Giardia/giardiasis — A perspective on diagnostic and analytical tools

Performance of the Vetscan Imagyst in point-of-care detection of Giardia duodenalis in canine fecal samples

Giardia duodenalis is a common parasite of the gastrointestinal tract of dogs, with an especially high prevalence in dogs <1-y-old. Methods for detecting G. duodenalis are point-of-care (POC) tests such as lateral-flow tests or fecal flotation. The Vetscan Imagyst (Zoetis) is a new POC device for the detection of G. duodenalis in fecal samples using zinc sulfate flotation, automated slide scanning, and image recognition with artificial intelligence. Vetscan results are the number of Giardia cysts per coverslip. We compared the performance of the Vetscan and another POC test (SNAP Giardia test; Idexx) with a direct immunofluorescence assay (IFA) performed in a specialized parasitology laboratory as the reference test. We included 164 dogs <19-mo-old. We used pooled fecal samples from 3 defecations gained within 2-3 d and tested the repeatability of the Vetscan by triplicate measurement. Compared to IFA, Vetscan had a diagnostic sensitivity of 88.4% and specificity of 98.1%; SNAP had a diagnostic sensitivity of 74.4% and specificity of 98.1%. A variation coefficient of 67.0% was determined for the Vetscan results. The performance of the Vetscan is acceptable for the qualitative evaluation of fecal samples (Giardia positive or negative), and the device can be used by untrained personnel. Given its high variation coefficient, we do not recommend the Vetscan for monitoring the number of cysts.

Comparative performance evaluation of four different methods for diagnosing Giardia infection in dogs and zoonotic assemblages' identification

Giardia duodenalis (syn. G. intestinalis or G. lamblia) is a parasitic protozoan that infects the upper intestinal tract of a broad range of hosts, including humans and domestic animals. Thus, it has raised concerns about the public health risk due to companion animals. Recently, with the improvement of living standards and increasing contacts between pets and humans, the zoonotic transmission of Giardia has dramatically increased. From a genetic point of view, G. duodenalis should be viewed as a complex species that includes eight different species-specific genetic assemblages. The laboratory diagnosis is mainly based on the finding of microscopic cysts in stool samples by coprological examination. Other methods include the detection of antigens, immunoassays or PCR protocols, which allow the identification of Giardia assemblages. The study aimed to compare the performance of Direct Fluorescence Antibody test (DFA), zinc sulfate flotation technique (ZnSO4), rapid diagnostic test (RDT), end-point PCR amplification (PCR) for the detection of Giardia and to identify the concerning assemblages in a canine population from Central Italy. Direct fluorescence antibody test is the reference standard for laboratory diagnosis of Giardia in fecal samples from dogs, despite the microscopic examination after flotation remains the most useful method in many veterinary diagnostic centers. The present findings demonstrate the high performance of DFA and ZnSO4 in detecting Giardia, while RDT may be useful as alternative or complementary method to the DFA and ZnSO4. PCR performance was low, but it allowed determining Giardia B zoonotic assemblage in 25% of the PCR-positive specimens (15 out of 60), while the remaining PCR-positive isolates belonged to the dog-specific assemblage C. The 26% prevalence of G. duodenalis detected by DFA in owned dogs and the identification of potentially zoonotic assemblages underline the potential risk for public health and indicate frequent cross-species transmission of the parasite between humans and dogs.

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.

Biogenesis of extracellular vesicles in protozoan parasites: The ESCRT complex in the trafficking fast lane?

Extracellular vesicles (EVs) provide a central mechanism of cell-cell communication. While EVs are found in most organisms, their pathogenesis-promoting roles in parasites are of particular interest given the potential for medical insight and consequential therapeutic intervention. Yet, a key feature of EVs in human parasitic protozoa remains elusive: their mechanisms of biogenesis. Here, we survey the current knowledge on the biogenesis pathways of EVs secreted by the four main clades of human parasitic protozoa: apicomplexans, trypanosomatids, flagellates, and amoebae. In particular, we shine a light on findings pertaining to the Endosomal Sorting Complex Required for Transport (ESCRT) machinery, as in mammals it plays important roles in EV biogenesis. This review highlights the diversity in EV biogenesis in protozoa, as well as the related involvement of the ESCRT system in these unique organisms.

Development and Preliminary Evaluation of a Nanoparticle-Assisted PCR Assay for the Detection of Cryptosporidium parvum in Calves

C. parvum is an important diarrheal pathogen in humans and animals, especially in young hosts. To accurately and rapidly detect C. parvum infection in calves, we established a nano-PCR assay targeting the cgd3_330 gene for the specific detection of C. parvum. This nano-PCR assay was ten times more sensitive than that of the normal PCR assay by applying the same primers and did not cross-react with C. andersoni, C. bovis, C. ryanae, Balantidium coli, Enterocytozoon bieneusi, Giardia lamblia, and Blastocystis sp. To further test the nano-PCR in clinical settings, a total of 20 faecal samples from calves were examined by using the nano-PCR, the normal PCR, and the nested PCR assays. The positive rates were 30% (6/20), 30% (6/20), and 25% (5/20) for the nano-PCR, the normal PCR, and the nested PCR assays, respectively, indicating that the nano-PCR and the normal PCR assays had the same positive rate (30%). Taken together, the present study could provide a candidate method for the specific detection of C. parvum infection in calves in clinical settings.

The Anti-Apoptotic Role of COX-2 during In Vitro Infection of Human Intestinal Cell Line by Giardia duodenalis and The Potential Regulators

The protozoan parasite Giardia duodenalis inhabits the upper small intestine of mammals including humans and causes a disease known as giardiasis, which can lead to diarrhea, abdominal cramps, and bloating. G. duodenalis was known as a causative factor of intestinal epithelial cell (IEC) apoptosis. Cyclooxygenase-2 (COX-2) has been identified as an influencing factor of pathogen infection by participating in immune response, while its role in host defense against Giardia infection is not clear. Here we initially observed the involvement of COX-2 in the regulation of Giardia-induced IEC apoptosis. Inhibition of COX-2 activity could promote Giardia-induced reduction of IEC viability, increase of reactive oxygen species (ROS) production, and decrease of nitric oxide (NO) release, which would exacerbate IEC apoptosis. In addition, during Giardia-IEC interactions, COX-2 inhibition was able to accelerate caspase-3 activation and PARP cleavage, and inhibit the expressions of some anti-apoptotic proteins like cIAP-2 and survivin. In contrast, COX-2 over-expression could reduce Giardia-induced IEC apoptosis. We further investigated the regulatory mechanisms affecting COX-2 expression in terms of anti-apoptosis. The results showed that p38/ERK/AKT/NF-κB signaling could regulate COX-2-mediated ROS/NO production and anti-IEC apoptosis during Giardia infection. We also found that COX-2-mediated anti-IEC apoptosis induced by Giardia was related to TLR4-dependent activation of p38-NF-κB signaling. Collectively, this study identified COX-2 as a promoter for apoptotic resistance during Giardia-IEC interactions and determined the potential regulators, furthering our knowledge of anti-Giardia host defense mechanism.

Analytical challenges and perspectives of assessing viability of Giardia muris cysts and Cryptosporidium parvum oocysts by live/dead simultaneous staining

Giardia and Cryptosporidium are pathogenic protozoa often present in the environment in their infective form(cysts and oocysts). These parasites are very resistant to disinfection, which makes them important target organisms in environmental quality monitoring and sanitation. Viability assessment provides an interpretation of cell inactivation, and it can be evaluated by membrane integrity as well as enzyme activity, using different staining methods. These are straightforward and adequate to laboratories that lack infrastructure for molecular-based technologies or animal infectivity tests. This study investigated simultaneous staining by a commercial live/dead kit, in order to assess viability of Cryptosporidium parvum oocysts and Giardia muris cysts, comparing it to propidium iodide (PI) incorporation, a common stain applied in viability estimation. Results suggested that, although the central hypothesis of one-panel visualization (α = 0.05) was met, simultaneous staining impaired (oo)cyst detection by immunofluorescence assay (IFA), which was found to be essential to enumeration, as the live/dead test led to poor (oo)cyst labelling or a 10-fold lower recovery when carried out concomitantly to IFA. As for the viability assessment itself, although red dye uptake occurred as expected by dead or weakened organisms, neither live G. muris cysts or C. parvum oocysts present any green fluorescence by esterase metabolism. This may have been caused by low enzyme activity in the infective form and/or wall thickness of these parasites. The results do not exclude the possibility of simultaneous fluorescence staining for protozoa, but it is a starting point for a broader analysis, that may consider, for instance, different incubation conditions.

In silico to In vivo development of a polyherbal against Haemonchus contortus

Haemonchus contortus is a major constraint in the development of small ruminant subsector due to significant production losses incurred by it. The present study explores the antiparasitic potential of three anthelmintic plants (Butea monosperma, Vitex negundo and Catharanthus roseus (L.) G.Don) against H. contortus taking albendazole as the standard. In silico molecular docking and pharmacokinetic prediction studies were conducted with known bioactive molecules of these plants (palasonin, vinblastine, vincristine, betulinic acid and ursolic acid) against Glutamate Dehydrogenase (GDH) and tubulin molecules of the parasite. Methanolic extracts of these herbs were fractionated (hexane, ethyl acetate, chloroform and methanol) and used in in vitro larvicidal studies. Based on the in vitro data, two herbal prototypes were developed and clinically tested. All the 5 ligand molecules showed better binding affnity for GDH and tubulin protein as compared with albendazole and shared similar binding site in the core of the GDH hexamer with slight variations. Albendazole approximately stacked against GLY190A residue, showing hydrophobic interactions with PRO157A and a Pi-cation electrostatic interaction with ARG390 along with four hydrogen bonds. Vincristine formed 2 pi-anionic electrostatic bonds with ASP158 of B and C subunits alongwith hydrogen bonding and hydrophobic interaction and an additional pi-anion electrostatic interaction at ASP158A for vinblastine. Albendazole bound to α-tubulin next to colchicine site whereas vinblastine is bound at the nearby laulimalide/peloruside site of the dimer. Betulinic acid showed lateral interaction between the H2-H3 loop of one alpha subunit and H10 of the adjacent alpha subunit of two tubulin dimers. Ursolic acid and palasonin bound at the intradimer N site of microtubulin involving the H1-H7 and H1-H2 zone, respectively. The in vitro studies demonstrated good dose dependent anthelmintic potential. Both the prototypes were quite efficacious in clearing the infection, keeping it to a minimal for more than 5 months, probably, through direct anthelmintic effect through GDH, tubulin depolymerization and uncoupling as well as indirectly through immunomodulation along with antioxidant and anti-inflammatory properties.

Global epidemiology of Giardia duodenalis infection in cancer patients: a systematic review and meta-analysis

Background

Application of chemotherapeutics in cancer patients may provide an immunosuppressive milieu, favourable for parasitic infections. Giardia duodenalis is an important zoonotic intestinal parasite responsible for diarrhoea in humans worldwide.

Methods

The present systematic review and meta-analysis was conducted to estimate the prevalence of G. duodenalis and respective odds ratios (ORs) in cancer patients around the globe. Four online databases—PubMed, Scopus, Web of Science and Google Scholar—were carefully explored for relevant literature without time limitation until 28 November 2020. Meta-analysis was done based on a random effects model to pool the estimations and define 95% confidence intervals (CIs).

Results

The overall weighted prevalence of G. duodenalis infection in cancer patients was calculated to be 6.9% (95% CI 0.5 to 9.3) globally, based on data from 32 studies. Although not statistically significant, eight case–control studies revealed that cancer patients were 1.24 times (95% CI 0.66 to 2.31; p=0.501) more exposed to G. duodenalis infection than healthy controls. Moreover, the prevalence of infection was not significantly associated with quantitative variables, including publication year (regression coefficient −0.0135, p=0.578), sample size (regression coefficient −0.0007, p=0.074) and human development index (regression coefficient −1.6263, p=0.419). Also, subgroup analysis of the pooled G. duodenalis infection was performed for publication year, World Health Organization regions, countries, continents, cancer types and country income.

Conclusions

Altogether, the epidemiology of G. duodenalis infection and its associated risk factors in immunocompromised individuals, especially cancer patients, is still open to question and deserves comprehensive investigations.

Giardia lamblia: Laboratory Maintenance, Lifecycle Induction, and Infection of Murine Models

Giardia lamblia is a protozoan parasite that is found ubiquitously throughout the world and is a major contributor to diarrheal disease. Giardia exhibits a biphasic lifestyle existing as either a dormant cyst or a vegetative trophozoite. Infections are typically initiated through the consumption of cyst-contaminated water or food. Giardia was first axenized in the 1970s and can be readily maintained in a laboratory setting. Additionally, Giardia is one of the few protozoans that can be induced to complete its complete lifecycle using laboratory methods. In this article, we outline protocols to maintain Giardia and induce passage through its lifecycle. We also provide protocols for infecting and quantifying parasites in an animal infection model. © 2020 Wiley Periodicals LLC. Basic Protocol 1: In vitro maintenance and growth of Giardia trophozoites Basic Protocol 2: In vitro encystation of Giardia cysts Basic Protocol 3: In vivo infections using Giardia trophozoites.

Recent Advances in the Development of Broad-Spectrum Antiprotozoal Agents

Infections caused by Trypanosoma brucei, Trypanosoma cruzi, Leishmania spp., Entamoeba histolytica, Giardia lamblia, Plasmodium spp., and Trichomonas vaginalis, are part of a large list of human parasitic diseases. Together, they cause more than 500 million infections per year. These protozoa parasites affect both low- and high-income countries and their pharmacological treatments are limited. Therefore, new and more effective drugs in preclinical development could improve overall therapy for parasitic infections even when their mechanisms of action are unknown. In this review, a number of heterocyclic compounds (diamidine, guanidine, quinoline, benzimidazole, thiazole, diazanaphthalene, and their derivatives) reported as antiprotozoal agents are discussed as options for developing new pharmacological treatments for parasitic diseases.

FELINE GIARDIASIS IN TURKEY: PREVALENCE AND GENETIC AND HAPLOTYPE DIVERSITY OF GIARDIA DUODENALIS BASED ON THE β-GIARDIN GENE SEQUENCE IN SYMPTOMATIC CATS

Giardia duodenalis is a common zoonotic protozoan parasite with a broad host distribution. The main objectives of the present study were to determine the prevalence of giardiasis and to reveal the genetic and haplotype diversity of G. duodenalis in symptomatic cats in Turkey. Fecal samples were collected from cats (n = 102) with diarrhea that were admitted to different pet clinics in the Central Anatolia region of Turkey. All samples were analyzed by microscopic examination (ME), rapid immunochromatographic test (ICT), and PCR targeting the β-giardin (bg) loci of the parasite. Phylogenetic, haplotype, and network analyses of G. duodenalis based on the bg gene were carried out. Overall, G. duodenalis was detected in 70/102 (68.6%) of the cats with diarrhea by ME (38/102, 37.3%), ICT (51/102, 50%), and PCR (30/102, 29.4%). According to sequence analyses of the bg gene region, all isolates were identified as G. duodenalis assemblage B. Haplotype analyses revealed 2 known and 8 novel haplotypes for G. duodenalis assemblage B. This study provides first prevalence and genetic and haplotype diversity data on G. duodenalis assemblage B from cats in Turkey.

Cryptosporidium spp. and Giardia spp. (oo)cysts as target-organisms in sanitation and environmental monitoring: A review in microscopy-based viability assays

Cysts and (oo)cysts are the infective forms of parasitic protozoa, as Giardia and Cryptosporidium, which are widespread and associated to worldwide waterborne diseases outbreaks. These microorganisms pose a challenge to public health, as they are resistant to conventional disinfection methods, which make them important parameters when evaluating inactivation efficiency. However, when (oo)cysts are targets, it is challenging to infer inactivation efficacy, as it may require infectivity tests that are not often an option for laboratory routine analysis. In this scene, (oo)cyst viability based on induced excystation, membrane integrity and enzyme activity evaluated by dye inclusion and/or exclusion, as well as fluorescence reduction consist on microscopy-based techniques that may be options to estimate inactivation in the environmental context. This scoping review presents applications, advantages and limitations of these methodologies for viability assessment, in order to shed light on the (oo)cyst viability topic and provide insight strategies for choosing protocols in the environmental and sanitation field, in laboratory applications and novel research.

Enterocytozoon bieneusi of animals-With an 'Australian twist'

Enterocytozoon bieneusi is a microsporidian microorganism that causes intestinal disease in animals including humans. E. bieneusi is an obligate intracellular pathogen, typically causing severe or chronic diarrhoea, malabsorption and/or wasting. Currently, E. bieneusi is recognised as a fungus, although its exact classification remains contentious. The transmission of E. bieneusi can occur from person to person and/or animals to people. Transmission is usually via the faecal-oral route through E. bieneusi spore-contaminated water, environment or food, or direct contact with infected individuals. Enterocytozoon bieneusi genotypes are usually identified and classified by PCR-based sequencing of the internal transcribed spacer region (ITS) of nuclear ribosomal DNA. To date, ~600 distinct genotypes of E. bieneusi have been recorded in ~170 species of animals, including various orders of mammals and reptiles as well as insects in >40 countries. Moreover, E. bieneusi has also been found in recreational water, irrigation water, and treated raw- and waste-waters. Although many studies have been conducted on the epidemiology of E. bieneusi, prevalence surveys of animals and humans are scant in some countries, such as Australia, and transmission routes of individual genotypes and related risk factors are poorly understood. This article/chapter reviews aspects of the taxonomy, biology and epidemiology of E. bieneusi; the diagnosis, treatment and prevention of microsporidiosis; critically appraises the naming system for E. bieneusi genotypes as well as the phylogenetic relationships of these genotypes; provides new insights into the prevalence and genetic composition of E. bieneusi populations in animals in parts of Australia using molecular epidemiological tools; and proposes some areas for future research in the E. bieneusi/microsporidiosis field.

Specific IgG and IgA Antibody Reactivities in Sera of Children by Enzyme-Linked Immunoassay and Comparison With Giardia duodenalis Diagnosis in Feces

Background

Giardia duodenalis is conventionally diagnosed in fecal samples using parasitological methods. However, sensitivity is poor when only a single sample is analyzed, due to intermittent excretion of cysts in feces. Alternatively, the serum antibodies to G. duodenalis can be used for parasite diagnosis and epidemiological studies to determine previous exposure. We compared the rate of G. duodenalis infection between serum anti-Giardia IgG and IgA antibodies and fecal examination in Brazilian children.

Methods

Fecal and serum samples were tested from 287 children at a clinical laboratory and from 187 children at daycare centers. Fecal samples were processed using conventional parasitological methods and coproantigen detection for Giardia diagnosis. Serum samples were tested using an in-house ELISA for detection of anti-Giardia IgG and IgA.

Results

G. duodenalis was found in 8.2% (N=39) of the 474 children analyzed. The sensitivity and specificity of ELISA were 80.0% and 90.0% for IgG and 80.0% and 83.3% for IgA, respectively. The total positivity rate of anti-Giardia IgG and IgA in the sera was 13.9% (N=66) and 23.6% (N=112). The agreement between the positivity of specific antibodies and the detection of G. duodenalis in feces was moderate for ELISA-IgG, kappa index (95% CI)=0.543 (0.422–0.664), and mild for ELISA-IgA, kappa index (95% CI)=0.283 (0.162–0.404). Among the children infected with other enteroparasites, 11.6% (N=10) and 24.4% (N=21) showed reactivity to anti-Giardia IgG and to IgA, respectively. This cross-reactivity was more frequent in samples from children infected with Endolimax nana and Entamoeba coli.

Conclusions

The higher frequency of specific antibody reactivity compared with G. duodenalis diagnosis in feces could reflect continuous exposure of children to G. duodenalis infection, resulting in long-lasting immunological memory and/or cross-reactivity with other intestinal amoebas.

Molecular Characterization of Giardia duodenalis in Children and Adults Sampled in Algeria

The molecular epidemiology of giardiasis in Africa remains unclear. A study was carried out across four hospitals in Algeria. A total of 119 fecal samples from 55 children, 37 adults, and 27 individuals of undetermined age, all scored positive for intestinal parasites by microscopy, and were screened by real-time PCR for Giardia. Molecular characterization of Giardia was performed by assemblage-specific PCR and PCR targeting the triose phosphate isomerase gene (tpi). Of the 119 samples, 80 (67%) were Giardia-positive by real-time PCR. For 48 moderately-highly real-time PCR-positive samples, tpi genotyping assigned 22 samples to Assemblage A and 26 to Assemblage B. Contrary to Assemblage A, Assemblage B exhibited substantial genetic diversity and allelic heterozygosity. Assemblage-specific PCR proved to be specific for discriminating Assemblage A or B but not as sensitive as tpi genotyping. We confirmed that real-time PCR is more sensitive than microscopy for detecting Giardia in stool samples and that robust amplification and sequencing of the tpi gene is feasible when moderate-to-strongly real-time PCR-positive samples are used. This study is one of the few performed in Africa providing genotyping data on Giardia infections in humans. Both assemblages A and B were commonly seen and not associated with specific sociodemographic data.

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

BACKGROUND

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

METHODS

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

RESULTS

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

CONCLUSIONS

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

Cryptosporidiosis and Giardiasis in Buffaloes (Bubalus bubalis)

Cryptosporidium spp. and Giardia duodenalis infect the gastrointestinal tracts of animals and humans. Both parasite groups are distributed worldwide and cause significant economic losses in animal productivity. Infected hosts presenting with and without clinical manifestations can eliminate infective forms of these protozoa, which are particularly important to One Health. Compared to the published research on cattle, relatively few studies have examined the epidemiology of cryptosporidiosis and giardiasis in buffaloes. This short review describes the global occurrence of Cryptosporidium spp. and G. duodenalis in buffaloes, including the molecular techniques employed for the identification of species/assemblages and genotypes of these protozoa. Genetic analyses of isolates of G. duodenalis and Cryptosporidium spp. from various sources (environmental, animal, and human) have been performed to investigate their epidemiology. In buffaloes, the species Cryptosporidium parvum, Cryptosporidium ryanae, Cryptosporidium bovis, and Cryptosporidium suis-like have been characterized, as well as assemblages A and E of G. duodenalis. We demonstrate that buffaloes can be infected by species of Cryptosporidium spp. and G. duodenalis assemblages with zoonotic potential. Epidemiological studies that utilize molecular biology techniques represent an important resource for efforts to control and prevent the spread of these protozoans.

Occurrence and Molecular Typing of Giardia psittaci in Parakeets in Germany-A Case Study

A grey-hooded parakeet (Psilopsiagon aymara) and two budgerigars (Melopsittacus undulatus) from different owners presented with decreased activity, vomitus, and diarrhea. A microscopic examination of feces showed trophozoites of the protozoan flagellate Giardia. A commercial immunochromatographic dipstick test for Giardia sp. antigens confirmed the infection. These findings were assured by PCR of the small subunit ribosomal RNA (SSU rRNA) gene and coproantigen ELISA. Sequencing of PCR products of the SSU rRNA (292 bp) and β-giardin genes (511 bp) identified Giardia psittaci as the species involved. Therefore, our results show that a GSA 65-based coproantigen ELISA, which was established for diagnosis of Giardia duodenalis is applicable for the detection of G. psittaci. A treatment with ronidazole was started. Additionally, fecal examination and dissection of the dead birds revealed coinfection with the fungal pathogen Macrorhabdus ornithogaster. One budgerigar survived and repeatedly tested negative after treatment with ronidazole. The described cases indicate that a single infection with G. psittaci has a good prognosis, whereas the prognosis is poor when coinfections occur, especially with M. ornithogaster.

Prevalence and associated risk factors of Intestinal parasites in rural high-mountain communities of the Valle del Cauca-Colombia

The aim of this study was to measure the prevalence of gastrointestinal parasites (GI) in domestic animals and children in high mountain populations in the districts of Combia and Toche, Valle del Cauca-Colombia. These communities have been affected by the armed conflict in Colombia and are susceptible to health risk factors related to the Colombian post-conflict. Prevalence and risk factors were measured using Bayesian methods on 45 structured interviews applied to 29 families in Combia and 16 in Toche. This inquire aimed to analyze the socio-economic and demographic factors associated with the presence of parasites. This interview was conducted with 50 children: 40 (80%) from Rita Sabogal school district of Toche, and 10 (20%) from Tablones-Atanasio Girardot schools. 23 faecal samples from asymtomatic children from these schools were collected. Subsequently, 308 animals were characterized through the analysis of 64 faecal samples from asymptomatic individuals (20,8%); 18/41 from dogs (43,9%), 18/175 from poultry (10,3%), 7/13 from cats 56,84%, 6/20 from equines (30%) and from 15/59 cattle (25,43%). The prevalence of intestinal parasites among children under six years was 60% [95% PI = 41%-78%]; Endolimax nana, 24% [95% PI = 9,8%-42%]; Iodamoeba buetschlii, 16% [95% PI = 4,7%-32%]; Entamoeba coli, 35% [95% PI = 18%-55%]; Giardia lamblia, 12% [95% PI = 2,7%-27%]. In Equids the presence of Strongylus spp was 37% [95% PI = 10%-71%]; Parascaris equorum, 37% [95% PI = 10%-71%]; in dogs, Dipylidium caninum was 20% [95% PI = 6%-39%]; Trichuris trichiura, 9% [95% PI = 1,3%-26%]; Toxocara canis, 25% [95% PI = 9%-46%]; in cats, Toxocara cati had a prevalence of 44% [95% PI = 16%-75%]; cyst of Eimeria spp, 15% [95% PI = 3,4%-33%]; in poultry and Eimeria zuernii in cattle, 50% [95% PI = 23%-77%]. There was no association with exposure of humans to animal parasites. However, we conclude that female and children under 6 years of age are more likely OR (6,72-2,3) to get parasites.

Rectal Swabs as an Alternative Sample Collection Method to Bulk Stool for the Real-Time PCR Detection of Giardia duodenalis

Though bulk stool remains the gold standard specimen type for enteropathogen diagnosis, rectal swabs may offer comparable sensitivity with greater ease of collection for select pathogens. This study sought to evaluate the validity and reproducibility of rectal swabs as a sample collection method for the molecular diagnosis of Giardia duodenalis. Paired rectal swab and bulk stool samples were collected from 86 children ages 0-4 years living in southwest Niger, with duplicate samples collected among a subset of 50 children. Infection was detected using a previously validated real-time PCR diagnostic targeting the small subunit ribosomal RNA gene. Giardia duodenalis was detected in 65.5% (55/84) of bulk stool samples and 44.0% (37/84) of swab samples. The kappa evaluating test agreement was 0.81 (95% CI: 0.54-1.00) among duplicate stool samples (N = 49) and 0.75 (95% CI: 0.47-1.00) among duplicate rectal swabs (N = 48). Diagnostic sensitivity was 93% (95% CI: 84-98) by bulk stool and 63% (95% CI: 49-75) by rectal swabs. When restricting to the lowest three quartiles of bulk stool quantitation cycle values (an indication of relatively high parasite load), sensitivity by rectal swabs increased to 78.0% (95% CI: 64-89, P < 0.0001). These findings suggest that rectal swabs provide less sensitive and reproducible results than bulk stool for the real-time PCR diagnosis of G. duodenalis. However, their fair sensitivity for higher parasite loads suggests that swabs may be a useful tool for detecting higher burden infections when stool collection is excessively expensive or logistically challenging.

Intestinal Schistosomiasis and Giardiasis Co-Infection in Sub-Saharan Africa: Can a One Health Approach Improve Control of Each Waterborne Parasite Simultaneously?

Both intestinal schistosomiasis and giardiasis are co-endemic throughout many areas of sub-Saharan Africa, significantly impacting the health of millions of children in endemic areas. While giardiasis is not considered a neglected tropical disease (NTD), intestinal schistosomiasis is formally grouped under the NTD umbrella and receives significant advocacy and financial support for large-scale control. Although there are differences in the epidemiology between these two diseases, there are also key similarities that might be exploited within potential integrated control strategies permitting tandem interventions. In this review, we highlight these similarities and discuss opportunities for integrated control of giardiasis in low and middle-income countries where intestinal schistosomiasis is co-endemic. By applying new, advanced methods of disease surveillance, and by improving the provision of water, sanitation and hygiene (WASH) initiatives, (co)infection with intestinal schistosomiasis and/or giardiasis could not only be more effectively controlled but also better understood. In this light, we appraise the suitability of a One Health approach targeting both intestinal schistosomiasis and giardiasis, for if adopted more broadly, transmission of both diseases could be reduced to gain improvements in health and wellbeing.

Giardia lamblia mimicking acute graft versus host disease after allogeneic hematopoietic stem cell transplantation: A case report

RATIONALE

As the major complications post allogeneic hematopoietic stem cell transplantation (allo-HSCT), gastrointestinal disorders were most commonly ascribed to acute graft-versus-host disease (aGVHD) and opportunistic infections. Though Giardia lamblia (G lamblia) is the most common waterborne parasite of intestinal infection worldwide, seldom has it been reported in a patient with acute severe aplastic anemia after allo-HSCT.

PATIENT CONCERNS

A 23-year-old male with severe aplastic anemia developed diarrhea, abdominal cramps, bloating, nausea, vomiting, fever, weight loss, and fatigue after allo-HSCT.

DIAGNOSIS

Stool examinations for ova and parasites showed Giardia trophozoites and cysts.

INTERVENTIONS

Methylprednisolone was stopped and the patient was intravenously treated with a 7-day course of metronidazole (500 mg, tid.). Simultaneously, cyclosporine (5 mg/kg) was continually utilized for suspicious gut GVHD.

OUTCOMES

The Giardia lamblia in stool turned negative and his symptoms were resolved after the 7-day course.

LESSONS

Incorporating non-invasive monitoring of stool examination for ova and parasites in the follow-up algorithm for post-HSCT patients can expedite clinical decision-making in the differential diagnoses for aGVHD even in the non-endemic area. Metronidazole therapy can be well-tolerated in HSCT patients with giardiasis.

Molecular prevalence and genotyping of Giardia duodenalis in cattle in Central Anatolia Region of Turkey

The molecular prevalence and genotypes of Giardia duodenalis in cattle were investigated. A total of 450 fecal samples were collected from cattle in three provinces of Central Anatolia from August 2017 to July 2019. Genomic DNA was extracted from the fecal samples and used in molecular analysis carried out by nested PCR analyses of the β-giardin (bg) gene of G. duodenalis. Positive samples were further analyzed by nested PCR at two gene loci (triosephosphate isomerase (tpi) and glutamate dehydrogenase (gdh)) for genotyping of G. duodenalis isolates. PCR analyses of the bg gene indicated that the overall prevalence of G. duodenalis was 30.2%. However, lower rates were determined with PCR analyses for gdh and tpi loci. The sequence analyses of the bg, gdh, and tpi genes revealed the presence of zoonotic assemblage A and livestock-specific assemblage E. Combined-sequence analyses revealed that assemblage E was the most common in the study area. Our study provides the first data on the wide prevalence of livestock-specific assemblages E in cattle in Turkey. The prevalence of assemblage A in cattle also reveals the importance of cattle for zoonotic transmission of giardiasis in Turkey.

Application of a recombinase polymerase amplification (RPA) assay and pilot field testing for Giardia duodenalis at Lake Albert, Uganda

Background

Giardia duodenalis is a gastrointestinal protozoan causing 184 million cases of giardiasis worldwide annually. Detection is by microscopy or coproantigen assays, although sensitivity is often compromised by intermittent shedding of cysts or trophozoites, or operator expertise. Therefore, for enhanced surveillance field-applicable, point-of-care (POC), molecular assays are needed. Our aims were to: (i) optimise the recombinase polymerase amplification (RPA) assay for the isothermal amplification of the G. duodenalis β-giardin gene from trophozoites and cysts, using published primer and probes; and (ii) perform a pilot field validation of RPA at a field station in a resource-poor setting, on DNA extracted from stool samples from schoolchildren in villages around Lake Albert, Uganda. Results were compared to an established laboratory small subunit ribosomal RNA (SSU rDNA) qPCR assay with additional testing using a qPCR targeting the triose phosphate isomerase (tpi) DNA regions that can distinguish G. duodenalis of two different assemblages (A and B), which are human-specific.

Results

Initial optimisation resulted in the successful amplification of predicted RPA products from G. duodenalis-purified gDNA, producing a double-labelled amplicon detected using lateral flow strips. In the field setting, of 129 stool samples, 49 (37.9%) were positive using the Giardia/Cryptosporidium QuikChek coproantigen test; however, the RPA assay when conducted in the field was positive for a single stool sample. Subsequent molecular screening in the laboratory on a subset (n = 73) of the samples demonstrated better results with 21 (28.8%) RPA positive. The SSU rDNA qPCR assay resulted in 30/129 (23.3%) positive samples; 18 out of 73 (24.7%) were assemblage typed (9 assemblage A; 5 assemblage B; and 4 mixed A+B). Compared with the SSU rDNA qPCR, QuikChek was more sensitive than RPA (85.7 vs 61.9%), but with similar specificities (80.8 vs 84.6%). In comparison to QuikChek, RPA had 46.4% sensitivity and 82.2% specificity.

Conclusions

To the best of our knowledge, this is the first in-field and comparative laboratory validation of RPA for giardiasis in low resource settings. Further refinement and technology transfer, specifically in relation to stool sample preparation, will be needed to implement this assay in the field, which could assist better detection of asymptomatic Giardia infections.

Improvement in cyst recovery and molecular detection of Giardia duodenalis from stool samples

Molecular detection of Giardia duodenalis by polymerase chain reaction (PCR) is difficult in faecal samples due to inhibitors that contaminate DNA preparations, or due to low cyst concentrations. In order to eliminate inhibitors, improve cyst recovery and molecular detection of G. duodenalis, different types of water, distillates (MDs), deionized (MDz), injection (MI) or Milli-Q^® (MM) were used instead of formaldehyde (F) in the laboratory routine method (Ritchie). Cysts were isolated from faecal samples with low cyst concentrations (< 1 cyst/field), medium (1-2 cysts/field) or high (> 2 cysts/field). Cyst recovery was improved using all water types (MDs, MDz, MI, MM) compared to formaldehyde. At all cyst concentrations, the use of MM consistently showed the greatest recovery of G. duodenalis cysts . DNA samples from recovered cysts were tested for the glutamate dehydrogenase (GDH) and β-giardin (βg) genes. The use of Milli-Q^® water allowed to detect both genes in all cyst concentrations, including low. The method processed with the other types of water amplified these genes at high and medium cyst concentrations. GDH and βg genes were not detected when the sample was processed with formaldehyde. These experimental results were confirmed in clinical samples. The results suggest that Milli-Q^® water provides the highest cyst recovery from stool samples and, correspondingly, the highest sensitivity for detecting G. duodenalis by microscopy or PCR for GDH and βg genes, even at low concentration of cysts.

Concordance of Giardia duodenalis assemblages determined by different PCR methodologies in three observational studies in Cuba

Giardia duodenalis is one of the most important intestinal parasites globally, especially in children, and in Cuba is the leading cause of chronic paediatric diarrhoea in this population. G. duodenalis is composed of eight genetic groups (or assemblages), two of which (A and B) are apparently zoonotic, occurring in both humans and other animals. However, consensus on the most appropriate genotyping scheme for optimal characterization of G. duodenalis isolates is lacking. In this article we present the results of three descriptive observational studies conducted in Havana, Cuba between 2010 and 2013, with the aim of comparing the results from molecular (PCR) approaches targeting different genes in order to assign with confidence 224 isolates of G. duodenalis to the correct assemblages. In each sub-study, following DNA isolation by the phenol/chloroform/isoamyl alcohol extraction method, PCR targeting the triose phosphate isomerase (tpi) gene was used for molecular characterization, as well as one additional PCR-method targeting another gene or pair of genes. DNA amplification was obtained in 87%, 83%, and 80% in the three sub-studies. Although excellent agreement (kappa index = 1) was recorded between results from some pairs of genes, for other combinations only moderate or substantial agreement was achieved. These results highlight the importance of interpretation of genotyping data, especially when single genetic markers are used. From the results of our studies, PCR targeting a combination of the tpi gene and the intergenic spacer region of rDNA may be a useful approach for the molecular characterization of G. duodenalis isolates.

Giardia intestinalis and Fructose Malabsorption: A Frequent Association

Nowadays, scientific studies are emerging on the possible etiological role of intestinal parasites in functional digestive disorders. Our study was carried out with healthy individuals (control group; n = 82) and symptomatic patients with lactose or fructose malabsorption, including positive (malabsorbers; n = 213) and negative (absorbers; n = 56) breath test, being analyzed for the presence of intestinal parasites. A high parasitic prevalence was observed in malabsorbers (41.8%), exclusively due to single-cell eukaryotes but not helminths. Giardia intestinalis was the predominant parasite in cases of abnormal absorption (26.5%), significantly associated with fructose malabsorption and doubling the probability of developing this pathology. Within controls, Blastocystis sp. (13.4%) was almost the only parasite, being the second among patients (12.6%), and Cryptosporidium parvum, the last species of clinical relevance, was detected exclusively in two malabsorbers (0.9%). The consumption of ecological food and professions with direct contact with humans arose as risk factors of parasitism. A diagnosis of carbohydrate malabsorption in adulthood is the starting point, making the search for the primary cause necessary. Accurate parasitological diagnosis should be considered another tool in the clinical routine for patients with recurrent symptoms, since their condition may be reversible with adequate therapeutic intervention.

Occurrence and multilocus genotyping of Giardia duodenalis from post-weaned dairy calves in Sichuan province, China

Giardia duodenalis is a zoonotic parasitic protist and poses a threat to human and animal health. This study investigated the occurrence of G. duodenalis infection in post-weaned calves from Sichuan province, China. Faecal samples were collected from a total of 306 post-weaned calves (3–12 months old) from 10 farms, including 4 intensive feeding farms and 6 free-ranging farms. The overall infection rate of G. duodenalis was 41.2% (126/306) based on the PCR results at any of the three genetic loci: beta-giardin (bg), triose-phosphate isomerase (tpi) and glutamate dehydrogenase (gdh) genes. Giardia duodenalis assemblages E (n = 115, 91.3%), A (n = 3, 2.4%), and A mixed with E (n = 8, 6.3%) were identified among the 126 positive specimens. Multilocus sequence typing of G. duodenalis revealed 34 assemblage E multilocus genotypes (MLGs), 1 assemblage A MLG and 7 mixed assemblage (A and E) MLGs. The eBURST data showed a high degree of genetic diversity within assemblage E MLGs. The phylogenetic tree revealed that MLG E3 was the primary MLG subtype in Sichuan province and also the most widely distributed in China.

Prevalence and potential risk factors for gastrointestinal parasitic infections in children in urban Bissau, Guinea-Bissau

BACKGROUND

Gastrointestinal (GI) parasitic infections cause significant morbidity and mortality in tropical and subtropical countries. We aimed to investigate the prevalence of GI parasitic infections in children from Bissau, Guinea-Bissau and to identify the possible risk factors for these infections.

METHODS

We performed an observational study on two comparable cohorts of children 2-15 y of age: one study covering health care-seeking children (n=748) and one study covering children from the background population (n=851). A total of 1274 faecal samples from the two cohorts were investigated for parasites by microscopy and the risk factors for infection were identified by logistic regression.

RESULTS

Intestinal parasitic infections were found in 54.8% of health care-seeking children and 55.5% of children from the background population. Helminth infections were more common among health care-seeking children and were mainly due to hookworms. Pathogenic protozoa included Entamoeba histolytica/dispar and Giardia lamblia. The risk factors for infections included increasing age, household crowding and poor sanitation and water supply.

CONCLUSIONS

We found a high prevalence of intestinal parasites among both health care-seeking children and children from the background population. Compared with previous studies, we found a decreasing prevalence of intestinal helminths. This study further identifies potential risk factors for infections, including inadequate sanitation and water supply.

Molecular epidemiology of Giardia and Cryptosporidium infections - What's new?

New information generated since 2016 from the application of molecular tools to infections with Giardia and Cryptosporidium is critically summarised. In the context of molecular epidemiology, nomenclature, taxonomy, in vitro culture, detection, zoonoses, population genetics and pathogenicity, are covered. Whole genome sequencing has had the greatest impact in the last three years. Future advances will provide a much better understanding of the zoonotic potential of both parasites, their diversity and how this is linked to pathogenesis in different hosts.

First Molecular Detection and Phylogenetic Analyses of Zoonotic Giardia intestinalis in Horses in Turkey

The goal of our study was to investigate the molecular prevalence of Giardia intestinalis in naturally infected horses in Kayseri, Central Anatolia Region in Turkey, to determine the molecular characterization of the obtained isolates and to exhibit the potential role of horses in zoonotic transmission of G. intestinalis. Fecal samples were randomly collected from totally 150 horses with clinically healthy between March and June of 2018. After the genomic DNA extractions, 25 (16.6%) of the 150 fecal samples, were found positive for G. intestinalis by nested PCR analyses of β-giardin gene. Phylogenetic analysis of the β-giardin gene sequences of G. intestinalis showed that the sequences detected in this study belonged to assemblage A that is regarded as zoonotic. Our study is the first report on the presence of G. intestinalis in horses in Turkey. The findings of the present study indicate that future research studies are required to determine molecular epidemiology and geographical distribution of G. intestinalis infections in horses nationwide. In addition, this study also may be helpful to assess the zoonotic potential for public health of G. intestinalis infections.

[Technological surveillance and competitive intelligence for a new technique to detect Giardia: an innovation in healthVigilância tecnológica e inteligência competitiva de um avanço tecnológico para detecção de Giardia, uma inovação em saúde]

La giardiasis es una enfermedad causada por Giardia duodenalis, protozoario enteropatógeno que también es responsable de la enfermedad diarreica aguda y la gastroenteritis en humanos. Dadas las características de excreción intermitente propias de este parásito, la probabilidad de obtener resultados falsos negativos durante el proceso de diagnóstico es alta. En el Grupo de Parasitología del Instituto Nacional de Salud de Colombia se identificaron proteínas inmunogénicas presentes en quistes y trofozoítos del parásito en aislamientos colombianos de Giardia con potencial comercial y posibilidad de ser patentadas. Se realizó un estudio exploratorio descriptivo a partir de las características de la técnica en estudio, su estado de desarrollo y la viabilidad comercial de la invención. Se encontraron 390 patentes y se seleccionaron cinco invenciones similares que no representaban ningún riesgo frente a una eventual solicitud de patente. De los 36 estuches para el diagnóstico de Giardia disponibles en el mercado y las 21 licencias sanitarias otorgadas hasta diciembre del 2017, sólo cuatro y tres, respectivamente, proponen técnicas similares a la de la estudiada, pero ninguna de ellas cuenta con un registro de patente relacionado. La técnica en desarrollo es innovadora y puede aplicarse en el campo de la salud pública en la Región de las Américas con beneficios previsibles.

Prevalence and multilocus genotypes of Giardia duodenalis infecting pigs in Ogun state, Nigeria

Giardia duodenalis is an intestinal flagellated protozoan parasite that is infectious to humans and a wide range of animals worldwide. While varying prevalence rates have been reported in pigs worldwide, there are currently no published reports on the genotypes of Giardia infecting pigs in any African country. The present study is on the prevalence and genotypes of G. duodenalis in 209 pigs raised on four farms in Ogun State Nigeria. Using an enzyme-linked immunosorbent assay (ELISA) kit, Giardia duodenalis coproantigens were detected on all farms and in 25.4% (53/209) of pigs sampled. However, there was no significant influence (p > 0.05) of age, sex and stool consistencies of the pigs on the distribution of the infection. Genotyping of Giardia duodenalis in all ELISA-positive samples, achieved by the amplification of the small subunit ribosomal RNA (ssu rRNA), glutamate dehydrogenase (gdh), triosephosphate isomerase (tpi) and beta giardin (bg) genes, identified 14 and 37 assemblage B and E isolates respectively while mixed infection by both assemblages was recorded in two isolates. Novel nucleotide substitutions were identified in four assemblage B isolates at the ssu rRNA locus. Genetic diversity was observed among the assemblage B isolates after multiple alignment analyses of the gdh, tpi and bg sequences whereby sub-assemblages BII (n = 2), BIII (n = 9) and BIV (n = 3) were identified. The assemblage B isolates from pigs in this study were phylogenetically related to isolates from humans, marmoset and cattle while the assemblage E isolates were related to isolates from sheep, goats and cattle. These findings suggest that pigs in southwest Nigeria predominantly harbour G. duodenalis isolates that could be infectious to other animal species and to a lesser extent, isolates that may be of zoonotic importance.

Comparison of multiplexed-tandem real-time PCR panel with reference real-time PCR molecular diagnostic assays for detection of Giardia intestinalis and Tritrichomonas foetus in cats

Giardia intestinalis and Tritrichomonas foetus are frequent enteric protozoan parasites of the gastrointestinal track of domestic cats. Because of different treatment options for the parasites, confirmation of presence of one or both pathogens is necessary. The PCR based assays are suitable for differential diagnosis. We evaluated the performance of Small Animal Diarrhoea panel, a multiplexed-tandem real-time PCR (MT-PCR) assay, that detects DNA of both G. intestinalis and T. foetus. The sensitivity and specificity were compared to reference real-time PCR assays using 105 faecal samples, 39.05% (n = 41) positive for G. intestinalis and 30.48% (n = 32) were positive for T. foetus. The faecal samples positive for T. foetus had a high proportion of late amplifiers, determined by an arbitrary threshold of C_t-values > 35. On the other hand, only one G. intestinalis positive sample was considered a late amplifier. For G. intestinalis DNA, the MT-PCR assay had 95.1% sensitivity and 92.1% specificity. For T. foetus DNA, the MT-PCR assay had 41.9% sensitivity and 100.0% specificity. To evaluate the interlaboratory reproducibility of the MT-PCR assay, results were compared in two different laboratories and found to be in a very good agreement (Kappa = 0.9). Further analysis of the DNA using conventional PCR determined presence of G. intestinalis Assemblage F and T. foetus genotype 'feline'. In conclusion, the MT-PCR Small Animal Diarrhoea panel had a good and poor performance against reference assays for G. intestinalis and T. foetus, respectively. The assay is suitable for detection and differential diagnosis of G. intestinalis and moderate to high burdens of T. foetus in small animal clinical practice.

Giardia: an under-reported foodborne parasite

Foodborne zoonotic pathogens are a serious public health issue and result in significant global economic losses. Despite their importance to public health, epidemiological data on foodborne diseases including giardiasis caused by the enteric parasite, Giardia duodenalis, are lacking. This parasite is estimated to cause ∼28.2 million cases of diarrhoea each year due to contamination of food, but very few foodborne outbreaks have been documented due to the limitations of current detection as well as surveillance methods. The current method for the recovery of Giardia cysts from food matrices using immunomagnetic separation requires further standardisation and cost reduction before it can be widely used. It also should incorporate downstream molecular procedures for genotyping, and traceback and viability analyses. Foodborne giardiasis can be potentially controlled through improvements in national disease surveillance systems and the establishment of Hazard Analysis and Critical Control Point interventions across the food chain. Studies are needed to assess the true prevalence and public health impact of foodborne giardiasis.

First report of Giardia duodenalis infection in bamboo rats

Background

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

Results

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

Conclusions

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

Electronic supplementary material

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

Methods for the detection of Cryptosporidium and Giardia: From microscopy to nucleic acid based tools in clinical and environmental regimes

The detection and characterization of genotypes and sub genotypes of Cryptosporidium and Giardia is essential for their enumeration, surveillance, prevention, and control. Different diagnostic methods are available for the analysis of Cryptosporidium and Giardia including conventional phenotypic tools that face major limitations in the specific diagnosis of these protozoan parasites. The substantial advancement in the development of genetic signature based molecular tools for the quantification, diagnosis and genetic variation analysis has increased the understanding of the epidemiology and preventive measures of related infections. The conventional methods such as microscopy, antibody and enzyme based approaches, offer better detection results when combined with advanced molecular methods. Gene based approaches increase the precision of identification, for example, many signatures detected in environmental matrices represent species/genotype that are not infectious to humans. This review summarizes the available methods and the advantages and limitations of advance detection techniques like nucleic acid-based approaches for the detection of viable oocysts and cysts of Cryptosporidium and Giardia along with the conventional and widely accepted detection techniques like microscopy, antibody and enzyme based ones. This technical article also encourages the wide application of molecular methods in genetic characterization of distinct species of Cryptosporidium and Giardia, to adopt necessary preventive measures with reliable identification and mapping the source of contamination.

Multilocus genotyping of Giardia duodenalis infecting rabbits in Ogun State, Nigeria

Giardiasis is a cosmopolitan gastrointestinal protozoal parasite that infects humans and various animals worldwide. To assess the zoonotic transmission potential of Giardia, molecular characterization is required. We are unaware of any report on the genotypes of Giardia infecting rabbits in Nigeria. Molecular detection and genotyping of Giardia duodenalis were conducted in a herd of adult Chinchilla rabbits (Oryctolagus cuniculus) managed on the Teaching and Research farm of the Federal University of Agriculture, Abeokuta located in a southwestern state of Nigeria by analysis of the small-subunit ribosomal RNA (ssu rRNA), glutamate dehydrogenase (gdh), triosephosphate isomerase (tpi) and beta-giardin (bg) genes. An overall prevalence of 72.3% (60/83) was recorded in the rabbits with no statistically significant (p > .05) influence of sex on the distribution of the infection in the herd. All the 19 isolates amplified at the four genetic loci were identified as G. duodenalis assemblage BIV by multiple alignment analysis of their consensus sequences. Novel nucleotide substitutions were identified in two isolates at the ssu rRNA locus. Phylogenetic analysis revealed that all ssu rRNA genotypes were closely related to G. duodenalis assemblage B of cattle and human origin. Findings of this study suggest that the rabbits harbour potentially zoonotic assemblage BIV that portends a high risk to students and staff of the University who are in regular contact with the animals.

Intestinal Giardiasis Disguised as Ulcerative Colitis

Parasite-associated colitis is quite rare in clinical practice of Ulcerative Colitis (UC). Here we reported an intestinal giardiasis case that has been diagnosed with UC. Further examination of stool revealed cysts of Giardia. This case completely responded to Albendazole. Giardiasis should be included for the differential diagnosis of UC.

Assessment of the diagnostic performance of four methods for the detection of Giardia duodenalis in fecal samples from human, canine and feline carriers

Enteric parasitic diseases including giardiasis are of public health concern. Different methods are available for the diagnosis of this parasitic infection in fecal samples such as the identification of protozoan cysts and trophozoites by light microscopy, detection of specific antigens by ELISA, and amplification of DNA fragments by PCR. The present study aimed at assessing the performance of four laboratory tests for the detection of Giardia duodenalis in fecal specimens from three different host species with a previous diagnosis of giardiasis; canine, feline and human patients provided new stool samples to be retested for Giardia before initiating treatment with antiprotozoal drugs. For this purpose, triplicate fecal specimens from 54 humans, 24 dogs and 18 cats living in the city of Niterói, RJ, southeast Brazil, were analysed by light microscopy, ELISA, immunochromatography, and nested PCR. The centrifugal-flotation method detected Giardia cysts in 89.6% (86/96) of the fecal samples. The protozoan parasite was detected via immunochromatography in 87.5% (84/96) of these samples. Giardia was detected by ELISA in 69.8% (67/96) of the stool specimens from carriers with a previous diagnosis of Giardia infection. Giardia was detected by PCR in only 39.6% (38/96) of the fecal specimens. Based on these findings, we suggest that, among the four assays that were used in this study, the zinc sulphate flotation technique (Faust et al., 1939) is the best diagnostic assay in terms of sensitivity and specificity to detect G. duodenalis on serially collected samples from dogs, cats and humans.

Prevalence and molecular characterization of Giardia intestinalis in racehorses from the Sichuan province of southwestern China

Giardia intestinalis, a cosmopolitan zoonotic parasite, is one of the most common causes of protozoal diarrhea in both humans and animals worldwide. Although G. intestinalis has been detected in many animals, information regarding its prevalence and genotype in Chinese racehorses is scarce. In the present study, we investigated the prevalence of G. intestinalis in racehorses and performed molecular characterization of the pathogen to assess its zoonotic potential. Two hundred and sixty-four racehorse fecal samples from six equestrian clubs located in different regions of the Sichuan province of southwestern China were examined. Nested polymerase chain reaction (PCR) analysis of the gene encoding triose-phosphate isomerase (tpi) showed the prevalence of G. intestinalis to be 8.3% (22/264), and the prevalence in different clubs varied from 3.6% to 13.5%. Three assemblages were identified in the successfully sequenced samples, including the potentially zoonotic assemblages A (n = 5) and B (n = 14), the mouse-specific assemblage G (n = 3), and a mixed A and B assemblage. Sequence analysis of tpi, glutamate dehydrogenase (gdh), and beta giardin (bg) loci revealed that the majority of sequences isolated from assemblage A were identical to the subtype AIV and assemblage B isolates showed variability among the nucleotide sequences of the subtype BIV. Using the nomenclature for the multilocus genotype (MLG) model, one each of multilocus genotypes A (MLG1) and B (MLG2) were identified, with MLG2 being a novel genotype. To the best of our knowledge, this is the first study to investigate G. intestinalis in Chinese racehorses. The presence of both animal and human assemblages of G. intestinalis in racehorses indicated that these animals might constitute a potential zoonotic risk to human beings.

Prevalence and multilocus genotyping of Giardia duodenalis in pigs of Shaanxi Province, northwestern China

Background

Giardiasis, caused by Giardia duodenalis (syn. Giardia intestinalis, Giardia lamblia), is a significant zoonotic parasitic disease of animals and humans worldwide. Accurate genotyping of G. duodenalis is essential for efficient control and management of giardiasis. The objectives of the present study were to investigate the prevalence and assemblages of giardiasis in pigs in Shaanxi Province, northwestern China, and for the first time study multilocus genotypes (MLGs) in pigs using multilocus genotyping technology in this region.

Results

Of 560 faecal samples collected from five farms in Shaanxi Province, 45 were positive for G. duodenalis and significant differences in prevalence were observed among different locations. Differences in prevalence were also detected in pigs of different age groups, with the highest prevalence in sows and the lowest in boars. Two assemblages, A and E, were identified, and a mixed infection of both A and E was identified in one faecal sample. Assemblage E was predominant and widely distributed in all investigated areas and age groups. Genetic viability was detected for both assemblages, and four different multi-locus genotypes (MLGs) within assemblage E were found, MLGE1-MLGE4.

Conclusions

Giardia duodenalis was detected in pigs from Shaanxi Province, northwestern China, and genetic diversity was observed in these infections. Both assemblages A and E were detected, and four distinct MLGs within assemblage E were identified. These findings provide new data for controlling G. duodenalis infection in pigs.

The influence of serial fecal sampling on the diagnosis of giardiasis in humans, dogs, and cats

Giardia infection is a common clinical problem in humans and pets. The diagnosis of giardiasis is challenging as hosts intermittently excrete protozoan cysts in their feces. In the present study, we comparatively evaluated two methods of serial fecal sampling in humans, dogs, and cats from Rio de Janeiro, Brazil. The Faust et al. technique was used to examine fecal specimens collected in triplicate from 133 patients (52 humans, 60 dogs, and 21 cats). Specimens from 74 patients were received from the group assigned to carry out sampling on consecutive days - 34 humans, 35 dogs, and 5 cats, and specimens from 59 patients were received from the group assigned to carry out sampling on non-consecutive, separate days - 18 human beings, 25 dogs, and 16 cats. G. duodenalis cysts were found in stools of 30 individuals. Multiple stool sampling resulted in an increase in the number of samples that were positive for Giardia in both groups. The authors therefore conclude that multiple stool sampling increases the sensitivity of the Faust et al . technique to detect G. duodenalis cysts in samples from humans, cats and dogs.

Curcumin alters the cytoskeleton and microtubule organization on trophozoites of Giardia lamblia

Giardia lamblia is a worldwide protozoan responsible for a significant number of intestinal infections. There are several drugs for the treatment of giardiasis, but they often cause side effects. Curcumin, a component of turmeric, has antigiardial activity; however, the molecular target and mechanism of antiproliferative activity are not clear. The effects of curcumin on cellular microtubules have been widely investigated. Since tubulin is the most abundant protein in the cytoskeleton of Giardia, to elucidate whether curcumin has activity against the microtubules of this parasite, we treated trophozoites with curcumin and the cells were analyzed by scanning electron microscopy and confocal microscopy. Curcumin inhibited Giardia proliferation and adhesion in a time-concentration-dependent mode. The higher inhibitory concentrations of curcumin (3 and 15μM) disrupted the cytoskeletal structures of trophozoites; the damage was evident on the ventral disk, flagella and in the caudal region, also the membrane was affected. The immunofluorescence images showed altered distribution of tubulin staining on ventral disk and flagella. Additionally, we found that curcumin caused a clear reduction of tubulin expression. By docking analysis and molecular dynamics we showed that curcumin has a high probability to bind at the interface of the tubulin dimer close to the vinblastine binding site. All the data presented indicate that curcumin may inhibit Giardia proliferation by perturbing microtubules.

Stool antigen immunodetection for diagnosis of Giardia duodenalis infection in human subjects with HIV and cancer

Human infection with the protozoan parasite Giardia duodenalis is one the most common parasitic diseases worldwide. Higher incidence rates of giardiasis have been reported from human subjects with multiple debilitating chronic conditions, including hypogammaglobulinemia and common variable immunodeficiency (CVID). In the current study, stool specimens were collected from 199 individuals diagnosed with HIV or cancer and immunocompetent subjects. The sensitivity of microscopy-based detection on fresh stool preparations, trichrome staining and stool antigen immunodetection for the diagnosis of G. duodenalis were 36%, 45.5% and 100%, respectively when compared with a highly sensitive stool-based PCR method as the gold standard. Further multilocus molecular analyses using glutamate dehydrogenase (gdh) and triose phosphate isomerase (tpi) loci demonstrated that the AI genotype of G. duodenalis was the most prevalent, followed by the AII genotype and mixed (AI+B) infections. We concluded that stool antigen immunodetection-based immunoassays and stool-based PCR amplification had comparable sensitivity and specificity for the diagnosis of G. duodenalis infections in these populations. Stool antigen detection-based diagnostic modalities are rapid and accurate and may offer alternatives to conventional microscopy and PCR-based diagnostic methods for the diagnosis of G. duodenalis in human subjects living with HIV or cancer.

Antigiardial Activity of Podophyllotoxin-Type Lignans from Bursera fagaroides var. fagaroides

Giardiasis, a diarrheal disease, is highly prevalent in developing countries. Several drugs are available for the treatment of this parasitosis; unfortunately, all of them have variable efficacies and adverse effects. Bursera fagaroides has been known for its anti-inflammatory and antidiarrheal properties in Mexican traditional medicine. We investigated the in vitro anti-giardial activities of four podophyllotoxin-type lignans from Bursera fagaroides var. fagaroides, namely, 5'-desmethoxy-β-peltatin-A-methylether (5-DES), acetylpodophyllotoxin (APOD), burseranin (BUR), and podophyllotoxin (POD). All lignans affected the Giardia adhesion and electron microscopy images revealed morphological alterations in the caudal region, ventral disk, membrane, and flagella, to different extents. Only 5-DES, APOD, and POD caused growth inhibition. Using the Caco-2 human cell line as a model of the intestinal epithelium, we demonstrated that APOD displayed direct antigiardial killing activity and low toxicity on Caco-2 cells. This finding makes it an attractive potential starting point for new antigiardial drugs.

First survey of Cryptosporidium, Giardia and Enterocytozoon in diarrhoeic children from Wuhan, China

Intestinal protozoan pathogens cause significant diarrhoeal diseases in children. However, to date, there has been limited genetic study of the intestinal pathogens Cryptosporidium, Giardia and Enterocytozoon in humans in China, with the exception of research in a small number of cities/provinces. In the present study, PCR-based tools were used to detect and characterise these protistan parasites from 500 children with a history of diarrhoea in Wuhan and environs, Hubei province, China. Genomic DNAs from faecal samples were screened for the particular protists by PCR utilising regions in the small subunit (SSU) of the nuclear ribosomal RNA, the 60kDa glycoprotein (gp60), the internal transcribed spacer of nuclear ribosomal DNA (ITS) and/or the triose phosphate isomerase (tpi) genes as markers. Cryptosporidium meleagridis subtype IIIb (10/500, 2.0%), Giardia duodenalis assemblage A (7/500, 1.4%) and Enterocytozoon bieneusi genotype D (1/500, 0.2%) were identified in small percentages of the 500 samples. No significant gender- or age-associated differences in the prevalence of Cryptosporidium and Giardia infections were found. Future studies might focus on the occurrence of these protists in children as well as animals, with an emphasis on Cryptosporidium meleagridis in pets and agriculturally important birds, in different parts of Hubei province.