Local and global genetic diversity of protozoan parasites: Spatial distribution of Cryptosporidium and Giardia genotypes

Genetic characterization of Cryptosporidium spp. in the North African hedgehog (Atelerix algirus) in the Canary Islands, Spain

The North African hedgehog (Atelerix algirus) is an introduced species from Northwest Africa and is currently distributed in the Canary Islands. This species of hedgehog has been studied as a reservoir of enteropathogens, including Cryptosporidium spp. However, there are no data at species level. Therefore, the aim of the present study was to identify the Cryptosporidium species present in a population of hedgehogs (n = 36) in the Canary Islands. Molecular screening was performed using conventional polymerase chain reaction (PCR) targeting the small subunit ribosomal RNA (18S rRNA) gene of Cryptosporidium spp. Seven of the 36 fecal samples (19.45%) were positive and confirmed by nested PCR targeting the 18S rRNA gene and Sanger sequencing. Cryptosporidium parvum and Cryptosporidium muris were identified in 11.1% (4/36) and 5.6% (2/36) of the samples, respectively, while one sample could only be identified at the genus level. The zoonotic subtypes IIdA15G1 (n = 1), IIdA16G1b (n = 1), and IIdA22G1 (n = 1) of C. parvum were identified by nested PCR followed by analysis of the 60 kDa glycoprotein (gp60) gene sequence. This study is the first genetic characterization of Cryptosporidium spp. in A. algirus, identifying zoonotic species and subtypes of the parasite.

Year-round monitoring of three water sources in Québec, Canada, reveals site-specific differences in conditions for Cryptosporidium and Giardia contamination

Cryptosporidium and Giardia are protozoan parasites responsible for gastrointestinal illnesses in humans and in animal species. The main way these parasites are transmitted is by ingestion of their (oo)cysts in drinking water. Monitoring (oo)cysts in water sources is beneficial to evaluate the quality of raw water supplying treatment plants. Currently, the only standardized protocol to enumerate these parasites from water samples is United States Environmental Protection Agency (USEPA) Method 1623.1. With this method, we monitored three major water sources in Quebec over a year to assess temporal and geographical variations of these parasite (oo)cysts. These three water sources have independent watersheds despite being in the same region. We found a general pattern for Giardia, with high concentrations of cysts during cold and transition periods, and significantly lower concentrations during the warm period. Cryptosporidium's concentration was more variable throughout the year. Statistical correlations (Pearson's correlation coefficients) were established between the concentration of each parasite and various environmental parameters. The three study sites each showed unique factors correlating with the presence of both protozoa, supporting the idea that each water source must be seen as a unique entity with its own particular characteristics and therefore, must be monitored independently. Although some environmental parameters could be interesting proxies to the parasitic load, no parameter was strongly correlated throughout the whole sampling year and none of the parameters could be used as a single proxy for all three studies sources.

Rabbits as reservoirs: An updated perspective of the zoonotic risk from Cryptosporidium and Giardia

Rabbits are highly abundant in many countries and can serve as reservoirs of diseases for a diversity of pathogens including the enteric protozoan parasites, Cryptosporidium and Giardia. Both parasites shed environmentally robust environmental stages (oo/cysts) and have been responsible for numerous waterborne outbreaks of diseases. Cryptosporidium hominis and C. parvum are responsible for most infections in humans, while Giardia duodenalis assemblages A and B, cause most human cases of giardiasis. Cryptosporidium cuniculus, the dominant species infecting rabbits, is the only spceies other than C. hominis and C. parvum to have caused a waterborne outbreak of gastritis, which occurred in the United Kingdom in 2008. This review examines the prevalence of Cryptosporidium and Giardia species in rabbits to better understand the public health risks of contamination of water sources with Cryptosporidium and Giardia oo/cysts from rabbits. Despite the abundance of C. cuniculus in rabbits, reports in humans are relatively rare, with the exception of the United Kingdom and New Zealand, and reports of C. cuniculus in humans from the United Kingdom have declined substantially since the 2008 outbreak. Subtyping of C. cuniculus has supported the potential for zoonotic transmission. Relatively few studies have been conducted on Giardia, but assemblage B dominates. However, improved typing methods are required to better understand the transmission dynamics of Giardia assemblages in rabbits. Similarly, it is not well understood if pet rabbits or contaminated water are the main source of C. cuniculus infections in humans. Well-planned studies using high-resolution typing tools are required to understand the transmission dynamics better and quantify the public health risk of Cryptosporidium and Giardia from rabbits.

Profiling pathogenic protozoan and their functional pathways in wastewater using 18S rRNA and shotgun metagenomics

Despite extensive research, little is known about the composition of eukaryotic protists in environmental samples. This is due to low parasite concentrations, the complexity of parasite diversity, and a lack of suitable reference databases and standardized protocols. To bridge this knowledge gap, this study used 18S rRNA short amplicon and shotgun metagenomic sequencing approaches to profile protozoan microbial communities as well as their functional pathways in treated and untreated wastewater samples collected from different regions of South Africa. Results demonstrated that protozoan diversity (Shannon index P-value = 0.03) and taxonomic composition (PERMANOVA, P-value = 0.02) was mainly driven by the type of wastewater samples (treated & untreated) and geographic location. However, these WWTPs were also found to contain a core community of protozoan parasites. The untreated wastewater samples revealed a predominant presence of free-living, parasitic, and potentially pathogenic protists typically found in humans and animals, ranging from Alveolata (27 %) phylum (Apicomplexa and Ciliophora) to Excavata (3.88 %) (Discoba and Parasalia) and Amoebozoa (2.84 %) (Entamoeba and Acanthamoeba). Shotgun metagenomics analyses in a subset of the untreated wastewater samples confirmed the presence of public health-importance protozoa, including Cryptosporidium species (3.48 %), Entamoeba hystolitica (6.58 %), Blastocystis hominis (2.91 %), Naegleria gruberi (2.37 %), Toxoplasma gondii (1.98 %), Cyclospora cayetanensis (1.30 %), and Giardia intestinalis (0.31 %). Virulent gene families linked to pathogenic protozoa, such as serine/threonine protein phosphatase and mucin-desulfating sulfatase were identified. Additionally, enriched pathways included thiamine diphosphate biosynthesis III, heme biosynthesis, Methylerythritol 4-Phosphate Pathway, methyl erythritol phosphate (MEP), and pentose phosphate pathways. These findings suggest that protozoan pathogens may possess metabolic and growth potential within WWTPs, posing a severe risk of transmission to humans and animals if inadequately disinfected before release. This study provides a baseline for the future investigation of diverse protozoal communities in wastewater, which are of public health importance.

Molecular detection and characterization of Giardia spp., Cryptosporidium spp., and Blastocystis in captive wild animals rescued from central Colombia

Cryptosporidium, Giardia, and Blastocystis are significant causes of diarrhea worldwide. However, studies on their prevalence in wild animals are limited, compared to humans and domestic animals. In this study, we collected 23 stool samples from captive wild rescued animals in Boyacá, Colombia. Using conventional PCR, we detected Cryptosporidium spp., Giardia spp., and Blastocystis in over half of the samples (69.6%). Cryptosporidium spp. (43.5%) were the most commonly found, followed by Giardia spp. (39.1%) and Blastocystis (13.0%). Co-infections involving these parasites were also observed. Subsequent genotyping revealed Cryptosporidium canis and Cryptosporidium ryanae as the predominant species. These findings contribute valuable information about the ecoepidemiology of intestinal parasites in Colombian wild animals.

Distribution of Cryptosporidium parvum subgenotypes in pre-weaned calves in Germany

Cryptosporidium parvum is a main cause of severe diarrhea in young calves leading to economic loss and animal suffering. Little is known about the epidemiology of the genetic subtypes that may differ in their infectiousness and zoonotic potential. The present study analyzes the distribution of Glycoprotein 60 (GP60) variants in C. parvum positive samples obtained from young calves in Germany where individual fecal samples of 441 pre-weaned calves collected from 98 German dairy herds were evaluated for cryptosporidiosis (Göhring et al., 2014). DNA was extracted for Restriction Fragment Length Polymorphism (RFLP) analysis from 268 samples that were positive for Cryptosporidium by coproantigen EIA originating from 91 farms confirming C. parvum as the only species occurring. GP60 subtype analysis revealed 12C. parvum subtypes, all belonging to the zoonotic allele family IIa. The most widespread subtype was IIaA15G2R1 (71.4%). Other subtypes occurred sporadically: IIaA16G2R1, IIaA16G3R1 and IIaA17G2R1 (6.2%), IIaA13G1R2 (3.5%), IIaA14G1R1 (3.1%), IIaA14G2R1 (1.3%), IIaA17G1R1 (0.9%) and IIaA13G2R1, IIaA16G1R2, IIaA17G1R2 and IIaA24G1R1 (0.4%). Altogether a high diversity of subgenotypes was found with IIaA15G2R1 clearly dominating irrespective of geographic region. All subgenotypes are considered zoonotic underscoring that pre-weaned calves are likely to be a reservoir for zoonotic C. parvum and thus may be a risk for animal-to-human transmission.

Uncovering the genetic diversity of Giardia intestinalis in isolates from outbreaks in New Zealand

Background

Giardia intestinalis is one of the most common causes of diarrhoea worldwide. Molecular techniques have greatly improved our understanding of the taxonomy and epidemiology of this parasite. Co-infection with mixed (sub-) assemblages has been reported, however, Sanger sequencing is sometimes unable to identify shared subtypes between samples involved in the same epidemiologically linked event, due to samples showing multiple dominant subtypes within the same outbreak. Here, we aimed to use a metabarcoding approach to uncover the genetic diversity within samples from sporadic and outbreak cases of giardiasis to characterise the subtype diversity, and determine if there are common sequences shared by epidemiologically linked cases that are missed by Sanger sequencing.

Methods

We built a database with 1109 unique glutamate dehydrogenase (gdh) locus sequences covering most of the assemblages of G. intestinalis and used gdh metabarcoding to analyse 16 samples from sporadic and outbreak cases of giardiasis that occurred in New Zealand between 2010 and 2018.

Results

There is considerable diversity of subtypes of G. intestinalis present in each sample. The utilisation of metabarcoding enabled the identification of shared subtypes between samples from the same outbreak. Multiple variants were identified in 13 of 16 samples, with Assemblage B variants most common, and Assemblages E and A present in mixed infections.

Conclusions

This study showed that G. intestinalis infections in humans are frequently mixed, with multiple subtypes present in each host. Shared sequences among epidemiologically linked cases not identified through Sanger sequencing were detected. Considering the variation in symptoms observed in cases of giardiasis, and the potential link between symptoms and (sub-) assemblages, the frequency of mixed infections could have implications for our understanding of host–pathogen interactions.

Graphical Abstract

Supplementary Information

The online version contains supplementary material available at 10.1186/s40249-022-00969-x.

Molecular Detection of Cryptosporidium cuniculus in Rabbits (Oryctolagus cuniculus) from Tenerife, Canary Islands, Spain

Cryptosporidium cuniculus is a zoonotic parasite responsible for cryptosporidiosis cases and outbreaks in both humans and rabbits. Since there are no molecular Cryptosporidium spp. infection data in rabbits (Oryctolagus cuniculus) from Spain, our aim was to gather information about this parasite in wild European rabbits from Tenerife, Canary Islands (Spain). A total of 100 faecal samples were collected from rabbits from eight municipalities of Tenerife. Microscopic analysis showed that 4.0% of the samples presented structures compatible with Cryptosporidium oocyst. A nested polymerase chain reaction (PCR) targeting 18S ribosomal RNA (rRNA) gene fragments was carried out, and sequencing confirmed the identity of C. cuniculus in one sample (1.0%). The sample was successfully subtyped using nested PCR analysis of the 60-kDa glycoprotein (gp60) gene as the subtype VbA26R3. This study confirms the presence of C. cuniculus in wild rabbits from Tenerife, providing new information on the occurrence of this zoonotic parasite. Further studies are required to better understand the epidemiology of Cryptosporidium spp. in wild rabbits in Spain and their possible public health repercussions.

Giardia duodenalis in Wildlife: Exploring Genotype Diversity in Italy and across Europe

Fragmented data are so far available on genotype diversity of G. duodenalis in wildlife in different countries in Europe, in particular, in Italy. In the present study, G. duodenalis sequences obtained from different Italian wild animals [12 porcupines (Hystrix cristata), 4 wild boars (Sus scrofa), 1 wolf (Canis lupus italicus), 6 Alpine chamois (Rupicapra rupicapra rupicapra)] were compared with those available from wild host species in Europe to add new data on the geographic distribution of Giardia assemblages/sub-assemblages and their transmission patterns among natural hosts. Thirty-eight sequences were obtained by MLG analysis (SSU-rRNA, bg, gdh, and tpi genes) and subsequently compared by phylogenetic and network analyses with those from wild species monitored in the last decades in Europe. The results revealed the presence of potentially zoonotic (A-AI, A-AII from wild boar; B from porcupine) and host-adapted (D from wolf; E, A-AIII from chamois) assemblages and sub-assemblages and represent the first report for Italian wild boar. The analysis did not find any evidence of spatial or host segregation for specific genetic variants, mostly shared between different hosts from different European countries. However, conflicting evidence was found in genotypic assignment, advocating for data improvement and new genomic approaches.

Canine and Feline Parasitology: Analogies, Differences, and Relevance for Human Health

Cats and dogs are treated as family members by most pet owners. Therefore, a high quality of veterinary care and preventive medicine is imperative for animal health and welfare and for the protection of humans from zoonotic pathogens. There is a general perception of cats being treated as "small dogs," especially in the field of clinical parasitology. As a result, several important differences between the two animal species are not taken into proper consideration and are often overlooked. Dogs and cats are profoundly different under evolutionary, biological, ethological, behavioral, and immunological standpoints. These differences impact clinical features, diagnosis, and control of canine and feline parasites and transmission risk for humans. This review outlines the most common parasitoses and vector-borne diseases of dogs and cats, with a focus on major convergences and divergences, and discusses parasites that have (i) evolved based on different preys for dogs and cats, (ii) adapted due to different immunological or behavioral animal profiles, and (iii) developed more similarities than differences in canine and feline infections and associated diseases. Differences, similarities, and peculiarities of canine and feline parasitology are herein reviewed in three macrosections: (i) carnivorism, vegetarianism, anatomy, genetics, and parasites, (ii) evolutionary adaptation of nematodes, including veterinary reconsideration and zoonotic importance, and (iii) behavior and immune system driving ectoparasites and transmitted diseases. Emphasis is given to provide further steps toward a more accurate evaluation of canine and feline parasitology in a changing world in terms of public health relevance and One Health approach.

An Update on Zoonotic Cryptosporidium Species and Genotypes in Humans

The enteric parasite, Cryptosporidium is a major cause of diarrhoeal illness in humans and animals worldwide. No effective therapeutics or vaccines are available and therefore control is dependent on understanding transmission dynamics. The development of molecular detection and typing tools has resulted in the identification of a large number of cryptic species and genotypes and facilitated our understanding of their potential for zoonotic transmission. Of the 44 recognised Cryptosporidium species and >120 genotypes, 19 species, and four genotypes have been reported in humans with C. hominis, C. parvum, C. meleagridis, C. canis and C. felis being the most prevalent. The development of typing tools that are still lacking some zoonotic species and genotypes and more extensive molecular epidemiological studies in countries where the potential for transmission is highest are required to further our understanding of this important zoonotic pathogen. Similarly, whole-genome sequencing (WGS) and amplicon next-generation sequencing (NGS) are important for more accurately tracking transmission and understanding the mechanisms behind host specificity.

Phylogeography and population differentiation in Hepatozoon canis (Apicomplexa: Hepatozoidae) reveal expansion and gene flow in world populations

BACKGROUND

Hepatozoon canis is a protozoan transmitted to dogs and other wild carnivores by the ingestion of ticks containing mature oocysts and is considered the principal cause of canine hepatozoonosis in the world. Here, we examined ribosomal RNA 18S gene sequence variation to determine the genetic differences and phylogeographic diversity of H. canis from various geographical areas around the world.

METHODS

We used 550 publicly available sequences of H. canis from 46 countries to assess haplotype relationships, geographical structure, genetic diversity indices, and relationships among populations. We performed neutrality tests and pairwise comparisons of fixation index (FST) values between groups and pairwise comparisons of FST values between populations. To determine whether populations are structured, analyses of molecular variance (AMOVAs) and spatial analysis of molecular variance (SAMOVA) were performed.

RESULTS

The dataset of H. canis yielded 76 haplotypes. Differentiation among populations indicated that there is no phylogeographical structure (GST = 0.302 ± 0.0475). Moreover, when samples were grouped by continents a significant FST was obtained, meaning that populations were genetically differentiated. The AMOVA showed that 57.4% of the genetic variation was explained by differences within populations when all locations were treated as a single group and revealed that there is no population structure when populations are grouped into two, three, and four groups (FCT, p > 0.05), suggesting that dispersal between populations is high. SAMOVA revealed significant FCT values for groups K = 5. The Tajima's D and Fu's Fs show that populations have undergone recent expansion, and the mismatch distribution analysis showed population expansion (multimodal distribution).

CONCLUSIONS

The current molecular data confirmed that H. canis does not show phylogeographic or population structure. The haplotypes exhibit low genetic differentiation, suggesting a recent expansion due to gene flow among populations. These results provide pivotal information required for future detailed population genetic analysis or to establish control strategies of this parasite.

Giardia duodenalis in colony stray cats from Italy

Giardia duodenalis is the most common intestinal protozoan in humans and animals worldwide, including eight morphologically identical assemblages, infecting pets, livestock, wildlife and human beings. Assemblages A and B are those with the higher zoonotic potential, and they have been detected in several mammals other than humans; the others (C to H) show a higher host specificity. Cats can harbour both the specific Assemblage F and the zoonotic ones A and B. Several studies have been carried out on G. duodenalis genotypes in cats; however, the role of this species in the epidemiology of giardiasis is still poorly understood. In this scenario, the present study carried out the detection and genetic characterization at sub‐assemblage level of G. duodenalis from colony stray cats in central Italy. In the period 2018–2019, 133 cat faecal samples were analysed for the presence of G. duodenalis cysts by a direct immunofluorescence assay. Positive samples were subsequently subjected to molecular analyses for assemblage/sub‐assemblage identification. Forty‐seven samples (35.3%) were positive for G. duodenalis cysts by immunofluorescence. G. duodenalis DNA was amplified at SSU‐rDNA locus from 39 isolates: 37 were positive for zoonotic Assemblage A and 2 showed a mixed infection (A + B). Positive results for the β‐giardin gene were achieved for 25 isolates. Sequence analysis revealed 16 isolates belonging to Sub‐assemblage AII and 8 to Sub‐assemblage AIII. One isolate resulted as ambiguous AI/AIII. Large sequence variability at the sub‐assemblage level was detected, with several double peaks and mutations, making complex a proper isolate allocation. When compared with previous studies, the 35.3% prevalence of G. duodenalis in cats reported in the present article was surprisingly high. Moreover, all positive cats resulted to be infected with zoonotic assemblages/sub‐assemblages, thus indicating stray cats as a possible source of human giardiasis and highlighting the sanitary relevance of cat colonies in the study area.

Detection of Cryptosporidium spp. and Giardia duodenalis in small wild mammals in northeastern Brazil

This study investigated the occurrence of Giardia duodenalis and Cryptosporidium spp. in rodents and marsupials from the Atlantic Forest in southern Bahia, northeastern Brazil. Two hundred and four fecal samples were collected from different forest areas in the municipalities of Ilhéus, Una, Belmonte, and Mascote. Identifications were performed using PCR and nested PCR followed by sequencing of the gdh and tpi genes for G. duodenalis, and the gp60 and Hsp-70 genes for Cryptosporidium. The total frequency of positive PCR samples for both G. duodenalis and Cryptosporidium spp. was 5.4% (11/204). Giardia duodenalis occurred in 2.94% (4/136) of rodents and 2.94% (2/68) of marsupials. The prevalence of Cryptosporidium in rodents and marsupials was 1.47% (2/136) and 4.41% (3/68), respectively. In the areas sampled, the frequency of parasitism was 50% (7/14), while the Mascote region alone had no parasitized animals. The G. duodenalis subgenotype AI was identified in the rodent species Hylaeamys laticeps, Oecomys catherinae, Oligoryzomys nigripes and Akodon cursor, and in the marsupials Gracilinanus agilis and Monodelphis americana. In the rodents Rhipidomys mastacalis, H. laticeps and in the marsupial Marmosa murina the protozoa Cryptosporidium fayeri, Cryptosporidium parvum and Cryptosporidium ubiquitum with subtypes IIa and IVg by the gp60 gene were found. In conclusion, this study provides the genetic characterization of Giardia and Cryptosporidium species and genotypes in rodents and marsupials. And, these findings reinforce that the rodent and marsupial species mentioned above play a role as new hosts for Giardia and Cryptosporidium.

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.

Absence of Cryptosporidium hominis and dominance of zoonotic Cryptosporidium species in patients after Covid-19 restrictions in Auckland, New Zealand

Coronavirus disease-2019 (Covid-19) nonpharmaceutical interventions have proven effective control measures for a range of respiratory illnesses throughout the world. These measures, which include isolation, stringent border controls, physical distancing and improved hygiene also have effects on other human pathogens, including parasitic enteric diseases such as cryptosporidiosis. Cryptosporidium infections in humans are almost entirely caused by two species: C. hominis, which is primarily transmitted from human to human, and Cryptosporidium parvum, which is mainly zoonotic. By monitoring Cryptosporidium species and subtype families in human cases of cryptosporidiosis before and after the introduction of Covid-19 control measures in New Zealand, we found C. hominis was completely absent after the first months of 2020 and has remained so until the beginning of 2021. Nevertheless, C. parvum has followed its typical transmission pattern and continues to be widely reported. We conclude that ~7 weeks of isolation during level 3 and 4 lockdown period interrupted the human to human transmission of C. hominis leaving only the primarily zoonotic transmission pathway used by C. parvum. Secondary anthroponotic transmission of C. parvum remains possible among close contacts of zoonotic cases. Ongoing 14-day quarantine measures for new arrivals to New Zealand have likely suppressed new incursions of C. hominis from overseas. Our findings suggest that C. hominis may be controlled or even eradicated through nonpharmaceutical interventions.

A review on application of next-generation sequencing methods for profiling of protozoan parasites in water: Current methodologies, challenges, and perspectives

The advancement in metagenomic techniques has provided novel tools for profiling human parasites in environmental matrices, such as water and wastewater. However, application of metagenomic techniques for the profiling of protozoan parasites in environmental matrices is not commonly reported in the literature. The key factors leading to the less common use of metagenomics are the complexity and large eukaryotic genome, the prevalence of small parasite populations in environmental samples compared to bacteria, difficulties in extracting DNA from (oo)cysts, and limited reference databases for parasites. This calls for further research to develop optimized methods specifically looking at protozoan parasites in the environment. This study reviews the current workflow, methods and provide recommendations for the standardization of techniques. The article identifies and summarizes the key methods, advantages, and limitations associated with metagenomic analysis, like sample pre-processing, DNA extraction, sequencing approaches, and analysis methods. The study enhances the understanding and application of standardized protocols for profiling of protozoan parasite community from highly complexe samples and further creates a resourceful comparison among datasets without any biases.

Molecular Epidemiology of Human Cryptosporidiosis in Low- and Middle-Income Countries

Cryptosporidiosis is one of the most important causes of moderate to severe diarrhea and diarrhea-related mortality in children under 2 years of age in low- and middle-income countries. In recent decades, genotyping and subtyping tools have been used in epidemiological studies of human cryptosporidiosis. Results of these studies suggest that higher genetic diversity of Cryptosporidium spp. is present in humans in these countries at both species and subtype levels and that anthroponotic transmission plays a major role in human cryptosporidiosis. Cryptosporidium hominis is the most common Cryptosporidium species in humans in almost all the low- and middle-income countries examined, with five subtype families (namely, Ia, Ib, Id, Ie, and If) being commonly found in most regions. In addition, most Cryptosporidium parvum infections in these areas are caused by the anthroponotic IIc subtype family rather than the zoonotic IIa subtype family. There is geographic segregation in Cryptosporidium hominis subtypes, as revealed by multilocus subtyping. Concurrent and sequential infections with different Cryptosporidium species and subtypes are common, as immunity against reinfection and cross protection against different Cryptosporidium species are partial. Differences in clinical presentations have been observed among Cryptosporidium species and C. hominis subtypes. These observations suggest that WASH (water, sanitation, and hygiene)-based interventions should be implemented to prevent and control human cryptosporidiosis in low- and middle-income countries.

Cryptosporidium species and subtypes in river water and riverbed sediment using next-generation sequencing

This study uncovered the prevalence, harboured species, and subtype diversity of Cryptosporidium species in river water and its sediment from the Apies River in South Africa. Cryptosporidium spp. concentrations in freshwater and its sediment were determined using Ziehl-Neelsen staining and quantitative Polymerase Chain Reaction (qPCR) techniques. Next-generation sequencing (NGS) targeting the 60 kDa glycoprotein (gp60) gene of Cryptosporidium spp. was performed to reveal the species, subtype families and subtypes harboured in freshwater and its sediment. Although the results revealed that water samples had a higher prevalence (30%) compared with sediment (28%), the number of observable Cryptosporidium spp. oocysts in sediment samples (ranging from 4.90 to 5.81 log₁₀ oocysts per 1 Liter) was higher than that of river water samples (ranging from 4.60 to 5.58 log₁₀ oocysts per 1 L) using Ziehl-Neelsen staining. The 18S ribosomal ribonucleic acid (rRNA) gene copy of Cryptosporidium in riverbed sediments ranged from 6.03 to 7.65 log₁₀, whereas in river water, it was found to be between 4.20 and 6.79 log₁₀. Subtyping results showed that in riverbed sediments, Cryptosporidium parvum accounted for 40.72% of sequences, followed by Cryptosporidium hominis with 23.64%, Cryptosporidium cuniculus with 7.10%, Cryptosporidium meleagridis with 4.44% and the least was Cryptosporidium wrairi with 2.59%. A considerable percentage of reads in riverbed sediment (21.25%) was not assigned to any subtype. River water samples had 45.63% of sequences assigned to C. parvum, followed by 30.32% to C. hominis, 17.99% to C. meleagridis and 5.88% to C. cuniculus. The data obtained are concerning, as Cryptosporidium spp. have intrinsic resistance to water treatment processes and low infectious doses, which can pose a risk to human health due to the various uses of water (for human consumption, leisure, and reuse).

Prevalence and molecular characterization of Cryptosporidium spp. and Giardia duodenalis in dairy cattle in Gansu, northwest China

Cryptosporidium spp. and Giardia duodenalis are common gastrointestinal parasites with a broad range of hosts, including humans, livestock, and wildlife. To examine the infection status and assess the zoonotic potential of Cryptosporidium spp. and G. duodenalis in dairy cattle in Gansu, China, a total of 1414 fecal samples were collected from the rectum, with one sample collected from each individual animal. All the samples were tested using nested PCR based on the small subunit ribosomal RNA (SSU rRNA) gene of Cryptosporidium spp. and G. duodenalis. The overall infection rates of Cryptosporidium spp. and Giardia duodenalis were 4.2% (n = 59) and 1.0% (n = 14), respectively. Four Cryptosporidium species were identified: C. andersoni (n = 42), C. parvum (n = 12), C. bovis (n = 5), and C. ryanae (n = 1). In further analyses of subtypes of C. parvum isolates based on the 60 kDa glycoprotein (gp60) gene, five were successfully subtyped as IIdA19G1 (n = 4) and IIdA15G1 (n = 1). All 14 G. duodenalis isolates were identified as assemblage E using the triosephosphate isomerase (tpi) gene. The relatively low positive rates of Cryptosporidium spp. and G. duodenalis detected here and the predominance of non-human pathogenic species/assemblages of these parasites indicated their unique transmission dynamics in this area and the low level of threat posed to public health. However, continuous monitoring and further studies of these parasites should be conducted for the prevention and control of these pathogens.

Molecular characterization of Cryptosporidium spp. from patients with diarrhoea in Lusaka, Zambia

Cryptosporidium is a major etiological agent of diarrhoeal diseases among children and immune-compromised individuals in sub-Saharan African countries. We conducted a study to determine the prevalence and genetic characteristics of Cryptosporidium spp. in stool samples from patients with diarrhoea who presented at the University Teaching Hospital in Lusaka, Zambia. Cryptosporidium species and subtypes from 71 microscopically confirmed cryptosporidiosis stool samples collected between 2017 and 2019 were determined by polymerase chain reaction followed by partial sequencing of the small subunit rRNA and 60-kDa glycoprotein (gp60) gene. Additionally, data for the period between 2014 and 2019 were reviewed and analysed for cryptosporidiosis seasonal and age distribution. Cryptosporidium was more prevalent in the rainy season. The highest number of cases was reported among the 1–4 year age group. By sequence analysis of the 71 positive isolates, Cryptosporidium hominis (n = 42; 59.2%), C. parvum (n = 27; 38%), C. felis (n = 1; 1.4%), and C. meleagridis (n = 1; 1.4%) were identified. Four C. hominis subtype families (Ia, Ib, Id, and Ie) and three C. parvum subtype families (IIc, IIe, and IIs) were identified. The most frequent subtypes were IeA11G3T3 (n = 20; 28.2%), IIcA5G3 (n = 12; 16.9%), IIeA12G1 (n = 11; 15.5%) and IaA30R3 (n = 10; 14.1%). The observed species/subtypes of C. hominis and C. parvum indicated that the infection was mainly transmitted through the anthroponotic route. The identification of C. felis and C. meleagridis suggests that an atypical zoonotic transmission cycle also exists.

Comparative genetic diversity of Cryptosporidium species causing human infections

Parasites sometimes expand their host range and cause new disease aetiologies. Genetic changes can then occur due to host-specific adaptive alterations, particularly when parasites cross between evolutionarily distant hosts. Characterizing genetic variation in Cryptosporidium from humans and other animals may have important implications for understanding disease dynamics and transmission. We analyse sequences from four loci (gp60, HSP-70, COWP and actin) representing multiple Cryptosporidium species reported in humans. We predicted low genetic diversity in species that present unusual human infections due to founder events and bottlenecks. High genetic diversity was observed in isolates from humans of Cryptosporidium meleagridis, Cryptosporidium cuniculus, Cryptosporidium hominis and Cryptosporidium parvum. A deviation of expected values of neutrality using Tajima's D was observed in C. cuniculus and C. meleagridis. The high genetic diversity in C. meleagridis and C. cuniculus did not match our expectations but deviations from neutrality indicate a recent decrease in genetic variability through a population bottleneck after an expansion event. Cryptosporidium hominis was also found with a significant Tajima's D positive value likely caused by recent population expansion of unusual genotypes in humans. These insights indicate that changes in genetic diversity can help us to understand host-parasite adaptation and evolution.

Prevalence and Molecular Genotyping of Cryptosporidium Spp. in Diarrheic Patients from Bandar Abbas City, Southern Iran

Background: Cryptosporidium species are recognized as one of the most important gastrointestinal pathogens of humans and livestock. Objectives: This study aimed to determine the prevalence and sub-genotypes of Cryptosporidium spp. among diarrheic patients in Bandar Abbas City, Iran. Methods: Diarrheic fecal samples were collected from 170 patients in three hospitals of Bandar Abbas, Iran, from October 2018 to May 2019. Initial parasitological identification of Cryptosporidium spp. was performed by modified Ziehl-Neelsen (ZN) staining. For molecular analysis, the positive specimens and the suspected ones of Cryptosporidium spp. were evaluated by sequence analysis of the 60-kDa glycoprotein gene (gp60). The collected data were analyzed using SPSS software and the relationship between the variables and the presence of Cryptosporidium spp. assessed by the chi-square test. To assess the degree of agreement between PCR and ZN staining, Cohen’s kappa-index was applied. Results: Of the 170 diarrheic patients, 98 (57.6%) were male, and 72 (42.4%) were female. Prevalence of Cryptosporidium spp. by parasitological examination was 1.8% (3/170). However, using PCR, Cryptosporidium spp. was detected in 12% (6/50) of the positive microscopically samples (3 samples) and 47 suspected specimens. Sequence analysis of the gp60 gene showed that all of the positive isolates were Cryptosporidium parvum in which all subtypes belonged to allele family IId. Two distinct nucleotide sequences obtained from this study were deposited in GenBank under the accession numbers MN820453 and MN820454. Conclusions: The predominance of C. parvum (subtype family IId) in this study emphasizes the importance of zoonotic Cryptosporidium transmission in Bandar Abbas, Southern Iran.

Species and genotypes causing human cryptosporidiosis in New Zealand

Cryptosporidium is one of the most common causes of diarrhoea around the world. Successful management and prevention of this infectious disease requires knowledge of the diversity of species and subtypes causing human disease. We use sequence data from 2598 human faecal samples collected during an 11-year period (2009-2019) to better understand the impact of different species and subtypes on public health and to gain insights into the variation of human cryptosporidiosis in New Zealand. Human cryptosporidiosis in New Zealand is caused by a high diversity of species and subtypes. Six species cause human disease in New Zealand: C. hominis, C. parvum, C. cuniculus, C. erinacei, C. meleagridis and C. tyzzeri. Sequence analysis of the gp60 gene identified 16 subtype families and 101 subtypes. Cryptosporidium hominis IbA10G2 and C. parvum IIaA18G3R1 were the most frequent causes of human cryptosporidiosis with 27% and 29% of infections, respectively. Cryptosporidium hominis presented a peak of notified human cases during autumn (March-May) whereas most cases of human cryptosporidiosis caused by C. parvum are found during the calving and lambing season in spring (September-November). We also reported some subtypes that have been rarely detected in other countries such as IbA20G2 and IIoA13G1 and a low prevalence of the hypertransmissible and virulent IIaA15G2R1. This study provides insight into the variability of cryptosporidiosis in New Zealand essential for disease management and surveillance to prevent the introduction or spread of new species and subtypes in the country.

Molecular detection and genotyping of intestinal protozoa from different biogeographical regions of Colombia

Background

Intestinal parasitic protozoa represent a serious problem of public health particularly in developing countries. Protozoa such as Blastocystis, Giardia intestinalis, Entamoeba histolytica and Cryptosporidium spp. are associated with diarrheal symptoms. In Colombia, there is little region-specific data on the frequency and circulating genotypes/species of these microorganisms. Therefore, the main objective of our study was to employ molecular detection and genotyping of G. intestinalis and Blastocystis, Cryptosporidium and Entamoeba spp. in samples from different biogeographical regions of Colombia.

Methods

We collected 649 human fecal samples from five biogeographical regions of Colombia: the Amazon, Andean, Caribbean, Orinoco and Pacific regions. Blastocystis, G. intestinalis, Cryptosporidium spp. and Entamoeba complex were detected by microscopy and conventional PCR. Molecular genotyping was conducted to identify Blastocystis subtypes (STs) (18s), G. intestinalis assemblages (triose phosphate isomerase and glutamate dehydrogenase) and Cryptosporidium species (18s). Genetic diversity indices were determined using dnasp.5.

Results

We detected G. intestinalis in 45.4% (n = 280) of samples, Blastocystis in 54.5% (n = 336) of samples, Cryptosporidium spp. in 7.3% (n = 45) of samples, Entamoeba dispar in 1.5% (n = 9) of samples, and Entamoeba moshkovskii in 0.32% (n = 2) of samples. Blastocystis STs 1–4, 8 and 9 and G. intestinalis assemblages AII, BIII, BIV, D and G were identified. The following Cryptosporidium species were identified: C. hominis, C. parvum, C. bovis, C. andersoni, C. muris, C. ubiquitum and C. felis. The Caribbean region had the highest frequency for each of the microorganisms evaluated (91.9% for G. duodenalis, 97.3% for Blastocystis, 10.8% for Cryptosporidium spp., 13.5% for E. dispar and 2.7% for E. moshkovskii). The Orinoco region had a high frequency of Blastocystis (97.2%) and the Andean region had a high frequency of G. intestinalis (69.4%). High and active transmission was apparent in several regions of the country, implying that mechanisms for prevention and control of intestinal parasitosis in different parts of the country must be improved.

Direct Sequencing of Cryptosporidium in Stool Samples for Public Health

The protozoan parasite Cryptosporidium is an important cause of diarrheal disease (cryptosporidiosis) in humans and animals, with significant morbidity and mortality especially in severely immunocompromised people and in young children in low-resource settings. Due to the sexual life cycle of the parasite, transmission is complex. There are no restrictions on sexual recombination between sub-populations, meaning that large-scale genetic recombination may occur within a host, potentially confounding epidemiological analysis. To clarify the relationships between infections in different hosts, it is first necessary to correctly identify species and genotypes, but these differentiations are not made by standard diagnostic tests and more sophisticated molecular methods have been developed. For instance, multilocus genotyping has been utilized to differentiate isolates within the major human pathogens, Cryptosporidium parvum and Cryptosporidium hominis. This has allowed mixed populations with multiple alleles to be identified: recombination events are considered to be the driving force of increased variation and the emergence of new subtypes. As yet, whole genome sequencing (WGS) is having limited impact on public health investigations, due in part to insufficient numbers of oocysts and purity of DNA derived from clinical samples. Moreover, because public health agencies have not prioritized parasites, validation has not been performed on user-friendly data analysis pipelines suitable for public health practitioners. Nonetheless, since the first whole genome assembly in 2004 there are now numerous genomes of human and animal-derived cryptosporidia publically available, spanning nine species. It has also been demonstrated that WGS from very low numbers of oocysts is possible, through the use of amplification procedures. These data and approaches are providing new insights into host-adapted infectivity, the presence and frequency of multiple sub-populations of Cryptosporidium spp. within single clinical samples, and transmission of infection. Analyses show that although whole genome sequences do indeed contain many alleles, they are invariably dominated by a single highly abundant allele. These insights are helping to better understand population structures within hosts, which will be important to develop novel prevention strategies in the fight against cryptosporidiosis.

Genotypes and public health potential of Enterocytozoon bieneusi and Giardia duodenalis in crab-eating macaques

BACKGROUND

Enterocytozoon bieneusi and Giardia duodenalis are common human and animal pathogens. Studies have increasingly shown that non-human primates (NHPs) are common hosts of these two zoonotic parasites. However, few studies have explored the genetic diversity and public health potential of these pathogens in laboratory monkeys. In this study, we examined the genetic diversity of the two pathogens in crab-eating macaques (Macaca fascicularis) in a commercial facility in Hainan, China.

RESULTS

Enterocytozoon bieneusi and G. duodenalis were detected by PCR analysis in 461/1452 (31.7%) and 469/1452 (32.3%) fecal specimens from the animals, respectively. Significantly higher detection rates of E. bieneusi were detected in males (36.5%, 258/706) than in females (26.7%, 160/599; χ2 = 14.391, P = 0.0001), in animals with loose stools (41.4%, 151/365) than those with normal stool (28.5%, 310/1087; χ2 = 20.83, P < 0.0001), and in animals of over 3 years of age (38.6%, 135/350) than those of 1-3 years (29.6%, 326/1,102; χ2 = 9.90, P = 0.0016). For G. duodenalis, the detection rate in males (33.4%, 236/706) was higher than in females but not statistically significant (30.2%, 181/599; χ2 = 1.54, P = 0.2152), in monkeys with loose stools (41.1%, 150/365) than those with normal stools (29.3%, 319/1087; χ2 = 17.25, P < 0.0001), and in monkeys of 1-3 years of age (36.6%, 403/1102) than those over 3 years (18.9%, 66/350; χ2 = 38.11, P < 0.0001). Nine E. bieneusi genotypes were detected in this study by DNA sequence analysis of the internal transcribed spacer of the rRNA gene, namely Type IV (236/461), Peru8 (42/461), Pongo2 (27/461), Peru11 (12/461), D (4/461) and PigEbITS7 (1/461) previously seen in NHPs as well as humans, and CM1 (119/461), CM2 (17/461) and CM3 (3/461) that had been only detected in NHPs. DNA sequence analyses of the tpi, gdh and bg loci identified all G. duodenalis specimens as having assemblage B. Altogether, eight (4 known and 4 new), seven (6 known and 1 new) and seven (4 known and 3 new) subtypes were seen at the tpi, gdh and bg loci, leading to the detection of 53 multi-locus genotypes (MLG-B-hn01 to MLG-B-hn53). Most of them were genetically related to those previously seen in common Old-World monkeys.

CONCLUSIONS

Data from this study indicate a common occurrence of zoonotic genotypes of E. bieneusi and assemblage B of G. duodenalis in farmed crab-eating macaques in Hainan, China.

Epidemiology of Cryptosporidium infection in different hosts in Nigeria: A meta-analysis

Cryptosporidium is a medical and veterinary significant protozoan parasite that infects all classes of vertebrates. Environmental contamination with infective oocyst increases the risk of transmission to susceptible host. Estimates of Cryptosporidium prevalence in humans and animals are lacking in Nigeria, therefore a systematic review and meta-analysis were performed to understand the epidemiology of the disease over a period of 30 years using publications from EMBASE, Ovid MEDLINE, Web of Science, AJOL and Google Scholar databases. Studies that met the inclusion criteria of Cryptosporidium infections under the preferred reporting items for systematic reviews and meta-analyses (PRISMA) checklist were analysed. Point estimates prevalence and subgroup analyses based on potential risk factors and diagnostic techniques were evaluated at 95% confidence interval (CI). A total of 64 eligible studies published between 1987 and 2017 were selected for meta-analysis. The prevalence of Cryptosporidium infection using quality effects model among human, cattle, sheep, goat, pigs, laboratory animals and birds was estimated as 15.0, 26.1, 16.6, 26.0, 20.1, 9.0 and 7.2%, respectively. The high report of C. parvum subtype family IIc indicates the importance of anthroponotic transmission of Cryptosporidium in Nigeria. Heterogeneity of subgroup (regions, species) and risk factors (HIV status, age, gender, faecal type) analyses were determined. The pooled prevalence of Cryptosporidium spp. in different hosts were high and linked with several risk factors such as environmental contamination and animal contact. There is need for increased awareness on the prevalence of the disease to provide strategies that mitigate the disease in humans and animals.

Molecular and descriptive epidemiology of intestinal protozoan parasites of children and their pets in Cauca, Colombia: a cross-sectional study

BACKGROUND

Parasitic infections, particularly those caused by protozoa, represent a considerable public health problem in developing countries. Blastocystis, Giardia duodenalis, Cryptosporidium spp. and the Entamoeba complex (Entamoeba histolytica, Entamoeba dispar and Entamoeba moshkovskii) are the most common etiological causes of intestinal parasitic infections.

METHODS

We carried out a descriptive cross-sectional study in school-age children attending a daycare institution in commune eight of Popayán, Cauca (Southwest Colombia). A total of 266 fecal samples were collected (258 from children and eight from pets). Blastocystis, G. duodenalis, Cryptosporidium spp. and the Entamoeba complex were identified by microscopy, quantitative real-time PCR (qPCR) and conventional PCR. The concordance of qPCR and microscopy was assessed using the Kappa index. Molecular characterization was conducted to identify Blastocystis subtypes (18S), G. duodenalis assemblages (tpi and gdh) and Cryptosporidium species/subtypes (18S and GP60). Potential associations between intestinal parasitism and sociodemographic factors were examined using bivariate analyses.

RESULTS

A total of 258 fecal samples from children were analyzed by microscopy and 255 samples were analyzed by qPCR. The prevalence of Blastocystis was between 25.19% (microscopy) and 39.22% (qPCR), that of G. duodenalis was between 8.14% (microscopy) and 10.59% (qPCR), that of Cryptosporidium spp. was estimated at 9.8% (qPCR), and that of the Entamoeba complex was between 0.39% (conventional PCR) and 0.78% (microscopy). The concordance between microscopy and qPCR was very low. Blastocystis ST1 (alleles 4, 8, and 80), ST2 (alleles 11, 12, and 15), ST3 (alleles 31, 34, 36, 38,57, and 151), and ST4 (alleles 42 and 91), G. duodenalis assemblages AII, BIII, BIV and D, C. parvum subtype IIa and C. hominis subtype IbA9G3R2 were identified. The only identified member of the Entamoeba complex corresponded to E. histolytica. No statistically significant association was identified between parasitic infection and any sociodemographic variable.

CONCLUSION

This study revealed the usefulness of molecular methods to depict the transmission dynamics of parasitic protozoa in southwest Colombia. The presence of some of these protozoa in domestic animals may be involved in their transmission.

Distribution of Cryptosporidium parvum gp60 subtypes in calf herds of Saxony, Germany

Cryptosporidiosis is a common protozoan parasitic infection that causes diarrhoea in neonatal calves. The high shedding of environmentally resistant oocysts facilitates outbreaks of cryptosporidiosis in humans. In total, 58 farms (512 calves) in Germany (Saxony and Brandenburg) were visited three times each. Faecal samples of pre-weaned calves were microscopically examined for oocysts of Cryptosporidium spp. using Heine staining and were scored with regard to their consistency. Overall, 88.9% of calves tested microscopically positive for Cryptosporidium spp. in at least one sample, and the excretion of oocysts was significantly (P < 0.01) associated with a higher faecal score (diarrhoea). After DNA extraction from pooled farm isolates, 47 samples were successfully subtyped by sequence analysis of the 60 kDa glycoprotein gene (gp60). All isolates belonged to subtype family IIa. IIaA15G2R1 was the most common subtype (present on 66% of the farms), followed by IIaA16G3R1 (13%). Subtypes IIaA14G1R1, IIaA14G2R1, IIaA1612R1, IIaA16G2R1, IIaA17G1R1, IIaA17G2R1, IIaA17G4R1 and IIaA19G2R1 were found sporadically. This is the first description of gp60 subtype IIaA17G4R1 in cattle in Germany.

Evaluation of prevalence and risk factors associated with Cryptosporidium infection in rural population of district Buner, Pakistan

BACKGROUND

Cryptosporidium spp are important intestinal protozoan parasites that cause diarrhea in humans, domestic and wild animals. Its infection remains a main public health concern however, the epidemics in human being is still unclear, particularly in developing countries. There are several factors that may enhance the spreading of this parasite in human population especially in young children.

METHODOLOGY

A questionnaire was designed to obtain the demographic and clinical data from the participants. A total of 425 stool samples were collected from suspected children (aged 3-10 years) in different hospitals and villages. The initial screening was performed with modified Ziehl Neelsen (mZN) staining technique followed by polymerase chain reaction (PCR). Several potential risk factors were also assessed through the obtained information from suspected individuals.

RESULTS

Out of all 425 collected samples, 127 were observed positive by mZN with a prevalence of 29.88% (127/425). The 127 mZN positive samples together with 50 mZN negative samples were processed for molecular analysis through PCR assay. Among them, 71 out of 127 mZN positive samples and 4 out of 50 mZN negative samples were found positive by PCR. The molecular analysis showed that Cryptosporidium parvum was the main cause of infection in children. The results revealed that individuals exposed to diarrhea were more likely to be infected with Cryptosporidium infection while several environmental factors may also play a key role in spreading of this parasite.

CONCLUSIONS/SIGNIFICANCE OF THE STUDY

The current high prevalence of Cryptosporidium infection may be due to the lack of awareness and routine based testing in identification of this parasite in District Buner. Further studies are required to determine the importance of Cryptosporidium infection in this area as well as across the country and to find out the possible risk factors that may be associated with the occurrence of this protozoan. There is, however, an urgent need for laboratory-based observational studies to develop a more dynamic estimate of the cryptosporidial disease burden in the region.

Genetic variability and transcontinental sharing of Giardia duodenalis infrapopulations determined by glutamate dehydrogenase gene

Microevolutionary data of Giardia duodenalis sub-assemblages is a prerequisite for determining the invasion zoonotic patterns of the parasite. To infer transmission patterns that could not be differentiated by the phenotypic features, a population genetic investigation is crucial for the elucidation of the genetic structure of G. duodenalis among the continents. Forty G. duodenalis positive fecal samples were collected from different foci of Northwest Iran. The specimens were subjected to Trichrome staining and sucrose gradient flotation. DNA samples were extracted, amplified, and sequenced by targeting glutamate dehydrogenase (gdh) gene. The global gdh sequences of sub-assemblages AII and BIV retrieved from NCBI GenBank were analyzed to estimate diversity indices, neutrality indices, and gene migration tests. Sequencing analyses indicated various levels of genetic variability of sub-assemblages AII and BIV among the five continents. Sub-assemblage BIV had greater genetic variability (haplotype diversity: 0.975; nucleotide diversity: 0.04246) than sub-assemblage AII. The statistical Fst value demonstrated that the genetic structure of sub-assemblages AII and BIV are moderately differentiated between European-American populations (Fst: 0.05352-0.15182), whereas a significant differentiation was not seen among other geographical population pairs. We conclude that a high gene flow of G. duodenalis sub-assemblages AII and BIV is unequivocally sharing among the continents. The current findings strengthen our knowledge to assess the evolutionary patterns of G. duodenalis in endemic foci of the world and it will become the basis of public health policy to control human giardiasis.