Giardia lamblia infection in patients with irritable bowel syndrome and dyspepsia: A prospective study

Microbial Influences on Irritable Bowel Syndrome

Since the description of postinfection irritable bowel syndrome (IBS), a role for gut microbes in the pathogenesis of IBS has been proposed. Molecular microbiological tools have now been applied to IBS, though data are largely derived from fecal samples with attendant limitations. Metagenomics, metabolomics, and other 'omics facilitate a comprehensive picture of the microbiome and its metabolic activity. Has a microbial signature characteristic of IBS been identified? The answer is no; this should not be a surprise given the heterogeneity of the phenotype and each individual's microbiome profile.

Dermatologic manifestations of zoonotic diseases transmitted by dogs: "Spot" could give you spots

The bond between humans and dogs is precious and has been treasured since ancient times. Dog ownership is linked to numerous health benefits, such as increased physical activity and social functioning and decreased depression and cardiovascular events. However, dogs can transmit zoonotic diseases to humans, many of which present with cutaneous findings. This review summarizes the dermatologic manifestations, transmission routes, diagnosis, and treatment of zoonotic diseases transmitted by dogs, including vector-borne, bacterial, viral, fungal, and parasitic infections. This review emphasizes the significance of clinicians obtaining a comprehensive exposure history when patients exhibit a rash of unknown origin. Such an approach can provide valuable epidemiological clues related to diagnosing a zoonotic disease transmitted by a pet dog. Furthermore, identifying the dog as an infection source and subsequent veterinary treatment can help prevent recurrent infections in dermatologic patients.

Diagnosis of protozoa diarrhoea in Campylobacter patients increases markedly with molecular techniques

Cryptosporidium and Giardia are major causes of diarrhoea globally, and two of the most notified infectious diseases in New Zealand. Diagnosis requires laboratory confirmation carried out mostly via antigen or microscopy-based techniques. However, these methods are increasingly being superseded by molecular techniques. Here we investigate the level of protozoa detection by molecular methods in campylobacteriosis cases missed through antigen-based assays and investigate different molecular testing protocols. We report findings from two observational studies; the first among 111 people during a Campylobacter outbreak and the second during normal surveillance activities among 158 people presenting with diarrhoea and a positive Campylobacter test, but negative Cryptosporidium and Giardia antigen-based test results. The molecular methods used for comparison were in-house end-point PCR tests targeting the gp60 gene for Cryptosporidium and gdh gene for Giardia. DNA extraction was performed with and without bead-beating and comparisons with commercial real-time quantitative (qPCR) were made using clinical Cryptosporidium positive sample dilutions down to 10-5. The Cryptosporidium prevalence was 9% (95% CI: 3-15; 10/111) and Giardia prevalence 21% (95% CI: 12-29; 23/111) in the 111 Campylobacter outbreak patients. The Cryptosporidium prevalence was 40% (95% CI: 32-48; 62/158) and Giardia prevalence 1.3% (95% CI: 0.2-4.5; 2/158) in the 158 routine surveillance samples. Sequencing identified Cryptosporidium hominis, C. parvum, and Giardia intestinalis assemblages A and B. We found no statistical difference in positive test results between samples using end-point PCR with or without bead-beating prior to DNA extraction, or between the in-house end-point PCR and qPCR. The qPCR Ct value was 36 (95% CI: 35-37) for 1 oocyst, suggesting a high limit of detection. In conclusion in surveillance and outbreak situations we found diagnostic serology testing underdiagnoses Cryptosporidium and Giardia coinfections in Campylobacter patients, suggesting the impact of protozoa infections may be underestimated through underdiagnosis using antigen-based assays.

A systematic review and meta-analysis on the co-infection of Helicobacter pylori with intestinal parasites: public health issue or neglected correlation?

The current study was conducted to assess the prevalence and odds ratio (OR) of co-infection of Helicobacter pylori (H. pylori) and intestinal parasites (IPs). English databases were searched. A total of 18 studies including 14 studies with cross-sectional design (a total of 3739 participants) and 4 studies with case-control design (397 patients and 320 controls) met the eligibility criteria. The pooled prevalence of H. pylori, intestinal parasite infections (IPIs), and their co-infections in different populations were 48.3% (95% CI, 34.1-62.8%), 15.4% (95% CI, 10-22.8%), and 11% (95% CI, 6.7-17.6%), respectively. The co-infection of H. pylori and Giardia was 7.6% (95% CI, 4.9-11.7%). Although statistically not significant, the risk of co-infection of H. pylori and IPIs was higher in case group compared to control group (OR, 1.59; 95% CI, 0.77-3.25). The overlaps between H. pylori and IPIs in countries with lower human development index (HDI) and income levels were high.

Giardia spp. and the Gut Microbiota: Dangerous Liaisons

Alteration of the intestinal microbiome by enteropathogens is commonly associated with gastrointestinal diseases and disorders and has far-reaching consequences for overall health. Significant advances have been made in understanding the role of microbial dysbiosis during intestinal infections, including infection with the protozoan parasite Giardia duodenalis, one of the most prevalent gut protozoa. Altered species composition and diversity, functional changes in the commensal microbiota, and changes to intestinal bacterial biofilm structure have all been demonstrated during the course of Giardia infection and have been implicated in Giardia pathogenesis. Conversely, the gut microbiota has been found to regulate parasite colonization and establishment and plays a critical role in immune modulation during mono and polymicrobial infections. These disruptions to the commensal microbiome may contribute to a number of acute, chronic, and post-infectious clinical manifestations of giardiasis and may account for variations in disease presentation within and between infected populations. This review discusses recent advances in characterizing Giardia-induced bacterial dysbiosis in the gut and the roles of dysbiosis in Giardia pathogenesis.

Assessment of the Nutritional Status, Diet and Intestinal Parasites in Hosted Saharawi Children

Since the early 1990s, Spanish humanitarian associations have welcomed Saharawi children from the refugee camps in Tindouf (Argelia). These children are the most affected by the lack of food, water, hygienic measures and health care. The main objective of this study was to analyze the anthropometric, nutritional and parasitological data of 38 Saharawi boys and girls (from 10 to 13 years old) under a holiday host program in the city of Valencia. Our results confirm that malnutrition and multiparasitism are highly frequent, so it is understood that living conditions in refugee camps continue to be precarious with a lack of proper hygiene and nutrition. Furthermore, biochemical alterations, lactose malabsorption and the risk of celiac disease, also detected in our study as a secondary objective, will complicate nutritional management and restoration of health. For this reason, sustainable feeding alternatives and interventions from a hygienic and nutritional point of view are proposed, emphasizing in an improvement in the education of parents and children.

Mucosal Tuft Cell Density Is Increased in Diarrhea-Predominant Irritable Bowel Syndrome Colonic Biopsies

Tuft cells are rare chemosensory sentinels found in the gut epithelium. When triggered by helminth infection, tuft cells secrete interleukin-25 (IL-25) basolaterally and subsequently evoke an immune response. Irritable bowel syndrome (IBS) is a common and heterogeneous disorder characterized by bowel dysfunction and visceral pain sensitivity. Dysfunctional gut-brain communication and immune activation contribute to the pathophysiology of this disorder. The study aims were to investigate changes in tuft cell density in non-post-infectious IBS patients. Immunofluorescent labeling of DCLK1-positive tuft cells was carried out in mucosal biopsies from the distal colons of diarrhea and constipation-predominant IBS patients and healthy controls. Tuft cell numbers were also assessed in animal models. Concentrations of interleukin-25 (IL-25) secreted from colonic biopsies and in plasma samples were analyzed using an immunoassay. The density of tuft cells was increased in diarrhea-but not constipation-predominant IBS patient colonic biopsies. Biopsy secretions and plasma concentrations of IL-25 were elevated in diarrhea-but not constipation-predominant IBS participants. Tuft cell hyperplasia was detected in a rat model of IBS but not in mice exposed to chronic stress. Tuft cell hyperplasia is an innate immune response to helminth exposure. However, the patients with diarrhea-predominant IBS have not reported any incidents of enteric infection. Moreover, rats exhibiting IBS-like symptoms displayed increased tuft cell density but were not exposed to helminths. Our findings suggest that factors other than helminth exposure or chronic stress lead to tuft cell hyperplasia in IBS colonic biopsies.

Giardia spp. promote the production of antimicrobial peptides and attenuate disease severity induced by attaching and effacing enteropathogens via the induction of the NLRP3 inflammasome

Polymicrobial infections of the gastro-intestinal tract are common in areas with poor sanitation. Disease outcome is the result of complex interactions between the host and pathogens. Such interactions lie at the core of future management strategies of enteric diseases. In developed countries of the world, Giardia duodenalis is a common cause of diarrheal disease. In contrast, giardiasis appears to protect children against diarrhea in countries with poor sanitation, via obscure mechanisms. We hypothesized that Giardia may protect its host from disease induced by a co-infecting pathogen such as attaching and effacing Escherichia coli. This enteropathogen is commonly implicated in pediatric diarrhea in developing countries. The findings indicate that co-infection with Giardia attenuates the severity of disease induced by Citrobacter rodentium, an equivalent of A/E E. coli in mice. Co-infection with Giardia reduced colitis, blood in stools, fecal softening, bacterial invasion, and weight loss; the protective effects were lost when co-infection occurred in Nod-like receptor pyrin-containing 3 knockout mice. In co-infected mice, elevated levels of antimicrobial peptides Murine β defensin 3 and Trefoil Factor 3, and enhanced bacterial killing, were NLRP3-dependent. Inhibition of the NLRP3 inflammasome in human enterocytes blocked the activation of AMPs and bacterial killing. The findings uncover novel NLRP3-dependent modulatory mechanisms during co-infections with Giardia spp. and A/E enteropathogens, and demonstrate how these interactions may regulate the severity of enteric disease.

The Frequency of the Intestinal Parasites Giardia Lamblia and Entamoeba Histolytica in Pediatric Diarrhea Specimens from Central Iran

Introduction:

Intestinal parasitic infections, particularly those caused by Giardia lamblia, are among the major health problems that exist worldwide, especially in developing countries. This study aimed to investigate the prevalence of the intestinal parasites Giardia lamblia and Entamoeba histolytica that were isolated from samples of infectious diarrhea in pediatric patients from Central Iran.

Methods:

This descriptive cross-sectional study included 230 samples of infectious diarrhea that were collected from May 2015 to February 2016. Direct observation, the formalin-ether sedimentation method and the technique using the Polymerase Chain Reaction (PCR) of β-giardin and EH primers were used for the identification of Giardia lamblia and Entamoeba histolytica.

Results:

Out of 230 samples of infectious diarrhea, five cases (2.1%) of Giardia lamblia and no cases (0%) of Entamoeba histolytica were identified using the formalin-ether sedimentation method and the same result were obtained using PCR technique. Of the five patients who had Giardia lamblia, three (60%) were male and two (40%) were female. The most common clinical symptoms in these patients were stomach ache and diarrhea (100%) and mucus in the stool (80%).

Conclusion:

Giardia lamblia was introduced as a parasitic agent causing diarrhea from Central Iran. The results indicate that pediatricians and, even more importantly, experts in laboratories should pay special attention to the identification of this parasite to treat the patients as effectively and as quickly as possible.

Pathogenesis and post-infectious complications in giardiasis

Giardia is an important cause of diarrhoea, and results in post-infectious and extra-intestinal complications. This chapter presents a state-of-the art of our understanding of how this parasite may cause such abnormalities, which appear to develop at least in part in Assemblage-dependent manner. Findings from prospective longitudinal cohort studies indicate that Giardia is one of the four most prevalent enteropathogens in early life, and represents a risk factor for stunting at 2 years of age. This may occur independently of diarrheal disease, in strong support of the pathophysiological significance of the intestinal abnormalities induced by this parasite. These include epithelial malabsorption and maldigestion, increased transit, mucus depletion, and disruptions of the commensal microbiota. Giardia increases epithelial permeability and facilitates the invasion of gut bacteria. Loss of intestinal barrier function is at the core of the acute and post-infectious complications associated with this infection. Recent findings demonstrate that the majority of the pathophysiological responses triggered by this parasite can be recapitulated by the effects of its membrane-bound and secreted cysteine proteases.

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.

Giardia lamblia miRNAs as a new diagnostic tool for human giardiasis

Background

Giardia lamblia is a very common cause of gastrointestinal symptoms worldwide. There are several methods for the diagnosis of Giardia infection, however none are ideal. We aim to find a new, microRNA-based method that will improve the currently available diagnostic methods for giardiasis.

Methods

Deep-sequence profiling of Giardia small-RNA revealed that miR5 and miR6 are highly expressed in Giardia. These miRNAs were tested by qRT-PCR in duodenal biopsies of patients with giardiasis who were positive by microscopic pathological evaluation. The gastric biopsies of the same patients served as negative control tissues. Additionally, these miRNAs were evaluated in stool samples of patients with proven giardiasis.

Results

All histologically proven duodenal biopsies of patients with Giardia infection were positive for Giardia miR5, with a mean threshold cycle (Ct) of 23.7, as well as for Giardia DNA qPCR (16S-like gene, mean Ct 26.3). Gastric biopsies which were tested as a control all were negative. Stool evaluation of miR6 in patients with giardiasis showed 90% specificity but only 66% sensitivity, and a lower accuracy rate was obtained with miR5.

Conclusion

Giardia miR5 testing in duodenal biopsies may be a new method for the diagnosis of giardiasis. It seems to be more sensitive when compared with testing for Giardia DNA by qPCR in duodenal biopsies. It will be important to investigate the contribution of routine Giardia miRNA testing in duodenal biopsies from patients with persistent abdominal symptoms

Giardiasis is a major cause of diarrheal disease throughout the world. It is more common in areas with poor sanitation such as in many low-income countries, but it occurs in high-income countries as well. It is the most commonly identified intestinal parasite in the United States and it is endemic in other industrialized countries. The causative agent is the flagellate protozoan Giardia lamblia, and transmission is mainly by the fecal-oral route. The basic method of diagnosis is stool examination. It is usually found through stool microscopy examination which should be performed on fresh stool and repeated in 3 days. Despite some newer diagnostic methods, Giardia is still difficult to detect, often leading to misdiagnoses.

In this study we show that using Giardia microRNA (miR5) as a marker for Giardia infection in duodenal biopsies may be a new method for diagnosis of giardiasis. It appears to be more sensitive than histological diagnosis and also more sensitive than Giardia DNA testing in duodenal biopsies. Interestingly, in our patients, duodenal biopsies were done for persistent abdominal symptoms and the finding of Giardia in their biopsy was unexpected. Thus, testing duodenal biopsies for Giardia miRNA in patients with persistent abdominal symptoms might contribute to diagnosis and prompt treatment for those with giardiasis.

A prospective study on incidence, risk factors, and validation of a risk score for post-infection irritable bowel syndrome in coastal eastern India

BACKGROUND AND AIM

Post-infection irritable bowel syndrome (PI-IBS) can occur following acute gastroenteritis (AGE). This study was designed to evaluate the incidence and risk factors of PI-IBS following AGE and to validate a PI-IBS risk score.

METHODS

This prospective study was performed between September 2014 and October 2016 on AGE patients by documenting their AGE severity and following up after 3 and 6 months to study the development of IBS (ROME III criteria). The risk score was calculated for all the subjects, and its discrimination ability was tested.

RESULTS

Out of 136 hospitalized AGE patients, 35 developed PI-IBS after 6 months. The factors associated with PI-IBS were younger age, longer duration of AGE, anxiety, depression, abdominal pain, bloody stool, vomiting, fever, family history of IBS, and positive stool culture (univariate analysis); however, on multivariate analysis, younger age (adjusted odds ratio [AOR] 0.5; p 0.03), prolonged duration of AGE (AOR 8.6; p 0.01), and abdominal cramps (AOR 2.1; p 0.02) were the independent factors influencing its occurrence. PI-IBS occurred even after infection with Vibrio cholerae. The PI-IBS risk score was significantly higher in patients who developed PI-IBS (72.4 ± 14.48 vs. 31.56 ± 20.4, p-value < 0.001); score > 50 had a sensitivity and specificity of 91.4% and 84.2%, respectively.

CONCLUSION

One fourth of AGE patients developed PI-IBS after 6 months. Factors influencing its development were younger age, long duration of AGE, and abdominal pain. The PI-IBS risk score had good predictive accuracy in our population.

Cytopreparation of duodenal biopsy fixative improves detection rate of giardia in clinically suspected cases

INTRODUCTION

Giardia intestinalis is a flagellated protozoan, frequently documented as an agent for enteric illness worldwide. Laboratory procedures for diagnosis include stool examination, antigenic detection assays and, at times, mucosal biopsy. We hypothesised that the formalin fixative used as a preservative for mucosal biopsy can be a good diagnostic sample for detecting surface mucosal and luminal infective agents such as giardia. The aim of the study was to find out the utility of processing the remaining formalin fixative as a complementary diagnostic method for detecting giardia.

METHODS

This study included 200 cases of duodenal biopsies sampled over 6 months. The biopsies were picked up using clean forceps and the remaining fixative was processed using standard cytospin protocol. The cytospin preparation and formalin-fixed paraffin-embedded tissue sections were examined by two pathologists independently blinded to each others findings.

RESULTS

On cytology, trophozoites of giardia were detected in 23 out of 200 cases (11.50%). The cytomorphology of pear-shaped organism with paired flagella and nuclei is very diagnostic. One case also showed presence of cryptosporidium spores. No other intestinal parasite was seen. Out of the 23 positive cytology samples, only 12 (6%) corresponding formalin-fixed paraffin-embedded tissue sections showed presence of giardia.

CONCLUSION

Concurrent examination of duodenal biopsy and the formalin fixative cytopreparation in cases with high index of clinical suspicion of giardiasis proved to be a useful adjunct to biopsy diagnosis of giardiasis, which was statistically significant (P < .0001). This approach adds negligible cost and effort but with good diagnostic yield. We recommend that the formalin cytopreparation be used as a complementary technique to biopsy for cases suspected of intestinal parasitic infection.

Co-infection of intestinal parasites and Helicobacter pylori among upper gastrointestinal symptomatic adult patients attending Mekanesalem Hospital, northeast Ethiopia

OBJECTIVE

Intestinal parasites and H. pylori are well-known for their high prevalence worldwide. Thus, the objective of this study waste assess risk factors and co-infection of intestinal parasites and H. pylori among adult patients with upper gastrointestinal complaints. A hospital-based cross sectional study was conducted among 363 consecutive adult patients from December 10, 2015 to February 30,2016. Stool and venous blood were collected for analysis of Intestinal parasites and H. pylori infection, respectively. Data was analyzed using SPSS version 16 and logistic regression analysis was carried out to assess predictors of co-infection. A p ≤ 0.05 was considered as statistically significant.

RESULTS

Helicobacter pylori IgG and intestinal parasites were detected in 70.25-38.3% of participants, respectively while G. lamblia accounted 22.3%. G. lamblia prevalence was significantly higher among H. pylori infected participants (COR: 2.76; 95% CI: 1.46-5.23), but E. hystolytica/dispar infection didn't show significant variation (p = 0.15). H. pylori and intestinal parasites concomitant co-infection was associated with male sex (AOR: 1.61; 95% CI: 1.01-2.56), consumption of river water (AOR: 1.85; 95% CI: 1.11-3.07) and ground/spring water (AOR: 4.10; 95% CI: 1.97-8.52). Thus, besides H. pylori investigation, upper gastrointestinal symptomatic patients should be screened for G. lamblia infection and other intestinal parasites.

Cytology Preparations of Formalin Fixative Aid Detection of Giardia in Duodenal Biopsy Samples

Giardiasis is the most common intestinal parasitic infection in the United States. The organism elicits no, or minimal, inflammatory changes in duodenal biopsy samples, so it can be easily overlooked. We performed this study to determine whether Giardia could be isolated from the formalin fixative of biopsy samples, and to evaluate the value of fluid analysis in the assessment for potential infection. We prospectively evaluated duodenal biopsy samples from 92 patients with a clinical suspicion of giardiasis or symptoms compatible with that diagnosis (ie, diarrhea, bloating, or abdominal pain) Biopsy samples were routinely processed and stained with hematoxylin and eosin. Histologic diagnoses included giardiasis (5 cases, 4%), normal findings (64 cases, 70%), peptic injury/active duodenitis (12 cases, 13%), and intraepithelial lymphocytosis with villous blunting (10 cases, 12%). Fifteen cases (13%) showed detached degenerated epithelial cells or mucus droplets in the intervillous space that resembled Giardia. Cytology slides were prepared from formalin in the biopsy container using the standard Cytospin protocol and reviewed by a cytopathologist blinded to the biopsy findings. Cytologic evaluation revealed Giardia spp. in all 5 biopsy-proven cases, and identified an additional case that was not detected by biopsy analysis. Organisms were significantly more numerous (mean: 400 trophozoites; range, 120 to 810) and showed better morphologic features in cytology preparations compared with tissue sections (mean: 129 trophozoites; range, 37 to 253 organisms; P=0.05). Our findings suggest that cytology preparations from formalin fixative can resolve diagnostically challenging cases and even enhance Giardia detection in some cases.

Interactions of Giardia sp. with the intestinal barrier: Epithelium, mucus, and microbiota

Understanding how intestinal enteropathogens cause acute and chronic alterations has direct animal and human health perspectives. Significant advances have been made on this field by studies focusing on the dynamic crosstalk between the intestinal protozoan parasite model Giardia duodenalis and the host intestinal mucosa. The concept of intestinal barrier function is of the highest importance in the context of many gastrointestinal diseases such as infectious enteritis, inflammatory bowel disease, and post-infectious gastrointestinal disorders. This crucial function relies on 3 biotic and abiotic components, first the commensal microbiota organized as a biofilm, then an overlaying mucus layer, and finally the tightly structured intestinal epithelium. Herein we review multiple strategies used by Giardia parasite to circumvent these 3 components. We will summarize what is known and discuss preliminary observations suggesting how such enteropathogen directly and/ or indirectly impairs commensal microbiota biofilm architecture, disrupts mucus layer and damages host epithelium physiology and survival.

Potential of in vivo real-time gastric gas profiling: a pilot evaluation of heat-stress and modulating dietary cinnamon effect in an animal model

Gastroenterologists are still unable to differentiate between some of the most ordinary disorders of the gut and consequently patients are misdiagnosed. We have developed a swallowable gas sensor capsule for addressing this. The gases of the gut are the by-product of the fermentation processes during digestion, affected by the gut state and can consequently provide the needed information regarding the health of the gut. Here we present the first study on gas sensor capsules for revealing the effect of a medical supplement in an animal (pig) model. We characterise the real-time alterations of gastric-gas in response to environmental heat-stress and dietary cinnamon and use the gas profiles for understanding the bio-physiological changes. Under no heat-stress, feeding increases gastric CO2 concentration, while dietary cinnamon reduces it due to decrease in gastric acid and pepsin secretion. Alternatively, heat-stress leads to hyperventilation in pigs, which reduces CO2 concentration and with the cinnamon treatment, CO2 diminishes even more, resulting in health improvement outcomes. Overall, a good repeatability in gas profiles is also observed. The model demonstrates the strong potential of real-time gas profiler in providing new physiological information that will impact understanding of therapeutics, presenting a highly reliable device for monitoring/diagnostics of gastrointestinal disorders.

Disruptions of Host Immunity and Inflammation by Giardia Duodenalis: Potential Consequences for Co-Infections in the Gastro-Intestinal Tract

Giardia duodenalis (syn. G. intestinalis, or G. lamblia) is a leading cause of waterborne diarrheal disease that infects hundreds of millions of people annually. Research on Giardia has greatly expanded within the last few years, and our understanding of the pathophysiology and immunology on this parasite is ever increasing. At peak infection, Giardia trophozoites induce pathophysiological responses that culminate in the development of diarrheal disease. However, human data has suggested that the intestinal mucosa of Giardia-infected individuals is devoid of signs of overt intestinal inflammation, an observation that is reproduced in animal models. Thus, our understanding of host inflammatory responses to the parasite remain incompletely understood and human studies and experimental data have produced conflicting results. It is now also apparent that certain Giardia infections contain mechanisms capable of modulating their host's immune responses. As the oral route of Giardia infection is shared with many other gastrointestinal (GI) pathogens, co-infections may often occur, especially in places with poor sanitation and/or improper treatment of drinking water. Moreover, Giardia infections may modulate host immune responses and have been found to protect against the development of diarrheal disease in developing countries. The following review summarizes our current understanding of the immunomodulatory mechanisms of Giardia infections and their consequences for the host, and highlights areas for future research. Potential implications of these immunomodulatory effects during GI co-infection are also discussed.

Frequency of abnormal fecal biomarkers in irritable bowel syndrome

PRIMARY STUDY OBJECTIVE

Determine the frequency of abnormal fecal biomarker test results in patients with 13 irritable bowel syndrome (IBS)-related ICD-9 (International Statistical Classification of Diseases and Related Health Problems) codes.

STUDY DESIGN

Quantitative review of de-identified records from patients in whom IBS was a possible diagnosis.

METHODS

Records were selected for analysis if they included any of 13 IBS-related diagnostic codes and laboratory test results of fecal testing for all biomarkers of interest. Data collection was restricted to one 12-month period. Frequency distributions were calculated to identify rates of abnormal results for each biomarker within the total number of tests conducted in the eligible population.

RESULTS

Two thousand, two hundred fifty-six records were included in the study, of which 1867 (82.8%) included at least one abnormal value. Quantitative stool culture for beneficial bacteria (Lactobacillus and Bifidobacterium) indicated low growth suggestive of intestinal dysbiosis in 73.1% of records, followed by abnormally elevated eosinophil protein X (suggestive of food allergy) in 14.3%, elevated calprotectin (suggestive of inflammation) in 12.1%, detection of parasites in 7.5%, and low pancreatic elastase (suggestive of exocrine pancreatic insufficiency) in 7.1%.

CONCLUSIONS

Abnormal fecal biomarkers are prevalent in patients with diagnoses suggestive of IBS. Abnormal fecal biomarker testing, if confirmed in additional independent clinical trials, could substantially reduce the economic costs associated with diagnosis and management of IBS.

Novel Testing Enhances Irritable Bowel Syndrome Medical Management: The IMMINENT Study

Primary Study Objective:

To evaluate the economic utility of a fecal biomarker panel structured to suggest alternative, treatable diagnoses in patients with symptoms of irritable bowel syndrome (IBS) by quantifying, comparing, and contrasting health service costs between tested and non-tested patients.

Study Design:

Retrospective, matched cohort study comparing direct medical costs for IBS patients undergoing fecal biomarker testing with those of matched control subjects.

Methods:

We examined de-identified medical and pharmacy claims of a large American pharmacy benefit manager to identify plan members who underwent panel testing, were eligible for covered benefits for at least 180 days prior to the test date, and had data available for 30, 90, and 365 days after that date. We used propensity score matching to develop population-based control cohorts for each tested cohort, comprised of records with IBS-related diagnoses but for which panel testing was not performed. Primary outcome measures were diagnostic and medical services costs as determined from claims data.

Results:

Two hundred nine records from tested subjects met inclusion criteria. The only significant baseline differences between groups were laboratory costs, which were significantly higher in each tested cohort. At each follow-up time point, total medical and gastrointestinal procedural costs were significantly higher in non-tested cohorts. Within tested cohorts, costs declined significantly from baseline, while costs rose significantly in non-tested control cohorts; these differences were also significant between groups at each time point.

Conclusions:

Structured fecal biomarker panel testing was associated with significantly lower medical and gastrointestinal procedural costs in this study of patients with IBS symptoms.

Protozoa as a cause of recurrent abdominal pain in children

OBJECTIVES

The aim of this study was to investigate whether protozoa can be identified as a cause of recurrent abdominal pain (RAP), and whether protozoan infections can be recognized by a specific clinical presentation.

METHODS

For 2 years, all patients (ages 4-16 years) fulfilling the Apley criteria of RAP referred to secondary care were prospectively evaluated for protozoa (Giardia lamblia, Dientamoeba fragilis, Blastocystis hominis) and treated if positive. Re-examination followed at least 10 days after treatment. Disappearance of pain with eradication and a pain-free follow-up of at least 6 months were considered to be indicative of a causal relation with RAP. The predictive value of the characteristics of the pain for protozoan infections was calculated.

RESULTS

Of 220 included patients (92 boys, mean age 8.8 years), 215 brought a stool sample; 73 (34%) carried parasites, 10 of whom had 2 parasites, 2 had 3 parasites. Sixty-five patients were treated. Twenty-five (11%) were pain-free after eradication (21 had D fragilis, 8 B hominis, 4 G lamblia), of whom 11 had another infection (2) or constipation (9) as second diagnosis for the pain. Five had recurrence of infection with D fragilis and were again pain-free with eradication. Patients with protozoa as cause of their pain did not show differences with respect to their presentation when compared with patients with an asymptomatic infection and patients without protozoa.

CONCLUSIONS

Protozoa were found as the cause of pain in 6% to 11% of children with RAP. These patients did not show a characteristic presentation when compared with patients with other causes of abdominal pain.

Prevalence and distribution of Cryptosporidium and Giardia in wastewater and the surface, drinking and ground waters in the Lower Rhine, Germany

Samples from different water sources (n = 396) were collected during 2009 and 2011. Wastewater (2-5 l) was purified by aluminium sulphate flocculation. Surface, ground and drinking waters (400-6400 l) were collected by filtration. Cryptosporidium oocysts and Giardia cysts were further concentrated by sucrose centrifugation. (Oo)cysts were identified by IFT (immunofluorescence test), DAPI (4',6-diamidino-2-phenylindole) staining and DICM (difference interference contrast microscopy). Out of 206 wastewater samples, 134 (65·0%) were found to be positive for Giardia cysts and 64 (31·1%) for Cryptosporidium oocysts. Parasite numbers ranged from 0 to 2436 cysts/l and 0 to 1745 oocysts/l. Eight (4·2%) surface and drinking water samples (n = 190) were found to be positive for Giardia cysts (0-56000/100 l), and 18 (9·5%) for Cryptosporidium oocysts (2400/100 l). The purpose of this study was to establish the prevalence and concentrations of Giardia lamblia and Cryptosporidium spp. by detecting (oo)cysts from water samples. This study provides substantial evidence that G. lamblia cysts and Cryptosporidium spp. oocysts are able to enter and circulate in the aquatic environment with negative implications for public health.

Asian consensus report on functional dyspepsia

BACKGROUND AND AIM

Environmental factors such as food, lifestyle and prevalence of Helicobacter pylori infection are widely different in Asian countries compared with the West, and physiological functions and genetic factors of Asians may also be different from those of Westerners. Establishing an Asian consensus for functional dyspepsia is crucial in order to attract attention to such data from Asian countries, to articulate the experience and views of Asian experts, and to provide a relevant guide on management of functional dyspepsia for primary care physicians working in Asia.

METHODS

Consensus team members were selected from Asian experts and consensus development was carried out by using a modified Delphi method. Consensus teams collected published papers on functional dyspepsia especially from Asia and developed candidate consensus statements based on the generated clinical questions. At the first face-to-face meeting, each statement was reviewed and e-mail voting was done twice. At the second face-to-face meeting, final voting on each statement was done using a keypad voting system. A grade of evidence and strength of recommendation were applied to each statement according to the method of the GRADE Working Group.

RESULTS

Twenty-nine consensus statements were finalized, including seven for definition and diagnosis, five for epidemiology, nine for pathophysiology, and eight for management. Algorithms for diagnosis and management of functional dyspepsia were added.

CONCLUSIONS

  This consensus developed by Asian experts shows distinctive features of functional dyspepsia in Asia and will provide a guide to the diagnosis and management of functional dyspepsia for Asian primary care physicians.

Asian consensus report on functional dyspepsia

BACKGROUND/AIMS

Environmental factors such as food, lifestyle and prevalence of Helicobacter pylori infection are widely different in Asian countries compared to the West, and physiological functions and genetic factors of Asians may also be different from those of Westerners. Establishing an Asian consensus for functional dyspepsia is crucial in order to attract attention to such data from Asian countries, to articulate the experience and views of Asian experts, and to provide a relevant guide on management of functional dyspepsia for primary care physicians working in Asia.

METHODS

Consensus team members were selected from Asian experts and consensus development was carried out using a modified Delphi method. Consensus teams collected published papers on functional dyspepsia especially from Asia and developed candidate consensus statements based on the generated clinical questions. At the first face-to-face meeting, each statement was reviewed and e-mail voting was done twice. At the second face-to-face meeting, final voting on each statement was done using keypad voting system. A grade of evidence and a strength of recommendation were applied to each statement according to the method of the GRADE Working Group.

RESULTS

Twenty-nine consensus statements were finalized, including 7 for definition and diagnosis, 5 for epidemiology, 9 for pathophysiology and 8 for management. Algorithms for diagnosis and management of functional dyspepsia were added.

CONCLUSIONS

This consensus developed by Asian experts shows distinctive features of functional dyspepsia in Asia and will provide a guide to the diagnosis and management of functional dyspepsia for Asian primary care physicians.

Giardiasis: a review on assemblage distribution and epidemiology in India

Giardiasis is a significant cause of diarrheal disease and associated morbidity in children and adults worldwide. In addition to diarrhea, it can also lead to malnutrition and cognitive deficits in children from developing countries. Giardia duodenalis is considered to be a species complex of several assemblages, of which assemblage A and B are predominantly associated with human infections. Assemblage type has been associated with risk of occurrence of symptoms and duration of illness. Hence genotyping of giardial isolates may help understand better the epidemiology and transmission ecology of the disease in a particular setting or area. In India, prevalence rates of Giardia infection in patients with diarrhea range from 0.4% to 70%, and asymptomatic cyst passage has been found to be as high as 50% in rural southern India. In this review, the global distribution of giardial assemblage, zoonotic transmission and the association of assemblage with disease have been discussed, followed by epidemiology of giardiasis in India.

The prevalence of giardia intestinalis in dyspeptic and diabetic patients

Background and Aims. We aimed to investigate the prevalence of Giardiasis in patients with dyspepsia and patients with diabetes mellitus. Methods. 400 patients and 100 healthy persons were included in this clinical prospective study. The number of patients in each group was equal, 200 dyspeptic and 200 diabetic, respectively. The antigen of G. lntestinalis was determined in the stool specimens by ELISA method. Results. The frequency of Giardiasis was 7% in dyspeptic and 15% in diabetic patients. There was no positive results in any of the healthy persons. There was a significant difference in prevalence rate of Giardiasis between patients with dyspepsia and diabetes mellitus (P < 0.05). Conclusions. These results revealed that the prevalence of Giardiasis in dyspepsia and with diabetes mellitus was high in our country. This is the first study investigating the prevalence of Giardiasis in diabetic patients. To investigate Giardiasis in diabetic patients, who have dyspepsia or not, may be a good approach for public health.

Post-infectious irritable bowel syndrome: the past, the present and the future

BACKGROUND

Irritable bowel syndrome (IBS), once thought to be a psychosomatic disease, is being considered to be more organic. Post-infectious IBS (PI-IBS), defined as acute onset IBS (by Rome criteria) after gastrointestinal infection in an individual without prior IBS with two or more of the followings: fever, vomiting, diarrhea, a positive stool culture. The recent and old literature of PI-IBS will be reviewed. Future directions for research will be presented.

METHODS

Literature on PI-IBS was reviewed by electronic search and cross references of these papers.

RESULTS

Interest in studies on PI-IBS, which was described five to six decades ago, re-surfaced recently. 3.6 to 32% patients with acute gastroenteritis develop PI-IBS during 3-12 month follow-up. PI-IBS is commonly diarrhea predominant. Factors implicated in development include nature of pathogens, duration and severity of diarrhea, younger age, female gender and psychological co-morbidities like anxiety and depression. The pathogenesis of PI-IBS is largely related to continuing gut inflammation due to inability of the host to contain the inflammatory reaction, altered gut microbiota, increased intestinal permeability, muscle hyper-contractility and visceral hypersensitivity. There could be an overlap between PI-IBS and post-infectious malabsorption syndrome (PI-MAS), popularly known as tropical sprue.

CONCLUSIONS

Development of IBS in a subset of patients with acute gastroenteritis is uncontested. This is expected to open a paradigm shift in understanding the pathogenesis of IBS. Future studies should address the issue of overlap of PI-IBS and PI-MAS. Exploring the molecular mechanisms of pathogenesis of PI-IBS may help to design preventive and therapeutic strategies.

Bugs and irritable bowel syndrome: The good, the bad and the ugly

Recently, there has been strong interest in the therapeutic potential of probiotics for irritable bowel syndrome (IBS). At the same time, there is a rapidly growing body of evidence to support an etiological role for gastrointestinal infection and the associated immune activation in the development of post-infectious IBS. In a more controversial area, small intestinal bacterial overgrowth has been associated with a subset of patients with IBS; the issue of whether it is appropriate to treat a subset of IBS patients with antibiotics and probiotics is currently a matter for debate. Thus, it appears that the gastrointestinal microbial flora may exert beneficial effects for symptoms of IBS under some circumstances, while in other situations gut microbes could give rise to symptoms of IBS. How do we make sense of the apparently diverse roles that 'bugs' may play in IBS? To address this question, we have conducted an in-depth review, attempting where possible to draw lessons from Asian studies.

Severity of Giardia infection associated with post-infectious fatigue and abdominal symptoms two years after

BACKGROUND

A high rate of post-infectious fatigue and abdominal symptoms two years after a waterborne outbreak of giardiasis in Bergen, Norway in 2004 has previously been reported. The aim of this report was to identify risk factors associated with such manifestations.

METHODS

All laboratory confirmed cases of giardiasis (n = 1262) during the outbreak in Bergen in 2004 received a postal questionnaire two years after. Degree of post-infectious abdominal symptoms and fatigue, as well as previous abdominal problems, was recorded. In the statistical analyses number of treatment courses, treatment refractory infection, delayed education and sick leave were used as indices of protracted and severe Giardia infection. Age, gender, previous abdominal problems and symptoms during infection were also analysed as possible risk factors. Simple and multiple ordinal logistic regression models were used for the analyses.

RESULTS

The response rate was 81% (1017/1262), 64% were women and median age was 31 years (range 3-93), compared to 61% women and 30 years (range 2-93) among all 1262 cases. Factors in multiple regression analysis significantly associated with abdominal symptoms two years after infection were: More than one treatment course, treatment refractory infection, delayed education, bloating and female gender. Abdominal problems prior to Giardia infection were not associated with post-infectious abdominal symptoms. More than one treatment course, delayed education, sick leave more than 2 weeks, and malaise at the time of infection, were significantly associated with fatigue in the multiple regression analysis, as were increasing age and previous abdominal problems.

CONCLUSION

Protracted and severe giardiasis seemed to be a risk factor for post-infectious fatigue and abdominal symptoms two years after clearing the Giardia infection.

Irritable bowel syndrome: role of food in pathogenesis and management

Patients with the irritable bowel syndrome (IBS) commonly report the precipitation of symptoms on food ingestion. Though the role of dietary constituents in IBS has not been extensively studied, food could contribute to symptom onset or even the causation of IBS through a number of mechanisms. First, the physiological response of the intestine to food ingestion could precipitate symptoms in predisposed individuals; second, there is some evidence that allergy or intolerance to a particular food can produce IBS-like symptoms, third, certain foods may alter the composition of the luminal milieu, either directly or indirectly through effects on bacterial metabolism, and thus induce symptoms and, finally, IBS may develop following exposure to food-borne pathogens. Anticipatory, psychological factors generated by previous negative experiences with food ingestion or other factors may also contribute though their contribution has been scarcely quantified. Not surprisingly, there is considerable interest in the potential roles of diet and food supplements in the therapy of IBS; for the most part, the evidence base for such recommendations remains slim though certain probiotics show considerable promise.

Do Patients with Functional Gastrointestinal Disorders have an Altered Gut Flora?

The description of the de novo development of irritable bowel syndrome (IBS) following an episode of bacterial gastroenteritis (postinfectious IBS) illustrated the potential for a luminal factor (a bacterial pathogen) to cause this common gastrointestinal ailment. As a consequence of these and other observations as well as results of experiments involving animal models, the enteric flora and the immune response that it generates in the host have, somewhat surprisingly, come centre-stage in IBS research with their potential to induce the pathophysiological changes that are associated with IBS. While evidence for immune dysfunction both in the mucosa and systemically continues to accumulate, methodological limitations have hampered a full delineation of the nature of the microbiota in IBS. The latter is eagerly awaited and may yet provide a firm rationale for the use of certain probiotics and antibiotics in IBS, whose benefits have now been described with some consistency.

Development of functional gastrointestinal disorders after Giardia lamblia infection

Background

Functional gastrointestinal disorders (FGID) may occur following acute gastroenteritis. This long-term complication has previously not been described after infection with the non-invasive protozoan Giardia lamblia. This study aims to characterize persistent abdominal symptoms elicited by Giardia infection according to Rome II criteria and symptoms scores.

Methods

Structured interview and questionnaires 12–30 months after the onset of Giardia infection, and at least 6 months after Giardia eradication, among 82 patients with persisting abdominal symptoms elicited by the Giardia infection. All had been evaluated to exclude other causes.

Results

We found that 66 (80.5%) of the 82 patients had symptoms consistent with irritable bowel syndrome (IBS) and 17 (24.3%) patients had functional dyspepsia (FD) according to Rome II criteria. IBS was sub classified into D-IBS (47.0%), A-IBS (45.5%) and C-IBS (7.6%). Bloating, diarrhoea and abdominal pain were reported to be most severe. Symptoms exacerbation related to specific foods were reported by 45 (57.7%) patients and to physical or mental stress by 34 (44.7%) patients.

Conclusion

In the presence of an IBS-subtype pattern consistent with post-infectious IBS (PI-IBS), and in the absence of any other plausible causes, we conclude that acute Giardia infection may elicit functional gastrointestinal diseases with food and stress related symptoms similar to FGID patients in general.

Is there a role for routine duodenal biopsy in diagnosing giardiasis in a European population?

OBJECTIVE

Giardia lamblia is the most common enteric protozoan world-wide. The prevalence varies internationally. Patients with giardiasis typically have diarrhoea but may have atypical symptoms when referred for endoscopy. The purpose of this study was to investigate whether a policy of routine duodenal biopsies increased the yield of diagnosing Giardia and whether treatment improved the patient's presenting symptoms.

MATERIAL AND METHODS

Our hospital endoscopy database was examined retrospectively, from January 2003 to January 2004, to identify patients who had undergone gastroscopy and targeted duodenal biopsies. Thereafter, routine duodenal biopsies were carried out prospectively on unselected adult patients referred for gastroscopy from January 2004 to April 2006. Patients diagnosed with Giardia were assessed for symptoms and response to treatment.

RESULTS

In the retrospective group, of the 5979 gastroscopies performed, 1464 duodenal biopsies were carried out; 5 patients had giardiasis, a prevalence of 0.08%, CI 0.01-0.16%. In the prospective group, 2000 gastroscopies with duodenal biopsies were performed; 9 patients had giardiasis, a prevalence of 0.45%, CI 0.16-0.74%. The difference in prevalence was 0.37%, CI 0.06-0.67%, which was statistically significant with a Yates' chi(2)(CC) of 9.49, p<0.005. On comparing response to treatment, the Fisher exact test revealed a proportional difference that was not statistically significant.

CONCLUSIONS

In a UK population, the prevalence of Giardia was low. Although a policy of routine duodenal biopsy resulted in more cases of Giardia being identified, this increase in detection did not correspond with an improvement in patients' symptoms. This suggests that Giardia may be a coincidental finding. This study does not support the approach of routine duodenal biopsy in diagnosing giardiasis.

A survey about irritable bowel syndrome in South Korea: prevalence and observable organic abnormalities in IBS patients

The aims of the present study were: (1) to assess the prevalence of symptom-based irritable bowel syndrome (IBS) in Korean adults, (2) to assess several organic abnormalities which can be found in IBS patients, and (3) to analyze the risk or associated factors that influence the presence of IBS. Adult health examinees were requested to fill out a questionnaire. The prevalence of IBS was calculated using Rome II criteria. Using several tests, several organic abnormalities were identified in the IBS group. Risk factors were analyzed by comparing the IBS and normal groups. The prevalence value for IBS according to Rome II criteria was 16.8%. Mucosal hyperplasia, lymphocyte aggregation, and increased eosinophil counts were relatively common microscopic findings in IBS group. Female gender, self-consciousness of IBS, and irregular defecation were expressed as significantly independent risk or associated factors for IBS. Several colonic microscopic findings mentioned above may be helpful in accurate diagnosis of IBS. Therefore a more-precise and large population study about these findings is necessary to reach a definitive conclusion.

Persisting symptoms and duodenal inflammation related to Giardia duodenalis infection

OBJECTIVES

After a large waterborne outbreak of Giardia infection in Bergen, some patients experienced persisting abdominal symptoms despite metronidazole treatment. This study aimed at investigating possible causes for their symptoms.

METHODS

Over a 15 month period, 124 referred patients were evaluated in a prospective cohort analysis with a standardised investigation including duodenal biopsies and aspirate, blood tests and faecal parasite and calprotectin tests. Recovered subjects were recruited for symptom analysis.

RESULTS

Persisting Giardia duodenalis infection was found in 40 patients (32.3%). Duodenal biopsies showed signs of inflammation in 57 patients (47.1%). Microscopic duodenal inflammation was present in 34 (87.2%) of the Giardia positive and 23 (28.0%) of the Giardia negative patients. There were significant associations between persistent Giardia positivity, microscopic duodenal inflammation and a positive calprotectin test. Duodenal aspirate and duodenal biopsies performed poorly in diagnosis of persistent giardiasis.

CONCLUSIONS

In patients with persisting symptoms after metronidazole treated Giardia infection we commonly found chronic Giardia infection and microscopic duodenal inflammation, especially in illness duration less than 7 months. Both these findings subsided over time. Increasingly, investigations could not determine a definite cause for the persistent symptoms. The very long-term post-giardiasis diarrhoea, bloating, nausea and abdominal pain documented here need further study.

Infectious causation of chronic disease: Examining the relationship between Giardia lamblia infection and irritable bowel syndrome

AIM: To evaluate whether a higher prevalence of Giardia lamblia infection is associated with an increase in irritable bowel syndrome (IBS) prescriptions at the county level in Michigan.

METHODS: The Michigan Disease Surveillance System (MDSS) was used to ascertain both the numbers of Giardia lamblia infections as well as the total number of foodborne illnesses per population by county in Michigan during 2005. This was compared with Blue Cross Blue Shield (BCBS) of Michigan numbers of drug prescriptions for IBS per one thousand members per county in 2005. These data were also analyzed for associations with per capita income by county and the number of refugees entering each county in 2005.

RESULTS: There were a total of 786 confirmed cases of Giardia lamblia reported to MDSS in 2005. During the same time period, the number of prescriptions for IBS varied from 0.5 per 1000 members up to 6.0 per 1000 members per month. There was no trend towards higher numbers of IBS prescriptions in the counties with more Giardia lamblia infections. Per capita income was not associated with either IBS prescriptions or Giardiasis. There was a significant linear association between the number of refugees entering each county, and the number of Giardia lamblia cases per 100 000 population.

CONCLUSION: In this ecological study, there was no association found between BCBS prescriptions for IBS and Giardia lamblia infections in Michigan counties. Our findings may have been influenced by the disparate number of refugees admitted per county.

Giardia and Cryptosporidium and public health: the epidemiological scenario from the Italian perspective

Giardia and Cryptosporidium spp. are protozoa that cause human and animal disease worldwide and often exhibit zoonotic transmission. This review gives ample information concerning the epidemiology of these parasites in Italy, i.e. prevalence data in humans, farm and pet animals, shellfish and aquatic environment. Moreover, it reports genotyping results obtained from different isolates, with particular emphasis on the spread of host-specific and zoonotic species/genotypes of various origin, and on molecular data that make the Italian situation different from that of other countries. Finally, possible explanations are given for the infrequent reports of Giardia and Cryptosporidium spp. outbreaks, despite widespread faecal contamination by these parasites.

Irritable bowel syndrome: a review on the role of intestinal protozoa and the importance of their detection and diagnosis

Irritable bowel syndrome (IBS) is a functional gastrointestinal disorder in which abdominal pain is associated with a defect or a change in bowel habits. Gut inflammation is one of the proposed mechanisms of pathogenesis. Recent studies have described a possible role for protozoan parasites, such as Blastocystis hominis and Dientamoeba fragilis, in the etiology of IBS. Dientamoeba fragilis is known to cause IBS-like symptoms and has a propensity to cause chronic infections but its diagnosis relies on microscopy of stained smears, which many laboratories do not perform, thereby leading to the misdiagnosis of dientamoebiasis as IBS. The role of B. hominis as an etiological agent of IBS is inconclusive, due to contradictory reports and the controversial nature of B. hominis as a human pathogen. Although Entamoeba histolytica infections occur predominately in developing regions of the world, clinical diagnosis of amebiasis is often difficult because symptoms of patients with IBS may closely mimic those patients with non-dysenteric amoebic colitis. Clinical manifestations of Giardia intestinalis infection also vary from asymptomatic carriage to acute and chronic diarrhoea with abdominal pain. These IBS-like symptoms can be continuous, intermittent, sporadic or recurrent, sometimes lasting years without correct diagnosis. It is essential that all patients with IBS undergo routine parasitological investigations in order to rule out the presence of protozoan parasites as the causative agents of the clinical signs.