Dr Joel Barratt is a Chancellor’s Postdoctoral researcher at the University of Technology Sydney. He holds a Bachelor of Biotechnology and first class Honours degree from UTS, and a PhD in molecular parasitology. He worked as a research assistant at St Vincent’s Hospital, Sydney for 3 years on a project involving the diagnosis of gastrointestinal protozoa and other potential pathogens. He has extensive experience working with gut protozoa, particularly Dientamoeba fragilis.
Joels PhD research involved a detailed study of the human gastrointestinal parasite, D. fragilis. His thesis was ranked among the top 6 submitted at UTS in 2013, qualifying it for inclusion on the 2013 Chancellor’s List. Joel was awarded the prestigious Chancellor’s Postdoctoral position at UTS in 2014 and currently holds this appointment. His project investigates the molecular biology of parasitic flagellates (trypanosomatids and trichomonads), particularly those associated with human disease.
Joel also presently holds an editorial position with the open access, peer reviewed journal Parasites & Vectors (Associate Editor: Protozoan biology and diseases).
Awards & Funding
Joel was awarded his Chancellor's Postdoctoral position in 2014 (salary and project costs incl.). In 2010, he obtained runners up in the competitive UniQuest Trailblazer competition, for presentation of a 5 minute pitch entitled "Development of a diagnostic test for D. fragilis" (prize of $2,500). In 2013, Joel was also awarded a Bio-Innovation prize (as part of a group of four scientists) from the Technion Israel Institute of Technology for the development of a novel commercial concept: “A new diagnostic tool for detecting metastatic cancer” (prize of $25,000).
- Australian Society for Parasitology
- Australian Society for Microbiology
Can supervise: YES
General research interests:
- Parasitology (medical/veterinary)
- Molecular biology
Current Research Projects:
- Leishmania spp. and related organisms - taxonomy, genetics
- Dientamoeba fragilis – genetics, genomics, diagnostic development, transmission and life cycle
- Tissue-cyst forming coccidia – food (meat) safety, genetics
- Neospora caninum – genomics, transcriptomics
Joels work committments are currently 25% teaching and 75% research.
His primary teaching areas include:
- Molecular Biology
Barratt, JL & Ellis, J 2019, 'Angiostrongylus cantonensis: a review of its distribution, molecular biology and clinical significance as a human pathogen - CORRIGENDUM.', Parasitology, pp. 1-1.View/Download from: UTS OPUS or Publisher's site
Barratt, JLN, Park, S, Nascimento, FS, Hofstetter, J, Plucinski, M, Casillas, S, Bradbury, RS, Arrowood, MJ, Qvarnstrom, Y & Talundzic, E 2019, 'Genotyping Genetically Heterogeneous Cyclospora cayetanensis Infections to Complement Epidemiological Case Linkage', Parasitology.View/Download from: Publisher's site
Kaufer, A, Barratt, J, Stark, D & Ellis, J 2019, 'The complete coding region of the maxicircle as a superior phylogenetic marker for exploring evolutionary relationships between members of the Leishmaniinae', INFECTION GENETICS AND EVOLUTION, vol. 70, pp. 90-100.View/Download from: Publisher's site
Calarco, L, Barratt, J & Ellis, J 2018, 'Genome Wide Identification of Mutational Hotspots in the Apicomplexan Parasite Neospora caninum and the Implications for Virulence', GENOME BIOLOGY AND EVOLUTION, vol. 10, no. 9, pp. 2417-2431.View/Download from: UTS OPUS or Publisher's site
Flaherty, BR, Talundzic, E, Barratt, J, Kines, KJ, Olsen, C, Lane, M, Sheth, M & Bradbury, RS 2018, 'Restriction enzyme digestion of host DNA enhances universal detection of parasitic pathogens in blood via targeted amplicon deep sequencing', MICROBIOME, vol. 6.View/Download from: Publisher's site
Barratt, J, Kaufer, A, Peters, B, Craig, D, Lawrence, A, Roberts, T, Lee, R, McAuliffe, G, Stark, D & Ellis, J 2017, 'Isolation of Novel Trypanosomatid, Zelonia australiensis sp. nov. (Kinetoplastida: Trypanosomatidae) Provides Support for a Gondwanan Origin of Dixenous Parasitism in the Leishmaniinae.', PLoS Neglected Tropical Diseases, vol. 11, no. 1, pp. 1-26.View/Download from: UTS OPUS or Publisher's site
The genus Leishmania includes approximately 53 species, 20 of which cause human leishmaniais; a significant albeit neglected tropical disease. Leishmaniasis has afflicted humans for millennia, but how ancient is Leishmania and where did it arise? These questions have been hotly debated for decades and several theories have been proposed. One theory suggests Leishmania originated in the Palearctic, and dispersed to the New World via the Bering land bridge. Others propose that Leishmania evolved in the Neotropics. The Multiple Origins theory suggests that separation of certain Old World and New World species occurred due to the opening of the Atlantic Ocean. Some suggest that the ancestor of the dixenous genera Leishmania, Endotrypanum and Porcisia evolved on Gondwana between 90 and 140 million years ago. In the present study a detailed molecular and morphological characterisation was performed on a novel Australian trypanosomatid following its isolation in Australia's tropics from the native black fly, Simulium (Morops) dycei Colbo, 1976. Phylogenetic analyses were conducted and confirmed this parasite as a sibling to Zelonia costaricensis, a close relative of Leishmania previously isolated from a reduviid bug in Costa Rica. Consequently, this parasite was assigned the name Zelonia australiensis sp. nov. Assuming Z. costaricensis and Z. australiensis diverged when Australia and South America became completely separated, their divergence occurred between 36 and 41 million years ago at least. Using this vicariance event as a calibration point for a phylogenetic time tree, the common ancestor of the dixenous genera Leishmania, Endotrypanum and Porcisia appeared in Gondwana approximately 91 million years ago. Ultimately, this study contributes to our understanding of trypanosomatid diversity, and of Leishmania origins by providing support for a Gondwanan origin of dixenous parasitism in the Leishmaniinae.
Trypanosomatids are protozoan parasites of the class Kinetoplastida predominately restricted to invertebrate hosts (i.e. possess a monoxenous life-cycle). However, several genera are pathogenic to humans, animals and plants, and have an invertebrate vector that facilitates their transmission (i.e. possess a dixenous life-cycle). Phytomonas is one dixenous genus that includes several plant pathogens transmitted by phytophagous insects. Trypanosoma and Leishmania are dixenous genera that infect vertebrates, including humans, and are transmitted by hematophagous invertebrates. Traditionally, monoxenous trypanosomatids such as Leptomonas were distinguished from morphologically similar dixenous species based on their restriction to an invertebrate host. Nonetheless, this criterion is somewhat flawed as exemplified by Leptomonas seymouri which reportedly infects vertebrates opportunistically. Similarly, Novymonas and Zelonia are presumably monoxenous genera yet sit comfortably in the dixenous clade occupied by Leishmania. The isolation of Leishmania macropodum from a biting midge (Forcipomyia spp.) rather than a phlebotomine sand fly calls into question the exclusivity of the Leishmania-sand fly relationship, and its suitability for defining the Leishmania genus. It is now accepted that classic genus-defining characteristics based on parasite morphology and host range are insufficient to form the sole basis of trypanosomatid taxonomy as this has led to several instances of paraphyly. While improvements have been made, resolution of evolutionary relationships within the Trypanosomatidae is confounded by our incomplete knowledge of its true diversity. The known trypanosomatids probably represent a fraction of those that exist and isolation of new species will help resolve relationships in this group with greater accuracy. This review incites a dialogue on how our understanding of the relationships between certain trypanosomatids has shifted, and discusses new knowledge t...
Barratt, J, Chan, D, Sandaradura, I, Malik, R, Spielman, D, Lee, R, Marriott, D, Harkness, J, Ellis, J & Stark, D 2016, 'Angiostrongylus cantonensis: a review of its distribution, molecular biology and clinical significance as a human pathogen', PARASITOLOGY, vol. 143, no. 9, pp. 1087-1118.View/Download from: Publisher's site
Barratt, J, Gough, R, Stark, D & Ellis, J 2016, 'Bulky Trichomonad Genomes: Encoding a Swiss Army Knife', TRENDS IN PARASITOLOGY, vol. 32, no. 10, pp. 783-797.View/Download from: UTS OPUS or Publisher's site
Chan, D, Barratt, J, Roberts, T, Phillips, O, Slapeta, J, Ryan, U, Marriott, D, Harkness, J, Ellis, J & Stark, D 2016, 'Detection of Dientamoeba fragilis in animal faeces using species specific real time PCR assay', VETERINARY PARASITOLOGY, vol. 227, pp. 42-47.View/Download from: UTS OPUS or Publisher's site
Stark, D, Barratt, J, Chan, D & Ellis, JT 2016, 'Dientamoeba fragilis, the Neglected Trichomonad of the Human Bowel', CLINICAL MICROBIOLOGY REVIEWS, vol. 29, no. 3, pp. 553-580.View/Download from: UTS OPUS or Publisher's site
Barratt, JLN, Cao, M, Stark, DJ & Ellis, JT 2015, 'The Transcriptome Sequence of Dientamoeba fragilis Offers New Biological Insights on its Metabolism, Kinome, Degradome and Potential Mechanisms of Pathogenicity', PROTIST, vol. 166, no. 4, pp. 389-408.View/Download from: Publisher's site
Chan, D, Barratt, J, Roberts, T, Lee, R, Shea, M, Marriott, D, Harkness, J, Malik, R, Jones, M, Aghazadeh, M, Ellis, J & Stark, D 2015, 'The Prevalence of Angiostrongylus cantonensis/mackerrasae Complex in Molluscs from the Sydney Region', PLOS ONE, vol. 10, no. 5.View/Download from: UTS OPUS or Publisher's site
Roberts, T, Barratt, J, Sandaradura, I, Lee, R, Harkness, J, Marriott, D, Ellis, J & Stark, D 2015, 'Molecular Epidemiology of Imported Cases of Leishmaniasis in Australia from 2008 to 2014', PLOS ONE, vol. 10, no. 3.View/Download from: UTS OPUS or Publisher's site
Goodswen, SJ, Barratt, JLN, Kennedy, PJ & Ellis, JT 2015, 'Improving the gene structure annotation of the apicomplexan parasite Neospora caninum fulfils a vital requirement towards an in silico-derived vaccine', International Journal for Parasitology, pp. 305-318.View/Download from: UTS OPUS or Publisher's site
Neospora caninum is an apicomplexan parasite which can cause abortion in cattle, instigating major economic burden. Vaccination has been proposed as the most cost-effective control measure to alleviate this burden. Consequently the overriding aspiration for N. caninum research is the identification and subsequent evaluation of vaccine candidates in animal models. To save time, cost and effort, it is now feasible to use an in silico approach for vaccine candidate prediction. Precise protein sequences, derived from the correct open reading frame, are paramount and arguably the most important factor determining the success or failure of this approach. The challenge is that publicly available N. caninum sequences are mostly derived from gene predictions. Annotated inaccuracies can lead to erroneously predicted vaccine candidates by bioinformatics programs. This study evaluates the current N. caninum annotation for potential inaccuracies. Comparisons with annotation from a closely related pathogen, Toxoplasma gondii, are also made to distinguish patterns of inconsistency. More importantly, a mRNA sequencing (RNA-Seq) experiment is used to validate the annotation. Potential discrepancies originating from a questionable start codon context and exon boundaries were identified in 1943 protein coding sequences. We conclude, where experimental data were available, that the majority of N. caninum gene sequences were reliably predicted. Nevertheless, almost 28% of genes were identified as questionable. Given the limitations of RNA-Seq, the intention of this study was not to replace the existing annotation but to support or oppose particular aspects of it. Ideally, many studies aimed at improving the annotation are required to build a consensus. We believe this study, in providing a new resource on gene structure and annotation, is a worthy contributor to this endeavour.
Stark, DJ, Barratt, JL, Roberts, TJ, Marriott, DJ, Harkness, JL & Ellis, JT 2014, 'Activity of benzimidazoles against Dientamoeba fragilis (Trichomonadida, Monocercomonadidae) in vitro and correlation of beta-tubulin sequences as an indicator of resistance', Parasite, vol. 21.View/Download from: UTS OPUS or Publisher's site
Stark, DJ, Garcia, L, Barratt, JL, Phillips, O, Roberts, TJ, Marriott, DJ, Harkness, JL & Ellis, JT 2014, 'Description of Dientamoeba fragilis cyst and precystic forms from human samples', Journal Of Clinical Microbiology, vol. 52, no. 7, pp. 2680-2683.View/Download from: UTS OPUS or Publisher's site
Barratt, JL, Harkness, JL, Marriott, DJ, Ellis, JT & Stark, DJ 2011, 'A review of Dientamoeba fragilis carriage in man: Several reasons why this organism should be considered in the diagnosis of gastrointestinal illness', Gut Microbes, vol. 23, no. 1, pp. 1-10.View/Download from: UTS OPUS or Publisher's site
Dientamoeba fragilis is a protozoan that inhabits the human gut. It is approximately 100 years since Dientamoebas 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 Dientamoebas 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.
Barratt, JL, Harkness, JL, Marriott, DJ, Ellis, JT & Stark, DJ 2011, 'The ambiguous life of Dientamoeba fragilis: the need to investigate current hypotheses on transmission?', Parasitology, vol. 138, no. 5, pp. 557-572.View/Download from: UTS OPUS or Publisher's site
Dientamoeba fragilis is an inhabitant of the human bowel and is associated with gastrointestinal illness. Despite its discovery over a century ago, the details of Dientamoebas life cycle are unclear and its mode of transmission is unknown. Several theories exist which attempt to explain how Dientamoeba may be transmitted. One theory suggests that animals are responsible for the transmission of Dientamoeba. However, reports of Dientamoeba in animals are sporadic and most are not supported by molecular evidence. Another theory suggests that Dientamoeba may be transmitted via the ova of a helminth. Given that the closest relative of Dientamoeba is transmitted via the ova of a helminth, this theory seems plausible. It has also been suggested that Dientamoeba could be transmitted directly between humans. This theory also seems plausible given that other relatives of Dientamoeba are transmitted in this way. Despite numerous investigations, Dientamoebas mode of transmission remains unknown. This review discusses the strengths and weaknesses of theories relating to Dientamoebas mode of transmission and, by doing so, indicates where gaps in current knowledge exist. Where information is lacking, suggestions are made as to how future research could improve our knowledge on the life cycle of Dientamoeba.
Roberts, TJ, Barratt, JL, Harkness, JL, Ellis, JT & Stark, DJ 2011, 'Comparison of Microscopy, Culture, and Conventional Polymerase Chain Reaction for Detection of Blastocystis sp. in Clinical Stool Samples.', American Journal of Tropical Medicine and Hygiene, vol. 84, no. 2S, pp. 308-312.View/Download from: UTS OPUS or Publisher's site
We tested 513 stool samples from patients in Sydney, Australia for Blastocystis by using five diagnostic techniques: microscopy of a permanently stained smear using a modified iron-hematoxylin stain, two xenic culture systems (a modified Boeck and Drbohlav's medium and tryptone, yeast extract, glucose, methionine-9 medium), and two published conventional polymerase chain reaction methods specific for the small subunit ribosomal DNA. Ninety-eight (19%) samples were positive for Blastocystis in one or more of the diagnostic techniques. The PCR 2 method was the most sensitive at detecting Blastocystis with a sensitivity of 94%, and the least sensitive was microscopy of the permanent stain (48%). Subtype 3 was the most predominant subtype (present in 43% of samples assigned to this group). This study highlights the low sensitivity of microscopy when used as the sole diagnostic modality for detection of Blastocystis sp
Stark, DJ, Al-Qassab, SE, Barratt, JL, Stanley, K, Roberts, TJ, Marriott, DJ, Harkness, JL & Ellis, JT 2011, 'Evaluation of Multiplex Tandem Real-Time PCR for Detection of Cryptosporidium spp., Dientamoeba fragilis, Entamoeba histolytica, and Giardia intestinalis in Clinical Stool Samples', Journal Of Clinical Microbiology, vol. 49, no. 1, pp. 257-262.View/Download from: UTS OPUS or Publisher's site
The aim of this study was to describe the first development and evaluation of a multiplex tandem PCR (MT-PCR) assay for the detection and identification of 4 common pathogenic protozoan parasites; Cryptosporidium spp., Dientamoeba fragilis, Entamoeba histolytica, and Giardia intestinalis from human clinical samples. A total of 472 faecal samples submitted to the Department of Microbiology at St. Vincent's Hospital were included in the study. The MT-PCR assay was compared to four real-time PCR assays (RT-PCR) and microscopy by a traditional modified iron haematoxylin stain. The MT-PCR detected 28 G. intestinalis, 26 D. fragilis, 11 E. histolytica, and 9 Cryptosporidium spp. isolates. Detection and identification of the faecal protozoa by MT-PCR demonstrated 100% correlation with the RT-PCR results and when compared to RT-PCR the MT-PCR exhibited 100% sensitivity and specificity, while traditional microscopy of stained fixed faecal smears exhibited sensitivities and specificities of 56% and 100% for Cryptosporidium ssp., 38% and 99% for D. fragilis, 47% and 97% for E. histolytica and 50% and 100% for G. intestinalis respectively. No cross reactivity was detected in 100 stool samples containing various other bacterial, viral and protozoan species. The MT-PCR assay was able to provide rapid, sensitive and specific simultaneous detection and identification of the four most important diarrhoea causing protozoan parasites that infect humans. This study also highlights the lack of sensitivity demonstrated by microscopy and as such molecular methods such as MT-PCR must be considered the diagnostic method of choice for enteric protozoan parasites.
Banik, G, Barratt, JL, Marriott, DJ, Harkness, JL, Ellis, JT & Stark, DJ 2011, 'A case-controlled study of Dientamoeba fragilis infections in children', Parasitology, vol. 138, no. 7, pp. 819-823.View/Download from: UTS OPUS or Publisher's site
Dientamoeba fragilis is a pathogenic protozoan parasite that is implicated as a cause of human diarrhoea. A case-controlled study was conducted to determine the clinical signs associated with D. fragilis infection in children presenting to a Sydney Hospital. Treatment options are also discussed. Stool specimens were collected from children aged 15 years or younger and analysed for the presence of D. fragilis. In total, 41 children were included in the study along with a control group. Laboratory diagnosis was performed by microscopy of permanently stained, fixed faecal smears and by real-time PCR. Gastrointestinal symptoms were present in 40/41 (98%) of these children with dientamoebiasis, with diarrhoea (71%) and abdominal pain (29%) the most common clinical signs. Chronic gastrointestinal symptoms were present in 2% of cases. The most common anti-microbial used for treatment was metronidazole (n=41), with complete resolution of symptoms and clearance of parasite occurring in 85% of cases. A treatment failure rate occurred in 15% of those treated with metronidazole. Follow-up treatment comprised of an additional course of metronidazole or iodoquinol was needed in order to achieve complete resolution of infection and symptoms in this group. This study demonstrates the pathogenic potential of D. fragilis in children and as such it is recommended that all laboratories must routinely test for this organism and treat if detected.
Barratt, JL, Harkness, JL, Marriott, DJ, Ellis, JT & Stark, DJ 2010, 'Importance of Nonenteric Protozoan Infections in Immunocompromised People', Clinical Microbiology Reviews, vol. 23, no. 4, pp. 795-836.View/Download from: UTS OPUS or Publisher's site
There are many neglected nonenteric protozoa able to cause serious morbidity and mortality in humans, particularly in the developing world. Diseases caused by certain protozoa are often more severe in the presence of HIV. While information regarding neglected tropical diseases caused by trypanosomatids and Plasmodium is abundant, these protozoa are often not a first consideration in Western countries where they are not endemic.
Barratt, JL, Harkness, JL, Marriott, DJ, Ellis, JT & Stark, DJ 2010, 'The Importance of Non-enteric Protozoan Infections in Immunocompromised Patients', Clinical Microbiology Reviews, vol. 23, no. 4, pp. 795-836.View/Download from: UTS OPUS or Publisher's site
There are many neglected nonenteric protozoa able to cause serious morbidity and mortality in humans, particularly in the developing world. Diseases caused by certain protozoa are often more severe in the presence of HIV. While information regarding neglected tropical diseases caused by trypanosomatids and Plasmodium is abundant, these protozoa are often not a first consideration in Western countries where they are not endemic. As such, diagnostics may not be available in these regions. Due to global travel and immigration, this has become an increasing problem. Inversely, in certain parts of the world (particularly sub-Saharan Africa), the HIV problem is so severe that diseases like microsporidiosis and toxoplasmosis are common. In Western countries, due to the availability of highly active antiretroviral therapy (HAART), these diseases are infrequently encountered. While free-living amoebae are rarely encountered in a clinical setting, when infections do occur, they are often fatal. Rapid diagnosis and treatment are essential to the survival of patients infected with these organisms. This paper reviews information on the diagnosis and treatment of nonenteric protozoal diseases in immunocompromised people, with a focus on patients infected with HIV. The nonenteric microsporidia, some trypanosomatids, Toxoplasma spp., Neospora spp., some free-living amoebae, Plasmodium spp., and Babesia spp. are discussed.
James, R, Barratt, J, Marriott, D, Harkness, J & Stark, D 2010, 'Short Report: Seroprevalence of Entamoeba histolytica Infection among Men Who Have Sex with Men in Sydney, Australia', AMERICAN JOURNAL OF TROPICAL MEDICINE AND HYGIENE, vol. 83, no. 4, pp. 914-916.View/Download from: Publisher's site
Stark, DJ, Barratt, JL, Roberts, TJ, Marriott, DJ, Harkness, JL & Ellis, JT 2010, 'A review of the clinical presentation of dientamoebiasis', American Journal Of Tropical Medicine And Hygiene, vol. 82, no. 4, pp. 614-619.View/Download from: UTS OPUS or Publisher's site
Among 750 symptomatic and asymptomatic patients, Dientamoeba fragilis was detected at a prevalence of 5.2% and more common than Giardia intestinalis. Most infected patients presented with diarrhea and abdominal pain with symptoms greater than 2 weeks duration being common. Bacterial and viral causes of infection were excluded by routine microbiological techniques. Treatment of D. fragilis infection with either iodoquinol, paromomycin, or combination therapy resulted in the eradication of the parasite and complete resolution of symptoms. Treatment failure/relapses were associated only with the use of metronidazole. Nineteen patients were examined for pin worm, no Enterobius vermicularis, a proposed vector of transmission, were detected. Intermittent shedding of D. fragilis was found to be highly variable. These studies confirm the pathogenic nature of D. fragilis and we recommend laboratories routinely test for the organism.
Stark, DJ, Barratt, JL, Roberts, TJ, Marriott, DJ, Harkness, JL & Ellis, JT 2010, 'Comparison of microscopy, two xenic culture techniques, conventional and real-time PCR for the detection of Dientamoeba fragilis in clinical stool samples.', European Journal of Clinical Microbiology & Infectious Diseases, vol. 29, no. 4, pp. 411-416.View/Download from: UTS OPUS or Publisher's site
Dientamoeba fragilis is a pathogenic protozoan parasite that is notoriously difficult to diagnose. The aim of this study was to detennine the gold standard for laboratory detection of D. fragilis. A total of 650 human faecal samples were included in the study. All specimens underwent the following: microscopy using a pennanent stain (modified iron-haematoxylin), culture using a modified Boeck and Drbohlav's medium (MBD) and TYGM-9, a conventional polymerase chain reaction (peR) and a realtime PCR (RT-PCR). The overall prevalence of D. fragilis in the study population was 5.4% (35/650). RT-PCR detected 35 isolates, conventional PCR detected 15 isolates, MBD culture detected 14 isolates, TYGM-9 detected ten isolates, while microscopy' detected 12 isolates. RT-PCR detected an additional 15 positive samples compared to the other diagnostic methods, all of which were confinned by sequencing. When all methods were compared to each other, RT-PCR showed a sensitivity and specificity of 100 and 100%, conventional POR 42.9 and 100%, MBD culture 40 and 100%, TYGM-9 culture 28.6 and 100%, and microscopy 34.3 and 99%, respectively. These results show that RT-PCR is the diagnostic method of choice for the detection of D. fragilis in clinical samples and, as such, should be considered as the gold standard for diagnosis.
Barratt, JL, Banik, G, Harkness, JL, Marriott, DJ, Ellis, JT & Stark, DJ 2010, 'Newly defined conditions for the in vitro cultivation and cryopreservation of Dientamoeba fragilis: new techniques set to fast track molecular studies on this organism', Parasitology, vol. 137, no. 13, pp. 1867-1878.View/Download from: UTS OPUS or Publisher's site
Dientamoeba fragilis is a pathogen of the human gastrointestinal tract that is a common cause of diarrhoea. A paucity of knowledge on the in vitro cultivation and cryopreservation of Dientamoeba has meant that few studies have been conducted to investigate its biology. The objective of this study was to define, for the first time, in vitro culture conditions able to support the long-term in vitro growth of Dientamoeba. Also, we aimed to define a suitable method for cryopreserving viable Dientamoeba trophozoites. A modified BD medium, TYGM-9, Loeffler's slope medium, Robinson's medium, Medium 199, Trichosel and a Tritrichomonas fetus medium were compared, using cell counts, for their ability to support the growth of D. fragilis at various temperatures and atmospheric conditions. Loeffler's slope medium supported significantly better growth compared to other media. A temperature of 42°C and a microaerophilic atmosphere were also optimum for Dientamoeba growth. To our knowledge, this is the first study to describe and compare different culture media and conditions for the growth of clinical isolates of D. fragilis. This new technology will aid the development of diagnostics for dientamoebiasis as well as facilitate large-scale sequencing projects that will fast track molecular studies on D. fragilis.
Miyakis, S, van Hal, SJ, Barratt, J, Stark, D, Marriott, D & Harkness, J 2009, 'Absence of human Bocavirus in bronchoalveolar lavage fluid of lung transplant patients', JOURNAL OF CLINICAL VIROLOGY, vol. 44, no. 2, pp. 179-180.View/Download from: Publisher's site
Stark, DJ, Barratt, JL, Ellis, JT, Harkness, JL & Marriott, DJ 2009, 'Repeated Dientamoeba fragilis infections: a case report of two families from Sydney, Australia', Infectious Disease Reports, vol. 1, no. e4, pp. 7-9.View/Download from: UTS OPUS or Publisher's site
We report cases of two unrelated families who both presented with recurrent Dientamoeba fragilis infections. Subsequent antimicrobial therapy resulted in the clearance of D. fragilis and total resolution of gastrointestinal symptoms in both families. This report highlights the potentially recurrent nature of D. fragilis infections and the need for laboratories to routinely test for this organism.
Stark, DJ, Barratt, JL, Van Hal, SJ, Marriott, DJ, Harkness, JL & Ellis, JT 2009, 'Clinical significance of enteric protozoa in the immunosuppressed human population', Clinical Microbiology Reviews, vol. 22, no. 4, pp. 634-650.View/Download from: UTS OPUS or Publisher's site
Globally, the number of immunosuppressed people increases each year, with the human immunodeficiency virus (HIV) pandemic continuing to spread unabated in many parts of the world. Immunosuppression may also occur in malnourished persons, patients undergoing chemotherapy for malignancy, and those receiving immunosuppressive therapy. Components of the immune system can be functionally or genetically abnormal as a result of acquired (e.g., caused by HIV infection, lymphoma, or high-dose steroids or other immunosuppressive medications) or congenital illnesses, with more than 120 congenital immunodeficiencies described to date that either affect humoral immunity or compromise T-cell function. All individuals affected by immunosuppression are at risk of infection by opportunistic parasites (such as the microsporidia) as well as those more commonly associated with gastrointestinal disease (such as Giardia). The outcome of infection by enteric protozoan parasites is dependent on absolute CD4+ cell counts, with lower counts being associated with more severe disease, more atypical disease, and a greater risk of disseminated disease. This review summarizes our current state of knowledge on the significance of enteric parasitic protozoa as a cause of disease in immunosuppressed persons and also provides guidance on recent advances in diagnosis and therapy for the control of these important parasites.
Stark, DJ, Van Hal, SJ, Barratt, JL, Ellis, JT, Marriott, DJ & Harkness, JL 2009, 'Limited genetic diversity among genotypes of Enterocytozoon bieneusi strains Isolated from HIV-Infected patients from Sydney, Australia', Journal of Medical Microbiology, vol. 58, no. 3, pp. 355-357.View/Download from: UTS OPUS or Publisher's site
Microsporidia are intracellular parasites, with over 1200 species belonging to 143 genera described to date. They are opportunistic pathogens in humans and can cause chronic diarrhoea in immunosuppressed patients. Both Enterocytozoon bieneusi and Encephalitozoon intestinalis cause intestinal disease, with Enterocytozoon bieneusi more commonly identified in patients with human immunodeficiency virus (HIV) infection. In this study, intestinal microsporidial clinical isolates from patients in Sydney, Australia, were genotyped. All specimens were from HIV-infected men with low CD4(+) T-cell counts (<100 cells mm(-3)). Genotyping of the internal transcribed spacer regions of the rRNA gene showed the presence of only one genotype, the anthroponotic Enterocytozoon bieneusi genotype B strain. This study thus highlighted the limited genetic diversity among Australian Enterocytozoon bieneusi isolates, and it is hypothesized that, due to the reduced incidence of microsporidia. and the subsequent reduction in the human reservoir of the anthroponotic genotype B, locally acquired intestinal microsporidiosis will rarely be seen in HIV-infected persons undergoing highly active antiretroviral therapy in the future in Australia.
van Hal, SJ, Gilgado, F, Doyle, T, Barratt, J, Stark, D, Meyer, W & Harkness, J 2009, 'Clinical Significance and Phylogenetic Relationship of Novel Australian Pneumocystis jirovecii Genotypes', JOURNAL OF CLINICAL MICROBIOLOGY, vol. 47, no. 6, pp. 1818-1823.View/Download from: Publisher's site
Barratt, JL, Al-Qassab, SE, Reichel, MP & Ellis, JT 2008, 'The development and evaluation of a nested PCR assay for detection of Neospora caninum and Hammondia heydorni in feral mouse tissues', Molecular & Cellular Probes, vol. 22, no. 4, pp. 228-233.View/Download from: UTS OPUS or Publisher's site
The development of a novel nested polymerase chain reaction is desribed and used for detecting the presence of Neospora caninum and Hammondai heydorni DNA in DNA extracted from feral rodent tissues.
Barratt, J, Stark, D & Ellis, J 2012, 'Cytotoxic and Proteolytic Molecules of the Human Parasite Dientamoeba fragilis, Identified by RNA seq. Provide Support for its Pathogenic Capacity', TOXICON, 17th World Congress of the International-Society-on-Toxinology (IST)/Venom Week/4th International Scientific Symposium on All Things Venomous, PERGAMON-ELSEVIER SCIENCE LTD, Honolulu, HI, pp. 163-164.View/Download from: Publisher's site
Barratt, J, Stark, D, Roberts, T, Marriott, D, Harkness, J & Ellis, J 2010, 'Evaluation of diagnostic techniques for the detection of Dientamoeba fragilis in clinical stool specimens', 12th International Congress of Parasitology, Melbourne, Australia.
Ellis, J, Barratt, J, Harkness, J, Marriott, D & Stark, D 2010, 'Dientamoeba fragilis: Evidence for its role as a cause of human gastrointestinal disease', 12th International Congress of Parasitology, Melbourne, Australia.
Barratt, J, Al-Qassab, S, Reichel, M & Ellis, J 2008, 'The development and evaluation of a nested PCR assay for detection of Neospora caninum and Hammondia heydorni in feral mouse tissues', ASP & ARC/NHMRC Research Network for Parasitology Annual Conference, Adelaide, Australia.
Barratt, JOEL, Stark, D, Van Hal, S, Ellis, JOHN, Marriott, D & Harkness, J 2008, 'Limited genetic diversity among genotypes of Entercytozoon bieneusi strains isolated from HIV-infected patients from Sydney, Australia', ASP & ARC/NHMRC Research Network for Parasitology Annual Conference, Adelaide, Australia.
Roberts, T, Barratt, J, Stark, D, van hal, S, Ellis, J, Marriott, D & Harkness, J 2008, 'Limited genetic diversity among genotypes of Entercytozoon bieneusi strains isolated from HIV-infected patients from Sydney, Australia', The Australian Society for Microbiology scientific meeting & exhibition, Sydney, Australia.
Joel is currently involved in long term collaborations with researchers at St Vincent's Hospital and ICPMR, Westmead.