Comparative genomics of Cryptosporidium parvum reveals the emergence of an outbreak-associated population in Europe and its spread to the United States.

The zoonotic parasite Cryptosporidium parvum is a global cause of gastrointestinal disease in humans and ruminants. Sequence analysis of the highly polymorphic gp60 gene enabled the classification of C. parvum isolates into multiple groups (e.g., IIa, IIc, Id) and a large number of subtypes. In Europe, subtype IIaA15G2R1 is largely predominant and has been associated with many water- and food-borne outbreaks. In this study, we generated new whole-genome sequence (WGS) data from 123 human- and ruminant-derived isolates collected in 13 European countries and included other available WGS data from Europe, Egypt, China, and the United States (n = 72) in the largest comparative genomics study to date. We applied rigorous filters to exclude mixed infections and analyzed a data set from 141 isolates from the zoonotic groups IIa (n = 119) and IId (n = 22). Based on 28,047 high-quality, biallelic genomic SNPs, we identified three distinct and strongly supported populations: Isolates from China (IId) and Egypt (IIa and IId) formed population 1; a minority of European isolates (IIa and IId) formed population 2; and the majority of European (IIa, including all IIaA15G2R1 isolates) and all isolates from the United States (IIa) clustered in population 3. Based on analyses of the population structure, population genetics, and recombination, we show that population 3 has recently emerged and expanded throughout Europe to then, possibly from the United Kingdom, reach the United States, where it also expanded. The reason(s) for the successful spread of population 3 remain elusive, although genes under selective pressure uniquely in this population were identified.

JAK2V617F drives gut microbiota differences in patients with myeloproliferative neoplasms.

BACKGROUND: Essential thrombocythemia (ET), polycythemia vera (PV), and primary myelofibrosis (MF) are myeloproliferative neoplasms (MPN). Inflammation is involved in the initiation, progression, and symptomology of the diseases. The gut microbiota impacts the immune system, infection control, and steady-state hematopoiesis. METHODS: We analyzed the gut microbiota of 227 MPN patients and healthy controls (HCs) using next-generation sequencing. We expanded our previous results in PV and ET patients with additional PV, pre-MF, and MF patients which allowed us to compare MPN patients collectively, MPN sub-diagnoses, and MPN mutations (separately and combined) vs. HCs (N = 42) and compare within MPN sub-diagnoses and MPN mutation. RESULTS: MPN patients had a higher observed richness (median, 245 [range, 49-659]) compared with HCs (191.5 [range, 111-300; p = .003]) and a lower relative abundance of taxa within the Firmicutes phylum; for example, Faecalibacterium (6% vs. 14%, p < .001). The microbiota of CALR-positive patients (N = 30) resembled that of HCs more than that of patients with JAK2V617F (N = 177). In JAK2V617F-positive patients, only minor differences in the gut microbiota were observed between MPN sub-diagnoses, illustrating the importance of this mutation. CONCLUSION: The gut microbiota in MPN patients differs from HCs and is driven by JAK2V617F, whereas the gut microbiota in CALR patients resembles HCs more.

Neoehrlichia mikurensis-An emerging opportunistic tick-borne infection in immunosuppressed patients.

BACKGROUND: Neoehrlichia mikurensis (N. mikurensis) is a newly discovered tick-borne pathogen that can inflict life-threatening illness in immunocompromised patients. N. mikurensis infection is only detectable by polymerase chain reaction (PCR)-based methodologies. We describe three distinct clinical manifestations of N. mikurensis infection (neoehrlichiosis) in Danish patients receiving B-lymphocyte-depleting therapy, rituximab, for underlying hematological, rheumatological, or neurological disorders. All three patients went through a protracted pre-diagnostic period. METHODS: N. mikurensis DNA was detected and confirmed using two methods. Blood was tested by specific real-time PCR targeting the groEL gene and by 16S and 18S profiling followed by sequencing. Bone marrow was analyzed by 16S and 18S profiling. RESULTS: N. mikurensis was detected in blood samples in all three cases and in bone marrow from one of the three. The severity of the symptoms ranged from prolonged fever lasting more than 6 months to life-threatening hyperinflammation in the form of hemophagocytic lymphohistiocytosis (HLH). Interestingly, all patients presented with splenomegaly and two with hepatomegaly. After starting doxycycline therapy, symptoms were relieved within a few days, and biochemistry and organomegaly quickly normalized. CONCLUSION: We present three Danish patients recognized by the same clinician over a period of 6 months, strongly suggesting that many cases are going unrecognized. Second, we describe the first case of N. mikurensis-induced HLH and emphasize the potential severity of undetected neoehrlichiosis.

Further insight into the genetic diversity of Entamoeba coli and Entamoeba hartmanni.

Despite the species' wide distribution, studies of the genetic diversity within Entamoeba coli and Entamoeba hartmanni remain limited. In the present study, we provide further insight into the genetic diversity of both species based on analysis of partial nuclear small subunit ribosomal DNA sequences generated from human fecal DNAs from samples collected in Africa, South America, and Europe. Reinforcing the previous recognition that E. coli is a species complex, our data confirm the existence of the two subtypes, ST1 and ST2, previously identified plus, potentially, a new subtype, ST3. While ST1 appears to be genetically quite homogenous, ST2 shows a substantial degree of intrasubtype diversity. ST2 was more common in samples collected outside Europe, whereas ST1 showed no geographical restriction. The potentially novel subtype is represented to date exclusively by sequences from South American and African samples. In contrast to previous reports, our new data also indicate substantial variation in E. hartmanni that could also support the establishment of subtypes within this species. Here, however, no links were identified between subtype and geographical origin.

Metabarcoding of colonic cleansing fluid reveals unique bacterial members of mucosal microbiota associated with Inflammatory Bowel Disease.

BACKGROUND: Inflammatory Bowel Disease (IBD) is a group of chronic idiopathic inflammatory diseases of the gastrointestinal (GI) tract associated with the dysbiosis of gut microbiota. Metabarcoding-based profiling of the gut microbiota of IBD patients is generally based on the stool samples collected from individual patients which rarely represent the mucosa-associated microbiota. The ideal sampling strategy for routine monitoring of the mucosal component of IBD has yet to be determined. METHODS: We hereby compare the microbiota composition of the colonic cleansing fluid (CCF) collected during colonoscopy with stool samples from IBD patients. The relationship between IBD and gut microbiota was revealed through the application of the 16S rRNA amplicon sequencing-based metabarcoding approach. CCF and stool samples were collected from IBD patients with Crohn's disease and ulcerative colitis. RESULTS: The present study shows significant differences in the microbial composition of CCF samples, presumably indicating changes in the mucosal microbiota of IBD patients as compared to the control group. Short-chain fatty acid-producing bacteria under the family Lachnospiraceae, the actinobacterial genus Bifidobacterium, the proteobacterial Sutterella and Raoultella are found to contribute to the microbial dysbiosis of the mucosal flora in IBD patients. CONCLUSIONS: CCF microbiota has the capacity to distinguish IBD patients from healthy controls and, thus, may constitute an alternative analysis strategy for the early diagnosis and disease progression in IBD biomarker research.

A Cross-Sectional Study on the Occurrence of the Intestinal Protist, Dientamoeba fragilis, in the Gut-Healthy Volunteers and Their Animals.

Dientamoeba fragilis is a cosmopolitan intestinal protist colonizing the human gut with varying prevalence depending on the cohort studied and the diagnostic methods used. Its role in human health remains unclear mainly due to the very sporadic number of cross-sectional studies in gut-healthy populations. The main objective of this study was to expand knowledge of the epidemiology of D. fragilis in gut-healthy humans and their animals. A total of 296 stool samples from humans and 135 samples from 18 animal species were analyzed. Using qPCR, a prevalence of 24% was found in humans in contrast to conventional PCR (7%). In humans, several factors were found to influence the prevalence of D. fragilis. A more frequent occurrence of D. fragilis was associated with living in a village, traveling outside Europe and contact with farm animals. In addition, co-infection with Blastocystis spp. was observed in nearly half of the colonized humans. In animals, D. fragilis was detected in 13% of samples from eight species using qPCR. Our molecular phylogenies demonstrate a more frequent occurrence of Genotype 1 in gut-healthy humans and also revealed a likely a new protist species/lineage in rabbits related to D. fragilis and other related organisms.

Detection and Identification of Acanthamoeba and Other Nonviral Causes of Infectious Keratitis in Corneal Scrapings by Real-Time PCR and Next-Generation Sequencing-Based 16S-18S Gene Analysis.

Acanthamoeba is a free-living amoeba of extensive genetic diversity. It may cause infectious keratitis (IK), which can also be caused by bacteria, fungi, and viruses. High diagnostic sensitivity is essential to establish an early diagnosis of Acanthamoeba-associated keratitis. Here, we investigated the applicability of next-generation sequencing (NGS)-based ribosomal gene detection and differentiation (16S-18S) compared with specific real-time PCR for the detection of Acanthamoeba Two hundred DNAs extracted from corneal scrapings and screened by Acanthamoeba-specific real-time PCR were analyzed using an in-house 16S-18S NGS assay. Of these, 24 were positive by specific real-time PCR, of which 21 were positive by the NGS assay. Compared with real-time PCR; the specificity and sensitivity of the NGS assay were 100% and 88%, respectively. Genotypes identified by the NGS assay included T4 (n = 19) and T6 (n = 2). Fungal and bacterial species of potential clinical relevance were identified in 31 of the samples negative for Acanthamoeba, exemplified by Pseudomonas aeruginosa (n = 11), Moraxella spp. (n = 6), Staphylococcus aureus (n = 2), Fusarium spp. (n = 4), and Candida albicans (n = 1). In conclusion, the 16S-18S assay was slightly less sensitive than real-time PCR in detecting Acanthamoeba-specific DNA in corneal scrapings. Robust information on genotypes was provided by the NGS assay, and other pathogens of potential clinical relevance were identified in 16% of the samples negative for Acanthamoeba NGS-based detection of ribosomal genes in corneal scrapings could be an efficient screening method for detecting nonviral causes of IK, including Acanthamoeba.

Impact of Metronidazole Treatment and Dientamoeba Fragilis Colonization on Gut Microbiota Diversity.

OBJECTIVES: The intestinal parasite Dientamoeba fragilis is a common colonizer of children in Denmark. Metronidazole has been used to reduce gastrointestinal symptoms in children colonized with D fragilis. We aimed to identify gut microbiota changes associated with D fragilis carrier status and metronidazole treatment of D fragilis-positive children. METHODS: The fecal microbiota of 275 fecal samples from children treated with metronidazole (n = 48) or placebo (n = 48) were characterized by ribosomal DNA sequencing. Samples collected before (T1), 2 weeks after (T2), and 8 weeks (T5) after treatment were included. Seventy fecal samples from 70 age-matched parasite-negative children served as controls. RESULTS: The abundance of 24 bacterial genera differed significantly according to D fragilis carrier status, with Flavonifractor being remarkably more abundant in children testing negative for D fragilis. Eight bacterial genera changed significantly in abundance in children losing versus keeping D fragilis after metronidazole treatment. Of these, 7 returned to pretreatment (T1) levels at T5. Meanwhile, the abundance of Flavonifractor continued to differ at T5, whereas for Ruminococcus the abundance only remained high in children who were D fragilis-negative at T2 and T5. Increases in Hungatella, Sutterella, and Streptococcus abundances observed at T2 were specific to metronidazole exposure and hence independent of D fragilis colonization. CONCLUSIONS: This study revealed that specific bacterial genera were associated with D fragilis colonization. Metronidazole treatment had a short-term impact on the abundance of some bacterial genera, with most of these reverting to pretreatment levels 8 weeks after completed treatment.

Veterinary Students Have a Higher Risk of Contracting Cryptosporidiosis when Calves with High Fecal Cryptosporidium Loads Are Used for Fetotomy Exercises.

An outbreak of cryptosporidiosis among veterinary students performing fetotomy exercises on euthanized calves took place in September 2018 in Denmark. A prospective cohort investigation was performed to identify risk factors and provide guidance for preventing outbreaks of cryptosporidiosis in this setting. Ninety-seven students attended the fetotomy exercises and completed a questionnaire about symptoms and potential risk behavior. Real-time PCR was used to detect Cryptosporidium spp. in stool samples from students and to quantify the fecal parasite load in the calves used for the exercises. gp60 subtyping was carried out for the Cryptosporidium-positive samples. Our case definition was based on participation in a fetotomy exercise, reported symptoms, and laboratory results. Eleven laboratory-confirmed or probable cases (11%) were identified in two outbreaks during the prospective study period, with attack rates of 4/10 (40%) and 7/9 (78%), respectively. The risk factors for cryptosporidiosis we identified were performing the exercise on a diarrheic calf, reporting visible fecal contamination on the personal protective equipment (PPE), and reporting problems with PPE during the exercise. Cryptosporidium parvum IIaA15G2R1 was detected in both cases and calves. A significantly higher proportion of the calves aged 7 days old and above were positive compared with younger calves. Furthermore, a high fecal Cryptosporidium load in a calf was associated with a higher probability of an outbreak among the students. Based on our results, using noninfected calves for the exercises, appropriate use of PPE, and thorough hand hygiene are recommended to reduce the risk of contracting cryptosporidiosis in connection with fetotomy exercises.IMPORTANCECryptosporidium spp. can cause severe diarrhea in infected individuals. Cryptosporidium parvum is zoonotic, and cattle are the main reservoir. In several countries, outbreaks of cryptosporidiosis have occurred in veterinary students after handling calves. We carried out a 1-year-long prospective study to investigate the occurrence of these recurrent cryptosporidiosis outbreaks in Denmark. Our investigation used a One Health approach and combined comprehensive epidemiological approaches and laboratory methods applied to both students and calves in the setting of the fetotomy exercises. Two outbreaks took place during the study period; additionally, we retrospectively identified two more suspected outbreaks prior to the study period. The results illustrated a high risk of contracting cryptosporidiosis among veterinary students in the setting of the fetotomy exercises, especially when using calves with high fecal Cryptosporidium loads. Our data can be used to inform future efforts to prevent transmission of Cryptosporidium parvum to students during fetotomy exercises.

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

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

Evaluation of a PCR Method for Detection of Entamoeba polecki, with an Overview of Its Molecular Epidemiology.

Entamoebapolecki is a parasite of human and nonhuman primates, other mammals, and birds. Due to overlapping morphological features, cysts of E. polecki may be confused with those of other Entamoeba species commonly found in human fecal samples, including immature cysts of Entamoeba histolytica Although the presence of E. polecki in human Entamoeba-positive stool samples may be rare, its prevalence is likely underestimated due to such confusion. Here, we give examples of diagnostic approaches applied so far and summarize data on the molecular epidemiology of E. polecki, including host specificity and phylogeography. Moreover, we evaluate a novel diagnostic conventional PCR developed for the screening of fecal samples for E. polecki The assay was highly sensitive and specific when used on genomic DNA extracted directly from stool and Swedish wastewater samples. The PCR enabled the identification of all four subtypes (ST1 to ST4) of E. polecki by PCR product sequencing. Most (23/28) subtyped E. polecki-positive samples detected in patients in Sweden between 2002 and 2015 reflected colonization by ST4 and were seen in travelers/foreigners. Two and three human cases of ST2 and ST3, respectively, were also detected. Subtypes 1, 2, and 3 were detected in 3/21 wastewater samples, suggesting local endemicity of these E. polecki subtypes; interestingly, ST4 was not detected in wastewater. In conclusion, the current PCR assay enables simple and cost-effective screening of fecal and wastewater samples for E. polecki Human cases of E. polecki appear to involve primarily ST4, while E. polecki detected in wastewater may be primarily of animal origin.

Stability and resilience of the intestinal microbiota in children in daycare - a 12 month cohort study.

BACKGROUND: We performed a 12-month cohort study of the stability and resilience of the intestinal microbiota of healthy children in daycare in Denmark in relation to diarrheal events and exposure to known risk factors for gastrointestinal health such as travelling and antibiotic use. In addition, we analyzed how gut microbiota recover from such exposures. RESULTS: We monitored 32 children in daycare aged 1-6 years. Fecal samples were submitted every second month during a one-year observational period. Information regarding exposures and diarrheal episodes was obtained through questionnaires. Bacterial communities were identified using 16S rRNA gene sequencing. The core microbiota (mean abundance > 95%) dominated the intestinal microbiota, and none of the tested exposures (diarrheal events, travel, antibiotic use) were associated with decreases in the relative abundance of the core microbiota. Samples exhibited lower intra-individual variation than inter-individual variation. Half of all the variation between samples was explained by which child a sample originated from. Age explained 7.6-9.6% of the variation, while traveling, diarrheal events, and antibiotic use explained minor parts of the beta diversity. We found an age-dependent increase of alpha diversity in children aged 1-3 years, and while diarrheal events caused a decrease in alpha diversity, a recovery time of 40-45 days was observed. Among children having had a diarrheal event, we observed a 10x higher relative abundance of Prevotella. After travelling, a higher abundance of two Bacteroides species and 40% less Lachnospiraceae were seen. Antibiotic use did not correlate with changes in the abundance of any bacteria. CONCLUSION: We present data showing that Danish children in daycare have stable intestinal microbiota, resilient to the exposures investigated. An early age-dependent increase in the diversity was demonstrated. Diarrheal episodes decreased alpha diversity with an estimated recovery time of 40-45 days.

Evaluating rodent experimental models for studies of Blastocystis ST1.

Blastocystis is a common inhabitant of the human gut, colonizing at least one billion people at a prevalence ranging from <10% to 100% in healthy human populations globally. The majority of carriers remain asymptomatic, suggesting that Blastocystis is largely a commensal, though Blastocystis has also been implicated in disease in some people. However, there are no in vivo model systems in which to experimentally test the impact of Blastocystis on mammalian hosts and the gut ecosystem and determine which factors underlie these variable clinical outcomes. We evaluated a rat model for sustaining of a human-derived Blastocystis ST1 and assess colonization success and longevity. Because of the broad host range of Blastocystis, we compared the rat with three other rodent species to establish the reproducibility of our method. Blastocystis was introduced by esophageal gavage and colonization success evaluated by Blastocystis culture. Culture was also used to determine that all animals were negative prior to colonization and negative controls remain Blastocystis-free. In this study, Blastocystis ST1 established in 100% of the outbred rats (Rattus norvegicus) and gerbils (Meriones unguiculatus) challenged. Rats were colonized asymptomatically for more than one year, but Blastocystis ST1 was not transmitted between rats. Mus musculus strain CD1 and Mastomys coucha were not susceptible to Blastocystis ST1. Thus, rats appear to be a suitable in vivo model for studies of Blastocystis ST1, as do gerbils though testing was less extensive. This work lays the foundation for experimental work on the role of Blastocystis in health and disease.

Blastocystis in Health and Disease: Are We Moving from a Clinical to a Public Health Perspective?

Blastocystis is a genus of common single-celled intestinal parasitic protists with an unsettled role in human health and disease. Being a stable component of intestinal microbiota, once established, the Blastocystis parasite appears more common in healthy individuals than in patients with infectious, functional, or inflammatory bowel disease. Recent data suggest that the parasite is associated with certain gut microbiota profiles and health indices. Convincing data and tools differentiating asymptomatic colonization from infection are yet to be demonstrated. Although the parasite may elicit disease under certain circumstances, the focus on Blastocystis may be shifting from a clinical to a public health perspective.

The prevalence of intestinal parasites is not greater among individuals with irritable bowel syndrome: a population-based case-control study.

BACKGROUND & AIMS: The parasites Dientamoeba fragilis and Blastocystis have been detected in feces from patients with irritable bowel syndrome (IBS), therefore these parasites may be involved in IBS pathogenesis. We proposed that a higher prevalence of the parasites in IBS subjects compared with asymptomatic controls would support such a mechanism. We aimed to determine the prevalence of these parasites in IBS subjects (cases) and controls and to identify risk factors associated with parasite carriage. METHODS: We performed a population-based, case-control study of an adult population from an internet-based research institute in Denmark. In January 2010, subjects completed a questionnaire based on the Rome III criteria for IBS and answered questions on factors associated with parasite carriage. Respondents (n = 483) were asked to submit fecal samples for parasite testing; samples were analyzed from 124 cases and 204 controls. RESULTS: A greater proportion of controls than cases carried the parasites (50% vs 36%; P = .01). D fragilis was detected in a greater proportion of fecal samples from controls than cases (35% vs 23%; P = .03), as was Blastocystis (22% of controls vs 15% of cases; P = .09), and a greater percentage of controls carried more than 1 species of parasite (16% of controls vs 8% of cases; P = .05). D fragilis infection was associated with having children 5 to 18 years old in the household and Blastocystis infection was associated with high income (≥600,000 Danish Kroner/y, approximately $100,000 US dollars/y), no animals in the household, and drinking bottled water. CONCLUSIONS: D fragilis and Blastocystis were detected in a greater proportion of fecal samples from the asymptomatic background population in Denmark than from subjects with IBS symptoms. These findings indicate that these parasites are not likely to have a direct role in the pathogenesis of IBS. Longitudinal studies are required to understand their role in gastrointestinal health.

Development and Application of a Blastocystis Subtype-Specific PCR Assay Reveals that Mixed-Subtype Infections Are Common in a Healthy Human Population.

The human gut is host to a diversity of microorganisms, including the single-celled microbial eukaryote Blastocystis. Research has shown that most carriers host a single Blastocystis subtype (ST), which is unusual given the considerable within-host species diversity observed for other microbial genera in this ecosystem. However, our limited knowledge of both the incidence and biological significance of Blastocystis diversity within hosts (i.e., so-called mixed infections) is likely due to problems with existing methodologies. Here, we developed and applied Blastocystis ST-specific PCRs for the investigation of the most common subtypes of Blastocystis (ST1 to ST4) to a healthy human cohort (n = 50). We detected mixed infections in 22% of the cases, all of which had been identified as single-ST infections in a previous study using state-of-the-art methods. Our results show that certain STs occur predominantly as either single (ST3 and 4) or mixed (ST1) infections, which may reflect inter alia transient colonization patterns and/or cooperative or competitive interactions between different STs. Comparative analyses with other primers that have been used extensively for ST-specific analysis found them unsuitable for detection of mixed- and, in some cases, single-ST infections. Collectively, our data shed new light on the diversity of Blastocystis within and between human hosts. Moreover, the development of these PCR assays will facilitate future work on the molecular epidemiology and significance of mixed infections in groups of interest, including health and disease cohorts, and also help identify sources of Blastocystis transmission to humans, including identifying potential animal and environmental reservoirs.

Metronidazole therapy for treating dientamoebiasis in children is not associated with better clinical outcomes: a randomized, double-blinded and placebo-controlled clinical trial.

BACKGROUND: There is a paucity of evidence documenting the pathogenicity of Dientamoeba fragilis, an intestinal protozoan common in children. As case reports on successful treatment are numerous, many authors advocate treatment, despite no placebo-controlled trials being available. Metronidazole is often used for treatment, though eradication rates are relatively low (60%-80%). In the present study we determined the clinical and microbiological efficacy of metronidazole in Danish children. METHODS: In this parallel placebo-controlled double-blinded trial, children aged 3-12 years with >4 weeks of gastrointestinal symptoms were allocated using block randomization in a 1:1 ratio to a 10-day course of oral metronidazole or placebo. Primary outcome was change in level of gastrointestinal symptoms, measured on a visual-analog-scale (VAS), and secondary outcome was eradication of D. fragilis infection. Participants, caregivers, investigators, and sponsor were all blinded to group assignment. The trial was registered with clinicaltrials.gov (NCT01314976) prior to start. RESULTS: Of 96 participants, 48 were allocated to the metronidazole and placebo group each. Mean VAS change from pre- to post-treatment did not differ significantly (P = .8) between the metronidazole (-1.8 CI, [-2.5, -1.1]) and the placebo group (-1.6 CI, [-2.3, -.9]). Eradication of D. fragilis was significantly greater in the metronidazole group, although it declined rapidly from 62.5% 2 weeks after end of treatment to 24.9% 8 weeks after end of treatment. CONCLUSIONS: These findings do not provide evidence to support routine metronidazole treatment of D. fragilis positive children with chronic gastrointestinal symptoms. Study funded by Statens Serum Institut. CLINICAL TRIALS REGISTRATION: Trial was registered with clinicaltrials.gov (NCT01314976).

Current status of epidemiology and diagnosis of human sarcocystosis.

Species of Sarcocystis are Apicomplexan parasites requiring intermediate and definitive hosts to complete their life cycle. Humans are one of many natural host species and may serve as both intermediate and definitive hosts. However, the extent and public health significance of human Sarcocystis infection are incompletely known. In this minireview, we provide an update on the epidemiology and diagnosis of human sarcocystosis and propose some tools that could contribute to a better understanding of the clinical significance and epidemiology of Sarcocystis infections.

High applicability of a novel method for gp60-based subtyping of Cryptosporidium meleagridis.

Cryptosporidium meleagridis is a common cause of cryptosporidiosis in avian hosts and the third most common species involved in human cryptosporidiosis. Sequencing of the highly polymorphic 60-kDa glycoprotein (gp60) gene is a frequently used tool for investigation of the genetic diversity and transmission dynamics of Cryptosporidium. However, few studies have included gp60 sequencing of C. meleagridis. One explanation may be that the gp60 primers currently in use are based on Cryptosporidium hominis and Cryptosporidium parvum sequence data, potentially limiting successful amplification of the C. meleagridis gp60 gene. We therefore aimed to design primers for better gp60 subtyping of C. meleagridis. Initially, ∼1,440 bp of the gp60 locus of seven C. meleagridis isolates were amplified using primers flanking the open reading frame. The obtained sequence data (∼1,250 bp) were used to design primers for a nested PCR targeting C. meleagridis. Twenty isolates (16 from human and 4 from poultry) previously identified as C. meleagridis by analysis of small subunit (SSU) rRNA genes were investigated. Amplicons of the expected size (∼900 bp) were obtained from all 20 isolates. The subsequent sequence analysis identified 3 subtype families and 10 different subtypes. The most common subtype family, IIIb, was identified in 12 isolates, represented by 6 subtypes, 4 new and 2 previously reported. Subtype family IIIe was found in 3 isolates represented by 3 novel, distinct subtypes. Finally, IIIgA31G3R1 was found in 1 human isolate and 4 poultry isolates, all originating from a previously reported C. meleagridis outbreak at a Swedish organic farm.

Prevalence, incidence, and risk factors of intestinal parasites in Danish primary care patients with irritable bowel syndrome.

The gut microbiota may be involved in the aetiopathogenesis of irritable bowel syndrome (IBS). We studied the role of intestinal parasites by describing the epidemiology and risk factors for infection in primary care patients aged 18-50 y with IBS. One hundred and thirty-eight patients at baseline and 78/116 patients returning 1 y later, submitted faecal samples that were examined by microscopy, culture for Blastocystis, and real-time PCR for Dientamoeba fragilis, Entamoeba (dispar and histolytica), Cryptosporidium spp., and Giardia intestinalis. Overall, 42-45% of patients harboured intestinal parasites (baseline and follow-up, respectively): D. fragilis carriage was 35-41%; Blastocystis 14-20%. Incidence rates for D. fragilis and Blastocystis were 10 and 4 per 100 person-y, respectively. Blastocystis carriage increased the odds for carrying D. fragilis. Clinical comparisons showed D. fragilis to be associated with a low frequency of defecation. Further, D. fragilis was associated with having children aged 5-18 y and Blastocystis with increasing age.