Giardiasis as a re-emerging infectious disease and its zoonotic potential

Giardia duodenalis triggered neutrophil extracellular traps in goats

Giardia duodenalis is a globally distributed zoonotic parasite primarily transmitted through the fecal-oral route, infecting various vertebrates, and the infection of which is prevalent in goats. Immune cells play a crucial role in pathogens invasion, and neutrophil extracellular traps (NETs) released by neutrophils serve as a non-specific defense mechanism against pathogens including parasites. In this study, we investigated the characteristics, components, and molecular mechanisms of goat NETs upon stimulation with G. duodenalis trophozoites. This study demonstrates that G. duodenalis trigger dose-dependent NETs formation in goat neutrophils, composed of DNA, citrullinated histone H3 (CitH3), and neutrophil elastase (NE). Reactive oxygen species (ROS) accumulation synchronizes with NETosis during G. duodenalis infection. Inhibitor experiments confirmed that G. duodenalis-induced NETs and ROS production depend on TLR2/4 signaling and require NADPH oxidase (NOX), ERK1/2, and p38 MAPK activation. This work identifies TLR2/4, NOX, ERK1/2, and p38 MAPK pathways as key regulators of NETs/ROS coordination during G. duodenalis infection, providing the first evidence of G. duodenalis-triggered NETs in goats. The findings highlight NETs as critical components of anti-G. duodenalis immunity and suggest potential for NETs-targeted therapeutic strategies.

Prevalence and genotypic identification of Cryptosporidium spp., Giardia duodenalis and Enterocytozoon bieneusi in farmed ostriches (Struthio camelus) by the Yellow River in Zhengzhou city, central China

BACKGROUND

Cryptosporidium spp., Giardia duodenalis, and Enterocytozoon bieneusi are significant zoonotic protozoa causing gastrointestinal diseases in humans and animals. However, their prevalence and genotypic characterization in ostriches (Struthio camelus) remain poorly understood. This study aimed to investigate the occurrence and genetic diversity of these parasites in farmed ostriches by the Yellow River in Zhengzhou City, central China. A total of 156 fecal samples were collected and analyzed using polymerase chain reaction (PCR) to determine the prevalence and assess the potential epidemiological roles of ostriches in transmission.

RESULTS

The overall prevalence of Cryptosporidium spp., G. duodenalis and E. bieneusi was 2.56% (4/156), 1.28% (2/156) and 12.2% (19/156), respectively. C. baileyi and G. duodenalis assemblage B were identified in ostriches. Six E. bieneusi genotypes were identified in this study, comprising four previously reported genotypes (EbpA, EbpC, Henan-IV, and Type IV) and two novel genotypes (designated as COW1 and COW2, which differed from known genotypes by two single nucleotide polymorphisms). Among these, EbpC was identified as the predominant genotype. All six genotypes were phylogenetically assigned to zoonotic group 1.

CONCLUSIONS

Our findings suggest that ostriches harbor zoonotic genotypes of G. duodenalis and E. bieneusi, indicating they may serve as potential reservoirs for human infection. This underscores the need for effective control measures to prevent environmental contamination and reduce the risk of transmission to humans and other animals.

Environmental stressors and zoonoses in the Arctic: Learning from the past to prepare for the future

The risk of zoonotic disease transmission from animals to humans is elevated for people in close contact with domestic and wild animals. About three-quarters of all known human infectious diseases are zoonotic, and potential health impacts of these diseases are higher where infectious disease surveillance and access to health care and public health services are limited. This is especially the case for remote circumarctic regions, where drivers for endemic, emerging, and re-emerging zoonotic diseases include anthropogenic influences, such as pollution by long-range transport of industrial chemicals, climate change, loss of biodiversity and ecosystem alterations. In addition to these, indirect effects including natural changes in food web dynamics, appearance of invasive species and thawing permafrost also affect the risk of zoonotic disease spill-over. In other words, the Arctic represents a changing world where pollution, loss of biodiversity and habitat, and maritime activity are likely driving forward occurrence of infectious diseases. As a broad international consortium with a wide range of expertise, we here describe a selection of case studies highlighting the importance of a One Health approach to zoonoses in the circumarctic, encompassing human health, animal health, and environmental health aspects. The cases highlight critical gaps in monitoring and current knowledge, focusing on environmental stressors and lifestyle factors, and they are examples of current occurrences in the Arctic that inform on critically needed actions to prepare us for the future. Through these presentations, we recommend measures to enhance awareness and management of existing and emerging zoonoses with epidemic and pandemic potential while also focusing on the impacts of various environmental stressors and lifestyle factors on zoonoses in the Arctic.

Automatic classification of Giardia infection from stool microscopic images using deep neural networks

Introduction

Giardiasis is a common intestinal infection caused by the Giardia lamblia parasite, and its rapid and accurate diagnosis is crucial for effective treatment. The automatic classification of Giardia infection from stool microscopic images plays a vital role in this diagnosis process. In this study, we applied deep learning-based models to automatically classify stool microscopic images into three categories, namely, normal, cyst, and trophozoite.

Methods

Unlike previous studies focused on images acquired from drinking water samples, we specifically targeted stool samples. In this regard, we collected a dataset of 1610 microscopic digital images captured by a smartphone with a resolution of 2340 × 1080 pixels from stool samples under the Nikon YS100 microscope. First, we applied CLAHE (Contrast Limited Adaptive Histogram Equalization) histogram equalization a method to enhance the image quality and contrast. We employed three deep learning models, namely Xception, ResNet-50, and EfficientNet-B0, to evaluate their classification performance. Each model was trained on the dataset of microscopic images and fine-tuned using transfer learning techniques.

Results

Among the three deep learning models, EfficientNet-B0 demonstrated superior performance in classifying Giardia lamblia parasites from stool microscopic images. The model achieved precision, accuracy, recall, specificity, and F1-score values of 0.9599, 0.9629, 0.9619, 0.9821, and 0.9607, respectively.

Conclusion

The EfficientNet-B0 showed promising results in accurately identifying normal, cyst, and trophozoite forms of Giardia lamblia parasites. This automated classification approach can provide valuable assistance to laboratory science experts and parasitologists in the rapid and accurate diagnosis of giardiasis, ultimately improving patient care and treatment outcomes.

A scoping review of modifiable and behavioural drivers of infectious gastroenteritis among children in high-income countries

BACKGROUND

Globally, gastroenteritis (GE) significantly impacts children's health and contributes to societal, economic, and health burdens. Previous studies reporting risk factors of GE in children in high-income settings mainly rely on outbreak investigations, which inherently capture only a fractional representation of the overall spectrum of GE occurrences. In addition, there is paucity of comprehensive information pertaining to modifiable risk factors of GE. This scoping review aims to synthesize existing evidence concerning modifiable and behavioural risk factors associated with GE among children in high-income countries.

METHODS

PubMed, Embase, CINAHL, and Scopus were the databases from which articles were retrieved. A descriptive synthesis of the evidence was performed, following the Arksey and O'Malley scoping studies framework and enhanced by the Preferred Reporting Items for Systematic Reviews and Meta-analysis extension for Scoping Reviews checklist (PRISMA-ScR).

RESULTS

The systematic search identified 13,395 journal articles, which were subsequently screened, and duplicates removed, resulting in 19 articles for inclusion in the review. The majority of these studies (63.2%) employed a case-control design and were predominantly conducted in community settings (68.4%). Factors such as parental literacy, contact with individuals exhibiting gastrointestinal symptoms, and nappy-wearing were identified as significantly associated with childhood GE within domestic environments. Childcare-related variables, including enrolment size, mixing of personnel between child groups, the presence of central cleaning stations, and the implementation of hygiene and disease prevention policies, showed significant association with GE. In addition, the presence of sand pits, paddling pools, and animals in childcare centers correlated with increased incidences of GE among attending children.

CONCLUSIONS

The scoping review reveals a complex and varied research landscape on factors influencing gastroenteritis (GE) for children in high-income countries. The findings suggest that while some variables are closely linked to specific pathogens, others may not be, highlighting variability across GE aetiology. The significant association between various household level and childcare-related factors and childhood GE points to a valuable direction for future research and public health intervention.

The Benzoylpiperidine Fragment as a Privileged Structure in Medicinal Chemistry: A Comprehensive Review

The phenyl(piperidin-4-yl)methanone fragment (here referred to as the benzoylpiperidine fragment) is a privileged structure in the development of new drugs considering its presence in many bioactive small molecules with both therapeutic (such as anti-cancer, anti-psychotic, anti-thrombotic, anti-arrhythmic, anti-tubercular, anti-parasitic, anti-diabetic, and neuroprotective agents) and diagnostic properties. The benzoylpiperidine fragment is metabolically stable, and it is also considered a potential bioisostere of the piperazine ring, thus making it a feasible and reliable chemical frame to be exploited in drug design. Herein, we discuss the main therapeutic and diagnostic agents presenting the benzoylpiperidine motif in their structure, covering articles reported in the literature since 2000. A specific section is focused on the synthetic strategies adopted to obtain this versatile chemical portion.

Genotyping and epidemiological distribution of diarrhea-causing isolates of Giardia duodenalis in southeastern part of West Bengal, India

The prevalence and genetic diversity of the protozoan pathogen Giardia duodenalis have been extensively studied worldwide. There is currently a lack of data regarding the genetic variability of the organism in eastern India. Understanding the circulating genotypes and associated risk factors is crucial for effective planning and implementing control measures. Therefore, the objective of the study was to conduct an epidemiological study to determine the prevalence and identify the various genotypes present. This survey adds to our knowledge on the occurrence and distribution of Giardia genotypes in the studied region. The overall prevalence was found to be 6.8%. This parasitic infection was significantly associated with two age groups, i.e., >0-5 years and >5-12 years. Using a multilocus genotyping method, we genotyped 52 human Giardia isolates that were obtained from diarrheal patients. Two distinct assemblages were found in the population-30.8% belonged to assemblage A; 63.5% belonged to assemblage B, prevalent in the population; and 5.7% belonged to a combined assemblage A+B. Sub-assemblage AII was found in 17.3% of the cases, followed by sub-assemblage AI (13.5%). High levels of genetic diversity were found within the population of assemblage B undergoing balancing selection. Overall, the high prevalence of the parasite observed, particularly among children, raises a major concern and necessitates implementation of robust control measures. Furthermore, we report the presence of numerous unique genotypes, circulating in this limited geographical boundary, which can be useful dataset for future studies.

Genetic diversity and molecular diagnosis of Giardia

Giardia is a genus of flagellated protozoan parasites that infect the small intestine of humans and animals, causing the diarrheal illness known as giardiasis. Giardia exhibits significant genetic diversity among its isolates, which can have important implications for disease transmission and clinical presentation. This diversity is influenced by the coevolution of Giardia with its host, resulting in the development of unique genetic assemblages with distinct phenotypic characteristics. Although panmixia has not been observed, some assemblages appear to have a broader host range and exhibit higher transmission rates. Molecular diagnostic methods enable researchers to examine the genetic diversity of Giardia populations, enhancing our understanding of the genetic diversity, population structure, and transmission patterns of this pathogen and providing insights into clinical presentations of giardiasis.

Medicinal plants as a source of antiparasitics: an overview of experimental studies

Despite advances in modern human and veterinary medicine, gastrointestinal (GI) parasitic infections remain a significant health issue worldwide, mainly in developing countries. Increasing evidence of the multi-drug resistance of these parasites and the side effects of currently available synthetic drugs have led to increased research on alternative medicines to treat parasitic infections. The exploration of potential botanical antiparasitics, which are inexpensive and abundant, may be a promising alternative in this context. This study summarizes the in vitro/in vivo antiparasitic efficacy of different medicinal plants and their components against GI parasites. Published literature from 1990-2020 was retrieved from Google Scholar, Web of Science, PubMed and Scopus. A total of 68 plant species belonging to 32 families have been evaluated as antiparasitic agents against GI parasites worldwide. The majority of studies (70%) were conducted in vitro. Most plants were from the Fabaceae family (53%, n = 18). Methanol (37%, n = 35) was the most used solvent. Leaf (22%, n = 16) was the most used plant part, followed by seed and rhizome (each 12%, n = 9). These studies suggest that herbal medicines hold a great scope for new drug discoveries against parasitic diseases and that the derivatives of these plants are useful structures for drug synthesis and bioactivity optimization.

A shotgun metagenomic analysis of the fecal microbiome in humans infected with Giardia duodenalis

BACKGROUND

The mechanisms underlying the clinical outcome disparity during human infection with Giardia duodenalis are still unclear. In recent years, evidence has pointed to the roles of host factors as well as parasite's genetic heterogeneity as major contributing factors in the development of symptomatic human giardiasis. However, it remains contested as to how only a small fraction of individuals infected with G. duodenalis develop clinical gastrointestinal manifestations, whereas the majority of infected individuals remain asymptomatic. Here, we demonstrate that diversity in the fecal microbiome correlates with the clinical outcome of human giardiasis.

METHODS

The genetic heterogeneity of G. duodenalis clinical isolates from human subjects with asymptomatic and symptomatic giardiasis was determined using a multilocus analysis approach. We also assessed the genetic proximity of G. duodenalis isolates by constructing phylogenetic trees using the maximum likelihood. Total genomic DNA (gDNA) from fecal specimens was utilized to construct DNA libraries, followed by performing paired-end sequencing using the HiSeq X platform. The Kraken2-generated, filtered FASTQ files were assigned to microbial metabolic pathways and functions using HUMAnN 3.04 and the UniRef90 diamond annotated full reference database (version 201901b). Results from HUMAnN for each sample were evaluated for differences among the biological groups using the Kruskal-Wallis non-parametric test with a post hoc Dunn test.

RESULTS

We found that a total of 8/11 (72.73%) human subjects were infected with assemblage A (sub-assemblage AII) of G. duodenalis, whereas 3/11 (27.27%) human subjects in the current study were infected with assemblage B of the parasite. We also found that the parasite's genetic diversity was not associated with the clinical outcome of the infection. Further phylogenetic analysis based on the tpi and gdh loci indicated that those clinical isolates belonging to assemblage A of G. duodenalis subjects clustered compactly together in a monophyletic clade despite being isolated from human subjects with asymptomatic and symptomatic human giardiasis. Using a metagenomic shotgun sequencing approach, we observed that infected individuals with asymptomatic and symptomatic giardiasis represented distinctive microbial diversity profiles, and that both were distinguishable from the profiles of healthy volunteers.

CONCLUSIONS

These findings identify a potential association between host microbiome disparity with the development of clinical disease during human giardiasis, and may provide insights into the mechanisms by which the parasite induces pathological changes in the gut. These observations may also lead to the development of novel selective therapeutic targets for preventing human enteric microbial infections.

Individual and Community-Level Risk Factors for Giardiasis in Children under Five Years of Age in Pakistan: A Prospective Multi-Regional Study

OBJECTIVES

This study aimed to estimate the prevalence of Giardia lamblia infection and identify associated risk factors at both individual and community levels in a pediatric population in different agroecological zones of Khyber Pakhtunkhwa, Pakistan.

METHODS

A community-based cross-sectional study was conducted from March to December 2022. Using stratified sampling, 1026 households were recruited from nine agroecological zones. Stool samples were collected from 1026 children up to the age of five years and processed for detection of Giardia using a commercial ELISA kit. Data on potential risk factors were collected using a pre-structured questionnaire. A multivariable logistic regression model was used to identify risk factors associated with giardiasis.

RESULTS

The study found that the prevalence of giardiasis in the study area was 3.31%. Children aged 13-24 months were found to be at higher risk for giardiasis. Illiterate mothers and fathers attending daycare institutions/kindergartens, mothers not practicing hand washing during critical times, households with companion animals, and homes where stray dogs/cats enter were identified as predictors of giardiasis at the individual level. Children living in sub-mountain valleys use un-piped water, inadequate domestic water storage vessels, drink un-boiled or unfiltered water, live near rubbish heaps or un-paved streets/pathways, and have unimproved latrine facilities were identified as risk factors of giardiasis at the community level.

CONCLUSIONS

The study highlights the need for integrated intervention approaches at both individual and community levels to reduce the incidence of giardiasis in Khyber Pakhtunkhwa, Pakistan. Interventions aimed at promoting behavioral change and providing safe and adequate water sources, combined with individual-level interventions such as hand washing and awareness of giardiasis prevention methods, would be critical to addressing this health concern. Inter-sectoral collaboration between the health sector and other sectors would also be necessary to achieve meaningful progress in reducing the incidence of giardiasis in resource-limited areas.

Occurrence of Giardia duodenalis in Cats from Queretaro and the Risk to Public Health

Giardia is a protozoan that affects humans as well as a wide range of domestic species. It is distributed worldwide, and the highest frequency is seen in developing countries. Due to the potential for domestic cats to be carriers of this parasite and subsequently transmit the infection to humans, it is important to know the risk of transmission. For this reason, the objective of this study was to determine the frequency of this parasite in the cat population of the city of Santiago de Queretaro, Mexico, and identify the assemblages present to determine the role this host plays in public health, this being the first study of its type to be performed in the country. This was a cross-sectional study during which 200 fecal samples were collected from cats of both sexes and varying ages and strata of origin. The samples were analyzed by microscopy following the flotation technique, having obtained a general frequency of 25%. Giardia cysts were found at higher frequency in pasty stools. The assemblages found were zoonotic, specifically assemblage A, which suggests that the cat poses an important risk for the dissemination of the parasite to humans, making it an important public health problem.

Role of anti-Giardia recombinant cyst wall protein IgG polyclonal antibodies in diagnosis and protection

Giardia duodenalis (G. duodenalis) is an infectious protozoan that has a global distribution especially in the hot climate. Around 200 million people are infected worldwide annually by Giardia, but infection is not always accompanied by symptoms, especially in endemic countries. Using traditional microscopy techniques in diagnosis, both in stool and water samples were less sensitive when compared to immunological methods; and the need for new diagnostic methods was necessary. Also, protection from infection is required in endemic areas. Therefore, the study aimed to produce anti- G. duodenalis IgG polyclonal antibodies (pAbs) by immunizing rabbit by G. duodenalis cyst recombinant protein. The produced antibodies were evaluated in the detection of G. duodenalis antigens in patients' stool and water samples from endemic areas across River Nile; where pAbs were used as a coating and a peroxidase conjugate antibody in sandwich ELISA. Moreover, pAbs were tested for the protection of mice from giardiasis. Sandwich ELISA using pAb has succeeded in the detection of G. duodenalis coproantigens in stool samples by a sensitivity of 97% and a specificity of 92.72%. Moreover, G. duodenalis cyst was detected in only seven water samples by ordinary microscopy; while sandwich ELISA revealed nineteen positive results. IgG pAb (1/200 µg/ml) protected mice from giardiasis; which was evident from the reduction in cysts and trophozoites numbers. We recommended the use of sandwich ELISA to monitor water quality, investigate environmental contamination and diagnosis in patients' stools. The pAbs can be prepared in large amount and used in field diagnosis and protection. This will help in the early diagnosis of G. duodenalis in water, which in turn can control outbreaks in rural areas.

Antigiardial Activity of Novel Guanidine Compounds

From four focused compound libraries based on the known anticoccidial agent robenidine, 44 compounds total were synthesised and screened for antigiardial activity. All active compounds were counter-screened for antibiotic and cytotoxic action. Of the analogues examined, 21 displayed IC₅₀ <5 μM, seven with IC₅₀ <1.0 μM. Most active were 2,2'-bis{[4-(trifluoromethoxy)phenyl]methylene}carbonimidic dihydrazide hydrochloride (30), 2,2'-bis{[4-(trifluoromethylsulfanyl)phenyl]methylene}carbonimidic dihydrazide hydrochloride (32), and 2,2'-bis[(2-bromo-4,5-dimethoxyphenyl)methylene]carbonimidic dihydrazide hydrochloride (41) with IC₅₀ =0.2 μM. The maximal observed activity was a 5 h IC₅₀ value of 0.2 μM for 41. The clinically used metronidazole was inactive at this timepoint at a concentration of 25 μM. Robenidine off-target effects at bacteria and cell line toxicity were removed. Analogue 41 was well tolerated in mice treated orally (100 mg/kg). Following 5 h treatment with 41, no Giardia regrowth was noted after 48 h.

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.

Detection of Cryptosporidium spp. and Giardia spp. in Environmental Water Samples: A Journey into the Past and New Perspectives

Among the major issues linked with producing safe water for consumption is the presence of the parasitic protozoa Cryptosporidium spp. and Giardia spp. Since they are both responsible for gastrointestinal illnesses that can be waterborne, their monitoring is crucial, especially in water sources feeding treatment plants. Although their discovery was made in the early 1900s and even before, it was only in 1999 that the U.S. Environmental Protection Agency (EPA) published a standardized protocol for the detection of these parasites, modified and named today the U.S. EPA 1623.1 Method. It involves the flow-through filtration of a large volume of the water of interest, the elution of the biological material retained on the filter, the purification of the (oo)cysts, and the detection by immunofluorescence of the target parasites. Since the 1990s, several molecular-biology-based techniques were also developed to detect Cryptosporidium and Giardia cells from environmental or clinical samples. The application of U.S. EPA 1623.1 as well as numerous biomolecular methods are reviewed in this article, and their advantages and disadvantages are discussed guiding the readers, such as graduate students, researchers, drinking water managers, epidemiologists, and public health specialists, through the ever-expanding number of techniques available in the literature for the detection of Cryptosporidium spp. and Giardia spp. in water.

Molecular characterization of Giardia intestinalis assemblages in children among the rural and urban population of Pondicherry, India

Introduction:

Giardiasis is one of the greatest public parasitic infections causing diarrheal and also known to be associated with high morbidity and mortality, among the children's particularly in developing countries with less cleanliness practices. Thus, studying genomic variety of Giardia intestinalis aids to improve our perspective related to the variability in the genome of the parasite.

Materials and Methods:

In this cross-sectional study, 1006 stool samples were collected from the rural (n = 500) and urban settings (n = 506) from the children (<15 years) with and without symptoms and were screened for the presence of G. intestinalis by polymerase chain reaction (PCR) targeting triosephosphate isomerase gene. Further, all PCR-positive amplicons were subjected to restriction fragment length polymorphism using RsaI restriction enzyme.

Results:

Of the total 1006 stool samples, 500 samples from rural screened by PCR 108 (21%) were found to be positive for assemblage A, 116 (23.2%) belong to assemblage B, and 5 (1%) were mixed assemblages (A + B). Whereas in urban, of the 506 samples screened by PCR, 92 (18.1%) were found to be positive for assemblage A, 93 (18.3%) assemblage B, and 10 (1.9%) were mixed assemblages (A + B). No significant difference was found between the G. intestinalis assemblages with clinical details of symptomatic and asymptomatic in children.

Conclusions:

This signifies the first study inspection in our location to shed lights and delivers some preliminary data on assemblages and subassemblages. The results suggest that anthroponotic transmission could be a foremost transmission path for giardiasis among the study population.

Effect of dexamethasone on experimental enteritis produced by Giardia lamblia in a Meriones unguiculatus model

Our aim was to evaluate the impact of immunosuppression on the development of giardiasis. Thirty-six gerbils (4-6 weeks old) were distributed in four groups containing nine animals each: Control (CT); Control-Infected by Giardia lamblia (CTIn), Immunosuppressed (IS), and Immunosuppressed-Infected by G. lamblia (ISIn). Animals in the IS and ISIn groups received intramuscular dexamethasone solution for 25 days. On the 11th day, the animals in the CTIn and ISIn groups were inoculated with G. lamblia. After 14 days of infection, the 25th day of the experiment, all groups were euthanized. Four hours after euthanasia, the intestinal permeability was evaluated and sections of the duodenum and spleen were harvested for morphometric and histopathological analyses. Immunosuppressed groups showed a significant increase in intestinal permeability compared to control and infected groups. Considering that the infection can become chronic in immunosuppressed groups, we should be alert to the possibilities of chronic inflammatory changes, both locally and systemically, due to the loss of the intestinal barrier. Lesions were observed in the duodenal mucosa of the gerbils of the CTIn group, with reduced villi size, crypt hyperplasia, edema, and the presence of inflammatory infiltrate in the lamina propria. In the ISIn group, we observed no inflammation, long and intact villi, and a significant increase in the area of intestinal mucins, despite the large number of trophozoites identified. Our results suggest that exacerbation of the immune response has a direct relationship with the appearance of lesions during enteritis produced by G. lamblia in the assessed model.

Detection of Giardia intestinalis assemblages A and B among children from three villages in the West Delta region, Egypt using assemblage specific primers

Giardia intestinalis is a common diarrheagenic parasite infecting children globally. It has been classified into eight morphologically identical but genetically distinct genotypes. Human infection is mainly associated with A and B assemblages with variable geographical distribution. The present work aimed to study the epidemiology of assemblages A and B in children inhabiting different areas in Lower Egypt. Stool samples were collected from 315 children and examined microscopically for parasitic infections. Giardia positive samples were genotyped using tpi assemblage specific primers. The prevalence of Giardia was 18.1% among the examined children. Mixed assemblages A and B was more common (47.4%) than single assemblage B (36.8%) or A (15.8%). The distribution of different genotypes was significantly associated with the residence area, animal contact, and handwashing habits. A non-significant association was observed between Giardia assemblages and the clinical manifestations. Assemblage B is the predominant genotype among Egyptian children. The distribution of different Giardia assemblages is strongly associated with the studied area and the habits of its people.

Prevalence of intestinal parasites with molecular detection and identification of Giardia duodenalis in fecal samples of mammals, birds and zookeepers at Beni-Suef Zoo, Egypt

The current study aimed to investigate the prevalence of intestinal parasites from various species of mammals and birds housed in a zoological garden in Beni-Suef province, Egypt. A total of 77 fecal samples were collected from various primates (16), carnivores (7) and herbivores (54). Meanwhile, 123 fecal samples were collected from two Ostrichs (Struthio camelus), five Numida meleagris (Numida meleagris), twoIndian Peafowls (Pavo cristatus), two Emu (Dromaius novaehollandiae) 101 Pigeons (Columba livia domestica) and 11 Swan Goose (Anser sygnoides). In addition, seven stool samples from zookeepers who had been in close contact with animals and birds were examined. Salt flotation and formol ether sedimentation techniques were applied for parasitological examination. Positive samples of Giardia cysts were preserved in alcohol and kept at 4 °C until DNA extraction. Parasitological findings revealed that 48.05% of zoo animals were infected with intestinal parasites; 11.69% were positive with helminths and 27.27% with protozoa, however 9.09% had mixed infection. It was found that 75%, 57.14% and 38.89% of primates, carnivores and herbivores respectively were infected with intestinal parasites. In Primates the most prevalent parasites were Giardia spp. (43.75%) then Entamoeba histolytica/dispar (12.5%), Entamoeba coli (12.5%) and Trichuris spp. (6.25%). For carnivores, Ancylostomatidae had the highest prevalence (42.86%) followed by Spirometra spp. (14.29%). Meanwhile, Eimeria spp. (20.37%) was the most prevalent parasite in herbivores, followed by Blantidium coli (7.41%) and Tricuris spp. (7.41%), then Toxocara spp. (3.70%). Furthermore, the prevalence of infection in zoo birds was 21.95%. The identified parasites were Eimeria spp., Giardia spp., Capillaria spp., Ascaridia spp., Isospora spp. and Sublura brumpti. Stool examination of zookeepers revealed the presence of G. doudenalis and E. histolytica/ dispar cysts. The gdh gene of G. duodenalis was successfully amplified from fecal samples of zoo mammalsand zookeepers. In conclusion, the application of preventive and control measures against the propagation of infectious intestinal parasites is essential to prevent the spread of these parasites among zoo animals or to humans.

Supplementary Information

The online version contains supplementary material available at 10.1007/s12639-020-01341-2.

Molecular characterization of Giardia duodenalis and evidence for cross-species transmission in Northern Argentina

Anthropogenic activities, such as human population expansion and land-use change, create ecological overlap between humans, domesticated animals, and wildlife and can exacerbate the zoonotic transmission of parasites. To improve our understanding of this dynamic, we employed multi-locus genotyping to conduct a cross-sectional study of the potential for zoonotic transmission of the protozoan parasite Giardia duodenalis among humans, household associated livestock and dogs, and black and gold howler monkeys (Alouatta caraya) in the Corrientes Province of Argentina. We found Giardia prevalence to be highest in howler monkeys (90.3% (47/52)), followed by humans (61.1% (22/36)), dogs (44.4% (16/36)), and cattle (41.9% (18/43)). We further established that howler monkeys exclusively harbored strains of assemblage B (100%) while humans were infected with either assemblage A (13.3%) or B (80%) or A and B (6.7%), and cattle and dogs were infected with either assemblage A (cattle, 94.1%; dogs, 80%)), A and C (10%), or their host-adapted assemblage (cattle, 5.9%; dogs, 10%). Our finding of G. duodenalis in both humans and domesticated animals (assemblage A) and humans and wild primates (assemblage B) suggests that cross-species transmission of multiple assemblages of G. duodenalis may occur in rural complexes such as northern Argentina where people, domesticated animals, and wildlife overlap. We further highlight the need to investigate the implications of these results for human health, the economics of livestock production, and wildlife conservation in this and similar systems.

Genetic Diversity and Prevalence of Giardia duodenalis in Qatar

Background

Giardia duodenalis is a common human intestinal parasite worldwide, and the causative agent of diarrhea, with the severity of disease ranging from asymptomatic to intense and debilitating infection. G. duodenalis is known to consist of eight genetically distinct assemblages, named from A to H. No data available on the genotypes and genetic diversity of G. duodenalis circulating in Qatar.

Methods

We genotyped 54 human Giardia isolates, collected from asymptomatic immigrants in Qatar, using a multilocus genotyping (MLGs) tool. We also investigated relationships between the subjects’ genotypes and their demographic data.

Results

Genomic DNA from 54 isolates were tested by PCR and sequence analysis at three loci: glutamate dehydrogenase (gdh), β-giardin (bg) and triose phosphate (tpi)). Assemblage A was identified in nine (16.67%), assemblage B in thirty (55.55%), and a mixture of assemblages A+B in fifteen (27.78%) isolates. All assemblage A isolates, genotyped in different loci, were assigned to sub-assemblage AII, and six of them had MLGs AII-1 while one new MLG was identified in two isolates. Sequences of assemblage B isolates have high level of genetic diversity and high presence of heterogeneous peaks, especially within the gdh gene. No significant associations between genotypes and the immigrants’ demographic data were found due to the extensive number of new variants.

Conclusions

MLGs was used herein to genotype 54 immigrant Giardia isolates. The high level of genetic variability found in our isolates hampered MLGs determination, more investigations are now required to consolidate our findings, and to enable a comprehensive understanding of the diversity within G. duodenalis assemblage B isolates.

A Potent N-(piperidin-4-yl)-1H-pyrrole-2-carboxamide Inhibitor of Adenylyl Cyclase of G. lamblia: Biological Evaluation and Molecular Modelling Studies

In this work, we report a derivative of N-(piperidin-4-yl)-1H-pyrrole-2-carboxamide as a new inhibitor for adenylyl cyclase of Giardia lamblia which was obtained from a study using structural data of the nucleotidyl cyclase 1 (gNC1) of this parasite. For such a study, we developed a model for this specific enzyme by using homology techniques, which is the first model reported for gNC1 of G. lamblia. Our studies show that the new inhibitor has a competitive mechanism of action against this enzyme. 2-Hydroxyestradiol was used as the reference compound for comparative studies. Results in this work are important from two points of view. on the one hand, an experimentally corroborated model for gNC1 of G. lamblia obtained by molecular modelling is presented; on the other hand, the new inhibitor obtained is an undoubtedly excellent starting structure for the development of new metabolic inhibitors for G. lamblia.

A Complementary Herbal Product for Controlling Giardiasis

Giardiasis is an intestinal protozoal disease caused by Giardia lamblia. The disease became a global health issue due to development of resistance to commonly used drugs. Since many plant-derived products have been used to treat many parasitic infestations, we aimed to assess the therapeutic utility of Artemisia annua (A. annua) for giardiasis. We showed that NO production was significantly reduced whereas serum levels of IL-6, IFN-γ, and TNF-α were elevated in infected hamsters compared to uninfected ones. Additionally, infection resulted in increased numbers of intraepithelial lymphocytes and reduced villi heights, goblet cell numbers, and muscularis externa thickness. We also showed that inducible NO synthase (iNOS) and caspase-3 were elevated in the intestine of infected animals. However, treatment with A. annua significantly reduced the intestinal trophozoite counts and IEL numbers, serum IL-6, IFN-γ, and TNF-α, while increasing NO and restoring villi heights, GC numbers, and ME thickness. Moreover, A. annua treatment resulted in lower levels of caspase-3, which indicates a protective effect from apoptotic cell death. Interestingly, A. annua therapeutic effects are comparable to metronidazole. In conclusion, our results show that A. annua extract is effective in alleviating infection-induced intestinal inflammation and pathological effects, which implies its potential therapeutic utility in controlling giardiasis.

Interactions between Cryptosporidium, Enterocytozoon, Giardia and Intestinal Microbiota in Bactrian Camels on Qinghai-Tibet Plateau, China

Cryptosporidium spp., Enterocytozoon bieneusi, and Giardia duodenalis are zoonotic pathogens commonly found in the intestinal tract of mammalian hosts including livestock and humans. The prevalence of these eukaryote microorganisms in domestic animals and their interaction with intestinal microbiota are not yet fully recognized. We analyzed the intestinal microbiota composition with metagenomics and functional characterization with Cluster of Orthologous (COG) in Bactrian camels, which were raised on Qinghai-Tibet Plateau, Northwest China. Thus, fecal samples were collected from the animals to determine the parasite infection and the profile of microbiota. Analysis of intestinal microbiota at genus level revealed important features of interaction between parasites infection and bacterial community. Coprococcus and Prevotella were more abundant while Akkermansia had lower relative abundance with E. bieneusi infection. Bacteria of Akkermansia, Lactococcus, Oxalobacter, Sphaerochaeta, Paludibacter, Fibrobacter, Anaerovibrio, Pseudomonas, Mogibacterium, Pseudoramibacter_Eubacterium, YRC22, Flexispira, SMB53, AF12, and Roseburia genera were found under-presented and Oscillospira genus over-presented when G. duodenalis infection was present. Meanwhile, Cryptosporidium spp. and E. bieneusi co-infected animals showed lower relative abundance of Allobaculum, Rikenella, Shuttleworthia, Epulopiscium, Bilophila, Dorea, Fibrobacter, and TG5. Results demonstrate important interaction between the intestinal parasites and microbiota, and provide informative link for understanding the co-evolution of zoonotic pathogens and bacteria in domestic animals.

Giardia and Cryptosporidium in Neo-Tropical Rodents and Marsupials: Is There Any Zoonotic Potential?

Cryptosporidiosis and giardiasis have been identified as emerging diseases in both developed and developing countries. Wildlife has been highlighted to play a major role in the spread of these diseases to humans. This review aims to highlight the research findings that relate to Cryptosporidium spp. and Giardia spp., with a focus on (1) parasitism of neo-tropical hystricomorphic rodents and marsupials from the genus Didelphis and (2) prevention and treatment strategies for humans and animals for the neo-tropical region. It was found that there are few studies conducted on neo-tropical rodent and marsupial species, but studies that were found illustrated the potential role these animals may play as zoonotic carriers of these two parasites for the neo-tropical region. Thus, it is recommended that further studies be done to assess the threat of protozoan parasites in neo-tropical wildlife to humans and domestic animals, and to further determine the most effective prophylaxis adapted for the unique conditions of the region.

Observation of Giardia sp. in the termite gut of Heterotermes tenuis

Giardia comprises one genus with several morphologically distinct species described in mammals (including humans, marsupials, rodents), birds, and amphibians. This group of protists provokes diarrhoea diseases in humans and animals worldwide. Transmission of the parasite occurs through the faecal-oral route. Regarding the presence of Giardia in invertebrates, some works have shown that flies can transmit Giardia cysts by contact and transport between contaminated faeces and food. In this way, flies would eventually transmit this parasite. To date, Giardia's presence in the gut of other invertebrates has not been described in the literature. Here we show by first time, using scanning electron microscopy, the presence of Giardia-like trophozoites in the gut of termite Heterotermes tenuis. Two groups of Giardia were found based exclusively on the size and the flange shape of the protozoa: one presented eight flagella, a ventral disc, size, and shape very similar to Giardia intestinalis. In contrast, other cells were smaller and showed some differences in the external morphology. We cannot exclude the possibility that they correspond to the same species and that these differences result from protozoan heterogeneity.

Prevalence and Clinical Manifestations of Giardia intestinalis and Other Intestinal Parasites in Children and Adults in Algeria

Giardia intestinalis is one of the most common causes of parasite-induced diarrhea, abdominal pain, flatulence, and malabsorption. Yet, data on the epidemiology of G. intestinalis infections in North Africa are limited. The purpose of this study was to carry out a retrospective survey on the level of intestinal parasitism with a particular emphasis on G. intestinalis in children and adults in Algiers, Algeria. A total of 2,054 individuals from outpatient clinics or hospitalized at Beni-Messous University Hospital of Algiers undergoing stool microscopy for ova and parasites were included. The overall parasite infection rate was 28%. In the 567 parasite-positive samples, Blastocystis was found most frequently (57.3%), followed in frequency by Endolimax nana (41.0%), Entamoeba histolytica/dispar (19.6%), G. intestinalis (17.1%), Entamoeba coli (13.9%), Chilomastix mesnili (1.0%), Iodamoeba bütschlii (0.7%), Entamoeba hartmanni (0.5%), and Cryptosporidium spp. (0.2%). Intestinal parasites were generally more common in adults than in children, except for Giardia, which was more common in children (P = 0.0001). Giardia infection was independent of gender (P = 0.94). Compared with other intestinal parasitic infections, clinical manifestations, such as abdominal pain (P = 0.28) and diarrhea (P = 0.82), were found not to be significantly linked to Giardia infection. In conclusion, G. intestinalis is common in individuals referred to the University Hospital of Beni-Messous with digestive symptoms, particularly so in children. However, in our study, intestinal symptoms appeared not to be more linked to Giardia than to other intestinal parasites.

Rapid on-site diagnosis of canine giardiosis: time versus performance

BACKGROUND

Infections by protozoans of the genus Giardia are a common cause of diarrhea in dogs. Canine giardiosis constitutes a disease with a zoonotic potential; however, it is often underestimated due to its challenging diagnosis. The objective of the study was to assess the diagnostic performance of an immunochromatographic strip test (SpeedTM Giardia, Virbac, France) comparing it with microscopy (zinc sulfate flotation) by utilizing the combination of an enzyme immunoassay (ProSpecTTM Giardia EZ Microplate Assay, Oxoid Ltd., UK) and the PCR as the gold standard. A positive result in both ELISA and PCR was set as the gold standard.

METHODS

Initially, fecal samples from dogs with clinical signs compatible with giardiosis were tested with the SpeedTM Giardia test and separated into two groups of 50 samples each: group A (positive) and group B (negative). Thereafter, all samples were examined by zinc sulfate centrifugal flotation technique and assayed by the ProSpecTTM Giardia Microplate Assay and PCR. The performance of the SpeedTM Giardia and zinc sulfate centrifugal flotation tests were calculated estimating sensitivity, specificity, and positive and negative likelihood ratio; the chi-square and McNemar tests were used for the comparison of the two methods.

RESULTS

Giardia cysts were not detected by microscopy in 16 out of the 50 samples (32%) of group A and in none of group B samples. Eight out of 50 samples in group B (16%) were tested positive both with the ProSpecTTM Giardia Microplate Assay and PCR. Fecal examination with the SpeedTM Giardia test was more sensitive (86.2%) than the parasitological method (58.6%, P < 0.001) while the specificity of both methods was 100%.

CONCLUSIONS

The SpeedTM Giardia test is an easy-to-perform diagnostic method for the detection of Giardia spp., which can increase laboratory efficiency by reducing time and cost and decrease underdiagnosis of Giardia spp. infections. This immunochromatographic strip test may be routinely exploited when a rapid and reliable diagnosis is required, other diagnostic techniques are unavailable and microscopy expertise is inefficient. In negative dogs with compatible clinical signs of giardiosis, it is recommended either to repeat the exam or proceed with further ELISA and PCR testing.

The Predominance of Giardia duodenalis AII sub-assemblage in young children from Salvador, Bahia, Brazil

Introduction.

Giardia duodenalis is an intestinal protozoan with a high prevalence in children of developing countries. Molecular studies revealed a great genetic diversity of G. duodenalis, with assemblages A and B found mainly in humans. Despite its importance, the information on the molecular epidemiology of human giardiasis is still limited in Brazil.

Objective.

To characterize G. duodenalis molecular isolates in children from Salvador, Bahia, Brazil.

Materials and methods.

Giardia duodenalis positive fecal samples were obtained from 71 children from two day care centers and 39 users of a clinical analysis laboratory. Samples were analyzed by PCR-RFLP of the glutamate dehydrogenase (gdh) and beta-giardin genes and by the sequencing of beta-giardin.

Results.

Of the 110 G. duodenalis samples, 80 (72.7%) amplified one or both target genes. Of these, 62 (77.5 %) were identified as assemblage A and 18 (22.5%) as assemblage B. The subassemblage AII was identified in 58.8% (n=47) of isolates followed by the sub-assemblage AI (18.8%, n=15), BIV (11.2%, n=9), and BIII (5.0%, n=4). The AII sub-assemblage was the most frequent in children of both day care centers whereas AI was found only in the group attended at the clinical laboratory. Sub-assemblage AII predominated in children under two years.

Conclusions.

The higher frequency of AII sub-assemblage suggests that anthroponotic transmission is more common in Salvador, but that zoonotic transmission pathways are also present and a change in susceptibility to different molecular patterns of Giardia may occur during child growth.

First multilocus sequence typing (MLST) of Giardia duodenalis isolates from humans in Romania

Background

Giardia duodenalis is one of the most prevalent and highly diverse human parasites, encompassing a complex of eight genetically distinct assemblages, each further divided into sub-assemblages. While in recent years, G. duodenalis genotype distribution patterns in humans have been intensely studied, there is still very little information available on the diversity of Giardia genotypes and sub-assemblages infecting people in Romania. In the present study, we investigated the genetic diversity of Giardia duodenalis in asymptomatic patients from Romania.

Methods

Over an 11-month period, human feces from 7805 healthy adults were screened by microscopic analysis for G. duodenalis cysts during their obligatory periodic check-ups. DNA extraction was performed from microscopic-positive fecal samples, followed by multilocus sequence typing of four genetic loci of the ITS region, gdh, tpi and bg genes, followed by DNA sequencing and phylogenetic analysis. Statistical analysis was performed using EpiInfo 2000 software.

Results

The prevalence of giardiasis in the present study was 0.42% (33/7805). Twenty-three samples (76.67%) were successfully genotyped at each locus. The bg and tpi genes had the highest typing success rate (100%). The identified assemblages were assemblage A in 27 cases (subtypes A2 and A3), and B in 3 cases.

Conclusions

To our knowledge, the present study is the first report of multilocus sequence typing of G. duodenalis isolated from humans in Romania. The present results may shed light on G. duodenalis infection in humans at a regional and national level, thus increasing awareness against this parasitic infection.

Emerging zoonotic diseases originating in mammals: a systematic review of effects of anthropogenic land-use change

Zoonotic pathogens and parasites that are transmitted from vertebrates to humans are a major public health risk with high associated global economic costs. The spread of these pathogens and risk of transmission accelerate with recent anthropogenic land-use changes (LUC) such as deforestation, urbanisation, and agricultural intensification, factors that are expected to increase in the future due to human population expansion and increasing demand for resources.We systematically review the literature on anthropogenic LUC and zoonotic diseases, highlighting the most prominent mammalian reservoirs and pathogens, and identifying avenues for future research.The majority of studies were global reviews that did not focus on specific taxa. South America and Asia were the most-studied regions, while the most-studied LUC was urbanisation. Livestock were studied more within the context of agricultural intensification, carnivores with urbanisation and helminths, bats with deforestation and viruses, and primates with habitat fragmentation and protozoa.Research into specific animal reservoirs has improved our understanding of how the spread of zoonotic diseases is affected by LUC. The behaviour of hosts can be altered when their habitats are changed, impacting the pathogens they carry and the probability of disease spreading to humans. Understanding this has enabled the identification of factors that alter the risk of emergence (such as virulence, pathogen diversity, and ease of transmission). Yet, many pathogens and impacts of LUC other than urbanisation have been understudied.Predicting how zoonotic diseases emerge and spread in response to anthropogenic LUC requires more empirical and data synthesis studies that link host ecology and responses with pathogen ecology and disease spread. The link between anthropogenic impacts on the natural environment and the recent COVID-19 pandemic highlights the urgent need to understand how anthropogenic LUC affects the risk of spillover to humans and spread of zoonotic diseases originating in mammals.

Prevalence of contamination by intestinal parasites in vegetables (Lactuca sativa L. and Coriandrum sativum L.) sold in markets in Belém, northern Brazil

BACKGROUND

Previous studies have recorded a high prevalence of intestinal parasites in lettuce (Lactuca sativa L.) and coriander (Coriandrum sativum L.) destined for human consumption. This study determined the prevalence of contamination by intestinal parasites in these two plants sold in two street markets and two supermarkets in the city of Belém, northern Brazil.

RESULTS

A total of 200 plant samples were analyzed (100 of each species). The samples were collected randomly between August and October 2018, examined by the spontaneous sedimentation method with two washes, and stored for 24 h. The analysis found that 89% (89/100) of the lettuce samples and 86% (86/100) of the coriander samples were contaminated. Polyparasitism was more frequent in lettuce, but monoparasitism predominated in the coriander. A total of 226 intestinal parasites were found in the lettuce, with a predominance of non-pathogenic parasites in the supermarket samples and more pathogenic parasites in the samples from street markets. In the coriander samples, 172 intestinal parasites were identified, with a predominance of pathogenic parasites in samples from both types of market. In the case of the protozoans, the most prevalent species was Endolimax nana, followed by Blastocystis hominis, in both vegetables. In the helminths, hookworms predominated in the lettuce, and Trichuris trichiura in the coriander.

CONCLUSIONS

These results highlight the need for the monitoring of parasite contamination in vegetables destined for human consumption. Public health initiatives should include educational campaigns on the importance of disinfecting vegetables prior to consumption. © 2020 Society of Chemical Industry.

Prevalence and genotypic characterization of Giardia duodenalis isolates from asymptomatic school-going children in Lusaka, Zambia

Giardia duodenalis is one of the most common causes of diarrhea in humans with about 250–300 million cases per year. It is considered to be a species complex comprising of eight genetic assemblages (A to H), with assemblages A and B being the major causes of human infections. In this study we carried out genotypic characterization of G. duodenalis isolates detected in asymptomatic school-going children aged 3–16 years. Between May and September 2017, a total of 329 fecal samples were collected from school-going children from Chawama compound of Lusaka City and were screened for Giardia by microscopic examination. All microscopically positive fecal samples were analyzed by semi-nested polymerase chain reaction (PCR) targeting the glutamate dehydrogenase (gdh) gene. Genotyping of amplified PCR products was conducted by restriction fragment length polymorphism (RFLP) and DNA sequence analysis. Microscopically, Giardia was found in 10% (33/329) of fecal samples. The PCR-RFLP analysis of the gdh gene revealed assemblages A and B in 27.3% (9/33) and 72.7% (24/33), respectively. Furthermore, analysis with restriction enzymes identified sub-assemblages AII (27.3%, 9/33), BIII (12.1%, 4/33), BIV (51.5%, 17/33) and mixed infections of BIII and BIV (9.1%, 3/33). Phylogenetic analysis showed the clustering of 27.6% (8/29) and 72.4% (21/29) of Zambian Giardia gdh gene sequences into assemblages A and B, respectively. This study has revealed the presence of both assemblage A and B and that spread of G. duodenalis in school-going children appears to be mostly through anthroponotic transmission. To our knowledge, this is the first report of genotypic characterization of G. duodenalis identified in Zambia.

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Giardia duodenalis infection observed in asymptomatic children

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First report of genotypes circulating in Zambia

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Presence of sub-assemblages AII, BIII and BIV

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Co-infection with sub-assemblages BIII and BIV reported

Prevalence and risk factors of Giardia spp. from free living and owned dogs in Tunja-Boyacá, Colombia

Giardia spp. is a zoonotic protozoan that causes acute gastroenteritis in humans and other animal species across the world. The aim of this study was to determine the prevalence of Giardia spp. in free living and owned dogs from Tunja - Colombia by Ritchie concentration method and to identify the risk factors (living condition, age, sex, stool consistency, body condition and hair condition) associated with infection. To address the objective a cross-sectional study was carried out. The study population consisted of 200 dogs. Faecal samples were collected from 100 stray dogs and 100 owned dogs using a convenient sampling method. Risk factors were analysed by logistic regression analysis. Risk was expressed as an odds ratio (OR) with 95% confidence interval. Descriptive epidemiology and risk factors were performed using EpiInfo software. A P value of <0.05 was statistically significant. The overall prevalence of Giardia spp. was 39%; cysts were detected by microscopy in 38 of 100 stray dogs and 40 of 100 owned dogs. It was concluded that the prevalence of Giardia spp. in Tunja city was high, with no distinction between stray and owned dogs. We also found that the analysed variables (sex, age, hair condition, body condition and stool consistency) did not constitute risk factors for infection with Giardia spp.

Aminoguanidines: New leads for treatment of Giardia duodenalis infection

Giardia duodenalis is an ubiquitous parasitic pathogen that causes significant morbidity and mortality worldwide. Failures in drug therapy are commonly due to poor patient compliance as a result of the need for repeated administration, off target drug effects and increasing parasite drug resistance. In this study the in vitro efficacy and selectivity of the aminoguanidine compound robenidine and 2 structural analogues against Giardia were determined. After 5 h exposure to each compound the IC50 was as low as 0.2 μM with corresponding MLCs as low as 2.8 μM. This is in contrast to metronidazole which required 24 h to exhibit inhibitory activity. A modified adherence assay, developed for this study, demonstrated that three of the compounds inhibited in vitro adherence of the parasite. The lead compound exhibited rapid giardicidal activity (<5hr). In addition, microscopy studies demonstrated damage to the plasma membrane of trophozoites. In conclusion, a class of aminoguanidines, represented by robenidine, has shown antigiardial activity warranting further investigation.

Multilocus genotyping of Giardia duodenalis isolated from patients in Egypt

Human giardiasis is a common waterborne/foodborne parasitic disease worldwide, especially in developing countries. Prevalence and molecular identity of Giardia parasites are largely controversial. The present study was conducted to determine the occurrence of Giardia parasites and the genetic profile of circulating assemblage(s) in patients attended the outpatient clinic at Kafrelsheikh University hospital, Kafr El Sheikh Province, Egypt. A total of 318 patients, of different age and sex, referred to the clinic were subjected to fecal examination. Microscopic results revealed that 181/318 (56.9%) were positive for Giardia parasites. Multilocus genotyping by PCR/sequencing of beta-giardin (bg), triose phosphate isomerase (tpi), and glutamate dehydrogenase (gdh) genes of representative number of positive samples (65) revealed that assemblages A, B and mixed infections (A + B) occurred in 26/65 (40.0%), 32/65 (49.2%) and 10.8% (7/65) of the analyzed isolates, respectively. MLGs analysis indicated that assemblage A sequences clustered in two novel types of AII sub-assemblage. In assemblage B sequences, BIII was the predominant (22/23, 95.7%) sub-assemblage compared to BIV (1/23, 4.3%). Collectively, assemblage B MLGs displayed greater levels of genetic diversity compared to assemblage A. Our data indicate that assemblages A and B of G. duodenalis circulate in humans at Kafr El Sheikh Province, Egypt, and that high genetic diversity exists at the assemblage and/or sub-assemblage levels.

Multiplex PCR assay for simultaneous detection and differentiation of Entamoeba histolytica, Giardia lamblia, and Salmonella spp. in the municipality-supplied drinking water

BACKGROUND

The contamination with Entamoeba histolytica, Giardia lamblia, and Salmonella spp. in drinking water is the most prevalent in Indian subcontinent, but often difficult to detect all these pathogens from the drinking water.

MATERIALS AND METHODS

A multiplex polymerase chain reaction (mPCR) method was developed to detect contamination of municipality-supplied drinking water with E. histolytica, G. lamblia, and Salmonella spp. The primers were designed to target small subunit of 16S rRNA type gene of E. histolytica and G. lamblia, and invasive A gene of Salmonella typhimurium. The optimized mPCR assay was applied on 158 municipality-supplied drinking water samples collected from Delhi.

RESULTS

Out of total 158 water samples, 89 (56.32%) were found positive for the targeted pathogens by mPCR while conventional methods could be detected only in 11 (6.96%) samples. The mPCR assay showed 100% sensitivity and specificity for these pathogens in comparison with culture and microscopic detection. Of the 89 mPCR-positive samples, G. lamblia, E. histolytica, and Salmonella spp. were present in 35 (22.15%), 26 (16.45%), and 28 (17.72%), respectively. Nine (5.69%) samples were positive for both E. histolytica and G. lamblia, 10 (6.32%) were positive for G. lamblia and Salmonella spp., and 8 (5.06%) had Salmonella spp. and E. histolytica. Nonetheless, 3 (1.89%) samples were positive for all three pathogens.

CONCLUSIONS

The present assay is an alternative to conventional methods to serve as highly sensitive, specific, and economical means for water quality surveillance to detect the outbreak caused by E. histolytica, G. lamblia, and Salmonella spp. pathogens.

Prevalence and multilocus genotyping of potentially zoonotic Giardia duodenalis in pigs in Shanghai, China

Giardia duodenalis is a common intestinal parasite in humans and other mammals, and it causes major public and veterinary health problems worldwide. China is a major pig-raising country, and studies on Giardia in pigs have important public health significance. The present study was conducted to investigate the prevalence of Giardia and assess its genetic characterization. A total of 93 samples were collected from two farms in Shanghai. The presence of Giardia was determined using PCR and sequence analysis of glutamate dehydrogenase, beta-giardin and triose phosphate isomerase genes. The average prevalence of G. duodenalis infection was 26.88% (25/93) in the pigs, with 28.13% (18/64) in farm 1 vs 24.14% (7/29) in farm 2. All the PCR-positive products were successfully sequenced, and assemblage E was more prevalent. Zoonotic assemblages A and B and canine-specific assemblage C were identified in farm 1, whereas, only assemblage E was detected in farm 2. Interestingly, two pig isolates showed 100% homology with human-derived isolates from Australia and China at the bg and tpi loci respectively. Pigs infected with Giardia infect humans by polluting the environment; whether pigs are a potential environmental source of the human pathogen in China requires more epidemiological data.

The therapeutic prospect of crosstalk between prokaryotic and eukaryotic organisms in the human gut

The peaceful phenomenon of the co-evolution between the prokaryotes (microbiota) and the eukaryotes (parasites including protozoa and helminths) in the animal gut has drawn the researchers' attention. Importantly, exploring the potential of helminths for therapeutic uses was one of the reasons behind understanding the physiological and immunological crosstalk existing between them. Here we discuss the interactive immunological associations of helminths and microbial responses individually and in combination with their hosts. Considering that there is probably crosstalk between eukaryotic organisms like helminths and protozoa with their host's gut microbiota, in this review we searched the literature identifying the privileged and favourable relationship generated between them in the host. Understanding the possibilities of the role of helminths along with gut microbiota as a black box would certainly help decode the therapeutic intrusion with helminths in experimental clinical trials, and a successful trial could be used to consider possible future and safe treatments for various immune-inflammatory diseases in humans.

Main Microbiological Pollutants of Bottled Waters and Beverages

Although consumption of quality drinking water should be available to anyone, without any risk, in reality, for the people living in poor countries, safe water sources are often not an option. In order to eliminate the risk of disease, people prefer to use bottled water, or even bottle beverages, considering them uncontaminated, sterile products. However, the evidence showed that some microbial species belonging to autochthonous water microbiota or even pathogenic species may contaminate and could, in certain conditions, multiply beyond measure in the bottled products. Sometimes, although the bottled water or beverages meet the quality requirements, still, they could be responsible by some water- or food-borne diseases. This chapter presents the main microbial contaminants of these products and the associated risk for waterborne/food-borne diseases.

Treatment-refractory giardiasis: challenges and solutions

Giardia is the commonest parasitic diarrheal pathogen affecting humans and a frequent cause of waterborne/foodborne parasitic diseases worldwide. Prevalence of giardiasis is higher in children, living in poor, low hygiene settings in developing countries, and in travelers returning from highly endemic areas. The clinical picture of giardiasis is heterogeneous, with high variability in severity of clinical disease. It can become chronic or be followed by post-infectious sequelae. An alarming increase in cases refractory to the conventional treatment with nitroimidazoles (ie, metronidazole) has been reported in low prevalence settings, such as European Union countries, especially in patients returning from Asia. In view of its relevance, we aim in this review to recapitulate present clinical knowledge about Giardia, with a special focus on the challenge of treatment-refractory giardiasis. We propose a working definition of clinically drug-resistant giardiasis, summarize knowledge regarding resistance mechanisms, and discuss its clinical management according to research-based evidence and medical practice. Advances in development and identification of novel drugs and potential non-pharmacological alternatives are also reviewed with the overall aim to define knowledge gaps and suggest future directions for research.

Giardia duodenalis in the UK: current knowledge of risk factors and public health implications

Giardia duodenalis is a ubiquitous flagellated protozoan parasite known to cause giardiasis throughout the world. Potential transmission vehicles for this zoonotic parasite are both water and food sources. As such consumption of water contaminated by feces, or food sources washed in contaminated water containing parasite cysts, may result in outbreaks. This creates local public health risks which can potentially cause widespread infection and long-term post-infection sequelae. This paper provides an up-to-date overview of G. duodenalis assemblages, sub-assemblages, hosts and locations identified. It also summarizes knowledge of potential infection/transmission routes covering water, food, person-to-person infection and zoonotic transmission from livestock and companion animals. Public health implications focused within the UK, based on epidemiological data, are discussed and recommendations for essential Giardia developments are highlighted.

Stunting, Beyond Acute Diarrhoea: Giardia Duodenalis, in Cambodia

BACKGROUND

The adverse outcomes of malnutrition on the development of a child are well acknowledged as are the broad variety of contextual factors that may impact child nutritional status. Adequate nutrient intake and the adoption of appropriate water, sanitation and hygiene measures are largely documented for their positive influence on health. Improved sanitation and protection from human feces can significantly lower the incidence of diarrhea and environmental enteropathy. However, the impact of excessive exposure to animal feces on child health is less well documented.

OBJECTIVES

This study tests the hypothesis that there is a positive association between exposure to animal feces, morbidity and anthropometric outcomes in children under 5 years of age, in Cambodia. It aims to improve insights that can contribute to discerning high-impact policies that promote children can develop to their full potential.

METHODS

Data for this study was drawn from the third follow-up round of the MyHealth project cohort study that is conducted in six districts of three Cambodian provinces (Phnom Penh, Kratie and Ratanak Kiri). The analysis included a sample of 639 children under 5 years of age.

RESULTS

The presence of livestock and more particularly, pigs near the main household dwelling was found a risk factor associated with Giardia duodenalis infection (23%). Giardia duodenalis infection was found to be a protective factor for acute diarrhea, yet, associated with stunting in the univariate model.

CONCLUSIONS

Preventive measures that protect from extensive exposure to animal feces may be most effective to prevent infection with Giardia duodenalis and consequent stunting, thereby improving the potential for a healthy development in young Cambodian children. The results support the need for cross-sector policy measures that reinforce comprehensive early childhood interventions towards improving nutritional status as part of a wider set of child welfare and development measures.

A modified PCR-RFLP method to determine genetic diversity of Giardia lamblia human isolates based on triosephosphate isomerase (TPI) gene

An infection of digestive system, Giardiasis, caused by tiny parasites called Giardia lamblia (also known Giardia intestinalis or Giardia duodenalis). Giardia sp. is the most common intestinal parasite of humans and other animals throughout the world. Isolates of G. lamblia are classified into eight assemblages based on isoenzyme and DNA analyses. Assemblages A and B infect humans and a broad range of other hosts. The purpose of this study was to genotype human isolates of G. lamblia by PCR-RFLP in Karaj city. 60 positive fecal samples of G. lamblia were collected. DNA extraction and amplification of TPI gene were successfully conducted by nested-PCR. Subsequently, all samples were positive. Sequencing on 5 samples was conducted to determine genetic differences. The presence of 2 genotypes of G. lamblia (A and B) was revealed by the alignment of the TPI sequences obtained with reference sequences. The results of RFLP technique show that 35 of 60 (58.3%) isolates belonged to assemblage A, and 17 of 60 (28.3%) belonged to assemblage B but 1(1.7%) sample was not determined. Whereas, 7 (11.6%) specimens were detected as mixed infections. The latter RFLP was carried out to identify subtypes.The final results were 100% (35/35) AII, 82.3% (14/17) BIII, and 17.7% (3/17) BIV. This study suggests that the modified RFLP method is favorably time saving and easily achievable and highly economical. Hence, the sub-assemblage AII might be dominant in Karaj city.

First report of Giardia duodenalis infection in bamboo rats

Background

The zoonotic parasite, Giardia duodenalis (syns. G. lamblia and G. intestinalis), has been widely reported in humans and animals, including rodents. The bamboo rat, a rodent species belonged to the subfamily Rhizomyinae, is farmed in China because of its medicinal and edible values. However, no information of G. duodenalis infection was available in bamboo rats prior to the present study. Here, the prevalence and genetic diversity of G. duodenalis in bamboo rats from Hunan Province of China were investigated.

Results

Of 480 faecal samples collected from six farms located in four cities (Wugang, Chenzhou, Huaihua and Jishou) of Hunan Province, 52 (10.8%) were positive for G. duodenalis infection by using a nested PCR approach targeting the beta giardin (bg) gene. Significant differences (P < 0.01) in prevalence were found among different age groups and geographical localities, and among different farms in Wugang city. Sequence analysis revealed existence of the zoonotic assemblage B and genetic diversity of G. duodenalis in these animals. Multilocus genotyping analysis also indicated broad genetic diversity of assemblage B isolates in these bamboo rats.

Conclusions

This is the first report of the infection and genetic variations of G. duodenalis in bamboo rats. These findings will provide basic data for implementing effective strategies to control giardiasis in bamboo rats.

Electronic supplementary material

The online version of this article (10.1186/s13071-018-3111-2) contains supplementary material, which is available to authorized users.