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

Introduction

Giardiosis remains one of the most prevalent enteric parasitic infections globally. Earlier molecular-based studies conducted in Egypt have primarily focused on paediatric clinical populations and most were based on single genotyping markers. As a result, there is limited information on the frequency and genetic diversity of G. duodenalis infections in individuals of all age groups.

Methods

Individual stool samples (n = 460) from outpatients seeking medical care were collected during January-December 2021 in Kafr El-Sheikh governorate, northern Egypt. Initial screening for the presence of G. duodenalis was conducted by coprological examination. Microscopy-positive samples were further confirmed by real-time PCR. A multilocus sequence typing approach targeted amplification of the glutamate dehydrogenase (gdh), beta-giardin (bg), and triose phosphate isomerase (tpi) genes was used for genotyping purposes. A standardised epidemiological questionnaire was used to gather basic sociodemographic and clinical features of the recruited patients.

Results

Giardia duodenalis cysts were observed in 5.4% (25/460, 95% CI: 3.6-7.9) of the stool samples examined by conventional microscopy. The infection was more frequent in children under the age of 10 years and in individuals presenting with diarrhoea but without reaching statistical significance. Stool samples collected during the winter period were more likely to harbour G. duodenalis. All 25 microscopy-positive samples were confirmed by real-time PCR, but genotyping data was only available for 56.0% (14/25) of the isolates. Sequence analyses revealed the presence of assemblages A (78.6%, 11/14) and B (21.4%, 3/14). All assemblage A isolates were identified as sub-assemblage AII, whereas the three assemblage B sequences belonged to the sub-assemblage BIII. Patients with giardiosis presenting with diarrhoea were more frequently infected by the assemblage A of the parasite.

Conclusion

This is one of the largest epidemiological studies evaluating G. duodenalis infection in individuals of all age groups in Egypt. Our molecular data suggest that G. duodenalis infections in the surveyed population are primarily of anthropic origin. However, because assemblages A and B are zoonotic, some of the infections identified can have an animal origin. Additional investigations targeting animal (domestic and free-living) and environmental (water) samples are warranted to better understand the epidemiology of giardiosis in Egypt.

Genomic survey maps differences in the molecular complement of vesicle formation machinery between Giardia intestinalis assemblages

Giardia intestinalis is a globally important microbial pathogen with considerable public health, agricultural, and economic burden. Genome sequencing and comparative analyses have elucidated G. intestinalis to be a taxonomically diverse species consisting of at least eight different sub-types (assemblages A-H) that can infect a great variety of animal hosts, including humans. The best studied of these are assemblages A and B which have a broad host range and have zoonotic transmissibility towards humans where clinical Giardiasis can range from asymptomatic to diarrheal disease. Epidemiological surveys as well as previous molecular investigations have pointed towards critical genomic level differences within numerous molecular pathways and families of parasite virulence factors within assemblage A and B isolates. In this study, we explored the necessary machinery for the formation of vesicles and cargo transport in 89 Canadian isolates of assemblage A and B G. intestinalis. Considerable variability within the molecular complement of the endolysosomal ESCRT protein machinery, adaptor coat protein complexes, and ARF regulatory system have previously been reported. Here, we confirm inter-assemblage, but find no intra-assemblage variation within the trafficking systems examined. This variation includes losses of subunits belonging to the ESCRTIII as well as novel lineage specific duplications in components of the COPII machinery, ARF1, and ARFGEF families (BIG and CYTH). Since differences in disease manifestation between assemblages A and B have been controversially reported, our findings may well have clinical implications and even taxonomic, as the membrane trafficking system underpin parasite survival, pathogenesis, and propagation.

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.

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.

Gastrointestinal parasites in Africa: A review

Data on human gastrointestinal parasites (GIP) infections in the african sub-regions and countries are mainly lacking in terms of prevalence and population stratification by afflicted age group, symptomatology, multi-parasitism, and diagnostic methods. This study aims to describe the GIP reported in african countries and discuss the extent of the burden in the african context. Only 68.42% (39/57) of african countries reported human cases of GIP with helminths (45%, CI: 40-50%, I²: 99.79%) as the predominant parasitic group infecting the african population. On a regional scale, Central Africa had the highest pooled prevalence for GIP (43%, CI: 32-54%, I²: 99.74%), while the Central African Republic led all countries with a pooled prevalence of 90% (CI: 89-92%, I²: 99.96%). The vulnerable population (patients who are minorities, children, old, poor, underfunded, or have particular medical conditions) was the most affected (50%, CI: 37-62%, I²: 99.33%), with the predominance of GIP in the 6 to <20 years age group (48%, CI: 43-54%, I²: 99.68%). Reports on multi-parasitism (44%, CI: 40-48%, I²: 99.73%) were almost double the reports of single infections (43%, CI: 27-59%, I²: 99.77%) with combined molecular and non-molecular techniques demonstrating the best performance for GIP identification. The current review spans more than 40 years of GIP reports from the african continent. Geographical characteristics, environmental factors, habits of its inhabitants, and their health status play a crucial role in GIP modulation and behaviour in its captive hosts. Strategies for regular and enhanced surveillance, policy formation, and high-level community awareness are necessary to identify the true incidence in Africa and the transmission of the pathogens via water and food.

The controversies surrounding Giardia intestinalis assemblages A and B

Giardia intestinalis continues to be one of the most encountered parasitic diseases around the world. Although more frequently detected in developing countries, Giardia infections nonetheless pose significant public health problems in developed countries as well. Molecular characterisation of Giardia isolates from humans and animals reveals that there are two genetically different assemblages (known as assemblage A and B) that cause human infections. However, the current molecular assays used to genotype G. intestinalis isolates are quite controversial. This is in part due to a complex phenomenon where assemblages are incorrectly typed and underreported depending on which targeted locus is sequenced. In this review, we outline current knowledge based on molecular epidemiological studies and raise questions as to the reliability of current genotyping assays and a lack of a globally accepted method. Additionally, we discuss the clinical symptoms caused by G. intestinalis infection and how these symptoms vary depending on the assemblage infecting an individual. We also introduce the host-parasite factors that play a role in the subsequent clinical presentation of an infected person, and explore which assemblages are most seen globally.

A review of the molecular epidemiology of Cryptosporidium spp. and Giardia duodenalis in the Middle East and North Africa (MENA) region

Cryptosporidium spp. and Giardia duodenalis are important protozoan parasites which are associated with diarrheal diseases in humans and animals worldwide. Relatively little is known about the molecular epidemiology of Cryptosporidium spp. and Giardia duodenalis in the Middle East Countries and North Africa (MENA region). Therefore, this review aimed to inspect published genotyping and subtyping studies on Cryptosporidium spp. and Giardia duodenalis in the MENA region. These studies indicate that both anthroponotic and zoonotic transmission of Cryptosporidium occurs with the predominance of zoonotic transmission in most countries. Seven Cryptosporidium species were identified in humans (C. parvum, C. hominis, Cryptosporidium meleagridis, C. felis, Cryptosporidium muris, C. canis and C. bovis), with C. parvum by far being the most prevalent species (reported in 95.4% of the retrieved studies). Among C. parvum gp60 subtype families, IIa and IId predominated, suggesting potential zoonotic transmission. However, in four MENA countries (Lebanon, Israel, Egypt and Tunisia), C. hominis was the predominant species with five subtype families reported including Ia, Ib, Id, If and Ie, all of which are usually anthroponotically transmitted between humans. In animals, the majority of studies were conducted mainly on livestock and poultry, 15 species were identified (C. parvum, C. hominis, C. muris, Cryptosporidium cuniculus, C. andersoni, C. bovis, C. meleagridis, C. baileyi, C. erinacei, C. ryanae, C. felis, C. suis, Cryptosporidium galli, C. xiaoi and C. ubiquitum) with C. parvum (IIa and IId subtypes) the dominant species in livestock and C. meleagridis and C. baileyi the dominant species in poultry. With G. duodenalis, five assemblages (A, B, C, E and F) were identified in humans and six (A, B, C, E, D and F) in animals in MENA countries with assemblages A and B commonly reported in humans, and assemblages A and E dominant in livestock. This review also identified a major knowledge gap in the lack of Cryptosporidium spp. and Giardia duodenalis typing studies in water and food sources in the MENA region. Of the few studies conducted on water sources (including drinking and tap water), ten Cryptosporidium species and four genotypes were identified, highlighting the potential role of water as the major route of Cryptosporidium spp. transmission in the region. In addition, three G. duodenalis assemblages (A, B and E) were detected in different water sources with AI, AII and BIV being the main sub-assemblages reported. More research is required in order to better understand the molecular diversity and transmission dynamics of Cryptsporidum spp. and Giardia duodenalis in humans, animals, water and food sources in MENA region.

Evaluation for associations amongst Giardia duodenalis assemblages and diarrhea in dogs

Giardia duodenalis is a species complex comprising at least eight assemblages. Most dogs harbor the host-adapted assemblages C and D and approximately 30 % harbor the zoonotic assemblages. Humans and dogs with giardiosis can exhibit a variety of clinical manifestations ranging from the absence of clinical signs to acute or chronic diarrhea. Human studies report conflicting results concerning associations between clinical signs and assemblage type. The objective of this study was to use results of molecular and phylogenetic analyses to evaluate associations between G. duodenalis assemblages and diarrhea in client-owned dogs from the United States. Fecal samples that were positive for Giardia cysts were classified as normal or diarrheal. Samples were analyzed by PCR assays of the beta-giardin (bg), glutamate dehydrogenase (gdh), and triose phosphate isomerase (tpi) genes. Sequences of the three genes were analyzed by BLAST analysis and phylogenetic analysis was performed by Neighbor-Joining analysis. Two hundred and eighty-eight Giardia-positive fecal samples were evaluated by the three PCRs. One or more genes were amplified from 95 normal samples and 93 diarrheal samples, 27 samples were positive for one or more genes but could not be sequenced due to low quality DNA, and 73 samples tested negative. Ninety seven percent of the samples (182/188) in both the diarrheal and normal groups typed as dog-specific assemblages (D or C) by at least one gene. Phylogenetic analysis of the three genes placed the isolates from assemblages A, B, C and D separated from each other with strong bootstrap support. Diarrhea was not associated with the Giardia assemblage or other parasitic co-infection in this sample set. Other factors, such as the role of gut microbiota in giardiosis should be considered in future studies.

First report of novel assemblages and mixed infections of Giardia duodenalis in human isolates from New Zealand

Giardia duodenalis (syn. G. intestinalis and G. lamblia) is a protozoan parasite that cause disease (giardiasis) in humans and other animals. The pathogen is classified into eight assemblages, further divided into sub-assemblages, based on genetic divergence and host specificities. There are two zoonotic subtypes known as assemblages A and B, whilst assemblages from C to H are mainly found in domesticated animals, rodents and marine mammals. Here, we report for the first time the presence of assemblage E and sub-assemblage AIII in human isolates from the South Island in New Zealand. We identified a > 99% nucleotide similarity of assemblage E and sub-assemblage AIII with sequences of the gdh gene available in GenBank from individual human samples collected in Dunedin and Christchurch, respectively. We also performed a deep sequencing approach to assess intra-host assemblage variation. The sample from Dunedin showed evidence of mixed assemblage E and zoonotic sub-assemblage BIV. The report of two novel assemblages and mixed infections provides insights into the genetic diversity, epidemiology and transmission dynamics of Giardia duodenalis in New Zealand.

Differential antibody responses to Giardia lamblia strain variants expressing dissimilar levels of an immunogenic protein

AIMS

Giardia lamblia is a protozoan parasite that causes giardiasis, one of the most common worldwide gastrointestinal diseases. For rational development of a Giardia vaccine, increasing our understanding of the host-Giardia interaction is crucial. In this study, we analysed the immunogenicity and antigenicity of two G lamblia strain variants [GS and GS-5G8 (+)], which express different levels of the variant-specific surface protein (VSP) 5G8 and also analysed the intestinal histological changes associated with Giardia infection.

METHODS AND RESULTS

We evaluated the antibody responses induced by G lamblia strains in infected, reinfected and immunized C3H/HeJ mice using ELISA, flow cytometry, Western blotting and histological analysis. Our results showed that G lamblia GS-5G8 (+) was more immunogenic and antigenic than the GS strain. The antibody response against the GS-5G8 (+) strain primarily recognized 5G8 protein. Serum antibody from infected and reinfected mice exhibited specific agglutination of trophozoites in vitro. GS-5G8 (+)-infected mice showed higher CD19⁺ infiltrating cell levels compared to GS-infected animals.

CONCLUSION

G lamblia strains with different expression levels of an immunogenic antigen (VSP 5G8) induce differential antibody responses. A better understanding of the immunogenic proteins of G lamblia will contribute to the rational development of an effective vaccine against this parasitic disease.

Molecular Characterization of Giardia intestinalis Detected in Humans and Water Samples in Egypt

BACKGROUND

Giardia intestinalis is a common cause of gastrointestinal illness especially in children of developing countries. Giardia assemblages A and B are the major human infective genotypes.

OBJECTIVE

The present study aimed to investigate the role of water supply in the epidemiology of giardiasis via genotyping G. intestinalis detected in diarrheic children and in water samples in Egyptian rural areas.

METHODS

Stool samples of 100 diarrheic children, 40 drinking water samples and 10 raw water samples of canals were examined microscopically for Giardia. DNA was extracted from microscopically positive faecal samples and from all of the collected water samples. Amplification of Giardia tpi gene was performed by a nested PCR using assemblage A- and assemblage B-specific primers. Giardia gdh gene was amplified by a heminested PCR. Giardia genotypes were determined by restriction fragment polymorphism (RFLP) analysis of the amplified products. Sequencing of the amplified products was performed in two faecal and two water samples RESULTS: Giardia intestinalis was detected in 24 children, in none of the drinking water samples and in all canal water samples. Giardia sub-assemblage AII was identified in all stool and raw water samples. The RFLP pattern was confirmed in sequenced samples.

CONCLUSION

The presence of the same Giardia sub-assemblage in diarrheic children and in raw water samples shows by molecular evidence the potential for waterborne dissemination of Giardia in Egypt. Further studies are needed to monitor cyst levels and infectivity of the genotype detected in water for risk assessment and management.

Epidemiological distribution of genotypes of Giardia duodenalis in humans in Spain

BACKGROUND

Although the distribution of Giardia duodenalis genotypes in humans has been increasingly reported in recent years, data on possible differences in pathogen transmission between age groups and virulence between genotypes are scarce. The purpose of this study is to investigate the genetic diversity of G. duodenalis in humans in Spain and compare the distribution of G. duodenalis assemblages A and B between children and adults and clinical presentations between the two genotypes.

METHODS

In the present study, 125 microscopy-positive fecal samples were collected from humans in Spain over a 7-year period. PCR and sequence analyses of the triosephosphate isomerase, β-giardin and glutamate dehydrogenase genes were used to identify the multilocus genotypes of G. duodenalis.

RESULTS

Sequence analysis of three genetic loci identified both G. duodenalis assemblages A (29) and B (66), with co-infections of the two in two patients. Among the sequences obtained in this study, four multilocus genotypes (MLGs) of the sub-assemblage AII were observed within assemblage A. In contrast, 19 MLGs were detected within assemblage B due to the high sequence diversity at each locus. One MLG, however, was found in 51.9% (27/52) of assemblage B samples. Children were more commonly infected by assemblage B (44/53 or 83%) than adults (22/42 or 52.4%; χ2 = 10.371, df = 1, P = 0.001). Asymptomatic infection was more common in patients with assemblage A (4/29 or 13.8%) than in those with assemblage B (1/66 or 1.5%; χ2 = 6.091, df = 1, P = 0.029), and the frequency of abdominal pain occurrence was higher in assemblage B patients (65/66 or 98.5%) than assemblage A patients (25/29 or 86.2%; χ2 = 6.091, df = 1, P = 0.029).

CONCLUSIONS

These results illustrate the existence of differences in genotype distribution between children and adults and clinical presentations between G. duodenalis genotypes. They are useful in understanding the transmission of G. duodenalis in humans in Spain.

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.

Assemblages A and B of Giardia duodenalis reduce enteric glial cells in the small intestine in mice

Infection of Giardia duodenalis is one of the most common human parasitic disease worldwide. This infection may be related to important changes in the enteric nervous system. The objective of this study was to evaluate the myenteric and submucosal plexuses, the intestinal muscle layer, and gastrointestinal transit in mice infected with assemblages A and B of G. duodenalis. Swiss albino mice (Mus musculus) were infected with assemblages A and B of G. duodenalis for 15 days. Gastrointestinal transit time was evaluated before euthanasia. Duodenum and jejunum were removed for histological and immunohistochemical analyses. It was observed a reduction in the enteric glial cell count and a decrease in the ratio of enteric glial cells to neurons. The number of neurons did not change, but morphological changes were observed in the duodenum and jejunum in both plexuses, including an increase in the nuclear area and a reduction of cell bodies in the myenteric plexus and a decrease in the nuclear area in the submucosal plexus. A reduction of the thickness of the muscle layer was observed in the duodenum, with no significant differences in the gastrointestinal transit times. Assemblages A and B of G. duodenalis decrease the number of enteric glial cells in the myenteric and submucosal plexuses, decrease the thickness of the muscle layer, and change the morphology of neurons. Graphical abstract ᅟ.

Comparative study of effects of assemblages AII and BIV of Giardia duodenalis on mucosa and microbiota of the small intestine in mice

AIMS

Giardiasis is one of the major causes of diarrhea worldwide and its symptoms vary in intensity, which can be attributed to different parasite assemblages. The goal of the present study was to compare the effects of infection caused by assemblages AII and BIV ofGiardia duodenalis on the response of the small intestine, microbiota, and behavioral parameters in mice.

MAIN METHODS

Swiss mice were infected with assemblages AII and BIV of G. duodenalis for 15 days. Leucometry, pain, intestinal microbiota and histological parameters of the duodenum and jejunum were evaluated in the experimental groups.

KEY FINDINGS

Both assemblages modified the composition of the intestinal microbiota. Infection with assemblage AII promoted leukocytosis, reflected by increasing number of polymorphonuclear cells, intraepithelial lymphocytes and pain-related behavior, indicating that this was the more aggressive assemblage with regard to its effects on the intestinal mucosa and duodenum.

SIGNIFICANCE

The specific assemblage of the parasite is an important parameter that affects symptomatology in the host.

Molecular epidemiologic tools for waterborne pathogens Cryptosporidium spp. and Giardia duodenalis

Molecular diagnostic tools have played an important role in improving our understanding of the transmission of Cryptosporidium spp. and Giardia duodenalis, which are two of the most important waterborne parasites in industrialized nations. Genotyping tools are frequently used in the identification of host-adapted Cryptosporidium species and G. duodenalis assemblages, allowing the assessment of infection sources in humans and public health potential of parasites found in animals and the environment. In contrast, subtyping tools are more often used in case linkages, advanced tracking of infections sources, and assessment of disease burdens attributable to anthroponotic and zoonotic transmission. More recently, multilocus typing tools have been developed for population genetic characterizations of transmission dynamics and delineation of mechanisms for the emergence of virulent subtypes. With the recent development in next generation sequencing techniques, whole genome sequencing and comparative genomic analysis are increasingly used in characterizing Cryptosporidium spp. and G. duodenalis. The use of these tools in epidemiologic studies has identified significant differences in the transmission of Cryptosporidium spp. in humans between developing countries and industrialized nations, especially the role of zoonotic transmission in human infection. Geographic differences are also present in the distribution of G. duodenalis assemblages A and B in humans. In contrast, there is little evidence for widespread zoonotic transmission of giardiasis in both developing and industrialized countries. Differences in virulence have been identified among Cryptosporidium species and subtypes, and possibly between G. duodenalis assemblages A and B, and genetic recombination has been identified as one mechanism for the emergence of virulent C. hominis subtypes. These recent advances are providing insight into the epidemiology of waterborne protozoan parasites in both developing and developed countries.

Nested PCR targeting intergenic spacer (IGS) in genotyping of Giardia duodenalis isolated from symptomatic and asymptomatic infected Egyptian school children

Distinct sequences of Giardia duodenalis assemblages raised the hypothesis that certain assemblages may contribute to its clinical outcome. However, sequences analysis is time consuming, expensive, and needs many manual operations. Nested PCR targeting intergenic spacer (IGS) region was applied successfully to genotype G. duodenalis. This study aimed to identify the prevalence of G. duodenalis assemblages among giardiasis school children and its relation to the presence of symptoms using nested IGS/PCR. Of 65 microscopically confirmed Giardia-positive samples, 65 samples were genotyped proving high sensitivity (92.3%) of IGS/PCR. Negative IGS/PCR samples were also negative for β-giardin gene. Subassemblage AI was the commonest with 66.6% (20/30) among asymptomatic children compared to 53.3% (16/30) of symptomatic, while assemblage B was found in 40% (12/30) of symptomatic compared to 20% (6/30) of asymptomatic. The difference was significant. AII was only found in asymptomatic with 13.4% (4/30), while mixed infections (AI&B) were recorded only in 6.6% (2/30) of symptomatic group. A significant relation was found between younger children susceptibility for AI and B infections as presented in 77.7 (12/16) and 83.3% (10/12) of symptomatic, respectively, and 80 (16/80) and 33.4% (2/4) of asymptomatic, respectively. Significant relations were found between AI with intermittent diarrhea and B with chronic. A significant relation was found between assemblage distributions and heavy infection intensity. In conclusion, higher incidence of assemblage B among symptomatic children compared to asymptomatic could denote its possible pathogenic potential.

Prevalence of Giardia duodenalis assemblages and sub-assemblages in symptomatic patients from Damascus city and its suburbs

Giardia duodenalis is one of the most important human enteric parasites worldwide and is endemic throughout the world with a vast range of mammalian hosts. However, there is limited information on the prevalent genetic variability of G. duodenalis in Syria. This study aimed to evaluate the predominance of G. duodenalis assemblages/sub-assemblages causing humans infection in the city of Damascus and its suburbs. 40 symptomatic giardiasis patients were recruited in this study. Fecal samples were genotyped using PCR/RFLP assay targeting the β-giardin and glutamate dehydrogenase (gdh) genes. HaeIII, BspL1 and RsaI restriction enzymes were used to differentiate between G. duodenalis assemblages/sub-assemblages. Our data showed that 65% of isolates were of assemblage A; 45% belonged to sub-assemblage AII and 20% to sub-assemblage AI. Assemblage B was detected in 27.5% of isolates; 12.5% fit in sub-assemblage BIV, 5% fit in sub-assemblage BIII and 10.5% fit in Discordant genotype BIII/BIV. Mixed genotypes (AII+BIII and AI+BIV) were identified in 3 isolates (7.5%). Significant correlation was found between Giardia AII sub-assemblage and weight loss symptom (P-value=0.05) as well as between contact with domestic animals (cats, P-value=0.027). Moreover, a significant correlation was found between sub-assemblage AI and livestock breeding (P-value=0.000). In conclusion genotyping of human Giardia duodenalis isolates suggests anthroponotic transmission for the route of infection in Damascus and its suburbs. Further studies are needed to screen a wide geographic areas in Syria and to estimate the prevalence of G. duodenalis infection in our population.

First genetic characterisation of Giardia in human isolates from Jordan

Little is known about the epidemiology of Giardia in Jordan and to date, no genotyping studies have been conducted on Giardia isolates from Jordanians. In the present study, a total of 49 microscopy-positive faecal samples from Jordanian patients suffering from giardiasis were analysed at two loci: the triose phosphate isomerase (tpi) gene and the glutamate dehydrogenase (gdh) gene. At the tpi locus, a total of 28 samples amplified and assemblage A was identified in 46.4 % (13/28) samples, while assemblage B was identified in 50 % (14/28) samples and a mixed assemblage A and B was identified in one sample (3.6 %) (Table 1). At the gdh locus 48 isolates amplified and of these assemblages A was identified in 43.7 % (21/48) of isolates and assemblage B in 56.3 % (27/48) of isolates. No mixed infections were detected at the gdh locus. Subtyping at the gdh locus identified sub-assemblage AII in 43.7 % (21/48) of isolates and sub-assemblages BIII and BIV in 25 % (12/48) and 31.2 % (15/48) of isolates, respectively, with more genetic diversity in AII isolates than BIII or BIV isolates. Novel sub-types within each sub-assemblage were identified suggesting unique endemicity and anthroponotic transmission of Giardia in Jordanian patients suffering from giardiasis. Further studies are required to better understand the epidemiology and transmission of Giardia in Jordan.