Web of Science, and Cochrane electronic databases were searched (up to February 2017) to identify the relevant studies. Pooled odds ratio (OR) and 95% confidence intervals were estimated using a random effects meta-analysis model on data from included studies. A total of 17 studies including 5882 participants (2527 patients and 3310 controls) met the eligibility criteria. Individuals with Blastocystis infection were found to have a positive association with IBS (OR, 2.19; 95% CI, 1.54-3.13), while this association was not observed for D. fragilis infection (OR, 1.13; 95% CI, 0.22-5.72). In subgroup analysis for Blastocystis infection, the pooled ORs were OR 2.29, 95% CI 1.55-3.41; OR 1.70, 95% CI 0.83-3.44; and OR 3.83, 95% CI 2.34-6.27 for hospital-based, healthy volunteers, and combined controls, respectively. Considering the subtypes, meta-analysis result demonstrated significant positive ORs for ST1 (OR, 4.40; 95% CI, 2.81-6.90) and ST3 (OR, 1.94; 95% CI, 1.36-2.77) to be potential risk factors for IBS. Our results support the existence of a positive association between Blastocystis sp. and IBS. Further studies with more sample size should be performed to better investigate the real impact of these parasites on the occurrence of IBS.

Predominance and association risk of Blastocystis hominis subtype I in colorectal cancer: a case control study

Background

Blastocystis, a genetically diverse intestinal parasite with controversial pathogenic potential, has increasingly been incriminated for diarrheal illness in immunocompromised individuals including colorectal cancer (CRC) patients. The aim of the current study was to assess the possible association between Blastocystis infection and CRC condition in Makkah, Saudi Arabia (KSA).

Methods

Stool samples were collected from 80 non-cancer (NC) and 138 cancer subjects including 74 CRC patients and 64 patients with other cancers outside gastrointestinal tract (COGT). Molecularly confirmed Blastocystis isolates were genetically grouped and subtyped using multiplex polymerase chain reaction with restriction fragment length polymorphism (PCR-RFLP) and sequence-tagged site primers-based PCR (PCR-STS), respectively.

Results

Blastocystis hominis were confirmed in 29.7, 25 and 15% among CRC, COGT and NC patients, respectively. Obtained Blastocystis isolates were initially categorized into 2 groups (A and C), which were subsequently subtyped into 3 different subtypes; subtype-I (38%), subtype-II (44%) and subtype-V (22%). Interestingly, subtype-I was the most predominantly detected subtype (54.5%) among CRC patients with a significant association risk (COR 7.548; 95% CI: 1.629–34.987; P = 0.004).

Conclusion

To the best of our knowledge, the current study is the first to provide genetic insights on the prevalence of Blastocystis hominis among CRC patients in Makkah, KSA. Moreover, the study suggests for a possible association between subtype-I of Blastocystis hominis and CRC, which could indicate a potential influence of Blastocystis on CRC condition. Further studies are required to confirm this association risk and to investigate the possible underlying mechanism of postulated carcinogenic influence of Blastocystis hominis subtype-I.

Electronic supplementary material

The online version of this article (doi:10.1186/s13027-017-0131-z) contains supplementary material, which is available to authorized users.

Subtyping of Blastocystis sp. isolated from symptomatic and asymptomatic individuals in Makkah, Saudi Arabia

BACKGROUND

Blastocystis is a group of cosmopolitan gastrointestinal parasite of humans and a wide variety of animals. These anaerobic protozoans include more than 17 specific small-subunit ribosomal RNA subtypes, of which nine are found in humans with a variable geographical distribution. Until now, no study has described the Blastocystis subtypes present in Saudi Arabia.

METHODS

In total, 1,262 faecal samples were collected from patients with gastrointestinal complaints and asymptomatic individuals visiting two major hospitals. All samples were analysed by F1/R1 diagnostic PCR, microscopy and culture methods. The subtypes of Blastocystis sp. isolates were determined by the sequenced-tagged site (STS)-based method.

RESULTS

One-hundred-thirty-three positive cases were detected by F1/R1 diagnostic PCR, of which 122 were also positive by the culture method and 83 by direct microscopy. The sensitivities of direct microscopy and the culture method were 62% and 92%, respectively. Subtype (ST3) was the most prevalent (80.5%), followed by ST1 (14.5%) and ST2 (5%). ST4, ST5, ST6 and ST7 were not detected in this study. ST3 infections were significantly predominant (P < 0.05) among symptomatic patients.

CONCLUSIONS

To our knowledge, this study provides the first run-through information on Blastocystis sp. epidemiology in Makkah city, revealing a rather moderate prevalence of 10.5% and the presence of three subtypes, ST1, ST2, and ST3. ST3 was the most predominant, particularly among symptomatic patients.

Inter- and intra-subtype variation of Blastocystis subtypes isolated from diarrheic and non-diarrheic patients in Iran

Blastocystis is a common intestinal parasitic protist infecting birds and mammals. Blastocystis comprises at least 17 subtypes (ST), of which ST1-ST9 have been detected in humans. Significant correlation between certain subtypes and pathogenicity remains to be established. Nevertheless, some studies suggest a potential linkage between subtypes (inter- and intra-subtype variation) and clinical manifestations. The aim of this study was to identify intra-subtype genetic variation of subtypes of Blastocystis in stools samples submitted by diarrheic and non-diarrheic patients. A 550-bp fragment of the nuclear small subunit ribosomal rRNA gene was amplified from 58 culture-positive samples isolated from diarrheic and non-diarrheic Iranian patients. PCR products were sequenced and sequences subjected to phylogenetic analysis. Intra-and inter-subtype variation was calculated. Based on comparison with reference sequences in GenBank, ST1, ST2 and ST3 were found in 18 (31.03%), 21 (36.22%), and 19 (32.75%) of the samples, respectively. Diarrheic stools were observed in eight (44.44%), 10 (47.61%), and nine (47.36%) patients with ST1, ST2, and ST3, respectively. No statistically significant correlation was found between subtypes and diarrhea (P=1.000). Multiple sequence alignment exhibited a within-subtype similarity of 98.76%, 97.17%, and 99.78% in ST1, ST2, and ST3, respectively. Highest similarity was seen among ST3 isolates, while lowest similarity was seen among ST2 isolates. Phylogenetic analysis did not suggest any correlation between diarrhea and intra-subtype variation. Inter- and intra-subtype variation in SSU rRNA gene appears not to reflect differences in the clinical outcome of Blastocystis carriage.

[Blastocystis spp.: Advances, controversies and future challenges]

Blastocystis spp. is the most common protozoan detected in human stool samples. In developing countries, infection rates are higher than 20%. The presence of this parasite in the feces of several host species suggests its zoonotic potential. The clinical relevance and the pathogenic role of Blastocystis spp. in the intestinal tract remain unclear. There are several clinical reports that recognize it as the etiologic agent of several intestinal disorders such as diarrhea, inflammatory bowel disease and ulcerative colitis, although the pathogenicity of this parasite has not been proved yet. This wide range of clinical manifestations could be related to the genetic diversity exhibited by this parasite.

Blastocystis and irritable bowel syndrome: Frequency and subtypes from Iranian patients

There are inconsistent findings about the role of Blastocystis infection in irritable bowel syndrome (IBS). The present study was aimed to determine the frequency of Blastocystis and their subtypes (ST) in patients with IBS. A total of 122 patients with IBS and 122 healthy individuals referred to the medical laboratory centers in Ahvaz (southwest of Iran) participated in the study. The frequency of Blastocystis was determined. Blastocystis genomic DNA was extracted from positive feces, and PCR was performed using seven primer pairs targeting the SSU rDNA gene. Blastocystis was detected in 19.67% of patients with IBS and 17.2% of individuals without IBS. The difference between two groups was not statistically significant (P=0.3). Among the five subtypes of Blastocystis, ST3 was more common in patients with IBS and control group. However, there were no significant differences between two groups in terms of subtypes of Blastocystis (P=0.6). It seems, the role of Blastocystis in the etiology of IBS should be further investigated. Furthermore, a model of study should be designed to investigate the role of host factors in severity of parasitic disease.

Clarifying the Cryptic Host Specificity of Blastocystis spp. Isolates from Alouatta palliata and A. pigra Howler Monkeys

Although the presence of cryptic host specificity has been documented in Blastocystis, differences in infection rates and high genetic polymorphism within and between populations of some subtypes (ST) have impeded the clarification of the generalist or specialist specificity of this parasite. We assessed the genetic variability and host specificity of Blastocystis spp. in wild howler monkeys from two rainforest areas in the southeastern region of Mexico. Fecal samples of 225 Alouatta palliata (59) and A. pigra (166) monkeys, belonging to 16 sylvatic sites, were analyzed for infection with Blastocystis ST using a region of the small subunit rDNA (SSUrDNA) gene as a marker. Phylogenetic and genetic diversity analyses were performed according to the geographic areas where the monkeys were found. Blastocystis ST2 was the most abundant (91.9%), followed by ST1 and ST8 with 4.6% and 3.5%, respectively; no association between Blastocystis ST and Alouatta species was observed. SSUrDNA sequences in GenBank from human and non-human primates (NHP) were used as ST references and included in population analyses. The haplotype network trees exhibited different distributions: ST1 showed a generalist profile since several haplotypes from different animals were homogeneously distributed with few mutational changes. For ST2, a major dispersion center grouped the Mexican samples, and high mutational differences were observed between NHP. Furthermore, nucleotide and haplotype diversity values, as well as migration and genetic differentiation indexes, showed contrasting values for ST1 and ST2. These data suggest that ST1 populations are only minimally differentiated, while ST2 populations in humans are highly differentiated from those of NHP. The host generalist and specialist specificities exhibited by ST1 and ST2 Blastocystis populations indicate distinct adaptation processes. Because ST1 exhibits a generalist profile, this haplotype can be considered a metapopulation; in contrast, ST2 exists as a set of local populations with preferences for either humans or NHP.

Occurrence of Blastocystis sp. in water catchments at Malay villages and Aboriginal settlement during wet and dry seasons in Peninsular Malaysia

In the tropics, there are too few studies on isolation of Blastocystis sp. subtypes from water sources; in addition, there is also an absence of reported studies on the occurrence of Blastocystis sp. subtypes in water during different seasons. Therefore, this study was aimed to determine the occurrence of Blastocystis sp. subtypes in river water and other water sources that drained aboriginal vicinity of highly endemic intestinal parasitic infections during wet and dry seasons. Water samples were collected from six sampling points of Sungai Krau (K1–K6) and a point at Sungai Lompat (K7) and other water sources around the aboriginal villages. The water samples were collected during both seasons, wet and dry seasons. Filtration of the water samples were carried out using a flatbed membrane filtration system. The extracted DNA from concentrated water sediment was subjected to single round polymerase chain reaction and positive PCR products were subjected to sequencing. All samples were also subjected to filtration and cultured on membrane lactose glucuronide agar for the detection of faecal coliforms. During wet season, Blastocystis sp. ST1, ST2 and ST3 were detected in river water samples. Blastocystis sp. ST3 occurrence was sustained in the river water samples during dry season. However Blastocystis sp. ST1 and ST2 were absent during dry season. Water samples collected from various water sources showed contaminations of Blastocystis sp. ST1, ST2, ST3 and ST4, during wet season and Blastocystis sp. ST1, ST3, ST8 and ST10 during dry season. Water collected from all river sampling points during both seasons showed growth of Escherichia coli and Enterobacter aerogenes, indicating faecal contamination. In this study, Blastocystis sp. ST3 is suggested as the most robust and resistant subtype able to survive in any adverse environmental condition. Restriction and control of human and animal faecal contaminations to the river and other water sources shall prevent the transmission of Blastocystis sp. to humans and animals in this aboriginal community.

Comparison of faecal microbiota in Blastocystis-positive and Blastocystis-negative irritable bowel syndrome patients

BACKGROUND

We investigated whether the carriage of Blastocystis in IBS patients was associated with differences in the faecal microbiota. Forty patients with diarrhoea-predominant IBS (26 Blastocystis-positive and 14 Blastocystis-negative) and 57 healthy controls (HC) (42 Blastocystis-positive and 15 Blastocystis-negative) submitted faecal samples for metataxonomic analysis of the 16S ribosomal RNA gene. Differences in the relative abundance of bacteria in these IBS and HC groups were evaluated from phylum to genus level.

RESULTS

Significant changes were observed in two dominant phyla in IBS patients, regardless of Blastocystis infection status, namely a rise in Firmicutes and a statistically significant reduction in relative abundance of Bacteroidetes (with a threefold increase in the Firmicutes to Bacteoridetes ratio). Significant differences at genus level in IBS subjects compared to HC were also observed for many bacterial species. However, further clinical subgroup analysis of Blastocystis-positive and Blastocystis-negative subjects, regardless of symptoms, showed no significant differences at the phylum or genus level in IBS-P compared to IBS-N.

CONCLUSIONS

Significant differences in the faecal microbiota between diarrhoea-predominant IBS patients and healthy controls were confirmed, but the carriage of Blastocystis did not significantly alter the faecal microbiota. If Blastocystis-positive patients represent a separate clinical subtype of IBS, this group is not identified by changes in the microbiota.

Ex Vivo and In Vivo Mice Models to Study Blastocystis spp. Adhesion, Colonization and Pathology: Closer to Proving Koch's Postulates

Blastocystis spp. are widely prevalent extra cellular, non-motile anerobic protists that inhabit the gastrointestinal tract. Although Blastocystis spp. have been associated with gastrointestinal symptoms, irritable bowel syndrome and urticaria, their clinical significance has remained controversial. We established an ex vivo mouse explant model to characterize adhesion in the context of tissue architecture and presence of the mucin layer. Using confocal microscopy with tissue whole mounts and two axenic isolates of Blastocystis spp., subtype 7 with notable differences in adhesion to intestinal epithelial cells (IEC), isolate B (ST7-B) and isolate H (more adhesive, ST7-H), we showed that adhesion is both isolate dependent and tissue trophic. The more adhesive isolate, ST7-H was found to bind preferentially to the colon tissue than caecum and terminal ileum. Both isolates were also found to have mucinolytic effects. We then adapted a DSS colitis mouse model as a susceptible model to study colonization and acute infection by intra-caecal inoculation of trophic Blastocystis spp.cells. We found that the more adhesive isolate ST7-H was also a better colonizer with more mice shedding parasites and for a longer duration than ST7-B. Adhesion and colonization was also associated with increased virulence as ST7-H infected mice showed greater tissue damage than ST7-B. Both the ex vivo and in vivo models used in this study showed that Blastocystis spp. remain luminal and predominantly associated with mucin. This was further confirmed using colonic loop experiments. We were also successfully able to re-infect a second batch of mice with ST7-H isolates obtained from fecal cultures and demonstrated similar histopathological findings and tissue damage thereby coming closer to proving Koch’s postulates for this parasite.

Pathogenic mechanisms in Blastocystis spp. - Interpreting results from in vitro and in vivo studies

Blastocystis spp. are commonly reported intestinal protists but whose clinical significance remains controversial. Infections have ranged from asymptomatic carriage to non-specific gastrointestinal symptoms and have also been linked to irritable bowel syndrome and urticaria in some patient populations. In vitro studies showed that both parasite and parasite lysates have damaging effects on intestinal epithelial cells causing apoptosis and degradation of tight junction proteins occludin and ZO1, resulting in increased intestinal permeability. Adhesion of trophic forms to the intestinal epithelium and release of cysteine proteases appear to be the major triggers leading to pathogenesis. Two putative virulence factors identified are cysteine proteases legumain and cathepsin B. Blastocystis spp. also have immuno-modulatory effects including degradation of IgA, inhibition of iNOS and upregulation of proinflammatory cytokines, IL8 and GM-CSF in intestinal epithelial cells and IL1β, IL6 and TNFα in murine macrophages. Blastocystis spp. have also been reported to dampen response to LPS in intestinal epithelial cells and monocytes. Studies in rodent models and naturally infected pigs have shown that the parasite localizes to the lumen and mucosal surface of the large intestine mostly in the caecum and colon. The parasite has been found to cause mucosal sloughing, increase in goblet cell mucin, increased intestinal permeability and to induce a pro-inflammatory cytokine response with upregulation of TNFα, IFNγ and IL12. In this review, we summarize findings from in vitro and in vivo studies that demonstrate pathogenic potential but also show considerable inter and intra subtype variation, which provides a plausible explanation on the conflicting reports on clinical significance.