Giardiasis as a neglected disease in Brazil: Systematic review of 20 years of publications

Diversity of gastrointestinal parasites and molecular characterization of Giardia duodenalis in free-living and captive howler monkeys (Alouatta guariba clamitans) in southern Brazil

Non-human primates (NHPs) are the group that most share infectious agents with humans due to their close taxonomic relationship. The southern brown howler monkeys (Alouatta guariba clamitans) are endemic primates from Brazil and Argentina's Atlantic Forest. This study aimed to investigate the presence of intestinal parasites in free-living (FL) and captive (CA) southern brown howler monkeys. Thirty-nine stool samples were collected in two areas in southern Brazil, 15 FL and 24 CA. Stool sediments obtained by centrifugal sedimentation technique were used for microscopic analysis and direct immunofluorescence assay and evaluated by molecular analysis through amplification and sequencing of TPI fragments. Intestinal parasites Giardia duodenalis, Cryptosporidium spp., and Trypanoxyuris minutus were detected at coproparasitological analysis. This is the first report of the presence of Cryptosporidium spp. in free-living howlers. The molecular characterization of G. duodenalis isolates indicated assemblage B for the first time found in free-living A. guariba clamitans. The high prevalence of G. duodenalis transmission in CA howler monkeys can be explained by direct contact with humans and frequent soil contact. The presence of a potentially zoonotic assemblage in these animals indicates that the process of fragmentation and cohabitation with humans and livestock affects the wildlife, thus indicating a need for eco-health measures.

Detection of IgG Anti-Giardia duodenalis Antibodies in Sera by Indirect Immunofluorescence and Western Blotting Assays

INTRODUCTION

Serological assays are alternative laboratory tools for the diagnosis of parasitic infections. The aim of this work was to evaluate the performance of the indirect fluorescent antibody test (IFAT) and Western blotting (WB) for the detection of IgG anti-Giardia antibodies in human sera.

METHODOLOGY

Sera from individuals infected with Giardia duodenalis, other parasites or non-parasitized were selected for serological assays. Ninety-seven sera were tested by IFAT at 1:20 and 1:40 dilutions and of these, 40 samples were also analyzed by WB.

RESULTS

The sensitivity and specificity of the IFAT was 97% and 46.9% at 1:20 sera dilution, and 39.4% and 59.4% at 1:40 sera dilution. The low molecular weight polypeptides fractions of 25 kDa, 27-31 kDa and 45-55 kDa were the most frequently identified by the sera of individuals infected with G. duodenalis, along with low cross-reactivity, presenting an individual sensitivity of 42.8%, 50.0% and 57.1%, and specificity of 83.3%, 83.3% and 91.7%, respectively. The highest overall sensitivity of WB (85.7%) was based on the immunoreactivity of sera with at least one of those proteins. The concordance between the detection of G. duodenalis in feces by microscopy and the WB results was considered substantial (Kappa = 0.61).

CONCLUSION

Constant exposure to Giardia infection throughout a lifetime can maintain high levels of specific antibodies in serum, even without active infection. Moreover, proteins found in intestinal amoebas may hinder the serological diagnosis of giardiasis in endemic areas due to cross-reactivity, which can be partially solved using Giardia low molecular weight proteins.

Epidemiology of giardiasis and assemblages A and B and effects on diarrhea and growth trajectories during the first 8 years of life: Analysis of a birth cohort in a rural district in tropical Ecuador

BACKGROUND

There are limited longitudinal data on the acquisition of Giardia lamblia infections in childhood using molecular assays to detect and type assemblages, and measure effects of infections on diarrhea risk and childhood growth.

METHODS

We analysed stool samples from a surveillance sample within a birth cohort in a rural district in tropical Ecuador. The cohort was followed to 8 years of age for the presence of G. lamblia in stools by quantitative PCR and A and B assemblages by Taqman assay or Sanger sequencing. We explored risk factors associated with infection using generalized estimating equations applied to longitudinal binary outcomes, and longitudinal panel data analysis to estimate effects of infection on diarrhea and growth trajectories.

RESULTS

2,812 stool samples collected between 1 month and 8 years of age from 498 children were analyzed and showed high rates of infection: 79.7% were infected at least once with peak prevalence (53.9%) at 5 years. Assemblage B was accounted for 56.8% of genotyped infections. Risk factors for infection included male sex (P = 0.001), daycare attendance (P<0.001), having a household latrine (P = 0.04), childhood (P<0.001) and maternal soil-transmitted helminth (P = 0.029) infections, and exposures to donkeys (age interaction P = 0.034). G. lamblia was associated with increased risk of diarrhea (per episode, RR 1.03, 95% CI 1.01-1.06, P = 0.011) during the first 3 years of life and a transient impairment of weight (age interaction P = 0.017) and height-for-age (age interaction P = 0.025) trajectories between 1 and 4 years of age. There was no increased risk of either assemblage being associated with outcomes.

CONCLUSION

Our data show a relatively high edemicity of G. lamblia transmission during childhood in coastal Ecuador, and evidence that infection is associated with a transiently increased risk of diarrhea during the first 3 years of life and impairment of weight and height between 1 and 4 years.

First report of Giardia duodenalis in pet rabbits in Brazil

Giardia duodenalis is a flagellate protozoan that multiplies in the small intestine of a wide variety of hosts, animals and humans. It has a worldwide distribution, however it is considered a neglected disease by the World Health Organization (WHO). Nowadays, rabbits are being chosen as pets, especially by children. There are already reports of the occurrence of G. duodenalis in rabbits from other countries, but research has not been carried out in Brazil yet. Thus, the objective of our work was to verify the occurrence and molecularly characterize G. duodenalis that affect pet rabbits, through the polymerase chain reaction (PCR) in the northwest region of the state of São Paulo, Brazil. Fecal samples from 100 rabbits were collected, which later underwent a process of DNA extraction and amplification by nested-PCR (nPCR), using the SSU rRNA gene, and β-giardin (bg), glutamate dehydrogenase (gdh) and triosephosphate isomerase (tpi) to determine the assemblage. A questionnaire was answered by the owners with information about gender, age, deworming, diarrhea, water source, food, place of residence and contact with other animals. From those samples, 40 were positive for G. duodenalis. Good quality of the SSU rRNA gene by nPCR were obtained from two samples. For the first time, we report the occurrence of G. duodenalis assemblage A on pet rabbits in Brazil.

Molecular characterization of waterborne protozoa in surface water and sediment in Brazil: a taxonomic survey of ciliated protozoa and their correlation with Giardia duodenalis and Cryptosporidium spp

The detection of Giardia duodenalis and Cryptosporidium spp. was performed, along with the identification of the ciliated protozoa biodiversity, to evaluate the correlation between these protozoa in freshwater quality monitoring. Water and sediment samples from two sites in the Atibaia River (Campinas, São Paulo, Brazil) were collected monthly for 2 years (n = 96). Pathogenic protozoa in water and sediment were detected by using immunomagnetic separation, followed by visualization by immunofluorescence assay (IFA). All positive aliquots in IFA were subjected to DNA extraction and subsequently nested PCR. Qualitative (in vivo observation and silver impregnation) and quantitative (in vivo enumeration) analyses were performed for the ciliated protozoa. Giardia cysts were detected in 62.5% of the surface water samples and Cryptosporidium spp. in 25.0%. In the sediment, cysts were detected in 35.4% samples and oocysts in 16.6%. A total of 57 samples positive for Giardia cysts were subjected to sequencing, 40 of which were harboring G. duodenalis (24 were characterized as sub-assemblage AII). For ciliated protozoa, 73 taxa belonging to 53 genera were identified over the period of the study. These results revealed a high degree of contamination by waterborne protozoa in the main water source which supplies drinking water for more than one million people in Campinas (São Paulo), highlighting the need for continuous monitoring of this catchment site. In addition, the present study provides important data regarding the sources of the water body degradation, i.e., fecal contamination of human origin, in addition to the survey of the ciliated protozoa.

Giardiasis in children and dogs, and the first report of assemblage E in dogs from northeastern Brazil

Diagnosis is crucial for controlling giardiasis. We determined the prevalence and genetically characterize isolates of Giardia duodenalis of children and dogs from rural communities in northeastern Brazil. G. duodenalis cysts were concentrated by centrifugal flotation/sedimentation. Molecular characterization was carried out using the loci ssu-rRNA, bg, tpi, and gdh. By parasitological techniques, Giardia spp. infection was detected in 72/192 children (37.5%; 95% CI: 30.6%-44.7%) and 24/139 dogs (17.3%; 95% CI: 11.4%-24.6%). By molecular analysis, infection was detected in 60/141 children (42.5%; 95% CI: 34.3%-51.2%) and 26/92 dogs (28.3%; 95% CI: 19.4%-38.6%). The total prevalence of giardiasis was 54.9% in children (106/193; 95% CI: 47.1%-61.6%) and 32.9% in dogs (47/143; 95% CI: 25.2%-41.2%). Zoonotic assemblages A and B of G. duodenalis were detected in children, and assemblage E of G. duodenalis was detected in one child and two dogs. Parallel use of parasitological and molecular techniques proved to be a more effective strategy for detecting giardiasis in children and dogs from endemic areas.

Molecular characterization of Giardia lamblia and risk factors for giardiasis among immunocompromised patients in southern Brazil

Acute Giardia infections often cause diarrhea and stomach upset. Chronic infections can lead to malnutrition, micronutrient deficiencies, malabsorption and weight loss. This study assessed the prevalence of G. lambia infection and assessed associated risk factors among immunocompomised patients undergoing chemotherapeutic treatment in southern Brazil. A total of 110 immunocompromised patients in Pelotas, RS, Brazil, consented to participate in this study and were recruited. Socioeconomic and epidemiological profile of patients was collected by questionnaire. The prevalence for Giardia were determined through microscopy by the centrifugation-flotation technique using stool samples of every patient. In addition, the genetic characterization of the parasite was carried out by amplifying and sequencing the glutamate dehydrogenase (gdh) gene. By microscopy, the prevalence of giardiasis was 17.3% (19/110). Furthermore, the DNA sequences revealed that 7 (36.8%) out of 19 isolates belonged to assemblage B, while 6 of them (31.6%) belonged to assemblage C, 5 (26.3%) to assemblage A and 1 (5.3%) to assemblage D. Risk factors (p ≤ 0.05) for giardiasis were schooling level (OR=8.0 (1.02 - 62.91) sharing a house with more than three people (OR=14.1 (3.77 - 52.51), water sources (OR=38.9 (10.4 - 145.7), sewage treatment (OR=14.2 (3.1 - 65.5), waste destination (OR=7.44 (2.0 - 27.3), owning pets (OR=4.6 (1.0 - 21.2) and cultivating a vegetable garden (OR=4.2 (1.3 - 13.6). The prevalence of G. lamblia in immunocompromised patients was considered elevate with the identification of four assemblage of the parasite (A, B, C and D).

Burden and Epidemiology of Human Intestinal Giardia duodenalis Infection in Colombia: A Systematic Review

The genus Giardia is a unicellular protozoan able to parasitize both humans and animals. Cysts of Giardia can be found in soil samples, aquatic environments, food, and any surface that gets in contact with the feces of parasitized animals. The aim of this systematic review was to analyze the burden and epidemiology of Giardia infection in Colombia summarizing recent scientific reports and existing knowledge and to identify knowledge gaps that may be addressed in future investigations. This work follows the guidelines established by "Preferred Reporting Items for Systematic Reviews and Meta-Analyzes" (PRISMA). Published scientific literature from 1 January 2010 to 18 September 2022 was searched in six electronic scientific databases using the search terms: "Giardia" OR "Giardiasis" AND "Colombia". Twenty-three scientific articles were performed in 22 departments of Colombia at rural, urban, and a combination of rural and urban contexts. The prevalence of Giardia in the Colombian population was between 0.9 and 48.1% when the samples were analyzed with classical microscopy; the range of Giardia prevalence was even bigger (4.2-100%) when qPCR and nested PCR were used. The dominant Giardia assemblages found in Colombia were A and B, and most frequent subassemblages were AII, BIII, and BIV.

Circulation of Giardia duodenalis in domestic and wild animals from Amazon region: a Systematic Review

Giardia is an ubiquitous protozoa that infect a broad range of vertebrate hosts, including domestic and wild animals as well as humans. Giardia duodenalis is one of the most common parasite in humans and mammals worldwide. Human giardiasis is highly prevalent in the countries that make up from Amazon. The identification of genotypes in humans and animals improves the understanding of transmission routes and the control strategies. Thus, we carried out a systematic review on Giardia in animals from Amazon region/South American, following the PRISMA guidelines. Studies up to September, 2022 were searched for in public database. A total of seven out of 432 articles were selected: four, two and one from Brazil, Colombia and Peru, respectively. Based on these articles it is seen that the G. duodenalis cosmopolitan assemblages A and B prevail within domestic and wild animals in the Amazon. Moreover, a Giardia microscopic screening in aquatic animals from this biome showed its prevalence among aquatic mammals including the endangered species Trichechus inunguis (manatee). Therefore, a yet not accessed number of susceptible hosts, new G. duodenalis assemblages and species can be occurring in this huge hotspot of biodiversity that is Amazon region.

First report of Giardia duodenalis assemblage F in humans and dogs in southern Brazil

The present study aimed to molecularly characterize Giardia duodenalis from stool samples of humans, dogs, and cats. Molecular analyses were performed on 59 samples that tested positive for G. duodenalis on coproparasitological examinations. After extraction, the samples were first tested by nested polymerase chain reaction (n-PCR) analysis of the SSU-rRNA gene, and for the samples that were positive, the β-giardin, TPI, and GDH genes were analyzed. The amplicons obtained in the n-PCR of the β-giardin gene were subjected to PCR-restriction length polymorphism (RFLP) analysis and subsequent digestion with the enzyme HaeIII to differentiate the assemblages. Seven (11.8 %), 34 (57.7 %), and 18 (30.5 %) out of 59 samples were from humans, dogs, and cats, respectively. Nested-PCR results showed that 49.2 % (29/59) of samples were positive for the SSU-rRNA gene, with 42.9 % (3/7) of humans, 55.9 % (19/34) of dogs, and 38.9 % (7/18) of catsve. Of the other genes analyzed, β-giardin was amplified most frequently, in 34.5 % (10/29) of samples, followed by GDH in 27.6 % (8/29) of samples, and TPI in 10.3 % (3/29) of samples. Only one sample from a dog showed the amplification of all genes. PCR-RFLP analysis showed assemblage F in a human, dog, and cat samples; and assemblage C and D in dog samples. This is the first description of assemblage F in humans from Brazil and the first description of assemblage F in dogs. Further studies are needed to verify the frequency with which these infections occur, and provide information that will contribute to the molecular epidemiological understanding of giardiasis.

In vitro effects of the 4-[(10H-phenothiazin-10-yl)methyl]-N-hydroxybenzamide on Giardia intestinalis trophozoites

Giardiasis is an intestinal disease caused by the parasite protozoan Giardia intestinalis. For more than five decades, the treatment of this disease has been based on compounds such as nitroimidazoles and benzimidazoles. The parasite's adverse effects and therapeutic failure are largely recognized. Therefore, it is necessary to develop new forms of chemotherapy treatment against giardiasis. Lysine deacetylases (KDACs), which remove an acetyl group from lysine residues in histone and non-histone proteins as tubulin, are found in the Giardia genome and can become an interesting option for giardiasis treatment. In the present study, we evaluated the effects of 4-[(10H-phenothiazin-10-yl)methyl]-N-hydroxybenzamide, a new class I/II KDAC inhibitor, on G. intestinalis growth, cytoskeleton, and ultrastructure organization. This compound decreased parasite proliferation and viability and displayed an IC₅₀ value of 179 nM. Scanning electron microscopy revealed the presence of protrusions on the cell surface after treatment. In addition, the vacuoles containing concentric membranous lamella and glycogen granules were observed in treated trophozoites. The cell membrane appeared deformed just above these vacuoles. Alterations on the microtubular cytoskeleton of the parasite were not observed after drug exposure. The number of diving cells with incomplete cytokinesis increased after treatment, indicating that the compound can interfere in the late steps of cell division. Our results indicate that 4-[(10H-phenothiazin-10-yl)methyl]-N-hydroxybenzamide should be explored to develop new therapeutic compounds for treating giardiasis.

Detection and removal of Giardia spp. cysts and Cryptosporidium spp. oocysts by anaerobic reactors in Brazil

The discharge of raw wastewater into the environment can be a contamination source of Giardia spp. cysts and Cryptosporidium spp. oocysts. The UASB (Upflow Anaerobic Sludge Blanket) reactor is the most popular technology applied for wastewater treatment in Brazil, nevertheless there is little information concerning its capacity for (oo)cyst removal. In this context, this study investigated the occurrence and removal of Giardia spp. cysts and Cryptosporidium spp. oocysts by three different UASB reactors (i.e. Reactor A, B, and C) treating different wastewater types. In the wastewater influent, the concentration varied from 493.3 to 14,000 cysts·L^-1 for Giardia spp. and from 'not detected' to 53.3 oocysts·L^-1 for Cryptosporidium spp.. The (oo)cyst concentration increased after the anaerobic treatment in Reactors A and B, while Giardia spp. log-removal of 0.5 ± 0.2 was found in Reactor C. The increment in (oo)cyst concentration may happened due to the inefficacy for (oo)cyst removal by the specific UASB reactor and/or due to the reduction of matrix interference for reactor effluent samples in the detection method. The results suggest that hydraulic retention time (HRT) may be the key parameter for Giardia spp. removal by the UASB reactor. Furthermore, no parameter analysed (physical-chemical and indicator microorganisms) showed a common correlation with the (oo)cyst concentration in the three UASB reactors. Considering that official data of cryptosporidiosis and giardiasis cases are rarely reported in Brazil, monitoring Giardia spp. cysts and Cryptosporidium spp. oocysts in wastewater could be an alternative to estimate the occurrence of diseases in the served population.

Wastewater treatment performance in microbiological removal and (oo)cyst viability assessed comparatively to fluorescence decay

Municipal wastewater is a source of pathogenic protozoan (oo)cysts and may play a significant role in spreading waterborne diseases. This scenario becomes more critical as treated sewage from municipal wastewater treatment plants (WWTP) is discharged into springs, which are often used for water supply, irrigation, recreation and, further downstream, indirect potable reuse, quite common in Brazil. This study aimed to elucidate, regarding microbiological quality, the performance of a full-scale WWTP, consisting of preliminary treatment, upflow anaerobic sludge blanket (UASB) reactor, activated sludge system and ultraviolet (UV) radiation disinfection. Pathogenic protozoa (Giardia spp. cysts and Cryptosporidium spp. oocysts), as well as microbiological indicators (Escherichia coli and Clostridium perfringens), were evaluated in terms of their removal. In addition, (oo)cyst viability and fluorescence reduction were assessed. By using the data obtained from this research, the prevalence of infection estimated for the population served by the WWTP was between 7.4% and 14.8% for giardiasis, and between 0.055% and 0.11% for cryptosporidiosis.

Parasitological, microbiological, and antimicrobial resistance profiles of raw and drinking water in a tourist city in the tri-border region of South America

Despite the large amounts of freshwater available in Brazil, the deterioration of surface water can represent a risk of waterborne disease for national and international tourists. The main goal of this study was to assess the quality of drinking water in the triple border region of Brazil before and after being treated in water treatment plants (WTPs) and in Municipal Early Childhood Education Centers (MECECs), in terms of parasitological, microbiological, and physical-chemical aspects. Different water samples were monitored: raw water (RW), treated water (TW), and tap water from the MECECs, giving 60 samples in total, to investigate the presence of Giardia and Cryptosporidium, microbiological indicators, Pseudomonas aeruginosa, and antimicrobial resistance profiles using conventional microbiological assays and parasitological, immunological, and molecular techniques. The results obtained were compared with the reference values recommended by the legislation of drinking water in Brazil. For the first time, contamination by Cryptosporidium and Giardia was demonstrated in RW used to supply WTPs, in TW of Foz do Iguaçu, and in water destined for consumption by children. A total of 52 bacterial isolates were obtained, with high percentages of multidrug resistance to antibiotics, including a carbapenem-resistant profile, highlighting the need to improve quality control standards.

Towards global control of parasitic diseases in the Covid-19 era: One Health and the future of multisectoral global health governance

Human parasitic infections—including malaria, and many neglected tropical diseases (NTDs)—have long represented a Gordian knot in global public health: ancient, persistent, and exceedingly difficult to control. With the coronavirus disease (Covid-19) pandemic substantially interrupting control programmes worldwide, there are now mounting fears that decades of progress in controlling global parasitic infections will be undone. With Covid-19 moreover exposing deep vulnerabilities in the global health system, the current moment presents a watershed opportunity to plan future efforts to reduce the global morbidity and mortality associated with human parasitic infections. In this chapter, we first provide a brief epidemiologic overview of the progress that has been made towards the control of parasitic diseases between 1990 and 2019, contrasting these fragile gains with the anticipated losses as a result of Covid-19. We then argue that the complementary aspirations of the United Nations Sustainable Development Goals (SDGs) and the World Health Organization (WHO)’s 2030 targets for parasitic disease control may be achieved by aligning programme objectives within the One Health paradigm, recognizing the interdependence between humans, animals, and the environment. In so doing, we note that while the WHO remains the preeminent international institution to address some of these transdisciplinary concerns, its underlying challenges with funding, authority, and capacity are likely to reverberate if left unaddressed. To this end, we conclude by reimagining how models of multisectoral global health governance—combining the WHO's normative and technical leadership with greater support in allied policy-making areas—can help sustain future malaria and NTD elimination efforts.

Giardia duodenalis: Biology and Pathogenesis

Giardia duodenalis captured the attention of Leeuwenhoek in 1681 while he was examining his own diarrheal stool, but, ironically, it did not really gain attention as a human pathogen until the 1960s, when outbreaks were reported. Key technological advances, including in vitro cultivation, genomic and proteomic databases, and advances in microscopic and molecular approaches, have led to an understanding that this is a eukaryotic organism with a reduced genome rather than a truly premitochondriate eukaryote. This has included the discovery of mitosomes (vestiges of mitochondria), a transport system with many of the features of the Golgi apparatus, and even evidence for a sexual or parasexual cycle. Cell biology approaches have led to a better understanding of how Giardia survives with two nuclei and how it goes through its life cycle as a noninvasive organism in the hostile environment of the lumen of the host intestine. Studies of its immunology and pathogenesis have moved past the general understanding of the importance of the antibody response in controlling infection to determining the key role of the Th17 response. This work has led to understanding of the requirement for a balanced host immune response that avoids the extremes of an excessive response with collateral damage or one that is unable to clear the organism. This understanding is especially important in view of the remarkable ranges of early manifestations, which range from asymptomatic to persistent diarrhea and weight loss, and longer-term sequelae that include growth stunting in children who had no obvious symptoms and a high frequency of postinfectious irritable bowel syndrome (IBS).

Giardia spp. cysts and Cryptosporidium spp. oocysts in drinking water treatment residues: comparison of recovery methods for quantity assessment

Water treatment plant (WTP) residues, e.g. sludge and filter backwash water (FBW), may contain pathogenic microorganisms, as Giardia spp. and Cryptosporidium spp. However, recovering protozoa from such matrices lacks a formal and precise protocol, which is imperative to improve research in their detection, removal and inactivation. The latter includes a deeper challenge as some recovery methods may compromise viability. This study applied different recovery methods for G. muris cysts and C. parvum oocysts spiked into settled sludge and FBW obtained from a bench treatment. Procedures in sludge involved direct centrifugation, alkaline and acid flocculation, including purification by immunomagnetic separation (IMS). FBW samples were tested for membrane filtration (MF) and heated Tween^® scrapings followed or not by IMS. Propidium iodide (PI) inclusion was used for oocyst viability evaluation prior and after recovery. Results with purified suspensions lead to higher recovery efficiencies (RE) for C. parvum, which was assumed to relate to poor G. muris fluorescence. Analytical quality assessments were carried out with ColorSeed^® for the methods that stood out for each matrix and the results indicated lower RE than when organisms from purified suspensions were recovered. Ferric sulphate flocculation and MF, both followed by IMS reached 32.25% and 11.00% RE for Giardia spp. and 19.61% and 2.00% for Cryptosporidium spp., respectively. All of the tested methods affected oocyst viability. These results encourage further research to overcome the matrices complexity explained in this paper and increase RE, taking effects in protozoa viability into consideration.

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

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

Multilocus Genotyping of Giardia duodenalis in Mostly Asymptomatic Indigenous People from the Tapirapé Tribe, Brazilian Amazon

Little information is available on the occurrence and genetic variability of the diarrhoea-causing enteric protozoan parasite Giardia duodenalis in indigenous communities in Brazil. This cross-sectional epidemiological survey describes the frequency, genotypes, and risk associations for this pathogen in Tapirapé people (Brazilian Amazon) at four sampling campaigns during 2008–2009. Microscopy was used as a screening test, and molecular (PCR and Sanger sequencing) assays targeting the small subunit ribosomal RNA, the glutamate dehydrogenase, the beta-giardin, and the triosephosphate isomerase genes as confirmatory/genotyping methods. Associations between G. duodenalis and sociodemographic and clinical variables were investigated using Chi-squared test and univariable/multivariable logistic regression models. Overall, 574 individuals belonging to six tribes participated in the study, with G. duodenalis prevalence rates varying from 13.5–21.7%. The infection was positively linked to younger age and tribe. Infected children <15 years old reported more frequent gastrointestinal symptoms compared to adults. Assemblage B accounted for three out of four G. duodenalis infections and showed a high genetic diversity. No association between assemblage and age or occurrence of diarrhoea was demonstrated. These data indicate that the most likely source of infection was anthropic and that different pathways (e.g., drinking water) may be involved in the transmission of the parasite.

Recirculation of Giardia lamblia Assemblage A After Metronidazole Treatment in an Area With Assemblages A, B, and E Sympatric Circulation

Giardia lamblia is an intestinal protozoan subdivided into eight assemblages, labeled alphabetically from A to H. Assemblages A, B, and E infect humans and can have a sympatric circulation. We investigated the assemblage recirculation in children living within a high prevalence area of Giardia infection. One hundred and ninety-four children were evaluated and 85 tested positive for Giardia by PCR. These infected individuals were recruited, treated with metronidazole and then reexamined for infections at 20 and 40 days after treatment that included PCR and the genotyping was performed by sequencing beta-giardin and glutamate dehydrogenase gene targets. Giardia assemblages A (n = 43), B (n = 21), E (n = 17), and A/E (n = 4) were identified in infected children. Assemblage A was found in all reoccurrences of infection, including four that had been infected by assemblages B and E. Since both persistence and reinfection could account for the results, the level of nucleotide homology was determined before and after treatment. Most suggested that reinfections were by the same strain, but four presented a distinct genotypic profile. The results suggest that the differences in the genotypic profiles were due to reinfections, which appear to occur with frequency in high Giardia burden areas and soon after the end of therapy. It is not yet possible to define whether the recurrent cases were related to parasite resistance. However, the evidence of rapid reinfections and ready availability of treatment raises the potential for creating resistant strains. This highlights the need to address how Giardia burden is maintained within high prevalence areas.

Insights about the structure of farnesyl diphosphate synthase (FPPS) and the activity of bisphosphonates on the proliferation and ultrastructure of Leishmania and Giardia

Background

The enzyme farnesyl diphosphate synthase (FPPS) is positioned in the intersection of different sterol biosynthesis pathways such as those producing isoprenoids, dolichols and ergosterol. FPPS is ubiquitous in eukaryotes and is inhibited by nitrogen-containing bisphosphonates (N-BP). N-BP activity and the mechanisms of cell death as well as damage to the ultrastructure due to N-BP has not yet been investigated in Leishmania infantum and Giardia. Thus, we evaluated the effect of N-BP on cell viability and ultrastructure and then performed structural modelling and phylogenetic analysis on the FPPS enzymes of Leishmania and Giardia.

Methods

We performed multiple sequence alignment with MAFFT, phylogenetic analysis with MEGA7, and 3D structural modelling for FPPS with Modeller 9.18 and on I-Tasser server. We performed concentration curves with N-BP in Leishmania promastigotes and Giardia trophozoites to estimate the IC₅₀via the MTS/PMS viability method. The ultrastructure was evaluated by transmission electron microscopy, and the mechanism of cell death by flow cytometry.

Results

The nitrogen-containing bisphosphonate risedronate had stronger anti-proliferative activity in Leishmania compared to other N-BPs with an IC₅₀ of 13.8 µM, followed by ibandronate and alendronate with IC₅₀ values of 85.1 µM and 112.2 µM, respectively. The effect of N-BPs was much lower on trophozoites of Giardia than Leishmania (IC₅₀ of 311 µM for risedronate). Giardia treated with N-BP displayed concentric membranes around the nucleus and nuclear pyknosis. Leishmania had mitochondrial swelling, myelin figures, double membranes, and plasma membrane blebbing. The same population labelled with annexin-V and 7-AAD had a loss of membrane potential (TMRE), indicative of apoptosis. Multiple sequence alignments and structural alignments of FPPS proteins showed that Giardia and Leishmania FPPS display low amino acid identity but possess the conserved aspartate-rich motifs.

Conclusions

Giardia and Leishmania FPPS enzymes are phylogenetically distant but display conserved protein signatures. The N-BPs effect on FPPS was more pronounced in Leishmania than Giardia. This might be due to general differences in metabolism and differences in the FPPS catalytic site.

Giardiasis Alters Intestinal Fatty Acid Binding Protein (I-FABP) and Plasma Cytokines Levels in Children in Brazil

Giardiasis is an intestinal infection caused by ingestion of water or food contaminated with cysts of Giardia lamblia. Susceptibility is higher in children and overall prevalence can reach up to 90% in low-income areas, although outbreaks are also reported in developed countries. Both parasite and immune-mediated epithelial damage has been observed in vitro and in animal models. However, whether enterocytes are directly damaged during infection is not entirely known. Our goal was to identify whether plasma levels of intestinal fatty acid binding protein (I-FABP), a marker of enterocyte damage, are related to the immune response in giardiasis. Blood plasma was collected from 31 children (19 Giardia-positive) from a public day care in Rio de Janeiro, Brazil. The levels of I-FABP were increased in Giardia-infected children compared to children without detectable infection. There was no difference in I-FABP levels in giardiasis caused by different genetic assemblages of Giardia. Levels of IL-8 were decreased, while there was a trend to elevated IL-17 in the Giardia-positive children. A positive correlation was observed between I-FABP and IL-17 levels as well as TNF, suggesting that epithelial damage can be related to cytokine production during giardiasis. These results help elucidate the relationship between the disruption of the intestinal mucosal barrier and immune responses to G. lamblia in children.

Multilocus genotyping and risk factor analysis of Giardia duodenalis in dogs in Korea

Giardia duodenalis (syn. G. intestinalis, G. lamblia), a protozoan parasite that infects most mammals (including humans), has recently been classified into eight different groups/assemblages (A to H) based on host range and genetic characteristics. Assemblages A and B have been reported in humans and in many other animals, including dogs. This study analyzed Giardia infections, implementing multilocus genotyping, including the 18S rRNA, gdh, and β-giardin genes, in sheltered, companion, and special-purpose dogs throughout Korea. Of 640 dog stool samples, 99 (15.5%) were G. duodenalis-positive; this prevalence was similar to that previously reported in Korean calves. In addition, the prevalence was significantly higher in the southern region, and lower in non-sheltered dogs, older dogs, and in the autumn season. Phylogenetic analysis revealed that all G. duodenalis-positive samples belonged to assemblages C and D. Although no G. duodenalis assemblages A and B (mainly found in humans) were identified in this study, assemblage C was detected in the main types of dogs in contact with humans. Assemblage C, thought to be dog-specific, was recently identified in humans. As Giardia (including zoonotic assemblages) is distributed throughout Korea, dog living environments and the potential for dog-human transmission should be monitored.

Giardia spp. and Cryptosporidium spp. removal efficiency of a combined fixed-film system treating domestic wastewater receiving hospital effluent

Giardia and Cryptosporidium have caused numerous outbreaks of diarrhea as a result of the ingestion of water contaminated with sewage. In Brazil, the efficiency of Giardia and Cryptosporidium removal by combined fixed-film systems has rarely been studied. The aims of the present study were therefore to verify the removal efficiency of Giardia and Cryptosporidium by a combined system (anaerobic/anoxic filter and aerated submerged biofilter) and to perform the genetic characterization of these parasites. The (oo)cysts were detected by centrifuge concentration and membrane filtration from raw sewage, effluents, adhered biomass, and sludge samples. Immunofluorescence assay and differential interference contrast microscopy were used for the visualization of the (oo)cysts. Nested PCR was applied to confirm Giardia and Cryptosporidium. Giardia and Cryptosporidium were detected in 27% and 5.5% of the 144 analyzed samples of raw sewage and effluents, respectively. A total of 33,000 cysts/L were recovered in the adhered biomass samples (n = 25) from different points of the aerated submerged biofilter, while 6000 oocysts/L were registered in a single point. An average of 11,800 cysts/L were found in the sludge samples (n = 5). The combined system exhibited a removal efficiency of Giardia cysts of 1.8 ± 1.0 log removal. The C and BIV assemblages of Giardia were identified in the raw sewage while AII was found in the treated effluent sample. It was not possible to calculate the removal efficiency of Cryptosporidium oocysts by the combined system. The combined system exhibited some potential as a suitable treatment for the removal of parasites from sewage.

Reduced prevalence of soil-transmitted helminths and high frequency of protozoan infections in the surrounding urban area of Curitiba, Paraná, Brazil

Human populations living in the surrounding urban areas of large Brazilian cities have increased vulnerability to intestinal parasites. However, the epidemiological scenario of soil-transmitted helminths (STH) in Curitiba, Paraná's main city, remains largely unknown. To bridge this gap of knowledge, this study aims to determine the prevalence of intestinal parasites and to investigate potential transmission pathways of the most prevalent species detected. We conducted a cross-sectional epidemiological study between July and September 2014 among schoolchildren in urban and peri-urban (deprived) areas of the municipality of Campo do Tenente, Curitiba. A total of 549 stool samples were used for coproparasitological diagnosis. Microscopy-positive samples of the most common species found were re-assessed by PCR and sequencing methods at the small subunit rRNA gene. Prevalence of infection by any given enteroparasite was 24.8%, but soil-transmitted helminths were only detected in 3.5% of the examined samples. Frequency of protozoan infections reached 90% and 97.8% in single and multiple infections, respectively. Blastocystis sp. (38.9%) was the most frequently species found in the surveyed schoolchildren population. A total of 41 Blastocystis-positive samples were unambiguously typed as ST1 (36.4%), ST2 (21.2%), ST3 (39.4%), and ST1 + ST3 mixed infection (3.0%). These results indicate that Blastocystis transmission is primarily anthroponotic in origin. This data highlights the importance of maintaining the anthelminthic control programs currently in place and of improving sanitary disposal of human excreta in poor-resource settings.

Upregulation of Cathepsin B-like Protease Activity During Apoptosis inGiardia duodenalis

Background:

In eukaryotic cells, apoptosis signaling pathways are controlled mainly by aspartic acid cysteine proteases (caspases). However, certain unicellular microorganisms, such as Giardia duodenalis, lack these proteins. Thus, other cysteine proteases may play an important role in the parasite apoptosis signaling pathway.

Objective:

To understand the effect of cathepsin B-like inhibition on the cell viability of Giardia duodenalis and its cell death process.

Methods:

Bioinformatics analysis was performed to identify apoptotic proteases. Analysis showed that cathepsin B-like protease genes from G. duodenalis were the best candidate. A homology modeling technique was used to explore in silico the inhibitory effect of E-64 against cathepsin B-like proteases from G. duodenalis genome and to examine the effect of curcumin on cathepsin B-like activity regulation. In addition, the effect of E-64 on parasite survival and DNA fragmentation was tested.

Results:

Eight cathepsin B-like protease coding genes were identified in silico. Interestingly, while these sequences lacked the cathepsin B characteristic occluding loop, they maintained the catalytic active- site responsible for cathepsin B activity, which was evidenced by the increase in the degradation of the Z-RR-AMC substrate, suggesting the upregulation of the activity of these proteins. Additionally, inhibition of E-64 against G. duodenalis trophozoites caused a decrease in DNA fragmentation compared to control cells and had a positive effect on parasite survival after exposure to curcumin.

Conclusion:

Overall, these results suggested that Giardia duodenalis might have a cell death mechanism in which cathepsin B-like proteases play an important role.

Molecular genotyping, diversity studies and high-resolution molecular markers unveiled by microsatellites in Giardia duodenalis

BACKGROUND

Giardia duodenalis (synonyms G. lamblia and G. intestinalis) is an enteric protozoan parasite of a wide range of mammalian hosts, including humans and various domestic and wild animals. There is considerable genetic variability in G. duodenalis and isolates of this parasite have been divided into eight genetic assemblages. Microsatellites markers can be used to discriminate isolates with a high level of sensitivity. This study was conducted to identify and characterize genomic microsatellites (simple sequence repeats-SSRs), sequences of one- to six-nucleotide motifs repeated in tandem, present in the available genomes of G. duodenalis and to develop new markers that can serve as a tool for detection and for characterizing the genetic diversity of this parasite.

METHODOLOGY/ PRINCIPAL FINDINGS

For each genetic assemblage, polymorphism levels for the microsatellite markers were evaluated. After performing the analysis using the MISA and SciRoKo software, 1,853 simple sequence repeats (SSRs) were identified. In all the genomes, trinucleotide repeats were the most common class followed by tetranucleotide. Many of the SSR loci are assemblage-specific, and 36 SSR loci shared among all the genomes were identified. Together with hypothetical proteins, variant-specific surface proteins represented nearly half of the annotated SSR loci. The results regarding the most common repeat among the SSRs led us to infer that positive selection occurred to avoid frameshift mutations. Additionally, based on inter- and intra-genetic assemblages polymorphism analyses, we unveiled previously undetected genetic variation, indicating that the microsatellite markers we developed are useful molecular tools for epidemiological inferences based on population genetics patterns and processes.

CONCLUSIONS

There is increasing demand for the development of new molecular markers and for the characterization of pathogens at a higher resolution level. In this study, we present 60 G. duodenalis microsatellites markers that exhibited high polymerase chain reaction (PCR) amplification efficiency among the different genetic assemblages. Twenty of these markers presented nucleotide sequence polymorphisms and may be used as a genotyping tool. The monomorphic markers can be used for the detection of the parasite at the species and genetic assemblage level. These polymorphic markers revealed a genetic diversity that was previously undetectable, thus they can be considered valuable molecular tools for high resolution markers in future studies investigating Giardia and may also be used for epidemiological inferences based on populations genetics patterns and processes.

Parasites and allergy: Observations from Brazil

Brazil is a middle-income country undergoing the epidemiological transition. Effects of changes in daily life habits and access to clean water, sanitation and urban services on a growing urban population have contributed to a double burden of both infectious and noncommunicable chronic diseases. Studies have indicated that parasite infections may modulate the human immune system and influence the development of allergic conditions such as asthma. However, there is no consensus in the published literature on the effects of parasitic infections on allergy, perhaps as a consequence of factors determining the epidemiology of these infections that vary between populations such as age of first infection, duration and chronicity of infections, parasite burden and species, and host genetic susceptibility. In this review, we discuss the observations from Brazil concerning the relationship between parasite infections and allergy.

Prevalence of intestinal parasites, with emphasis on the molecular epidemiology of Giardia duodenalis and Blastocystis sp., in the Paranaguá Bay, Brazil: a community survey

Background

Intestinal protozoan parasites are major contributors to the global burden of gastrointestinal disease causing significant socioeconomic consequences. Children living in resource-poor settings with restricted access to water and sanitary services are particularly at risk of these infections.

Methods

A prospective, community-based, cross-sectional survey was conducted in Paraná (southern Brazil) between May 2015 and May 2016. A total of 766 stool samples were individually collected from volunteers (male/female ratio: 0.99; age range: 0–76 years) and used for investigating the presence of intestinal helminth and protozoan species by routine microscopic procedures including the Kato-Katz and modified Ritchie concentration methods and the Ziehl-Neelsen stain technique. Quantitative real-time PCR confirmed microscopy-positive samples for Giardia duodenalis and the assemblages and sub-assemblages determined by multilocus sequence-based genotyping of the glutamate dehydrogenase (gdh) and β-giardin (bg) genes of the parasite. Identification of Blastocystis subtypes was carried out by amplification and sequencing of a partial fragment of the small-subunit ribosomal RNA gene (SSU rDNA) of this heterokont microorganism.

Results

Overall, 46.1% (353/766) of the participants were infected/colonised by at least one intestinal parasite/commensal species. Protozoan and helminth species were detected in 42.7% and 10.1% of the surveyed population, respectively. Blastocystis sp. (28.2%), Endolimax nana (14.9%), and Giardia duodenalis (11.0%) were the most prevalent species found among protozoans and Ascaris lumbricoides (5.0%), Trichuris trichiura (4.6%) and hookworms (1.0%) among helminths. A total of 38 G. duodenalis-positive samples were genotyped at gdh and bg markers, revealing the presence of the sub-assemblages AII (47.4%), AII/AIII (2.6%), BIII (5.3%), BIV (26.3%) and BIII/BIV (13.1%). Two samples (5.3%) were only identified as assemblage B. AII was predominantly found in females aged 5–9 years and was associated with a higher likelihood of reporting gastrointestinal symptoms. A total of 102 Blastocystis-positive samples were successfully subtyped at the SSU rRNA gene revealing the presence of ST1 (36.3%), ST2 (15.7%), ST3 (41.2%), ST4 (2.9%), ST6 (1.0%) and ST8 (2.9%).

Conclusions

Data presented here indicate that enteric parasites still represent a pressing health concern in Paraná, Brazil, probably due to sub-optimal water, sanitation and hygiene conditions. A mostly anthroponotic origin is suspected for G. duodenalis and Blastocystis sp. infections.

Electronic supplementary material

The online version of this article (10.1186/s13071-018-3054-7) contains supplementary material, which is available to authorized users.

The presence of Giardia lamblia assemblage A in dogs suggests an anthropozoonotic cycle of the parasite in Rio de Janeiro, Brazil

BACKGROUND

Giardia lamblia is a zoonotic protozoan that is classified into 8 genotypes and is distributed worldwide. Assemblages A and B were found to infect dogs and humans, whereas assemblages C and D are dog host-specific. Our objective was to investigate the G. lamblia genotypes circulating in a canine population in Rio de Janeiro, RJ.

RESULTS

Sixty stool samples positive for G. lamblia from street dogs were characterized. Fragments of the conserved genes encoding beta-giardin (β-gia) and glutamate dehydrogenase (gdh) were used as targets. The sequences from beta-giardin and glutamate dehydrogenase genes obtained from all 60 dog samples were 100% similar to G. lamblia genotype A.

CONCLUSION

The detection of genotype A suggests that G. lamblia transmission in Rio de Janeiro has a predominantly anthropozoonotic cycle.

Beaver Fever: Whole-Genome Characterization of Waterborne Outbreak and Sporadic Isolates To Study the Zoonotic Transmission of Giardiasis

Giardia duodenalis causes large numbers of gastrointestinal illness in humans. Its transmission through the contaminated surface water/wildlife intersect is significant, and the water-dwelling rodents beavers have been implicated as one important reservoir. To trace human infections to their source, we used genome techniques to characterize genetic relationships among 89 Giardia isolates from surface water, humans, and animals. Our study showed the presence of two previously described genetic assemblages, A and B, with mixed infections detected from isolates collected during outbreaks. Study findings also showed that while assemblage A could be divided into A1 and A2, A1 showed little genetic variation among animal and human hosts in isolates collected from across the globe. Assemblage B, the most common type found in the study surface water samples, was shown to be highly variable. Our study demonstrates that the beaver is a possible source of human infections from contaminated surface water, while acknowledging that theirs is only one role in the complex cycle of zoonotic spread. Mixes of parasite groups have been detected in waterborne outbreaks. More information on Giardia diversity and its evolution using genomics will further the understanding of the epidemiology of spread of this disease-causing protozoan.

Giardia causes the diarrheal disease known as giardiasis; transmission through contaminated surface water is common. The protozoan parasite’s genetic diversity has major implications for human health and epidemiology. To determine the extent of transmission from wildlife through surface water, we performed whole-genome sequencing (WGS) to characterize 89 Giardia duodenalis isolates from both outbreak and sporadic infections: 29 isolates from raw surface water, 38 from humans, and 22 from veterinary sources. Using single nucleotide variants (SNVs), combined with epidemiological data, relationships contributing to zoonotic transmission were described. Two assemblages, A and B, were identified in surface water, human, and veterinary isolates. Mixes of zoonotic assemblages A and B were seen in all the community waterborne outbreaks in British Columbia (BC), Canada, studied. Assemblage A was further subdivided into assemblages A1 and A2 based on the genetic variation observed. The A1 assemblage was highly clonal; isolates of surface water, human, and veterinary origins from Canada, United States, and New Zealand clustered together with minor variation, consistent with this being a panglobal zoonotic lineage. In contrast, assemblage B isolates were variable and consisted of several clonal lineages relating to waterborne outbreaks and geographic locations. Most human infection isolates in waterborne outbreaks clustered with isolates from surface water and beavers implicated to be outbreak sources by public health. In-depth outbreak analysis demonstrated that beavers can act as amplification hosts for human infections and can act as sources of surface water contamination. It is also known that other wild and domesticated animals, as well as humans, can be sources of waterborne giardiasis. This study demonstrates the utility of WGS in furthering our understanding of Giardia transmission dynamics at the water-human-animal interface.

IMPORTANCEGiardia duodenalis causes large numbers of gastrointestinal illness in humans. Its transmission through the contaminated surface water/wildlife intersect is significant, and the water-dwelling rodents beavers have been implicated as one important reservoir. To trace human infections to their source, we used genome techniques to characterize genetic relationships among 89 Giardia isolates from surface water, humans, and animals. Our study showed the presence of two previously described genetic assemblages, A and B, with mixed infections detected from isolates collected during outbreaks. Study findings also showed that while assemblage A could be divided into A1 and A2, A1 showed little genetic variation among animal and human hosts in isolates collected from across the globe. Assemblage B, the most common type found in the study surface water samples, was shown to be highly variable. Our study demonstrates that the beaver is a possible source of human infections from contaminated surface water, while acknowledging that theirs is only one role in the complex cycle of zoonotic spread. Mixes of parasite groups have been detected in waterborne outbreaks. More information on Giardia diversity and its evolution using genomics will further the understanding of the epidemiology of spread of this disease-causing protozoan.

First identification and multilocus genotyping of Giardia duodenalis in pet chipmunks (Eutamias asiaticus) in Sichuan Province, southwestern China

Background

Giardia duodenalis is a flagellated parasite that causes diarrhea in humans and other animals. Although G. duodenalis is found in companion animals worldwide, information regarding the prevalence and genetic characteristics of G. duodenalis in pet chipmunks in China is limited. The present study therefore aimed to investigate the prevalence and genotypes of G. duodenalis in pet chipmunks in Sichuan province, southwestern China, as well as to assess zoonotic potential of revealed assemblages.

Results

A total of 279 fecal samples were collected from pet chipmunks in seven pet shops and one breeding facility in Sichuan province, southwestern China. The prevalence of G. duodenalis was 8.6% (24/279), as determined by nested PCR detection of the beta giardin (bg) gene. Giardia duodenalis assemblages and subtypes were determined using multilocus genotyping of the bg, triosephosphate isomerase (tpi), and glutamate dehydrogenase (gdh) loci. Two assemblages were identified: potentially zoonotic assemblage A (54.2%, 13/24) and rodent-specific assemblage G (45.8%, 11/24). A total of 24, 17 and 17 sequences of the bg, gdh and tpi loci, respectively, were successfully obtained, which formed four, four and three subtypes, respectively. Moreover, four assemblage A (MLGs A1-A4) and three assemblage G (MLGs G1-G3) multilocus genotypes were identified.

Conclusions

To our knowledge, this is the first study that investigated G. duodenalis in pet chipmunks in China. Detection of assemblage A in pet chipmunks and in previous studies in humans suggests a possible role of chipmunks as a reservoir for human giardiasis in Sichuan Province, China.

Electronic supplementary material

The online version of this article (10.1186/s13071-018-2790-z) contains supplementary material, which is available to authorized users.