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Clinical Microbiology Reviews Jan 2011Molecular diagnostic tools have been used recently in assessing the taxonomy, zoonotic potential, and transmission of Giardia species and giardiasis in humans and... (Review)
Review
Molecular diagnostic tools have been used recently in assessing the taxonomy, zoonotic potential, and transmission of Giardia species and giardiasis in humans and animals. The results of these studies have firmly established giardiasis as a zoonotic disease, although host adaptation at the genotype and subtype levels has reduced the likelihood of zoonotic transmission. These studies have also identified variations in the distribution of Giardia duodenalis genotypes among geographic areas and between domestic and wild ruminants and differences in clinical manifestations and outbreak potentials of assemblages A and B. Nevertheless, our efforts in characterizing the molecular epidemiology of giardiasis and the roles of various animals in the transmission of human giardiasis are compromised by the lack of case-control and longitudinal cohort studies and the sampling and testing of humans and animals living in the same community, the frequent occurrence of infections with mixed genotypes and subtypes, and the apparent heterozygosity at some genetic loci for some G. duodenalis genotypes. With the increased usage of multilocus genotyping tools, the development of next-generation subtyping tools, the integration of molecular analysis in epidemiological studies, and an improved understanding of the population genetics of G. duodenalis in humans and animals, we should soon have a better appreciation of the molecular epidemiology of giardiasis, the disease burden of zoonotic transmission, the taxonomy status and virulences of various G. duodenalis genotypes, and the ecology of environmental contamination.
Topics: Animals; Genotype; Giardia; Giardiasis; Humans; Molecular Epidemiology; Molecular Typing; Parasitology; Zoonoses
PubMed: 21233509
DOI: 10.1128/CMR.00033-10 -
PLoS Pathogens Sep 2018
Review
Topics: Animals; Diarrhea; Giardia lamblia; Giardiasis; Humans; Protozoan Vaccines; Vacuoles
PubMed: 30261050
DOI: 10.1371/journal.ppat.1007250 -
Trends in Parasitology Nov 2017Giardia lamblia is one of the most common infectious protozoans in the world. Giardia rarely causes severe life-threatening diarrhea, and may even have a slight... (Review)
Review
Giardia lamblia is one of the most common infectious protozoans in the world. Giardia rarely causes severe life-threatening diarrhea, and may even have a slight protective effect in this regard, but it is a major contributor to malnutrition and growth faltering in children in the developing world. Giardia infection also appears to be a significant risk factor for postinfectious irritable bowel and chronic fatigue syndromes. In this review we highlight recent work focused on the impact of giardiasis and the mechanisms that contribute to the various outcomes of this infection, including changes in the composition of the microbiota, activation of immune responses, and immunopathology.
Topics: Animals; Gastrointestinal Microbiome; Giardia; Giardiasis; Humans; Intestines; Research
PubMed: 28830665
DOI: 10.1016/j.pt.2017.08.001 -
Clinical Microbiology Reviews Jan 1992Giardiasis is one of the most common pathogenic intestinal protozoal infections worldwide. Giardia lamblia is the most frequently identified etiologic agent in outbreaks... (Review)
Review
Giardiasis is one of the most common pathogenic intestinal protozoal infections worldwide. Giardia lamblia is the most frequently identified etiologic agent in outbreaks associated with the ingestion of surface water, often due to ineffective filtration or pretreatment. In addition to humans, other sources of infection include beavers, perhaps muskrats, and possibly domestic animals. A low infecting dose (10 to 25 cysts) is reported to be sufficient to produce human infection. Clinical manifestations range from asymptomatic to a transient or persistent acute stage, with steatorrhea, intermittent diarrhea, and weight loss, or to a subacute or chronic stage that can mimic gallbladder or peptic ulcer disease. Diagnosis is usually based on repeated stool examinations but examination of duodenal fluid or biopsy material may also be necessary. Enzyme immunoassay or indirect immunofluorescence methods for direct detection of antigen or whole organisms in clinical specimens have also been developed. These tests are reported to be more sensitive than routine stool examination. Demonstration of serum immunoglobulin M and G antibodies may help differentiate recent from past infection or help detect recurrence in individuals who have been treated previously. Serum immunoglobulin A levels may be a useful indicator of exposure in waterborne outbreaks of diarrhea. Drugs available for treatment within the United States include metronidazole, quinacrine hydrochloride, and furazolidone.
Topics: Animals; Giardiasis; Humans
PubMed: 1735095
DOI: 10.1128/CMR.5.1.93 -
World Journal of Gastroenterology Dec 2013Giardiasis is the most common waterborne parasitic infection of the human intestine worldwide. The etiological agent, Giardia duodenalis (syn. G. intestinalis, G.... (Review)
Review
Giardiasis is the most common waterborne parasitic infection of the human intestine worldwide. The etiological agent, Giardia duodenalis (syn. G. intestinalis, G. lamblia), is a flagellated, binucleated protozoan parasite which infects a wide array of mammalian hosts. Human giardiasis is a true cosmopolitan pathogen, with highest prevalence in developing countries. Giardiasis can present with a broad range of clinical manifestations from asymptomatic, to acute or chronic diarrheal disease associated with abdominal pain and nausea. Most infections are self-limiting, although re-infection and chronic infection can occur. Recent evidence indicating that Giardia may cause chronic post-infectious gastrointestinal complications have made it a topic of intense research. The causes of the post-infectious clinical manifestations due to Giardia, even after complete elimination of the parasite, remain obscure. This review offers a state-of-the-art discussion on the long-term consequences of Giardia infections, from extra-intestinal manifestations, growth and cognitive deficiencies, to post-infectious irritable bowel syndrome. The discussion also sheds light on some of the novel mechanisms recently implicated in the production of these post-infectious manifestations.
Topics: Antiprotozoal Agents; Cognition Disorders; Failure to Thrive; Giardia lamblia; Giardiasis; Growth Disorders; Humans; Irritable Bowel Syndrome; Nutritional Status; Time Factors; Treatment Outcome
PubMed: 24379622
DOI: 10.3748/wjg.v19.i47.8974 -
British Medical Journal Aug 1977
Topics: Giardiasis; Humans; Metronidazole
PubMed: 890410
DOI: No ID Found -
Journal of Veterinary Internal Medicine 2024Giardia duodenalis (Gd) causes intestinal parasitosis. The involvement of the intestinal microbiome in determining the infection's clinical phenotype is unknown.
BACKGROUND
Giardia duodenalis (Gd) causes intestinal parasitosis. The involvement of the intestinal microbiome in determining the infection's clinical phenotype is unknown.
OBJECTIVE
Investigate the fecal microbiome features in dogs with giardiasis.
ANIMALS AND METHODS
Cross-sectional study, including fecal samples of kenneled dogs with Gd diagnosed by fecal Giardia antigen dot ELISA. The fecal microbial compositional characteristics and dysbiosis index (DI) were compared between diarrheic and nondiarrheic dogs.
RESULTS
Fecal samples of 38 Gd-infected dogs (diarrheic, 21; nondiarrheic, 17) were included. No differences were found in Faith's phylogenic diversity and beta diversity (weighted UniFrac distances) and in specific taxa abundances at the phylum, genus, and species levels, as well as in alpha and beta diversities between diarrheic and nondiarrheic dogs, and also when divided by sex or age. Among diarrheic dogs, alpha diversity was higher in males than in females (pairwise Kruskal-Wallis, q = 0.01). Among males, fecal abundances of the genus Clostridium (W = 19) and Clostridium spiroforme species (W = 33) were higher in diarrheic compared to nondiarrheic dogs. In diarrheic dog fecal samples, Proteobacteria were more prevalent (W = 1), whereas Verrucomicrobia were less prevalent in dogs <1 year of age than in older dogs. The fecal sample DI of 19 diarrheic and 19 nondiarrheic dogs was similar (median, -0.2; range, -4.3 to 4.5 and median, -1.0; range, -4.3 to 5.8, respectively).
CONCLUSIONS
The fecal microbial composition of symptomatic and asymptomatic dogs with giardiasis is similar. Based on fecal DI, giardiasis is not characterized by prominent dysbiosis. Other host and parasite characteristics might determine the severity of giardiasis in dogs.
Topics: Male; Female; Animals; Dogs; Giardiasis; Cross-Sectional Studies; Dysbiosis; Diarrhea; Feces; Microbiota; Dog Diseases
PubMed: 37890857
DOI: 10.1111/jvim.16894 -
Revista Brasileira de Parasitologia... 2023Diagnosis is crucial for controlling giardiasis. We determined the prevalence and genetically characterize isolates of Giardia duodenalis of children and dogs from rural...
Diagnosis is crucial for controlling giardiasis. We determined the prevalence and genetically characterize isolates of Giardia duodenalis of children and dogs from rural communities in northeastern Brazil. G. duodenalis cysts were concentrated by centrifugal flotation/sedimentation. Molecular characterization was carried out using the loci ssu-rRNA, bg, tpi, and gdh. By parasitological techniques, Giardia spp. infection was detected in 72/192 children (37.5%; 95% CI: 30.6%-44.7%) and 24/139 dogs (17.3%; 95% CI: 11.4%-24.6%). By molecular analysis, infection was detected in 60/141 children (42.5%; 95% CI: 34.3%-51.2%) and 26/92 dogs (28.3%; 95% CI: 19.4%-38.6%). The total prevalence of giardiasis was 54.9% in children (106/193; 95% CI: 47.1%-61.6%) and 32.9% in dogs (47/143; 95% CI: 25.2%-41.2%). Zoonotic assemblages A and B of G. duodenalis were detected in children, and assemblage E of G. duodenalis was detected in one child and two dogs. Parallel use of parasitological and molecular techniques proved to be a more effective strategy for detecting giardiasis in children and dogs from endemic areas.
Topics: Animals; Dogs; Giardiasis; Brazil; Giardia lamblia; RNA, Ribosomal; Prevalence; Feces; Genotype; Dog Diseases
PubMed: 36820730
DOI: 10.1590/S1984-29612023010 -
Current Opinion in Infectious Diseases Oct 2022Giardia is a common intestinal parasite worldwide, and infection can be associated with clear, and sometimes persistent symptomatology. However, in children in... (Review)
Review
PURPOSE OF REVIEW
Giardia is a common intestinal parasite worldwide, and infection can be associated with clear, and sometimes persistent symptomatology. However, in children in high-prevalence settings, it is most often not associated with or is perhaps even protective against acute diarrhea. Nonetheless, recent longitudinal studies in high-prevalence settings increasingly identify an association with long-term outcomes that has been difficult to discern.
RECENT FINDINGS
Recent studies have made progress in disentangling this apparent paradox. First, prospective, well characterized cohort studies have repeatedly identified associations between Giardia infection, gut function, and child growth. Second, experimental animal and in-vitro models have further characterized the biological plausibility that Giardia could impair intestinal function and subsequently child development through different pathways, depending upon biological and environmental factors. Finally, new work has shed light on the potential for Giardia conspiring with specific other gut microbes, which may explain discrepant findings in the literature, help guide future higher resolution analyses of this pathogen, and inform new opportunities for intervention.
SUMMARY
Recent prospective studies have confirmed a high, if not universal, prevalence of persistent Giardia infections in low-and-middle income countries associated with child-growth shortfalls and altered gut permeability. However, the predominance of subclinical infections limits understanding of the true clinical impact of endemic pediatric giardiasis, and global disease burdens remain uncalculated. Integrating the role of Giardia in multipathogen enteropathies and how nutritional, microbial, metabolic, and pathogen-strain variables influence Giardia infection outcomes could sharpen delineations between pathogenic and potentially beneficial attributes of this enigmatic parasite.
Topics: Animals; Diarrhea; Giardia; Giardiasis; Humans; Incidence; Prevalence; Prospective Studies
PubMed: 35980005
DOI: 10.1097/QCO.0000000000000877 -
Epidemiology and Infection Oct 2016Giardia intestinalis is the leading parasitic aetiology of human enteric infections in the United States, with an estimated 1·2 million cases occurring annually. To... (Review)
Review
Giardia intestinalis is the leading parasitic aetiology of human enteric infections in the United States, with an estimated 1·2 million cases occurring annually. To better understand transmission, we analysed data on all giardiasis outbreaks reported to the Centers for Disease Control and Prevention for 1971-2011. The 242 outbreaks, affecting ~41 000 persons, resulted from waterborne (74·8%), foodborne (15·7%), person-to-person (2·5%), and animal contact (1·2%) transmission. Most (74·6%) waterborne outbreaks were associated with drinking water, followed by recreational water (18·2%). Problems with water treatment, untreated groundwater, and distribution systems were identified most often during drinking water-associated outbreak investigations; problems with water treatment declined after the 1980s. Most recreational water-associated outbreaks were linked to treated swimming venues, with pools and wading pools implicated most often. Produce was implicated most often in foodborne outbreaks. Additionally, foods were most commonly prepared in a restaurant and contaminated by a food handler. Lessons learned from examining patterns in outbreaks over time can help prevent future disease. Groundwater and distribution system vulnerabilities, inadequate pool disinfection, fruit and vegetable contamination, and poor food handler hygiene are promising targets for giardiasis prevention measures.
Topics: Disease Outbreaks; Gastroenteritis; Giardiasis; Humans; United States
PubMed: 26750152
DOI: 10.1017/S0950268815003040