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Parasitology Research Apr 2018It remains controversial whether Dientamoeba fragilis is a commensal parasite or a pathogen. The objective of this systematic review was to establish the strength of the... (Review)
Review
It remains controversial whether Dientamoeba fragilis is a commensal parasite or a pathogen. The objective of this systematic review was to establish the strength of the evidence that Dientamoeba fragilis would cause diarrhea. A search was performed for studies that reported either the association between D. fragilis detection in stools and diarrhea or diarrhea outcomes with D. fragilis therapy or challenge. Data from seven studies of specific populations reported that 22% had D. fragilis in stools of which only 23% had diarrhea. Eleven studies of stool samples submitted to laboratories reported that 4.3% of individuals had D. fragilis of which 54% had diarrhea. Twelve studies reported that D. fragilis was detected from 1.6% of individuals with diarrhea and 9.6% of diarrheal stools. Five studies analyzed the prevalence of D. fragilis in individuals with and without diarrhea; the two with a statistically significant difference between groups had discordant results. The only cohort study with an appropriate control group reported diarrhea in a higher proportion of children with D. fragilis than in controls. No D. fragilis treatment studies included diarrhea as an outcome. There were only two challenge studies involving one person each. In conclusion, the evidence that D. fragilis would cause diarrhea or that treatment would hasten diarrhea resolution is inconclusive.
Topics: Child; Cohort Studies; Diarrhea; Dientamoeba; Dientamoebiasis; Feces; Humans; Prevalence
PubMed: 29404747
DOI: 10.1007/s00436-018-5771-4 -
Parasitology Aug 2019Dientamoeba fragilis (D. fragilis) is an intestinal parasite frequently detected in humans with abdominal pain and diarrhoea, but it is also commonly found in... (Review)
Review
Dientamoeba fragilis (D. fragilis) is an intestinal parasite frequently detected in humans with abdominal pain and diarrhoea, but it is also commonly found in asymptomatic subjects. Hence its clinical relevance is often disputed. The introduction of polymerase chain reaction (PCR) is a versatile and sensitive diagnostic technique for the detection of intestinal parasites, and in some Western world countries PCR has almost completely replaced microscopic diagnostics. PCR has however resulted in an increase in the number of D. fragilis-positive patients. The disputed pathogenic nature of this intestinal parasite and an apparent increase in the incidence of patients with positive PCR results have renewed the discussions between clinicians and microbiologists on how to deal with an infected patient. Moreover, treatment guidelines differ throughout the world which makes it difficult for clinicians to choose an optimal therapeutic regimen.AimTo summarize and discuss the current knowledge on the pathogenicity, best diagnostic approach, treatment and follow-up of children and adults infected with D. fragilis.
Topics: Adult; Animals; Antiprotozoal Agents; Child; Diarrhea; Dientamoeba; Dientamoebiasis; Feces; Humans; Practice Guidelines as Topic
PubMed: 30165915
DOI: 10.1017/S0031182018001385 -
Acta Tropica Aug 2018The flagellated protozoan Dientamoeba fragilis is one of the most commonly diagnosed parasite of the human gut, with a global distribution. Nevertheless, essential... (Review)
Review
The flagellated protozoan Dientamoeba fragilis is one of the most commonly diagnosed parasite of the human gut, with a global distribution. Nevertheless, essential aspects of its biology remain incompletely understood or controversial, most notably life cycle, host range, transmission routes and the ability to cause disease. Molecular epidemiologic studies are also scarce, and limited by the lack of informative genotyping tools. To date, two D. fragilis genotypes (1 and 2) are recognized, with a strong predominance of genotype 1 in both humans and few animal hosts. Recent studies have shown that a very low level of genetic variability characterizes parasite isolates collected in various geographic areas and from both symptomatic and asymptomatic cases. This has raised the hypothesis D. fragilis may be a clonal organism. The recent availability of transcriptome data should greatly assist the development of markers useful to understand genetic diversity of D. fragilis at the population level.
Topics: Animals; DNA, Protozoan; Dientamoeba; Dientamoebiasis; Genetic Variation; Genotype; Humans; Molecular Epidemiology; Prevalence
PubMed: 28697994
DOI: 10.1016/j.actatropica.2017.06.029 -
Clinical Microbiology Reviews Jul 2016Dientamoeba fragilis is a protozoan parasite of the human bowel, commonly reported throughout the world in association with gastrointestinal symptoms. Despite its... (Review)
Review
Dientamoeba fragilis is a protozoan parasite of the human bowel, commonly reported throughout the world in association with gastrointestinal symptoms. Despite its initial discovery over 100 years ago, arguably, we know less about this peculiar organism than any other pathogenic or potentially pathogenic protozoan that infects humans. The details of its life cycle and mode of transmission are not completely known, and its potential as a human pathogen is debated within the scientific community. Recently, several major advances have been made with respect to this organism's life cycle and molecular biology. While many questions remain unanswered, these and other recent advances have given rise to some intriguing new leads, which will pave the way for future research. This review encompasses a large body of knowledge generated on various aspects of D. fragilis over the last century, together with an update on the most recent developments. This includes an update on the latest diagnostic techniques and treatments, the clinical aspects of dientamoebiasis, the development of an animal model, the description of a D. fragilis cyst stage, and the sequencing of the first D. fragilis transcriptome.
Topics: Animals; Dientamoeba; Dientamoebiasis; Disease Models, Animal; Humans; Intestines; Life Cycle Stages; Phylogeny
PubMed: 27170141
DOI: 10.1128/CMR.00076-15 -
Journal of Clinical Microbiology Sep 2016Dientamoeba fragilis is a single-celled protozoan, closely related to the trichomonads. Reported worldwide as causing human gastrointestinal symptoms, D. fragilis is... (Review)
Review
Dientamoeba fragilis is a single-celled protozoan, closely related to the trichomonads. Reported worldwide as causing human gastrointestinal symptoms, D. fragilis is very common and is second only to Blastocystis spp. Dientamoebiasis equals or exceeds the incidence of giardiasis. This minireview includes diagnostic options, clinical relevance, therapy, an animal model, the confirmed cyst stage, and sequencing data. The development of a rodent model, fulfilling Koch's postulates, and the confirmation of a cyst stage have clarified transmission routes, including fecal-oral transmission. The prevalence of D. fragilis varies between 0% to over 82%; results depend on the geographic location, group studied, and diagnostic methods used.
Topics: Animals; Antiprotozoal Agents; Dientamoeba; Dientamoebiasis; Disease Models, Animal; Humans; Incidence; Intestinal Diseases, Parasitic; Neglected Diseases; Prevalence
PubMed: 27053676
DOI: 10.1128/JCM.00400-16 -
Travel Medicine and Infectious Disease 2022
Topics: Dientamoeba; Feces; Humans; Pruritus
PubMed: 35364300
DOI: 10.1016/j.tmaid.2022.102319 -
British Journal of Biomedical Science 1999Dientamoeba fragilis is a pathogenic protozoan parasite with a world-wide distribution. Although originally described as an amoeboid organism, it has been reclassified... (Review)
Review
Dientamoeba fragilis is a pathogenic protozoan parasite with a world-wide distribution. Although originally described as an amoeboid organism, it has been reclassified as a flagellate, on the basis of a number of electron microscopic and immunological findings. Except for its lack of a flagellum, D. fragilis closely resembles Histomonas and Trichomonas. Interestingly, a resistant cyst stage has not been demonstrated and it is unlikely that its trophozoites can survive successfully outside the human host. As a consequence of its higher than anticipated coincidence of infection with Enterobius vermicularis, transmission may occur via ova of this pinworm. D. fragilis infection may be acute or chronic, and has been reported in both children and adults. The most common clinical symptoms include abdominal pain, persistent diarrhoea, loss of appetite, weight loss and flatulence. Occasionally, eosinophilia, urticaria and pruritus have been described. Demonstration of the characteristic nuclear structure of D. fragilis, needed for a definitive diagnosis, cannot be achieved in unstained faecal material; therefore, permanently stained smears are essential. Treatment is recommended in symptomatic cases, and iodoquinol, tetracycline and metronidazole have been used successfully.
Topics: Animals; Dientamoeba; Dientamoebiasis; Humans
PubMed: 10795375
DOI: No ID Found -
Trends in Parasitology Mar 2014Recently, conflicting evidence has been published on the mode of transmission of the trichomonad Dientamoeba fragilis. Detection of D. fragilis DNA inside Enterobius... (Review)
Review
Recently, conflicting evidence has been published on the mode of transmission of the trichomonad Dientamoeba fragilis. Detection of D. fragilis DNA inside Enterobius vermicularis eggs agrees with the prediction of Dobell in 1940 that the eggs of a nematode act as a vector for transmission. However, the identification of a cyst stage of D. fragilis in the stool of rodents infected with a human isolate has also been reported, and this implies a life cycle similar to those of most other intestinal protistan parasites. Herein we discuss the recent data, identify gaps in the experimental evidence, and propose a method for determining which view of the life cycle of this organism is correct.
Topics: Animals; Dientamoeba; Dientamoebiasis; Disease Vectors; Enterobius; Feces; Humans; Life Cycle Stages; Rodentia
PubMed: 24492020
DOI: 10.1016/j.pt.2014.01.005 -
Parasitology International Feb 2021Dientamoeba fragilis is an intestinal protozoan, an inhabitant of the human gastrointestinal tract, with a worldwide distribution. The reported prevalence of D. fragilis...
Dientamoeba fragilis is an intestinal protozoan, an inhabitant of the human gastrointestinal tract, with a worldwide distribution. The reported prevalence of D. fragilis varies worldwide in different populations between 0.3% and 82.9%, and its role as a pathogen is still unclear. The parasite has been identified in the faeces of asymptomatic patients and with different acute and chronic symptoms, like abdominal pain, diarrhoea, flatulence, nausea and vomiting. The aims of this study were to evaluate the prevalence of D. fragilis in the North-East of Italy, and the clinical improvement of symptoms after recommended treatment with paromomycin or metronidazole. Furthermore, a literature review of D. fragilis prevalence studies in Italy was carried out to show the Italian situation. Of 575 enrolled people, 85 (14.8%) were positive for D. fragilis. The most prevalent symptoms were abdominal pain 28.2%, anal itching 27.1%, watery diarrhoea 18.8%, meteorism 16.5% and nausea/lack of appetite 14.1%. The high rate of anal itching was unexpected, because it wasn't a common symptom. 32 patients were co-infected with B. hominis (37.7%) and three with G. lamblia (3.5%). Our study showed paromomycin had a high efficacy for treatment of D. fragilis infections 100.0% (45/45), while caution must be used when using metronidazole 53.3% (24/40). We recommend paromomycin for empirical treatment, given its great effectiveness in our population.
Topics: Adolescent; Adult; Aged; Antiprotozoal Agents; Child; Child, Preschool; Cross-Sectional Studies; Dientamoeba; Dientamoebiasis; Female; Humans; Infant; Italy; Male; Metronidazole; Middle Aged; Paromomycin; Prevalence; Young Adult
PubMed: 33137500
DOI: 10.1016/j.parint.2020.102227 -
Gut Microbes 2011Dientamoeba fragilis is a protozoan that inhabits the human gut. It is approximately 100 years since Dientamoeba's discovery and first description when it was described... (Review)
Review
Dientamoeba fragilis is a protozoan that inhabits the human gut. It is approximately 100 years since Dientamoeba's discovery and first description when it was described as a rare and harmless commensal. Since then it has struggled to gain recognition as a pathogen despite the evidence supporting its pathogenicity. Dientamoeba remains neglected, probably due to the misconceptions that it is uncommon and non-pathogenic. Usually, carriage of Dientamoeba is associated with symptoms such as abdominal pain and diarrhea. Moreover, antimicrobial therapy followed by resolution of symptoms coincides with the eradication of Dientamoeba. This manuscript reviews the scientific literature relating to Dientamoeba's prevalence and pathogenicity. While much of the evidence supporting its pathogenicity is only circumstantial, it is apparent that most researchers agree that Dientamoeba is pathogenic. Therefore, in symptomatic patients who harbor Dientamoeba and no other pathogen, Dientamoeba should be considered as the etiological agent and treated as such.
Topics: Abdominal Pain; Adolescent; Adult; Age Distribution; Animals; Carrier State; Child; Child, Preschool; Diarrhea; Dientamoeba; Dientamoebiasis; Gastrointestinal Tract; Humans; Infant; Infant, Newborn; Intestinal Diseases, Parasitic; Middle Aged; Prevalence; Sex Distribution; Young Adult
PubMed: 21637013
DOI: 10.4161/gmic.2.1.14755