Giardia lamblia assemblages A and B isolated from symptomatic and asymptomatic persons in Hamadan, west of Iran

Occurrence and assemblage distribution of Giardia Duodenalis in symptomatic and asymptomatic patients in southeastern Iran (2019-2022)

BACKGROUND

The ubiquitous protozoan parasite Giardia duodenalis is a major contributor to the global burden of diarrhoea, particularly in young children living in poor-resource regions. Although rarely mortal, giardiasis is associated with growth retardation and cognitive impairment in early childhood. Here we investigate the epidemiology of human giardiasis in Iranshahr (south-eastern Iran), a region where this information was previously lacking.

METHODS

Stool samples were collected from 17,455 outpatients and inpatients attended at three major hospital settings during April 2020 and March 2022. Microscopy was used as a screening method for the presence of Giardia cysts, and the identification of G. duodenalis assemblages was carried out using PCR and Sanger sequencing.

RESULTS

The overall prevalence of giardiasis was 1.87 (326/17,455; 95% CI: 1.7-2.1). Being female was positively associated with higher odds of giardiasis (p = 0.014). Individuals without diarrhoea were less likely to have giardiasis (p = 0.022). Individuals attending the Iran Hospital were more likely to harbour G. duodenalis infections compared to those attending at the Khatam Hospital and the Clinical Reference Laboratory (p = 0.001). Our sequence analyses revealed the presence of assemblages A (56.5%, 13/23), B (39.1%, 9/23), and A + B (4.4%, 1/23). No association was observed between the occurrence of a given assemblage and the occurrence of diarhroea.

CONCLUSIONS

Giardia infections were found at relatively low prevalence rates in both symptomatic and asymptomatic individuals seeking medical attention. Being female, having diarrhoea, and being sampled during 2020-21 were predictors of giardiasis. Although limited, our molecular data indicate that some Giardia infections may be zoonotic in nature. These data should be corroborated and expanded in future epidemiological studies targeting simultaneously human, animal, and environmental (water) samples to improve our understanding of the epidemiology of giardiasis in Iran.

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.

Prevalence and molecular characterization of Giardia intestinalis isolated from children and calves in Babylon province, Iraq

Background and Aim

Giardia intestinalis is one of the most prevalent intestinal parasites in humans and animals, and children in close contact with livestock are particularly at risk of infection. This study aimed to detect assemblages of G. intestinalis and determine the origin of zoonotic transmission of Giardia in children and calves in different parts of Babylon province, Iraq.

Materials and Methods

One hundred stool samples from children (68 boys and 32 girls) and 100 fecal samples from calves (46 males and 54 females) of different ages were randomly collected. Molecular techniques were used to estimate the prevalence of G. intestinalis in children and calves. A nested polymerase chain reaction (PCR) was performed by targeting the triose phosphate isomerase gene in the samples to detect G. intestinalis assemblages.

Results

The overall rates of infection with G. intestinalis in children and calves were 21% and 34%, respectively, using the conventional microscopic method. The results illustrated that 61.90% (13/21) and 38.09% (8/21) of positive samples from children were allocated to assemblages A and B, respectively (p > 0.05). In calves, assemblages A and B were detecte in 82.35% (28/34) and 17.64% (6/34) of positive samples from calves, respectively (p ≤ 0.001). Ten PCR products were sequenced and submitted to the GenBank database. Phylogenetic analysis detected five human sequences each belonging to G. intestinalis assemblages A (OM850335-OM850339) and B (OM850340-OM850344). Similarly, five calf sequences each belonged to G. intestinalis assemblages A (ON75756-ON757660) and B (ON757661-ON757665).

Conclusion

The detection of large numbers of G. intestinalis assemblage A in both humans and cattle indicated that cattle could be a main source of zoonotic G. intestinalis infection in children in Babylon province, Iraq.

Multilocus sequence typing of Giardia duodenalis genotypes circulating in humans in a major metropolitan area

Giardia duodenalis is an intestinal protozoan parasite of humans and animal hosts and comprises eight microscopically indistinguishable molecularly-diverse lineages designated as assemblages A-H. Assemblages A and B are the primary sources of infections in humans and a wide range of mammals. Here, we identified assemblages, and inter-/intra-assemblage genetic diversity of human G. duodenalis isolates based on the multilocus sequence typing of the triosephosphate isomerase (tpi), β -giardin (bg), and glutamate dehydrogenase (gdh) loci. Multilocus sequence analysis of 62 microscopically-positive G. duodenalis fecal samples identified 26 (41.9%), 27 (43.5%), and nine (14.5%) isolates belonging to assemblages A, B, and discordant assemblages, respectively. The tpi locus assemblage-specific primers identified dual infections with A and B assemblages (45.2%). The sequence analysis of multiple alignments and phylogenetic analysis showed low genetic polymorphism in assemblage A isolates, classified as sub-assemblage AII at three loci, subtype A2 at tpi and gdh loci, and subtype A2 or A3 at bg locus. High genetic variations were found in assemblage B isolates with 14, 15, and 23 nucleotide patterns at tpi, bg, and gdh loci, respectively. Further concatenated sequence analysis revealed four multilocus genotypes (MLG) in 24 assemblages A isolates, two previously-identified (AII-1 and AII-5), with one novel multilocus genotype. However, the high genetic variations observed in assemblage B isolates among and within the three genetic loci prevented the definitive designation of specific MLGs for these isolates. Multilocus sequence typing may provide new insight into the genetic diversity of G. duodenalis isolates in Tehran, suggesting that humans are likely a potential source of G. duodenalis infection. Further host-specific experimental transmission studies are warranted to elucidate the modes of transmission within multiple host populations.

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.

Development of HRM real-time PCR for assemblage characterization of Giardia lamblia

A total of 90 stool samples were collected from dogs, referred to a dog shelter and a veterinary clinic. In addition, 395 stool samples obtained from pet dog owners and shelter keepers, as well as individuals referred to a medical laboratory as controls, were collected in Shahryar district, Tehran, Iran. Stool samples were parasitologically examined and the positive G. lamblia isolates were tested with Nested-PCR/sequencing for the tpi, gdh, and bg genes, and HRM real-time PCR. Microscopical examination revealed 20 (22.2%) and 34 (8.6%) Giardia-positive samples from dogs and humans, respectively. Regarding HRM real-time PCR, the prevalence of assemblages A and B in humans was 55.8% and 14.7%, respectively. In addition, 14.7% of samples were mix assemblages. HRM real-time PCR detected most of microscopically-positive samples in comparison to PCR/sequencing in both humans and dogs. The high prevalence of assemblages A and B in dogs signified the importance of a same source for infection between dogs and humans.

Detection of Point Prevalence and Assemblages of Giardia spp. in Dairy Calves and Sika Deer, Northeast China

Giardia lamblia (syn Giardia duodenalis) is an important protozoan parasite that can cause enterocyte damage and loss of brush border of the epithelial cells in the intestine, resulting in shortening of microvilli and altered epithelial barrier function. Many animals have been detected as the hosts of the G. lamblia. However, the information on the epidemiology and molecular detection of G. lamblia in dairy calves and sika deer in northeastern China is limited. To investigate the prevalence and genotypes of dairy calves and sika deer in northeastern China, a total of 321 fecal samples from dairy calves in Heilongjiang Province and 818 fecal samples from sika deer in four provinces (Jilin Province, Heilongjiang Province, Liaoning Province, and Inner Mongolia Autonomous Region) in China were conducted by PCR methods, between September 2017 and April 2018. The overall prevalence of G. lamblia in dairy calves in Heilongjiang Province and sika deer in the four provinces was 4.98% (16/321) and 0.61% (5/818), respectively. In this study, the point prevalence of Giardia spp. in different factor groups was dissimilar. A total of 16 Giardia spp. positive samples in dairy calves were identified as assemblage E based on the triosephosphate isomerase (tpi), β-giardine (bg), and glutamate dehydrogenase (gdh) genes. Furthermore, two positive samples of assemblage A and three positive samples of assemblage E were identified with gdh and bg genes in the sika deer. Assemblage A was zoonotic genotype of G. lamblia, and assemblage E was identified as the predominant assemblage in dairy calves and sika deer. This study reported the prevalence and genotypes of G. lamblia in dairy calves in Heilongjiang Province and sika deer in four provinces in China. These results provided basic information to understand the epidemiology of G. lamblia in dairy calves and sika deer in China.

Molecular and epidemiological characterization of Giardia Intestinalis assemblages detected in Djelfa, Algeria

Giardia intestinalis is a flagellated protozoan that lives and proliferates in the small intestine of the host causing giardiasis. The route of transmission is the fecal-oral route, either directly or indirectly. Limited genetic information on G. intestinalis is known in Algeria. This study aimed to estimate the prevalence of G. intestinalis assemblages in the city of Djelfa. A total of 355 fecal samples were collected from symptomatic and asymptomatic school children aged ranged between 6 and 11 years old. Genotyping was done to the Giardia positive samples (n = 30) targeting the beta-giardin gene by applying PCR/RFLP assay. Our data showed that most of the cases were asymptomatic (56.7%). Co-infection with other intestinal parasites was found in 16.6% of cases. We obtained 28/30 positive PCR products while two samples only showed false-negative results, and only 20 samples have shown strong PCR products suitable for RFLP analysis. Assemblage A (70%) was more prevalent than assemblage B (30%) and was more expressed by signs than assemblage B. Moreover, only assemblage A was associated with close contacts with domestic animals and birds. In conclusion, this study gave the first molecular data on G. intestinalis isolates in the city of Djelfa. Further expanded studies using more genes and covering other cities in Algeria are mostly needed.