Quantitative Microbial Risk Assessment of Cryptosporidium and Giardia in Public Drinking Water in China.

We aimed to assess the risks of Cryptosporidium and Giardia infections associated with drinking water for local residents, based on a quantitative microbial risk assessment, in three densely populated regions of China. In total, 45 source water samples and 45 treated water samples were collected from June to December 2014. Five Cryptosporidium-positive samples and 5 Giardia-positive samples were found. The annual probability of infection for individuals in Jintan (6.27 × 10 -4-2.05 × 10 -3 for Cryptosporidium and 7.18 × 10 -4-2.32 × 10 -3 for Giardia), Ezhou (6.27 × 10 -4-1.10 × 10 -2 for Cryptosporidium and 3.65 × 10 -4-1.20 × 10 -3 for Giardia), and Binyang (3.79 × 10 -4-1.25 × 10 -3 for Cryptosporidium) exceeded the tolerable risk of infection of 10 -4 set by the United States Environmental Protection Agency. Moreover, the corresponding disease burdens of cryptosporidiosis and giardiasis, due to direct drinking and residual water in these regions, exceeded the threshold of 10 -6 disability-adjusted life years per person per year set by the World Health Organization. These results provide insights into strategies to improve the safety of drinking water.

Regulatory role of the intestinal microbiota in the immune response against Giardia.

Giardia duodenalis is one of the most commonly found intestinal parasites in mammalian hosts. Infections can generally be cleared by mounting an adequate protective immune response that is orchestrated through IL-17A. This study was aimed to investigate if and how the intestinal microbiome affects the protective Th17 response against Giardia by analysing and comparing the immune response following a G. muris and G. duodenalis infection in antibiotic treated and untreated mice. Depletion of the intestinal flora by antibiotic treatment had a severe effect on the infection dynamics of both Giardia species. Not only duration of infection was affected, but also the parasite burden increased significantly. Markers associated with a protective immune response, such as IL-17A and mannose binding lectin 2 were still significantly upregulated following infection in the antibiotic-treated mice, despite the lack of protection. On the other hand, the antibiotic treatment significantly decreased the level of IgA in the intestinal lumen by affecting its transporter and by reducing the number of IgA+ B-cells at the Peyer's patches. Furthermore, the depletion of the gut microbiota by antibiotics also significantly lowered the intestinal motility. The combination of these factors likely results in a decreased clearance of the parasite from the intestinal tract.

Giardia lamblia and Helicobacter pylori coinfection in gastrointestinal biopsies: A retrospective single-center analysis from Switzerland.

BACKGROUND: The protozoan Giardia lamblia (GL) and the bacterium Helicobacter pylori (HP) are common causes of gastrointestinal disease. Coinfection is common and has been reported in studies from Africa, Europe, North America and Asia, but data for Switzerland are scarce. AIM: To investigate GL and HP prevalence and coinfection rate in gastrointestinal biopsies from the Zurich area of Switzerland. METHODS: Cases were retrieved from the laboratory information system (Medica Institute of Clinical Pathology, Zurich, Switzerland). Histological slides of cases with GL were reviewed, as were the concurrent gastric biopsies, where available. RESULTS: Between January 1, 2013 and December 31, 2020, GL was found in 88 (0.14%) of 62,402 patients with a small intestine biopsy and HP in 10,668 (15.5%) of 68,961 patients with a gastric biopsy. 74/88 (84.1%) of patients with GL had unremarkable small intestine biopsies, 13/88 (14.8%) had increased intraepithelial lymphocytes, 5/88 (5.7%) showed villous atrophy and 2/88 (2.3%) acute inflammation. 71/88 patients (80.7%) with GL had an available gastric biopsy, of which 12/71 (16.9%) were unremarkable, 28/71 (39.4%) had HP-associated gastritis, 11/71 (15.5%) showed reactive gastropathy and 1/71 (1.4%) had autoimmune gastritis. CONCLUSION: Coinfection with HP is common in patients with GL in gastrointestinal biopsies from the Zurich area of Switzerland. Therefore, gastroenterologists should consider sampling the stomach when GL is suspected for evaluation of possible concurrent HP-associated gastritis. Likewise, pathologists should scrutinize any small intestine biopsy for the presence of GL when HP-associated gastritis is seen, and vice versa.

Quantitative Microbial Risk Assessment of / 生物医学与环境科学（英文）

We aimed to assess the risks of

What's eating you? An update on Giardia, the microbiome and the immune response.

Giardia intestinalis has been observed in human stools since the invention of the microscope. However, it was not recognized as a pathogen until experimental infections in humans in the 1950s resulted in diarrheal illness [1]. We now know that this protozoan is capable of inducing a malabsorptive diarrhea and that the parasite is a major contributor to stunting in young children [2]. However, the majority of infections with this parasite are not accompanied by overt diarrhea and several studies indicate that it actually has a protective effect against moderate-severe diarrhea [3]. There is therefore significant interest in the mechanisms responsible for the wide variation observed in the clinical outcomes of infection with Giardia. This review will highlight recent work on the interactions among the parasite, the host microbiome and the immune response as contributing to this variation.

Giardiasis: Characteristics, Pathogenesis and New Insights About Treatment.

Giardia intestinalis infection causes enterocytes damage and loss of brush border of the epithelial cells of the intestine that leads to shortening of microvilli and altered epithelial barrier function. This pathology results in aqueous diarrhoea, steatorrhea, nausea, abdominal pain, vomiting and weight loss. However, most infections are asymptomatic. The main consequence of Giardia colonization is nutrients malabsorption. Several families of drugs with good efficacy are used for Giardia treatment, but sometime dosing regimens are suboptimal and emerging resistance begins to question their clinical value. Moreover, some of these drugs can cause side effects that result in patient discomfort and low adherence to the treatment. This paper reviews the drugs currently used for the treatment against Giardia: the mechanism of action, the efficacy, the normal dosing, side effects and in vitro and clinical studies. In addition, new therapies against Giardia such as those based on phytochemicals, Lactobacillus and nanotechnology are collected in this paper, trying to find the ideal treatment for this disease with maximum efficacy and minimum adverse effects.

The Intersection of Immune Responses, Microbiota, and Pathogenesis in Giardiasis.

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.

Molecular Characterization of Giardia lamblia: First Report of Assemblage B in Human Isolates from Rio de Janeiro (Brazil).

BACKGROUND: Despite the high prevalence of giardiasis, the genetic characterization of Giardia lamblia has been poorly documented in Brazil and molecular epidemiology research has only been conducted in the last few years. The aim of this study was to determine the prevalence of different G. lamblia assemblages and detect mixed infections among patients with giardiasis. METHODS AND PRINCIPAL FINDINGS: The cross-section survey was conducted among patients attending the FIOCRUZ in Rio de Janeiro. In order to discriminate the genetic assemblages/sub-assemblages, G. lamblia isolates were characterized by PCR-RFLP and qPCR using four loci genes (bg, gdh, tpi and orfC4). Of the 65 positive samples, 41 (63.1%) were successfully amplified by nested-PCR of bg and gdh genes. Among them, 16 were typed as sub-assemblage AII, 7 as BIII, 4 as BIV and 8 as a mixture of BIII and BIV. After the analysis by qPCR assay, a total of 55 (84.6%) samples were amplified using at least one locus: bg gene was amplified in 38 (58.5%) samples, gdh in 41 (63.1%), tpi in 39 (60%), and orfC4 in 39 (60%). Multilocus genotyping results showed that 29 (52.7%) samples belonged to Assemblage A and 26 (47.3%) samples belonged to Assemblage B. In 2011 and 2012, 20 (74.1%) samples belonged to Assemblage A and 7 (25.9%) belonged to Assemblage B. In subsequent years (2013-2015) there was a predominance of Assemblage B, 19 (67.9%) versus 9 (32.1%) Assemblage A. CONCLUSIONS: This is the first time that Assemblage B of G. lamblia was reported in human clinical samples from Rio de Janeiro (Brazil) and is the first report about genetic characterization using four genes. The qPCR assemblage-specific showed no mixed infections by Assemblages A and B. A switch in genetic profile over the years was observed, firstly predominance of Assemblage A and lastly of Assemblage B.

The Microbiota Contributes to CD8+ T Cell Activation and Nutrient Malabsorption following Intestinal Infection with Giardia duodenalis.

Giardia duodenalis is a noninvasive luminal pathogen that impairs digestive function in its host in part by reducing intestinal disaccharidase activity. This enzyme deficiency has been shown in mice to require CD8(+) T cells. We recently showed that both host immune responses and parasite strain affected disaccharidase levels during murine giardiasis. However, high doses of antibiotics were used to facilitate infections in that study, and we therefore decided to systematically examine the effects of antibiotic use on pathogenesis and immune responses in the mouse model of giardiasis. We found that antibiotic treatment did not overtly increase the parasite burden but significantly limited the disaccharidase deficiency observed in infected mice. Moreover, while infected mice had more activated CD8(+) αß T cells in the small intestinal lamina propria, this increase was absent in antibiotic-treated mice. Infection also led to increased numbers of CD4(+) αß T cells in the lamina propria and activation of T cell receptor γδ-expressing intraepithelial lymphocytes (IEL), but these changes were not affected by antibiotics. Finally, we show that activated CD8(+) T cells express gamma interferon (IFN-γ) and granzymes but that granzymes are not required for sucrase deficiency. We conclude that CD8(+) T cells become activated in giardiasis through an antibiotic-sensitive process and contribute to reduced sucrase activity. These are the first data directly demonstrating activation of CD8(+) T cells and γδ T cells during Giardia infections. These data also demonstrate that disruption of the intestinal microbiota by antibiotic treatment prevents pathological CD8(+) T cell activation in giardiasis.

Giardia duodenalis induces paracellular bacterial translocation and causes postinfectious visceral hypersensitivity.

Irritable bowel syndrome (IBS) is the most frequent functional gastrointestinal disorder. It is characterized by abdominal hypersensitivity, leading to discomfort and pain, as well as altered bowel habits. While it is common for IBS to develop following the resolution of infectious gastroenteritis [then termed postinfectious IBS (PI-IBS)], the mechanisms remain incompletely understood. Giardia duodenalis is a cosmopolitan water-borne enteropathogen that causes intestinal malabsorption, diarrhea, and postinfectious complications. Cause-and-effect studies using a human enteropathogen to help investigate the mechanisms of PI-IBS are sorely lacking. In an attempt to establish causality between giardiasis and postinfectious visceral hypersensitivity, this study describes a new model of PI-IBS in neonatal rats infected with G. duodenalis At 50 days postinfection with G. duodenalis (assemblage A or B), long after the parasite was cleared, rats developed visceral hypersensitivity to luminal balloon distension in the jejunum and rectum, activation of the nociceptive signaling pathway (increased c-fos expression), histological modifications (villus atrophy and crypt hyperplasia), and proliferation of mucosal intraepithelial lymphocytes and mast cells in the jejunum, but not in the rectum. G. duodenalis infection also disrupted the intestinal barrier, in vivo and in vitro, which in turn promoted the translocation of commensal bacteria. Giardia-induced bacterial paracellular translocation in vitro correlated with degradation of the tight junction proteins occludin and claudin-4. The extensive observations associated with gut hypersensitivity described here demonstrate that, indeed, in this new model of postgiardiasis IBS, alterations to the gut mucosa and c-fos are consistent with those associated with PI-IBS and, hence, offer avenues for new mechanistic research in the field.

Treatment of feline giardiasis during an outbreak of diarrhoea in a cattery: potential effects on faecal Escherichia coli resistance patterns.

OBJECTIVES: An outbreak of diarrhoea involving 16 cats at a cattery in Norway was investigated. Treatment and control of the outbreak were the primary objectives, but the effects of treatment on the antimicrobial resistance profiles of Escherichia coli isolated from faeces were also investigated. METHODS: Faecal samples were investigated for Giardia cysts by immunofluorescence microscopy, and multi-locus genotyping was performed to determine the Giardia genotype. Faecal E coli were assessed, before and after treatment for giardiasis, for antimicrobial resistance. RESULTS: The outbreak was probably caused by Giardia duodenalis, Assemblage F. Although infection was eliminated in most cats following treatment with fenbendazole, over 30% of the infected cats required a second treatment round (combined fenbendazole and metronidazole). Investigation of sensitivity to antibacterial drugs of E coli that had been isolated both prior to and following treatment demonstrated that fenbendazole treatment may select for resistant bacteria. CONCLUSIONS AND RELEVANCE: Controlling Giardia infections in dense cat populations can be challenging, and requires strict hygiene measures. In cases where fenbendazole alone does not result in treatment success, a combination treatment with fenbendazole and metronidazole may be effective. Although this study did not include untreated controls, we suggest that the potential for changes in gut microbiota and antimicrobial resistance development should be considered when choosing antiprotozoal drugs, particularly in cases of treatment failure and where repeat treatment is required.

Bioacumulación de coproantígenos de Giardia y Cryptosporidium en un entorno humano infantil / Bioaccumulation of Giardia and Cryptosporidium coproantigen in a child's human environment

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Quantitative microbial risk assessment of Cryptosporidium and Giardia in well water from a native community of Mexico.

Cryptosporidium and Giardia are gastrointestinal disease-causing organisms transmitted by the fecal-oral route, zoonotic and prevalent in all socioeconomic segments with greater emphasis in rural communities. The goal of this study was to assess the risk of cryptosporidiosis and giardiasis of Potam dwellers consuming drinking water from communal well water. To achieve the goal, quantitative microbial risk assessment (QMRA) was carried out as follows: (a) identification of Cryptosporidium oocysts and Giardia cysts in well water samples by information collection rule method, (b) assessment of exposure to healthy Potam residents, (c) dose-response modelling, and (d) risk characterization using an exponential model. All well water samples tested were positive for Cryptosporidium and Giardia. The QMRA results indicate a mean of annual risks of 99:100 (0.99) for cryptosporidiosis and 1:1 (1.0) for giardiasis. The outcome of the present study may drive decision-makers to establish an educational and treatment program to reduce the incidence of parasite-borne intestinal infection in the Potam community, and to conduct risk analysis programs in other similar rural communities in Mexico.

Association between Giardia duodenalis and coinfection with other diarrhea-causing pathogens in India.

Giardia duodenalis, is often seen as an opportunistic pathogen and one of the major food and waterborne parasites. Some insights of Giardia infestation in a diarrhoea-prone population were investigated in the present study. Our primary goal was to understand the interaction of this parasite with other pathogens during infection and to determine some important factors regulating the diarrhoeal disease spectrum of a population. Giardia showed a steady rate of occurrence throughout the entire study period with a nonsignificant association with rainfall (P > 0.05). Interestingly coinfecting pathogens like Vibrio cholerae and rotavirus played a significant (P ≤ 0.001) role in the occurrence of this parasite. Moreover, the age distribution of the diarrhoeal cases was very much dependent on the coinfection rate of Giardia infection. As per our findings, Giardia infection rate seems to play a vital role in regulation of the whole diarrhoeal disease spectrum in this endemic region.

Anti-giardial activity of Sambucus ebulus.

OBJECTIVES: Giardia (G.) lamblia is a parasite that causes giardiasis in humans and other mammals. The common treatment produces unpleasant side effects. The ethnopharmacology for management of parasitic infections accelerates and guides the search for new chemical objects. This study assessed the in vitro cytotoxicity of Sambucus (S.) ebulus fruit against Cysts of G. lamblia. MATERIALS AND METHODS: Giardia cysts were isolated from patients' fecal specimens; the cysts were isolated by sucrose 0.85 M solution. The plant extract was used at concentrations of 1, 10, 50 and 100 mg/mL throughout the experiments. The extracts were incubated with several isolates of G. lamblia for 5, 10, 30 and 60 minutes and then the viability were distinguished by eosin 0.01%. RESULTS: S. ebulus extract at the concentration of 100 mg/ml for 60 minutes had the most anti-giardial activity (78 ± 4%) than other concentrations. CONCLUSIONS: Considering excellent antigiardial activity of S. ebulus in vitro, it seems to have potential for the treatment of the parasitic disease caused by the protozoan G. lamblia.

Assessing the infection risk of Giardia and Cryptosporidium in public drinking water delivered by surface water systems in Sao Paulo State, Brazil.

A survey of Giardia and Cryptosporidium was conducted in surface water used as drinking water sources by public water systems in four densely urbanized regions of Sao Paulo State, Brazil. A Quantitative Microbial Risk Assessment, based on protozoa concentrations, was performed to estimate the probability of protozoa infection associated with drinking water ingestion. A total of 206 source water samples were analyzed over a 24 month period using the USEPA Method 1623. The risk of infection was estimated using an exponential dose response model, children and adults exposure and a gamma distribution for (oo)cyst concentrations with three scenarios for treating censored data. Giardia was detected in 102 of the samples, and 19 of them were also positive for Cryptosporidium, with maximum concentrations of 97.0 cysts/L and 6.0 oocysts/L, respectively. Risk distributions were similar for the three scenarios. In the four regions, the estimated risk of Giardia infection per year, for adults and children, ranged from 0.29% to 2.47% and from 0.08% to 0.70%, respectively. Cryptosporidium risk infection varied from 0.15% to 0.29% for adults and from 0.04% to 0.08% for children. In both cases, the calculated risk surpassed the risk of infection of 10(-4) (1:10,000) defined as tolerable by USEPA for a yearly exposure. The probability of Giardia infection was very close to the rates of acute diarrheic disease for adults (1% to 3%) but lower for children (2% to 7%). The daily consumption of drinking water was an important contributing factor for these differences. The Microbiological Risk Assessment carried out in this study provides an indication of infection risks by Giardia and Cryptosporidium in the population served by these source waters. Strategies for source water protection and performance targets for the water treatment should be established to achieve the required level of public health risk.

Inflammation drives dysbiosis and bacterial invasion in murine models of ileal Crohn's disease.

BACKGROUND AND AIMS: Understanding the interplay between genetic susceptibility, the microbiome, the environment and the immune system in Crohn's Disease (CD) is essential for developing optimal therapeutic strategies. We sought to examine the dynamics of the relationship between inflammation, the ileal microbiome, and host genetics in murine models of ileitis. METHODS: We induced ileal inflammation of graded severity in C57BL6 mice by gavage with Toxoplasma gondii, Giardia muris, low dose indomethacin (LDI; 0.1 mg/mouse), or high dose indomethacin (HDI; 1 mg/mouse). The composition and spatial distribution of the mucosal microbiome was evaluated by 16S rDNA pyrosequencing and fluorescence in situ hybridization. Mucosal E. coli were enumerated by quantitative PCR, and characterized by phylogroup, genotype and pathotype. RESULTS: Moderate to severe ileitis induced by T. gondii (day 8) and HDI caused a consistent shift from >95% gram + Firmicutes to >95% gram - Proteobacteria. This was accompanied by reduced microbial diversity and mucosal invasion by adherent and invasive E. coli, mirroring the dysbiosis of ileal CD. In contrast, dysbiosis and bacterial invasion did not develop in mice with mild ileitis induced by Giardia muris. Superimposition of genetic susceptibility and T. Gondii infection revealed greatest dysbiosis and bacterial invasion in the CD-susceptible genotype, NOD2(-/-), and reduced dysbiosis in ileitis-resistant CCR2(-/-) mice. Abrogating inflammation with the CD therapeutic anti-TNF-α-mAb tempered dysbiosis and bacterial invasion. CONCLUSIONS: Acute ileitis induces dysbiosis and proliferation of mucosally invasive E. coli, irrespective of trigger and genotype. The identification of CCR2 as a target for therapeutic intervention, and discovery that host genotype and therapeutic blockade of inflammation impact the threshold and extent of ileal dysbiosis are of high relevance to developing effective therapies for CD.

[Scientific and methodological rationale for the pathomorphism of Lamblia infection in children during chemical contamination of the biosphere].

The paper analyzes the clinical and laboratory features of Lamblia infection in children living under long-term low-dose chemical load. The scientific search methodology comprised the meticulous examination of the patients randomized by the presence or absence of protozoonosis and the statistical processing and expert analysis of the results. The comprehensive approach could define the main signs of the pathomorphism of lambliosis in the areas with high anthropogenic loads and identify immunological disorders, intoxication, and hepatobiliary dysfunctions. The impact of environmentally induced chemical contamination of the biosphere on the natural history of protozoonosis should be borne in mind when evaluating the biological hazard and risk of environmental biological factors on the population health and when scheduling and implementing hygienic and sanitary-and-epidemiological measures to prevent lambliosis in the high anthropogenic load areas.