A cross-sectional survey of Blastocystis sp. and Dientamoeba fragilis in non-human primates and their caregivers in Czech zoos.

Intestinal protists in the gut microbiome are increasingly studied, but their basic epidemiology is not well understood. We explored the prevalence, genetic diversity, and potential zoonotic transmission of two protists colonizing the large intestine - Blastocystis sp. and Dientamoeba fragilis - in 37 species of non-human primates (NHPs) and their caregivers in six zoos in the Czech Republic. We analyzed 179 fecal samples (159 from NHPs, 20 from humans) by qPCR. Blastocystis sp. was detected in 54.7% (98/179) of samples, in 24 NHP species and in 57.2% of NHP samples (prevalence ranged between 36 and 80%), and in 35% of human samples (prevalence ranged between 0 and 67%). Using next generation amplicon sequencing, nine Blastocystis subtypes (ST1-ST5, ST7, ST8, and two novel subtypes) were identified. The two new Blastocystis subtypes (named ST47 and ST48) were described using Nanopore sequencing to produce full-length reference sequences of the small subunit ribosomal RNA gene. Some subtypes were shared between NHPs and their caregivers, suggesting potential zoonotic transmission. Mixed subtype colonization was frequently observed, with 52% of sequenced samples containing two or more subtypes. Dientamoeba was found only in NHPs with a prevalence of 6%. This study emphasizes the critical role of molecular diagnostics in epidemiological and transmission studies of these protists and calls for further research to better understand their impact on public health.

The Low Genetic Diversity of Dientamoeba fragilis Isolates in Southwest Turkey and Analysis of Clinical Findings.

PURPOSE: Dientamoeba fragilis (D. fragilis) is a common intestinal protozoan with a global distribution. In the present study, we aimed to determine genetic diversity of D. fragilis isolates with multilocus sequence typing (MLST) in the southwest of Turkey and analyse the clinical findings. MATERIALS AND METHODS: The study included faecal samples from 200 individuals in Aydin, Turkey. The positivity of D. fragilis was determined with 18 S rRNA gene-based PCR assay. Six nested-PCR reactions were set to amplify partial D. fragilis housekeeping genes in the positive samples. The sequences were aligned with the references from GenBank to detect nucleotide polymorphisms and haplotypes. Additionally, the clinical findings and demographic characteristics of patients were statistically analysed between D. fragilis-infected and non-infected cases. RESULTS: The positivity of D. fragilis was 16% (32 out of 200 cases) with 18 S rRNA based-PCR, and all were classified as "genotype 1". The analysis of six MLST loci revealed different haplotypes only at one locus; the remaining five loci exhibited no polymorphisms. The haplotypes in the present study were identical to at least one previously reported reference, except the locus "large subunit of RNA polymerase II" locus. There were no significant differences in any of the clinical findings or demographic characteristics between the infected and non-infected groups. CONCLUSIONS: Our study revealed a low genetic diversity of D. fragilis isolates from Turkey, like other countries including Italy, Denmark, the UK, Australia, and Brazil. The high degree of sequence similarity in housekeeping genes indicated the clonal distribution of D. fragilis.

No evidence of pathogenicity of Dientamoeba fragilis following detection in stools: A case-control study.

Dientamoeba fragilis is a ubiquitous intestinal parasite with detection in the stools that has become increasingly frequent following the advent of PCR as a routine screening tool. However, the pathogenicity of this parasite is still much debated. In order to assess the potentially pathogenic nature of this protozoan, a retrospective case-control study was carried out between January and December 2020 on patients from Toulouse University Hospital, with the aim of evaluating the potential clinical effects and changes in laboratory parameters linked to the presence and load of D. fragilis in stools. After matching age, sex and mode of care (consultation or hospitalisation), no significant difference was observed in the frequency of clinical signs between the 36 patients who tested positive for Dientamoeba fragilis PCR in their stools and the 72 control patients who were PCR negative for this protozoan. The presence of D. fragilis in the faeces was not associated with changes in laboratory parameters. Furthermore, a high digestive load of D. fragilis had no identifiable impact on clinical and laboratory parameters. Only the concomitant presence of Blastocystis sp. in stools was significantly more frequent in the D. fragilis group (uni- and multivariate analysis). Finally, this study showed no significant difference in clinical or laboratory signs between patients carrying Dientamoeba fragilis and the control group, regardless of the intestinal parasite load, suggesting that D. fragilis could be considered a commensal of the digestive tract.

Title: Aucune preuve de la pathogénicité de Dientamoeba fragilis détecté dans les selles : une étude cas-témoins. Abstract: Dientamoeba fragilis est un parasite digestif ubiquitaire dont la détection dans les selles est devenue de plus en plus fréquente avec l'avènement de la PCR comme outil de détection de routine. Cependant, la pathogénicité de ce parasite est encore très discutée. Afin d'évaluer le caractère potentiellement pathogène de ce protozoaire, une étude rétrospective cas-témoins a été réalisée entre janvier et décembre 2020 sur des patients du CHU de Toulouse, dans le but d'évaluer les effets cliniques et biologiques potentiels associés à la présence et à la charge de D. fragilis dans les selles. Après appariement sur l'âge, le sexe et le mode de prise en charge (consultation ou hospitalisation), aucune différence significative n'a été observée dans la fréquence des signes cliniques entre les 36 patients testés positifs pour la PCR de Dientamoeba fragilis dans les selles et les 72 patients témoins avec une PCR négative pour ce protozoaire. La présence de D. fragilis dans les selles n'était pas associée à des modifications des paramètres biologiques. De plus, une charge digestive élevée de D. fragilis n'avait pas d'impact identifiable sur les paramètres cliniques et biologiques. Seule la présence concomitante de Blastocystis sp. dans les selles était significativement plus fréquente dans le groupe D. fragilis (analyse uni- et multivariée). En conclusion, cette étude n'a pas montré de différence significative concernant les signes cliniques ou biologiques entre les patients porteurs de Dientamoeba fragilis et le groupe témoin, quelle que soit la charge parasitaire digestive, indiquant que D. fragilis pourrait être considéré comme un commensal du tube digestif.

A tale of two studies: is peripheral eosinophilia associated with Dientamoeba fragilis detection in adult stool samples?

The protozoan parasite Dientamoeba fragilis is a frequently isolated stool organism and postulated cause of gastrointestinal symptoms. Peripheral blood eosinophilia has been described. This is the first study amongst the Australasian adult population to assess the relationship between organism detection and eosinophilia. A case-control study took place over 7 years at a single Sydney laboratory site, evaluating patients with D. fragilis identified on stool using real-time PCR with a recent full blood count, to control groups with Giardia spp. and sequential negatives with neither organism. A nested study compared those with microscopic evidence of D. fragilis as a marker of disease burden, to molecular diagnosis alone. Sixty-four D. fragilis, 30 Giardia spp., and 94 sequential controls were enrolled. Only 60.1% of samples were preserved in sodium acetate-acetic acid formalin (SAF) fixative, indication mostly not documented. The major co-organism detected amongst all participants was Blastocystis sp., particularly in the D. fragilis cohort (37.2%). The most common pathogen amongst sequential controls was Campylobacter spp. (7.4%). Patients with D. fragilis were more likely (12.5%) to have a clinically significant eosinophilia (>0.5×109/L) compared to those with Giardia spp. (3.3%) or sequential controls (4.3%) (p=0.03). A significant difference was also noted in the overall median eosinophil count of those with D. fragilis versus all controls (0.2 vs 0.1×109/L, p=0.01); however, this was within the reference interval (where up to >0.5×109/L is accepted in healthy individuals within a typical population). No eosinophil difference was found between those with molecular versus additional microscopic detection of D. fragilis (0.1 vs 0.1×109/L). These results support an association between the identification of clinically significant peripheral blood eosinophilia and D. fragilis presence, which may impact the diagnostic approach to the patient with unexplained eosinophilia. Further prospective trials may help assess any significance further and the implication of co-carriage with other enteric organisms. The importance of clinical indication and need for appropriate fixative media in diagnostic parasitology are also highlighted.

Molecular detection and genotyping of Dientamoeba fragilis and Blastocystis sp. in housefly Musca domestica (Diptera: Muscidae): first report for Dientamoeba fragilis.

Dientamoeba fragilis and Blastocystis sp. are single-celled protozoan parasites of humans and animals. Although they are found in the intestines of healthy hosts, the pathogenicity of them is still unclear. To date, there is no report on D. fragilis and only two studies (without subtyping) on the occurrence of Blastocystis sp. in Musca domestica. In this study, fly samples were collected from livestock farms and their surroundings in the Kirsehir province (Central Anatolia Region) of Türkiye from May to August 2023. A total of 150 microscopically identified M. domestica samples were analyzed for the detection of D. fragilis and Blastocystis sp. molecularly. The overall prevalence of Blastocystis sp. and D. fragilis in M. domestica was determined to be 3.3% (5/150) and 8.0% (12/150), respectively. The SSU rRNA gene sequences of the isolates indicated genotype 1 of D. fragilis. Eleven isolates were identical and represented a single isolate (KAU-Dfrag1). BLAST analysis of KAU-Dfrag1 indicated identity with the isolates reported from humans, cattle, sheep, and budgerigars. The other isolate (KAU-Dfrag2) was polymorphic at two nucleotides from KAU-Dfrag1 and three nucleotides from known genotypes from GenBank and represented a variant of genotype 1. The Blastocystis sp. isolates were found to be identical and represent a single genotype (KAU-Blast1). BLAST analysis revealed that the KAU-Blast1 genotype belonged to the potentially zoonotic subtype 5 (ST5) and exhibited the highest genetic identity (ranging from 99.4 to 99.6%) with pigs, cattle, and sheep from different countries. Our study provides the first data on the molecular prevalence, epidemiology, and genotypic characterization of D. fragilis and Blastocystis sp. in M. domestica.

Detection of Blastocystis sp. and Dientamoeba fragilis using conventional and molecular methods in patients with celiac disease.

Blastocystis sp. and Dientamoeba fragilis are intestinal protists, which are common worldwide, but the pathogenic role of these organisms in gastrointestinal diseases is still controversial. This study aimed to investigate the frequency of Blastocystis sp. and D. fragilis in stool samples from adult patients with celiac disease (CD) by using conventional and molecular methods. A total of 75 patients with CD and 75 healthy individuals were included in this study. Fresh stool specimens collected from each individual were analyzed by conventional and molecular methods. The overall prevalence of Blastocystis sp. and D. fragilis was 41.3% (31/75) and 24% (18/75) in patients with CD, and 46.7% (35/75) and 13.3% (10/75) in healthy controls, respectively. There was no statistically significant difference in the prevalence of Blastocystis sp. and D. fragilis between CD patients and healthy individuals. Blastocystis sp. subtypes were identified in 20 CD and 16 control patients and the overall subtype distribution was observed as ST1 13.9%, ST2 30.6%, and ST3 55.6%. The prevalence of Blastocystis sp. and D. fragilis in adults with CD is similar to the prevalence of protozoa in healthy adults. In this study, the most prevalent Blastocystis subtype was ST3 and the most frequent allele was a34 in both CD patients and healthy individuals. No significant difference was found between the two groups in terms of the detection rates of Blastocystis sp. and D. fragilis, and it is thought that both protists may be colonisers of the intestinal microbiome.

Observations on the transmission of Dientamoeba fragilis and the cyst life cycle stage.

Little is known about the life cycle and mode of transmission of Dientamoeba fragilis. Recently it was suggested that fecal­oral transmission of cysts may play a role in the transmission of D. fragilis. In order to establish an infection, D. fragilis is required to remain viable when exposed to the pH of the stomach. In this study, we investigated the ability of cultured trophozoites to withstand the extremes of pH. We provide evidence that trophozoites of D. fragilis are vulnerable to highly acidic conditions. We also investigated further the ultrastructure of D. fragilis cysts obtained from mice and rats by transmission electron microscopy. These studies of cysts showed a clear cyst wall surrounding an encysted parasite. The cyst wall was double layered with an outer fibrillar layer and an inner layer enclosing the parasite. Hydrogenosomes, endoplasmic reticulum and nuclei were present in the cysts. Pelta-axostyle structures, costa and axonemes were identifiable and internal flagellar axonemes were present. This study therefore provides additional novel details and knowledge of the ultrastructure of the cyst stage of D. fragilis.

Molecular detection and genetic diversity of Dientamoeba fragilis and Enterocytozoon bieneusi in fecal samples submitted for routine parasitological examination

Objective: To detect Dientamoeba (D.) fragilis and Enterocytozoon (E.) bieneusi and to assess their genetic characteristics in stool samples submitted for routine examination in a clinical laboratory in Southeastern Brazil. Methods: In this survey, 348 stool samples from female and male individuals with age ranging from 0 to ≥55 years were analyzed by PCR amplifying and sequencing based on the small subunit ribosomal RNA (SSU rRNA) gene of D. fragilis and the internal transcribed spacer of E. bieneusi. Results: D. fragilis and E. bieneusi isolates were observed in 2.29% (8/348) and 4.59% (16/348) of the samples, respectively. These parasites were detected in stool samples from individuals of both genders, including young children under nine until adults over 55 years old. No statistically significant differences were found. All D. fragilis isolates were classified as genotype 1 and E. bieneusi isolates included genotypes D (n=15) and A (n=1). Conclusions: The findings provide relevant findings on occurrence and genetic diversity of D. fragilis and E. bieneusi, pointing to the need for the diagnosis of these parasites in routine examinations in clinical laboratories. In addition to sensitive diagnostic methods, it is mandatory that these parasites be considered relevant for physicians and laboratory staff.

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.

Manifestaciones clínicas y diagnóstico parasitológico de la infección intestinal causada por dientamoeba Fragilis

Dientamoeba fragilis (Df), un flagelado intestinal humano del orden Trichomonadida, ha sido asociado con síntomas gastrointestinales. El diagnóstico se hace por la observación de trofozoítos binucleados en las heces, en cultivo, o con biología molecular. En este trabajo se integran datos clínicos y parasitológicos de pacientes con Df, para establecer una relación con los síntomas, asociación con otros parásitos intestinales y evaluar los métodos de diagnóstico parasitológico. De 3729 pacientes evaluados entre 1974 y 2005, en el Laboratorio de Amibiasis, Cátedra de Parasitología, Facultad de Medicina de la Universidad Central de Venezuela, se encontró 51 casos (1,4%) con Df, en 33,3% como único agente y en 66,7% asociado con otros protozoarios. La asociación mas frecuente fue con Blastocystis hominis (Bh) (35,3 %), o Bh y otros protozoarios (31,4%). No se observó asociación con nemátodos intestinales. En 16 pacientes con Df sola y en 28 asociada con Bh y comensales, los síntomas más frecuentes fueron respectivamente: diarrea (64,7% y 32,1%), dolor abdominal (11,7% y 25%), vómitos (11,7% y 14,4%). La frecuencia de Df en el grupo etario entre 1-10 años fue 39,2% y resultó estadísticamente significativa (p<0,001). El examen seriado de heces con directo, coloración de Hematoxilina férrica (Hf) y cultivo en medio de Boeck- Drbohlav (modificado) detectó mayor número de casos (58,8%), siendo estadísticamente significativo (p=0,032) al comparar los casos detectados con el directo y Hf (41,2%). Se recomienda considerar a Df como un patógeno intestinal cuando se encuentra en personas con síntomas y en ausencia de otros patógenos conocidos, e investigarla con los métodos recomendados, especialmente con el cultivo que incrementará la posibilidad del hallazgo.

Dientamoeba fragilis (Df), a human intestinal flagellated of the Trichomonadida order, has been associated with gastrointestinal symptoms. The diagnosis is made by observation of binucleated trophozoites in faeces, culture, or by using molecular biology. In this work, clinical and parasitological data of patients with Df are integrated, to establish a relation with the symptoms, the association with other intestinal parasites and to evaluate the methods used for parasitological diagnosis. Of 3729 patients evaluated between 1974 and 2005, in Laboratorio de Amibiasis, Cátedra de Parasitología, Facultad de Medicina, Universidad Central de Venezuela, 51 cases were positive for Df (1.4%); of these, Df was the only agent in 33.3% and in 66.7% it was associated with other protozoa. The most frequent association found was with Blastocystis hominis (Bh) (35.3%), or Bh and other protozoa (31.4%). No intestinal nematodes were found. In 16 patients with Df alone and 28 patients with Df, Bh and comensals, the most frequent symptoms were, diarrhea (64.7% and 32.1%), abdominal pain (11.7% and 25%), vomits (11.7% and 14.4%) respectively. There was statistical significance (p<0.001) on the frequency of Df (39.2%) in the group between 1-10 years. The examination of more than one faecal sample using fresh unpreserved stools samples, ferric hematoxylin stain and culture on Boeck- Drbohlav modified medium detected a greater number of cases (58.8%), as compared when using the two first methods only (41.2%), being statistically significant (p=0.032). It is recommended to consider Df as a pathogen when found in people with intestinal symptoms, in absence of other known pathogens, and to follow the methods mentioned above, specially with the culture which will increase the possibility of recovering this protozoa.