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Clinical Microbiology Reviews Dec 2021Giardia duodenalis captured the attention of Leeuwenhoek in 1681 while he was examining his own diarrheal stool, but, ironically, it did not really gain attention as a...
Giardia duodenalis captured the attention of Leeuwenhoek in 1681 while he was examining his own diarrheal stool, but, ironically, it did not really gain attention as a human pathogen until the 1960s, when outbreaks were reported. Key technological advances, including cultivation, genomic and proteomic databases, and advances in microscopic and molecular approaches, have led to an understanding that this is a eukaryotic organism with a reduced genome rather than a truly premitochondriate eukaryote. This has included the discovery of mitosomes (vestiges of mitochondria), a transport system with many of the features of the Golgi apparatus, and even evidence for a sexual or parasexual cycle. Cell biology approaches have led to a better understanding of how Giardia survives with two nuclei and how it goes through its life cycle as a noninvasive organism in the hostile environment of the lumen of the host intestine. Studies of its immunology and pathogenesis have moved past the general understanding of the importance of the antibody response in controlling infection to determining the key role of the Th17 response. This work has led to understanding of the requirement for a balanced host immune response that avoids the extremes of an excessive response with collateral damage or one that is unable to clear the organism. This understanding is especially important in view of the remarkable ranges of early manifestations, which range from asymptomatic to persistent diarrhea and weight loss, and longer-term sequelae that include growth stunting in children who had no obvious symptoms and a high frequency of postinfectious irritable bowel syndrome (IBS).
Topics: Diarrhea; Giardia lamblia; Giardiasis; Humans; Irritable Bowel Syndrome; Male; Proteomics
PubMed: 34378955
DOI: 10.1128/CMR.00024-19 -
Trends in Parasitology Jul 2022
Topics: Feces; Genotype; Giardia; Giardia lamblia; Giardiasis; Humans; Prevalence
PubMed: 35074260
DOI: 10.1016/j.pt.2022.01.001 -
PLoS Pathogens Sep 2018
Review
Topics: Animals; Diarrhea; Giardia lamblia; Giardiasis; Humans; Protozoan Vaccines; Vacuoles
PubMed: 30261050
DOI: 10.1371/journal.ppat.1007250 -
Parasite (Paris, France) 2020While cryptosporidiosis is recognized as being among the most common causes of human parasitic diarrhea in the world, there is currently limited knowledge on... (Review)
Review
While cryptosporidiosis is recognized as being among the most common causes of human parasitic diarrhea in the world, there is currently limited knowledge on Cryptosporidium infection mechanisms, incomplete codification of diagnostic methods, and a need for additional therapeutic options. In response, the Seventh International Giardia and Cryptosporidium Conference (IGCC 2019) was hosted from 23 to 26 June 2019, at the Rouen Normandy University, France. This trusted event brought together an international delegation of researchers to synthesize recent advances and identify key research questions and knowledge gaps. The program of the interdisciplinary conference included all aspects of host-parasite relationships from basic research to applications to human and veterinary medicine, and environmental issues associated with waterborne parasites and their epidemiological consequences. In relation to Cryptosporidium and cryptosporidiosis, the primary research areas for which novel findings and the most impressive communications were presented and discussed included: Cryptosporidium in environmental waters, seafood, and fresh produce; Animal epidemiology; Human cryptosporidiosis and epidemiology; Genomes and genomic evolution encompassing: Comparative genomics of Cryptosporidium spp., Genomic insights into biology, Acquiring and utilizing genome sequences, Genetic manipulation; Host-parasite interaction (immunology, microbiome); and Diagnosis and treatment. High quality presentations discussed at the conference reflected decisive progress and identified new opportunities that will engage investigators and funding agencies to spur future research in a "one health" approach to improve basic knowledge and the clinical and public health management of zoonotic cryptosporidiosis.
Topics: Animals; Congresses as Topic; Cryptosporidiosis; Cryptosporidium; Diarrhea; Feces; France; Genotype; Giardia; Giardiasis; Humans; One Health
PubMed: 32167464
DOI: 10.1051/parasite/2020011 -
Advances in Parasitology 2020Giardia lamblia is a widespread parasitic protist with a complex MT cytoskeleton that is critical for motility, attachment, mitosis and cell division, and transitions... (Review)
Review
Giardia lamblia is a widespread parasitic protist with a complex MT cytoskeleton that is critical for motility, attachment, mitosis and cell division, and transitions between its two life cycle stages-the infectious cyst and flagellated trophozoite. Giardia trophozoites have both highly dynamic and highly stable MT organelles, including the ventral disc, eight flagella, the median body and the funis. The ventral disc, an elaborate MT organelle, is essential for the parasite's attachment to the intestinal villi to avoid peristalsis. Giardia's four flagellar pairs enable swimming motility and may also promote attachment. They are maintained at different equilibrium lengths and are distinguished by their long cytoplasmic regions and novel extra-axonemal structures. The functions of the median body and funis, MT organelles unique to Giardia, remain less understood. In addition to conserved MT-associated proteins, the genome is enriched in ankyrins, NEKs, and novel hypothetical proteins that also associate with the MT cytoskeleton. High-resolution ultrastructural imaging and a current inventory of more than 300 proteins associated with Giardia's MT cytoskeleton lay the groundwork for future mechanistic analyses of parasite attachment to the host, motility, cell division, and encystation/excystation. Giardia's unique MT organelles exemplify the capacity of MT polymers to generate intricate structures that are diverse in both form and function. Thus, beyond its relevance to pathogenesis, the study of Giardia's MT cytoskeleton informs basic cytoskeletal biology and cellular evolution. With the availability of new molecular genetic tools to disrupt gene function, we anticipate a new era of cytoskeletal discovery in Giardia.
Topics: Giardia; Microtubules; Organelles
PubMed: 32122531
DOI: 10.1016/bs.apar.2019.11.001 -
Parasitology Research Apr 2024Giardia duodenalis, the protozoan responsible for giardiasis, is a significant contributor to millions of diarrheal diseases worldwide. Despite the availability of... (Review)
Review
Giardia duodenalis, the protozoan responsible for giardiasis, is a significant contributor to millions of diarrheal diseases worldwide. Despite the availability of treatments for this parasitic infection, therapeutic failures are alarmingly frequent. Thus, there is a clear need to identify new therapeutic targets. Giardia telomeres were previously identified, but our understanding of these structures and the critical role played by Giardia telomerase in maintaining genomic stability and its influence on cellular processes remains limited. In this regard, it is known that all Giardia chromosomes are capped by small telomeres, organized and protected by specific proteins that regulate their functions. To counteract natural telomere shortening and maintain high proliferation, Giardia exhibits constant telomerase activity and employs additional mechanisms, such as the formation of G-quadruplex structures and the involvement of transposable elements linked to telomeric repeats. Thus, this study aims to address the existing knowledge gap by compiling the available information (until 2023) about Giardia telomeres and telomerase, focusing on highlighting the distinctive features within this parasite. Furthermore, the potential feasibility of targeting Giardia telomeres and/or telomerase as an innovative therapeutic strategy is discussed.
Topics: Humans; Telomerase; Giardiasis; Giardia; Telomere; Giardia lamblia
PubMed: 38584235
DOI: 10.1007/s00436-024-08200-6 -
Parasites & Vectors Apr 2017Cryptosporidium and Giardia are important causes of diarrhoeal illness. Adequate knowledge of the molecular diversity and geographical distribution of these parasites... (Review)
Review
Cryptosporidium and Giardia are important causes of diarrhoeal illness. Adequate knowledge of the molecular diversity and geographical distribution of these parasites and the environmental and climatic variables that influence their prevalence is important for effective control of infection in at-risk populations, yet relatively little is known about the epidemiology of these parasites in Africa. Cryptosporidium is associated with moderate to severe diarrhoea and increased mortality in African countries and both parasites negatively affect child growth and development. Malnutrition and HIV status are also important contributors to the prevalence of Cryptosporidium and Giardia in African countries. Molecular typing of both parasites in humans, domestic animals and wildlife to date indicates a complex picture of both anthroponotic, zoonotic and spill-back transmission cycles that requires further investigation. For Cryptosporidium, the only available drug (nitazoxanide) is ineffective in HIV and malnourished individuals and therefore more effective drugs are a high priority. Several classes of drugs with good efficacy exist for Giardia, but dosing regimens are suboptimal and emerging resistance threatens clinical utility. Climate change and population growth are also predicted to increase both malnutrition and the prevalence of these parasites in water sources. Dedicated and co-ordinated commitments from African governments involving "One Health" initiatives with multidisciplinary teams of veterinarians, medical workers, relevant government authorities, and public health specialists working together are essential to control and prevent the burden of disease caused by these parasites.
Topics: Africa; Animals; Antiprotozoal Agents; Child; Climate Change; Cost of Illness; Cryptosporidiosis; Cryptosporidium; Diarrhea; Disease Management; Feces; Genotyping Techniques; Giardia; Giardiasis; Humans; Nitro Compounds; Prevalence; Public Health; Thiazoles; Zoonoses
PubMed: 28427454
DOI: 10.1186/s13071-017-2111-y -
Traffic (Copenhagen, Denmark) Oct 2017The endoplasmic reticulum-Golgi-target organelle route is one of the most studied events and has fascinated researchers for years. However, the conservative mechanism of... (Review)
Review
The endoplasmic reticulum-Golgi-target organelle route is one of the most studied events and has fascinated researchers for years. However, the conservative mechanism of protein sorting and delivery is now being challenged by the finding of unconventional pathways driving protein sorting and transport. Protozoa parasites are being rediscovered as good models for analyzing alternative targeting pathways, associated with their ability to adapt to diverse environments and hosts. Here, we have gathered all the available information about secretory protein trafficking in Giardia lamblia, with a focus on how this protozoan parasite is able to sort and direct proteins to different compartments in the absence of a Golgi complex.
Topics: Endoplasmic Reticulum; Giardia lamblia; Golgi Apparatus; Protozoan Proteins; Receptors, Peptide; Secretory Pathway; Secretory Vesicles
PubMed: 28696551
DOI: 10.1111/tra.12500 -
Euro Surveillance : Bulletin Europeen... Jan 2018IntroductionThis paper reviews the current knowledge and understanding of spp and spp. in humans, animals and the environment in 10 countries in the eastern part of... (Review)
Review
IntroductionThis paper reviews the current knowledge and understanding of spp and spp. in humans, animals and the environment in 10 countries in the eastern part of Europe: Bosnia and Herzegovina, Croatia, Czech Republic, Estonia, Hungary, Latvia, Poland, Romania, Serbia and Slovenia. Published scientific papers and conference proceedings from the international and local literature, official national health service reports, national databases and doctoral theses in local languages were reviewed to provide an extensive overview on the epidemiology, diagnostics and research on these pathogens, as well as analyse knowledge gaps and areas for further research. spp. and spp. were found to be common in eastern Europe, but the results from different countries are difficult to compare because of variations in reporting practices and detection methodologies used. Upgrading and making the diagnosis/detection procedures more uniform is recommended throughout the region. Public health authorities should actively work towards increasing reporting and standardising reporting practices as these prerequisites for the reported data to be valid and therefore necessary for appropriate control plans.
Topics: Animals; Cryptosporidiosis; Cryptosporidium; Environment; Europe, Eastern; Feces; Foodborne Diseases; Giardia; Giardiasis; Humans; Prevalence; Public Health; Real-Time Polymerase Chain Reaction
PubMed: 29382412
DOI: 10.2807/1560-7917.ES.2018.23.4.16-00825 -
Clinics in Laboratory Medicine Jun 2015The coccidians Cryptosporidium spp, Cyclospora cayetanensis, and Cystoisospora belli and the flagellate Giardia duodenalis are pathogenic protozoa associated with... (Review)
Review
The coccidians Cryptosporidium spp, Cyclospora cayetanensis, and Cystoisospora belli and the flagellate Giardia duodenalis are pathogenic protozoa associated with gastrointestinal manifestations. Diagnosis relies heavily on microscopy, and although ova-and-parasite examinations can detect Giardia and Cystoisospora, Cryptosporidium and Cyclospora often require specific diagnostic requests. Approved non-microscopy methods are available for Giardia and Cryptosporidium, although negative results are frequently followed by microscopic assays. Polymerase chain reaction-based methods are not frequently used for diagnosis of Giardia and Cryptosporidium and have been used primarily for epidemiologic or outbreak investigations of Giardia and Cryptosporidium.
Topics: Antigens, Protozoan; Coccidia; Coccidiosis; Diagnosis, Differential; Giardia lamblia; Giardiasis; Humans; Immunoassay; Sensitivity and Specificity; Specimen Handling
PubMed: 26004650
DOI: 10.1016/j.cll.2015.02.010