Giardia Duodenalis Infection Research Articles

Clinical Manifestations and Molecular Identification of Giardia duodenalis in Pediatric and Adolescent Cancer Patients in Southwestern Iran.

This study aimed to investigate the clinical and molecular characteristics of Giardia duodenalis (G. duodenalis) infection and identify potential risk factors in children and teenagers with malignancies in Shiraz, southwestern Iran. A total of 200 fresh fecal samples were collected from children and adolescents suffering from 32 different cancer types at Amir, Nemazee, and Saadi hospitals affiliated with Shiraz University of Medical Sciences between October 2021 and May 2022. Direct microscopy using saline and iodine wet mount was conducted, and all fecal samples were rechecked by SSU-PCR. Subsequently, a specific fragment of the tpi gene was amplified on all samples for prevalence, sequencing, and assemblage identification. Our study found a 4% (8/200) prevalence of G. duodenalis using microscopy and PCR. The molecular findings were consistent with the microscopic results. All eight positive samples with SSU-rRNA gene were also detected as positive with tpi gene and were correctly sequenced. Among the examined cancer patients, two assemblages were identified: A [sub-assemblage AI (2/8, 25%) and sub-assemblage AII (3/8, 37.5%)] and B [sub-assemblage BIV (3/8, 37.5%)]. Notably, patients were more vulnerable to G. duodenalis infection after receiving at least 8 treatment episodes (p < 0.05) and displaying gastrointestinal symptoms (p > 0.05). The demographic characteristics of cancer patients with G. duodenalis infection and the statistical conclusions were separately detailed. The small sample size and low prevalence rate in this study hindered precise epidemiological conclusions. Nonetheless, the results suggest that G. duodenalis infection among cancer patients in Shiraz city originates from humans, without any specific animal groups (C-H) involved.

Hypoxia and Giardia duodenalis: The Role of Hypoxia-Inducible Factor in Altered Epithelial Glucose Metabolism

The gastrointestinal system experiences frequent oxygenic fluctuations and must be able to maintain barrier integrity during periods of suboptimal oxygen concentration, or hypoxia. Epithelial cells rely on the Hypoxia-Inducible Factor (HIF) complex to activate genes that combat cellular stress and adapt cellular metabolism during hypoxia. Importantly, protozoan parasites can modulate host tissue oxygen tension and HIF activation, yet little is known regarding the relationship between enteric protozoa and hypoxia. This research aims to uncover the role of HIF upon Giardia duodenalis infection, a top cause of global diarrheal disease and an excellent infection model for the study of GI physiology. We hypothesize that HIF-target genes are activated upon Giardia infection, promoting alternative cellular glucose metabolism to sustain bioenergetic homeostasis. Caco-2 colonic epithelial cells were infected with Giardia isolate GS/M (MOI 10) for 1.5 or 4.5 hours under normoxic (21% O2) or hypoxic (~1%O2, STEMCELL hypoxia incubator) conditions to capture the early or peak activation of the oxygen-dependent HIF subunit (HIF-1α). RNA was extracted for assessment of transcriptional alterations of HIF-target genes via reverse transcriptase quantitative polymerase chain reaction. Investigation of HIF-mediated intracellular metabolic changes was carried out via liquid-chromatography mass-spectrometry analysis (hydrophilic-interaction chromatography method) on cocultures supplemented with a hypoxia mimetic (DMOG) or a HIF inhibitor (PX-478). Metabolomics experiments were repeated using Caco-2 cells transfected with sodium-dependent glucose cotransporter 1 (SGLT1), a key glucose transporter in the small intestine where Giardia localizes which is not reliably expressed in Caco-2 cells. Under normoxic conditions, genes that aid in cell stress responses ( VEGFA, ANKRD37, GADD45A) and glycolysis ( HK2, LDHA) are upregulated in Giardia-infected cells in a time-dependent manner (p&lt;0.05). Fewer HIF-target genes are upregulated under hypoxic conditions (e.g., VEGFA, GADD45A, PGK1; p&lt;0.05), indicating Giardia-infected cells exhibit a transcriptional profile similar to hypoxic uninfected cells. Interestingly, HIF1α was upregulated in Giardia-infected cells under hypoxic conditions at 1.5 hours (p&lt;0.05). Analysis of the Caco-2 intracellular metabolome indicated HIF-dependent changes to nucleic acid (e.g., guanosine, inosine, uracil) and amino acid (e.g., glycine, threonine) metabolism. DMOG treatment increased the abundance of glycolytic intermediates (e.g., PEP, DHAP) in both cell lines and inhibited the depletion of the Kreb’s Cycle intermediate aconitate in the Caco-2-SGLT1 transfected cells, confirming the promotion of glycolytic flux by HIF. Taken together, our findings indicate Giardia-infected cells illustrate a hypoxic signature, a novel metabolic cell rescue mechanism in response to enteropathogens. Elucidating the role of HIF during enteric parasitic infections will aid in our understanding of the cellular adaptations underpinning GI pathophysiology, while also shedding light on the potential of HIF as a therapeutic target. Natural Science and Engineering Research Council of Canada. This is the full abstract presented at the American Physiology Summit 2024 meeting and is only available in HTML format. There are no additional versions or additional content available for this abstract. Physiology was not involved in the peer review process.

Microscopy detection and molecular characterisation of Giardia duodenalis infection in outpatients seeking medical care in Egypt.

Giardiosis remains one of the most prevalent enteric parasitic infections globally. Earlier molecular-based studies conducted in Egypt have primarily focused on paediatric clinical populations and most were based on single genotyping markers. As a result, there is limited information on the frequency and genetic diversity of G. duodenalis infections in individuals of all age groups. Individual stool samples (n = 460) from outpatients seeking medical care were collected during January-December 2021 in Kafr El-Sheikh governorate, northern Egypt. Initial screening for the presence of G. duodenalis was conducted by coprological examination. Microscopy-positive samples were further confirmed by real-time PCR. A multilocus sequence typing approach targeted amplification of the glutamate dehydrogenase (gdh), beta-giardin (bg), and triose phosphate isomerase (tpi) genes was used for genotyping purposes. A standardised epidemiological questionnaire was used to gather basic sociodemographic and clinical features of the recruited patients. Giardia duodenalis cysts were observed in 5.4% (25/460, 95% CI: 3.6-7.9) of the stool samples examined by conventional microscopy. The infection was more frequent in children under the age of 10 years and in individuals presenting with diarrhoea but without reaching statistical significance. Stool samples collected during the winter period were more likely to harbour G. duodenalis. All 25 microscopy-positive samples were confirmed by real-time PCR, but genotyping data was only available for 56.0% (14/25) of the isolates. Sequence analyses revealed the presence of assemblages A (78.6%, 11/14) and B (21.4%, 3/14). All assemblage A isolates were identified as sub-assemblage AII, whereas the three assemblage B sequences belonged to the sub-assemblage BIII. Patients with giardiosis presenting with diarrhoea were more frequently infected by the assemblage A of the parasite. This is one of the largest epidemiological studies evaluating G. duodenalis infection in individuals of all age groups in Egypt. Our molecular data suggest that G. duodenalis infections in the surveyed population are primarily of anthropic origin. However, because assemblages A and B are zoonotic, some of the infections identified can have an animal origin. Additional investigations targeting animal (domestic and free-living) and environmental (water) samples are warranted to better understand the epidemiology of giardiosis in Egypt.

The Influence of Giardia duodenalis on the Occurrence of Clinical Signs in Dogs.

Giardia duodenalis infections are common in dogs and are mainly caused by assemblages C and D. The aim of this study was to investigate the correlation between the presence of Giardia duodenalis and different Giardia assemblages detected in symptomatic and asymptomatic dogs and the occurrence of certain clinical signs. All the dogs included (n = 82) were clinically examined, and fecal samples were examined for other parasites and Clostridium spp. Also, G. duodenalis assemblages were detected and the occurrence of certain clinical signs was assessed. A total of 42/82 (51.2%) dogs were symptomatic and had one or more gastrointestinal signs, and 40/82 (48.8%) dogs were asymptomatic. G. duodenalis was found in 25/82 (30.5%) dogs: assemblage C in 10/25 (40%) and assemblage D in 15/25 (60%). Only Cryptosporidium spp. showed a higher coinfection rate with G. duodenalis but that did not have an influence on clinical sign appearance. There was no correlation between the presence of different assemblages of G. duodenalis and the sex of the host or the duration and appearance of certain clinical signs, except the presence of mucus in feces, which was more frequent in dogs invaded with G. duodenalis assemblage C. Further research of other assemblages is needed.

Microscopic and molecular diagnoses of Giardia duodenalis in pet animals in Babylon Province, Iraq.

The breeding of pet animals, especially dogs and cats, in Iraq has increased recently. However, no epidemiological or molecular data exist regarding Giardia duodenalis infection in pet animals, particularly in Babylon Province. Therefore, this study aimed to detect G. duodenalis and its genotypes in pets using microscopic and molecular techniques. For microscopic examination, 150 pet fecal samples (dogs = 75, cats = 75) were examined from October 1, 2022, to March 30, 2023. Fourteen isolates of G. duodenalis (7 per host) were genetically characterized using SSUrDNA gene sequencing. Microscopic examination revealed that the rates of G. duodenalis infection was 14.67% (11/75) and 12% (9/75) in dogs and cats, respectively. According to sex, the infection rate in dogs was 22.22% (8/36) for males and 7.69% (3/39) for females. Conversely, the infection rate in cats was 5.56% (2/36) for males and 17.95% (7/39) for females. The highest infection rates were recorded for animals under 6 months of age, with 16.67% (3/18) for dogs and 27.27% (3/11) for cats. In rural areas, the infection rate was higher than that in urban areas, with 17.65% (6/34) in dogs and 13.89% (5/36) in cats. For the molecular diagnosis, 14 isolates of G. duodenalis (7 per host) were genetically characterized using SSUrDNA gene sequencing. In dogs, the findings revealed specific genotypes, with D at 3/7 (42.86%) and C at 2/7 (28.57%). In addition, zoonotic genotype A was found in 2/7 (28.57%) of dogs. In cats, the specific assemblage F was present in 4/7 (57.14%), while zoonotic genotype A was found in 3/7 (42.86%). This study is considered the first in Babylon Province to detect G. duodenalis genotypes in pet animals (dogs and cats), as some have zoonotic genotypes that could transmit infections to humans. The results of this study illustrate the epidemiological importance of this parasite in this region.

Quinacrine - The Winding Road from the Most Important Antimalarial of Its Time to an Indispensable Antiparasitic (Orphan) Drug of our Days.

Quinacrine, the main antimalarial drug during World War II, has had a chequered history that included the successful repurposing as an intrapleural sclerosant for the treatment of malignant pleural effusions, a non-surgical method of female sterilisation, and the use as an immunomodulatory drug in lupus erythematosus. While no longer used for these former indications, quinacrine (re)emerged as an indispensable second-line drug for the treatment of nitroimidazole-refractory Giardia duodenalis infections, and thus depicts an indispensable "orphan drug".

Giardia duodenalis in Ugandan Children Aged 9-36 Months in Kampala, Uganda: Prevalence and Associated Factors.

Giardia duodenalis is a common gastrointestinal pathogen globally that has been associated with growth failure in children. Most of the studies have been done in school-age children, and there is a paucity of data in pre-school children. We determined the prevalence and factors associated with G. duodenalis infection in children aged 9-36 months presenting to Mulago Hospital with diarrhea or cough. Demographic and socio-economic characteristics, animal ownership, medical history, and physical examination findings were recorded. Stool was tested for G. duodenalis using real-time quantitative polymerase chain reaction (qPCR), and additional tests included stool microscopy and qPCR for Cryptosporidium. The overall prevalence of G. duodenalis infection was 6.7% (214/3,173). In children with diarrhea the prevalence was 6.9% (133/1,923), whereas it was 6.5% (81/1,250) in those with cough as the main symptom. Of 214 children with G. duodenalis infection, 19 (8.9%) were co-infected with Cryptosporidium. Older children (25-36 months) were more likely to have G. duodenalis infection (adjusted odds ratio [aOR]: 2.93, 95% CI: 1.93-4.43). Use of an unimproved toilet (aOR: 1.38, 95% CI: 1.04-1.83) and the wet season (aOR: 1.33, 95% CI: 1.00-1.77) were associated with increased infection. Other factors associated with infection were recurrent diarrhea (aOR: 2.46, 95% CI: 1.64-3.70) and passing of mucoid stool (aOR: 2.25, 95% CI: 1.08-4.66). Having a ruminant at the homestead was also associated with infection (aOR: 1.83, 95% CI: 1.20-2.79). Giardia duodenalis infection occurred in 1 of 15 children aged 9-36 months with diarrhea or cough in Kampala, Uganda. Further studies are needed to clarify the zoonotic significance of G. duodenalis infection in this setting.

Gut Microbiota Crosstalk with Resident Macrophages and Their Role in Invasive Amebic Colitis and Giardiasis-Review.

The innate immune response is highly dependent on the action of macrophages. They are abundant in the intestine subepithelial lamina propria of the mucosa, where they deploy multiple tasks and play a critical role. The balance between the gut microbiota and M2 macrophages is critical for gut health and homeostasis. Gut microbiota has the power to change macrophage phenotype and replenish the resident macrophage niche during and post infection. As far as the extracellular enteric parasitic infections invasive amebic colitis and giardiasis are concerned, a change of macrophages phenotype to a pro-inflammatory state is dependent on direct contact of the protozoan parasites with host cells. Macrophages induce strong pro-inflammatory response by inflammasome activation and secretion of interleukin IL-1β. Inflammasomes play a key role in the response to cellular stress and microbe attacks. The balance between gut mucosal homeostasis and infection is dependent on the crosstalk between microbiota and resident macrophages. Parasitic infections involve NLRP1 and NLRP3 inflammasome activation. For Entamoeba histolytica and Giardia duodenalis infections, inflammasome NLRP3 activation is crucial to promote the host defenses. More studies are needed to further elucidate possible therapeutic and protective strategies against these protozoan enteric parasites' invasive infections in humans.

Conserved Candidate Antigens and Nanoparticles to Develop Vaccine against Giardia intestinalis.

Giardia intestinalis (Giardia lambia, Giardia duodenalis) infections in humans may be asymptomatic or symptomatic and associated with diarrhea (without blood), abdominal cramps, bloating, flatulence, and weight loss. The protozoan Giardia is the third most common cause of diarrhea and death in children under five, preceded only by rotavirus and by Cryptosporidium parvum and C. hominis infections. Antimicrobial drugs, particularly 5-nitroimidazole (5-NIs), are used to treat giardiasis in humans. Immunologically naive or immunocompromised host are more vulnerable to Giardia infection, whereas a degree of resistance to this protozoan is present in humans living in endemic areas. This suggests that vaccination may be a potential and appropriate means to control this parasitic disease outbreak and protect the human population. This review discusses Giardia antigens related to vaccine development. Additionally, based on the latest development of nanoparticle technology, a combination of methods for future research and development is proposed for the design of the next generation of powerful immunogens and an effective vaccine against Giardia.

Strategies to Decrease the Prevalence of Soil-Transmitted Helminths in Central India.

Background Intestinal parasites are a major public health problem in tropical countries. Over 1.5 billion people are infected with soil-transmitted helminths (STH), of which 225 million are in India. Parasitic infections are associated with poor sanitation, lack of safe potable water, and improper hygiene. Materials and Methods The study was undertaken to ascertain the impact of control strategies, namely open-defecation free drive and mass drug administration of single dose albendazole. Stool samples received at AIIMS Bhopal Microbiology laboratory, across all age groups, were studied for protozoan trophozoites/cysts and helminthic ova. Results Out of 4,620 stool samples, 389 (8.41%) were positive either for protozoal or helminthic infections. Protozoan infections were more common than helminthic infections with Giardia duodenalis infection being the most common, 201 (51.67%), followed by Entamoeba histolytica , 174 (44.73%). The helminthic infections constituted 14 (3.5%) of the positive stool samples with Hookworm ova in 6 (1.5%) cases. Conclusion This study proves that strategies, namely "Swachh Bharat Abhiyan" and "National Deworming Day" started in 2014 and 2015 led to significant reduction of intestinal parasite infections in Central India, with a higher reduction of STH compared with protozoan parasite infection being ascribed to the activity spectrum of albendazole.

Single and Synergistic Effects of Fenbendazole and Metronidazole Against Subclinical Infection by Giardia duodenalis in Non-Human Primates in a Zoological Garden in Southern Italy.

The aim of this study was to assess the single and synergistic effects of fenbendazole (Fenb) and metronidazole (Metro) for the treatment of Giardia duodenalis infection in different species of non-human primates (NHPs) housed in a zoological garden of southern Italy. Moreover, the study also aimed to better define the circulation of G. duodenalis zoonotic assemblages in NHP and the potential occurrence of zoonotic transmission between the staff from the zoo and NHP. Briefly, six species that belonged to four families (Lemuridae, Cercopithecidae, Atelidae, and Hylobatidae) of NHP and housed in six cages (CG) were identified as Giardia positive and divided into two groups. Group F (N = 16 animals) was treated with Fenb (50 mg/kg, every 24 h for 5 consecutive days) and Group M (N = 7 animals) was treated with Metro (25 mg/kg, two times a day for 5 consecutive days). After the first round of therapy, all the animals were retreated for 5 days by inverting the drugs in each group. On each sampling day [study days (SDs) 3–24], the samples were tested for the presence of Giardia cysts using the FLOTAC technique. Multiple fecal tests for the antigen detection of Giardia, such as rapid ELISA and direct immunofluorescence (IFA), were performed at each sampling point only on samples that resulted in positive for Giardia cysts with FLOTAC. The efficacy of Fenb ranged from 30 to 67% and for Metro ranged from 82 to 96%. The results showed the synergistic effects of Metro and Fenb (98–100%) over the combination of Fenb and Metro (52–90%) against the infection by Giardia in NHPs. The overall k agreement between FLOTAC and IFA was reached 0.858 (p = 0.0001). In contrast, all the samples had a negative antigen result when using ELISA. At molecular analysis, six samples were confirmed positive for Giardia by nested PCR. Only two positive samples were successfully sequenced that showed 100% of identity with assemblage B. All the samples from the humans included in the study resulted in negative for Giardia cysts. Overall, the study emphasizes the need for regular monitoring of Giardia infections in NHP housed in zoos by traditional diagnostic tools combined with molecular characterization of the parasite.

Elimination of Giardia duodenalis BIV in vivo using natural extracts in microbiome and dietary supplements.

In this study, a combination therapy of several natural products was evaluated in vivo in the Giardia duodenalis infection model. G. duodenalis infected mice were treated as follows: distilled water (infected control C+), BIOintestil® (BIO; natural products of Cymbopogon martinii and Zingiber officinale), MicrobiomeX® (MBX; extract of Citrus sinensis and Citrus paradisi), MBX+BIO, Camellia sinensis tea (CPR; black tea). These natural compounds were administered in a dose of 100mg/day and were compared to G. duodenalis-infected mice treated with albendazole (ALB; 50mg/Kg/day) and metronidazole (MET; 500mg/Kg/day), the conventional therapies used to this day. One group remained un-infected and untreated as our control group (C-). Treatment started 8days after infection, and after 5days of treatment (7days for MET), all animals were followed for 15days. We continuously checked for the presence of G. duodenalis by Faust method, in association with detection of the parasite by PCR from feces, as well for the presence of trophozoites in the intestinal mucosa after sacrifice. Animals treated with MBX, BIO and MBX+BIO presented an undetectable parasitic load until the 15th day of monitoring, while animals treated with CPR, MET and ALB continued to release cysts. Animals in the MBX, MBX+BIO, ALB groups consumed lower feed, MBX, CPR, MET had greater weight and MBX, MBX+BIO, BIO, CPR, C- consumed more water when compared to infected-group control. MBX and BIO alone or associated eliminated G. duodenalis without apparent adverse effects and animals of these groups showed better clinical performance in relation to those with high parasitic load. MET, ALB and CPR only decreased the number of cysts, indicating limitations and therapeutic failure.

Household finished flooring as a guard against enteric illness in children

Soil-transmitted helminth and Giardia duodenalis infections are among the most common worldwide, and are major public health problems, especially for children from the poorest and most deprived communities around the world.1 Infection with enteric pathogens in children often results in malnutrition, absenteeism, and poor school performance, delayed physical growth, and impaired cognitive function and mental growth.2,3 The primary soil-transmitted helminth control strategy is administering mass preventive chemotherapy in populations at risk.

Prevalence and multi-locus genotyping of Giardia duodenalis in rabbits from Shaanxi province in northwestern China.

Giardia duodenalis is an important parasite with veterinary and public health significance worldwide. The presence and zoonotic assemblages of G. duodenalis have previously been reported in rabbits. In this study, to understand the infection status of G. duodenalis in rabbits from Shaanxi province, a total of 537 fecal samples were collected from two breeds of rabbits in four age groups (<30 days, 31–90 days, 91–200 days and >200 days) from four geographical origins (Fengxiang, Yangling, Tongchuan, and Shanyang). The presence of G. duodenalis in these samples was assessed using molecular assays based on beta-giardin (bg). The glutamate dehydrogenase (gdh) and triosephosphate isomerase (tpi) loci were then amplified in the bg-positive samples for multi-locus genotype (MLG) analysis. The total prevalence of G. duodenalis in these rabbits was 3.54% (19/537). Giardia duodenalis infection was found in both breeds of rabbits, and in all farms and age groups, but with no statistically significant differences related to these factors (p > 0.05). Two assemblages, including B and E, were identified, with the former the predominant assemblage detected in both breeds, and in all age groups and farms. Sequence analysis revealed 2 (named as rbg1-2), 1 (named as rtpi1), and 2 (named as rgdh1-2) haplotypes at the gene loci of bg, tpi, and gdh, respectively, forming a multilocus genotype (MLG) of assemblage B (rbg1, rtpi1, and rgdh1). These findings reveal the significant zoonotic potential and genetic diversity of G. duodenalis in rabbits in Shaanxi Province, PR China.

Frequency of Giardia duodenalis infection and its genetic variability in dogs in Cuiabá, Midwest Brazil.

Giardia duodenalis, a unicellular, eukaryotic, and flagellated protozoan, presents two evolutionary forms in its life cycle, namely, trophozoites and cysts. It causes diarrhea in humans, dogs, cats, rodents, and ungulates. Despite being morphologically similar, the isolates of G. duodenalis are genetically diverse, affecting the stability and unanimity of taxonomic classification. Since different Giardia assemblages may occur within one isolate, multilocus genotyping is recommended for the genetic identification. To determine the frequency of G. duodenalis infections in domiciled dogs in Cuiabá Municipality (State of Mato Grosso, Midwestern Brazil) and characterize its genetic variability, fecal samples were collected from 147 dogs. Overall, 6.8% (10/147) of the samples presented cysts of G. duodenalis, which sequencing and genotypic characterization using tpi and gluD revealed assemblages C and A, genetic grouping of G. duodenalis. Only three samples amplified by tpi and one sample amplified by gluD. The risk factors age, gender, breed, diet and the presence of other dogs in the same house were not correlationated with giardiasis. The host-specific and zoonotic genotype warns of the risk of inter and intraspecies transmission and it provides, for the first time, information about genetic characterization of G. duodenalis isolates in dogs in Cuiabá, Midwest region of Brazil.

Effects of anthropogenic habitat disturbance and Giardia duodenalis infection on a sentinel species' gut bacteria.

Habitat disturbance, a common consequence of anthropogenic land use practices, creates human–animal interfaces where humans, wildlife, and domestic species can interact. These altered habitats can influence host–microbe dynamics, leading to potential downstream effects on host physiology and health. Here, we explored the effect of ecological overlap with humans and domestic species and infection with the protozoan parasite Giardia duodenalis on the bacteria of black and gold howler monkeys (Alouatta caraya), a key sentinel species, in northeastern Argentina. Fecal samples were screened for Giardia duodenalis infection using a nested PCR reaction, and the gut bacterial community was characterized using 16S rRNA gene amplicon sequencing. Habitat type was correlated with variation in A. caraya gut bacterial community composition but did not affect gut bacterial diversity. Giardia presence did not have a universal effect on A. caraya gut bacteria across habitats, perhaps due to the high infection prevalence across all habitats. However, some bacterial taxa were found to vary with Giardia infection. While A. caraya's behavioral plasticity and dietary flexibility allow them to exploit a range of habitat conditions, habitats are generally becoming more anthropogenically disturbed and, thus, less hospitable. Alterations in gut bacterial community dynamics are one possible indicator of negative health outcomes for A. caraya in these environments, since changes in host–microbe relationships due to stressors from habitat disturbance may lead to negative repercussions for host health. These dynamics are likely relevant for understanding organism responses to environmental change in other mammals.

Giardia duodenalis infection in dogs from the metropolitan area of Lisbon, Portugal: prevalence, genotyping and associated risk factors.

Giardia duodenalis is a cosmopolitan enteric protozoan that affects a wide range of vertebrates, including humans and dogs. Genetic characterisation reveals eight different assemblages, with A and B having been found mainly in humans and several other animals, and thus considered potentially zoonotic, while C and D are adapted to infect dogs. This study aimed to determine the prevalence of G. duodenalis, their distribution into assemblages, and risk factors associated with their infection of dogs from the metropolitan area of Lisbon. Giardia duodenalis cysts were microscopically identified in 33.8% (27/80) of the faecal samples analysed. Multivariate logistic regression analysis revealed that dogs under 6months of age and from both breeders and shelters, had a significantly higher risk of being infected with G. duodenalis. Based on phylogenetic analysis of the partial coding sequences for β-giardin, glutamate dehydrogenase, and triosephosphate isomerase, the parasites found in three dog isolates were typed as G. duodenalis assemblage C, 11 were typed as D, and four were typed as C or D, depending on the targeted genes. The risk to public health seems to be reduced, as no genotypes with zoonotic potential have been detected. Nevertheless, better health management towards a minimisation of the environmental faecal pollution, as well as an increase in the awareness of health professionals, dog owners, dog breeders and caregivers regarding the risks posed by this protozoan to the health of animals and humans, are recommended.

Epidemiological study of Giardia duodenalis infection in companion dogs from the metropolitan area of São Paulo Brazil.

Giardia duodenalis is a zoonotic pathogen associated with gastrointestinal disease that has a direct life cycle, with cysts eliminated in the faeces of an infected host being ingested by a susceptible host. In Brazil, studies of chronically infected adult dogs estimated a prevalence of 10%-20%. Diagnosis of giardiasis, as a cause of diarrhoea is important for the global One-Health guidelines when controlling cyst dissemination in the environment. We investigated the prevalence of G.duodenalis in the pet dog population of the metropolitan area of Sao Paulo, compared the efficacy of direct tests available to the veterinary clinical practice and attempted to identify possible risk factors associated with the parasite. Ten veterinary practices distributed throughout the municipality randomly performed the rapid SNAP ELISA test on canine faecal samples, and dog owners provided information specific to the animal via a questionnaire. The samples were also analysed using sucrose and zinc sulphate flotation techniques. Sensitivity and specificity of the tests were used to calculate required number of samples and true prevalence. Significance, agreement among tests, and odds ratio (OR) were assessed with a confidence interval (CI) of 95%. The prevalence of G.duodenalis in dogs (n=265) was 6.9% (CI 3.47-11.21). Positive tests were significantly more frequent in animals younger than 1year, with an OR for G.duodenalis occurrence nearly 7-fold that of older dogs. Direct diagnosis tests showed high agreement (96.1%, κ=0.729; p<.0001) showing that the combined techniques provide a highly accurate diagnosis. Results indicated that the control of the pathogen has been improving in the pet dog population in metropolitan Sao Paulo, but management tools including diagnosis, immunization, and treatment, especially in puppies, must be continued in order to advance towards continuous decrease of the disease.

Report of Giardia assemblages and giardiasis in residents of Guilan province-Iran.

Giardia duodenalis is considered a highly diverse organism that infects a variety of mammalian hosts. Giardiasis is a significant public health problem in Iran. The purpose of this study was to investigate the occurrence of Giardia duodenalis (G. lamblia, G. intestinalis) infections in humans residing in the Guilan province of Iran. Stool samples were collected during 12months from 8356 individuals that had been referred to certain hospitals in the capital city of Rasht in the Guilan province, of which 4126 were males and 4230 were females. The samples were separated into three groups according to patient age: group A 1-9years old (n = 483); group B 10-19years old (n = 491); and group C greater than 20years old (n = 7382). The wet mount technique was performed directly on 8356 fecal samples for microscopy. Samples were examined using a saline and iodine direct smear technique in order to confirm the presence of G. duodenalis. The results indicated that 2.5% (206/8356) of the samples were identified as positive for G. duodenalis. A total of 30% of the infected patients (n = 62) had no symptoms. In symptomatic cases, the most common symptoms (46%, n = 95) were abdominal cramps and bloating. Twenty-four percent of patients (n = 50) had cramps, bloating, nausea, and diarrhea. Sixty positive samples were sent for G. duodenalis genotyping based on the amplification of the gdh gene. Forty-one PCR products were successfully selected and sequenced, where 38 (92.6%) samples were identified as genotype A/subgenotype II and in three samples (7.4%) genotype B/subgenotype IV. Genotype A-II had a dominant prevalence as compared to the genotype B-IV samples that were identified in the study. Based on the samples provided by the regional teaching hospitals and subsequent sample analysis, the authors concluded that assemblage A-II is most likely the most common Giardia subgroup infection in the Guilan region. Assemblages have been reported in both humans and animals; however, further studies need to investigate the role of domestic animals and water reservoirs as potential sources of Giardia infection in the Guilan region.

Epidemiology of Giardia duodenalis assemblages in Brazil: there is still a long way to go

Giardia duodenalis infection is distributed worldwide and can achieve prevalence around 60%, especially in developing countries. This protozoan is divided into eight assemblages, in which A and B have high zoonotic potential, whereas C to H are host-specific. This scenario is changing as molecular studies progress, highlighting that knowledge on host-specificity still has a long way to go. Understanding the players involved in transmission routes enables rational designs of control strategies. Considering the high prevalence of giardiasis, this review aims to gather together the data on available studies on the distribution of G. duodenalis assemblages in Brazil until September 2020.