First detection and molecular characterization of Dientamoeba fragilis in cattle.

Dientamoeba fragilis is a flagellated protozoan with amoeba-like morphology that inhabits the human gastrointestinal tract. It is endemic in a vast geography around the world, including developed countries. There are limited studies on non-human hosts of the parasite, and suitable hosts have not been clarified. The parasite has been detected in non-human primates, pigs, cats, dogs and rats. There is no study in the literature investigating and detecting the presence of this parasite in cattle. In this study, stool samples taken from 163 different cattle and calves from 11 different farms between March 2017 and May 2022 were examined for the detection of D. fragilis via PCR. Trichrome staining was performed on all PCR-positive samples. The isolates with the expected amplicon size were sequenced using the 18S ribosomal RNA region, and their genotypes were determined by BLAST analysis. Sequences were analysed with the most similar and reference sequences in the literature, forming a phylogenetic tree. We detected D. fragilis in 31 (19.01%) of the 163 stool samples. D. fragilis cysts/trophozoites were detected by trichrome staining method in six of 31 samples. All PCR products selected for molecular analysis from positive samples had the same nucleotide sequence. As a result of BLAST analysis, all sequences were determined to belong to D. fragilis genotype 1. This study determined for the first time that cattle are suitable hosts for D. fragilis. Furthermore, the parasite subtype we detected belongs to genotype 1, which is the most common type in humans, suggesting that the parasite may have a zoonotic character. Our result is important in terms of the epidemiology of the parasite, as the mode of transmission is controversial, and available data on its suitable hosts are limited.

Dientamoeba fragilis, the Neglected Trichomonad of the Human Bowel.

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.

Dientamoeba fragilis, One of the Neglected Intestinal Protozoa.

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.

Detection of Dientamoeba fragilis among diarrheal patients referred to Tabriz health care centers by nested PCR.

Dientamoeba fragilis is a protozoan parasite of the human large intestine which is implicated as a cause of gastrointestinal diseases. The diagnosis of this parasite in direct smear preparations is difficult due to the lack of a cyst stage. The permanent staining method is generally used for diagnosis of D. fragilis, but the technique is laborious and time consuming. The purpose of this study was to evaluate the performance of PCR for detection of D. fragilis in clinical specimen of health care center in Tabriz, northwest of Iran. Stool samples of 1000 patients were collected from different laboratories and were immediately examined via wet mount and permanent staining methods. All positive samples and 55 randomly selected negative samples were studied by PCR technique. Using direct smear examination, no positive sample was found among 1000 stool samples, whereas 21 (2.1%) positive and 26 suspicious cases were reported in stained smears. PCR screening indicated that from 21 positive cases, 17 were positive by primary PCR, whereas nested PCR detected all 21 positive cases as well as 3 new positive samples from the suspicious cases (overall 24 (2.4%) positive samples), yet all negative cases remained negative through both stages of PCR amplifications. In comparison with nested PCR (if considered as gold standard), primary PCR showed 81% sensitivity and 100% specificity and those of microscopy was determined to be 87.5% and 100%, respectively. Considering the favorable sensitivity and specificity of nested PCR and its other advantages such as relative simplicity and speed this technique is proposed for rapid diagnosis of D. fragilis in clinical samples.

Detection of Dientamoeba fragilis in patients with HIV/AIDS by using a simplified iron hematoxylin technique.

INTRODUCTION: Studies strongly indicate Dientamoeba fragilis as one of the causes of diarrhea in human immunodeficiency virus (HIV) patients. METHODS: The objective of the present study was to evaluate the prevalence of D. fragilis associated with the causes of diarrhea in 82 HIV/ AIDS patients hospitalized at the Instituto de Infectologia Emílio Ribas from September 2006 to November 2008. RESULTS: In total, 105 samples were collected from 82 patients. Unprotected sex was the most frequent cause of HIV infection (46.3%), followed by the use of injectable or non-injectable drugs (14.6%). Patients presented with viral loads of 49-750,000 copies/ mL (average: 73,849 ± 124,850 copies/mL) and CD4 counts ranging of 2-1,306 cells/mm³ (average: 159 ± 250 cells/mm³). On an average, the odds of obtaining a positive result by using the other techniques (Hoffman, Pons and Janer or Lutz; Ritchie) were 2.7 times higher than the chance of obtaining a positive result by using the simplified iron hematoxylin method. Significant differences were found between the methods (p = 0.003). CONCLUSIONS: The other techniques can detect a significantly greater amount of parasites than the simplified iron hematoxylin method, especially with respect to Isospora belli, Cryptosporidium sp., Schistosoma mansoni, and Strongyloides stercoralis, which were not detected using hematoxylin. Endolimax nana and D. fragilis were detected more frequently on using hematoxylin, and the only parasite not found by the other methods was D. fragilis.

Detection of Dientamoeba fragilis in patients with HIV/AIDS by using a simplified iron hematoxylin technique / Detecção de Dientamoeba fragilis em pacientes com HIV/AIDS utilizando a técnica de hematoxilina férrica simplificada

INTRODUCTION: Studies strongly indicate Dientamoeba fragilis as one of the causes of diarrhea in human immunodeficiency virus (HIV) patients. METHODS: The objective of the present study was to evaluate the prevalence of D. fragilis associated with the causes of diarrhea in 82 HIV/ AIDS patients hospitalized at the Instituto de Infectologia Emílio Ribas from September 2006 to November 2008. RESULTS: In total, 105 samples were collected from 82 patients. Unprotected sex was the most frequent cause of HIV infection (46.3%), followed by the use of injectable or non-injectable drugs (14.6%). Patients presented with viral loads of 49-750,000 copies/ mL (average: 73,849 ± 124,850 copies/mL) and CD4 counts ranging of 2-1,306 cells/mm³ (average: 159 ± 250 cells/mm³). On an average, the odds of obtaining a positive result by using the other techniques (Hoffman, Pons and Janer or Lutz; Ritchie) were 2.7 times higher than the chance of obtaining a positive result by using the simplified iron hematoxylin method. Significant differences were found between the methods (p = 0.003). CONCLUSIONS: The other techniques can detect a significantly greater amount of parasites than the simplified iron hematoxylin method, especially with respect to Isospora belli, Cryptosporidium sp., Schistosoma mansoni, and Strongyloides stercoralis, which were not detected using hematoxylin. Endolimax nana and D. fragilis were detected more frequently on using hematoxylin, and the only parasite not found by the other methods was D. fragilis.

INTRODUÇÃO: Estudos indicam a Dientamoeba fragilis como uma das causas de diarréia em pacientes com HIV/AIDS. MÉTODOS: Os objetivos deste estudo foram avaliar a prevalência de D. fragilis associadas com as causas de diarréia em pacientes com HIV/AIDS internados no Instituto de Infectologia Emílio Ribas (IIER). Oitenta e dois pacientes internados no IIER fizeram parte deste estudo de setembro de 2006 a novembro de 2008. RESULTADOS: No total, 105 amostras foram coletadas a partir de 82 pacientes neste estudo. Sexo desprotegido foi à causa mais frequente para a aquisição do HIV (46,3%), seguido pelo uso de drogas injetáveis ou não injetáveis (14,6%). Relações heterossexuais foram os mais citados (19,5%). Pacientes apresentaram carga viral entre 49 e 750.000 (média de 7.849 ± 124.850) e CD4 variando de 2 a 1.306 (média de 159 ± 250). Em média, as chances de um resultado ser positivo com outras técnicas foram 2,7 vezes maiores do que a chance de um resultado positivo com hematoxilina férrica simplificada. Foram encontradas diferenças significativas entre os métodos (p=0,003). CONCLUSÕES: As outras técnicas são capazes de detectar uma quantidade significativa maior de parasitas em comparação com a hematoxilina férrica simplificada, especialmente em relação à Isospora belli, Cryptosporidium sp., Schistossoma mansoni e Strongyloides stercoralis que não foram encontrados utilizando a hematoxilina e a Endolimax nana e D. fragilis foram mais detectados pela hematoxilina férrica simplificada, principalmente a D. fragilis que não foi detectada pelos outros métodos.

Direct amplification and genotyping of Dientamoeba fragilis from human stool specimens.

Dientamoeba fragilis is a globally occurring parasite that has been recognized as a causative agent of gastrointestinal symptoms. A single-round PCR was developed to detect D. fragilis DNA directly from human stool samples. The genetic diversity of D. fragilis from 93 patients and 6 asymptomatic carriers was examined by PCR followed by restriction fragment length polymorphism and sequencing of part of the small-subunit rRNA gene. The data show that D. fragilis sequences can be studied directly from fecal specimens despite the absence of a cyst stage and without the need for prior culturing. In addition, the results suggest strongly that D. fragilis shows remarkably little variation in its small-subunit rRNA gene.

[Dientamoeba fragilis: is it really fragile? Approach to specimen handling and rapid microscopic diagnosis]. / Dientamoeba fragilis: è realmente fragile? Approccio al trattamento del campione e diagnosi rapida al microscopio.

Dientamoeba fragilis is a pathogenic protozoan parasite with a world-wide distribution. Interestingly, a resistant cyst stage has not been demonstrated and it is still an unsolved problem how this parasite can survive successfully outside the human host. D. fragilis was found in 2% of approximately 2500 individuals unselected who submitted stools for parasitological examination during 2001 in Padua (Italy). The goal of this study was to detect the protozoan stages and the duration of persistence of this protozoa in faeces stored in different environmental conditions. The trophozoites of D. fragilis were detected up to 60 days after the collection of the faeces stored at 4 degrees C and Giemsa stained. The laboratory detection rate of the organism is greatly enhanced by use of preservative to fix stool specimens immediately after passage. Alternatively, a microscopic observation of the collected stool has to be performed immediately after passage followed by examination of permanently-stained smears. Demonstration of the charateristic "golf-club" and "acanthopodia-like" structures in unstained fixed faecal material by direct microscopy (400x) are suitable for a rapid identification of D. fragilis.

Dientamoeba fragilis: the unflagellated human flagellate.

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.

Dientamoeba fragilis masquerading as allergic colitis.

BACKGROUND: Dientamoeba fragilis is a rare cause of chronic infectious diarrhea and colitis in children. METHODS: Review of the clinical manifestations, diagnostic methods, and clinical course of D. fragilis infection in our hospital. RESULTS: Eleven pediatric patients are discussed, seven of whom had a history of recent travel. Clinical manifestations of infectious diarrhea included anorexia, intermittent vomiting, abdominal pain, and diarrhea, ranging from 1 to 100 weeks in duration. Peripheral eosinophilia was present in seven patients. One patient with well-documented bovine protein allergy had intermittent episodes of diarrhea and abdominal pain, despite an appropriate elimination diet. Eosinophilic colitis documented by colonoscopy, was due to D. fragilis. Metronidazole was effective in treating five patients, and iodoquinol was effective in treating four others. CONCLUSIONS: D. fragilis should be included in the differential diagnosis of chronic diarrhea and eosinophilic colitis. The identification of this pathogen requires clinical awareness of epidemiologic risk factors and presenting complaints, as well as the laboratory staining procedures essential to its proper identification.

Dientamebíase: relato de dois casos / Dientamoebiasis: a report of two cases

Os autores, após breve atualizaçäo sobre a Dientamoeba fragilis, relatam dois casos de infecçäo isolada da parasitose ocorridos no Recife, Pernambuco

Colitis due to Dientamoeba fragilis.

Clinical reports have suggested that the parasite Dientamoeba fragilis may be a cause of acute and chronic colitis in children and adults. The mechanism by which this parasite produces colitis has not been determined. The clinical findings in this case report suggest that D. fragilis causes colitis through an invasive ulcerating process.

Dientamoeba fragilis. An intestinal pathogen in children?

A retrospective study was conducted of 35 children in whom Dientamoeba fragilis was the only parasite found in the gastrointestinal (GI) tract. Gastrointestinal symptoms were present in 32 (91%) of these children; diarrhea was the most common finding in patients with acute symptoms, whereas abdominal pain was more common in children with chronic symptoms. Peripheral eosinophilia was present in half of the children examined and was statistically more significant in patients with D fragilis than in a control group of children admitted for elective surgery. Therapy with diiodohydroxyquin or metronidazole was effective; children's symptoms were diminished or were eliminated on follow-up evaluation after treatment. From this association between therapy and symptomatic relief, D fragilis should be considered pathogenic in those children with GI symptoms.