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

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.

Comparison of Giardia duodenalis point-of-care antigen faecal tests to reference laboratory assays in non-symptomatic dogs

Giardia duodenalis is one of the most prevalent enteric parasites of dogs. Point-of-care antigen tests (POC) are rapid and do not require additional equipment, or a specialised diagnostic laboratory. The aim of this study was to compare diagnostic tests available in veterinary practices and in a diagnostic laboratory for the detection of G. duodenalis on a cohort of group-housed dogs from New South Wales, Australia. Two different POC tests were used for the detection of G. duodenalis. Laboratory tests used were the multiplexed-tandem PCR panel (MT-PCR) that includes detection of G. duodenalis DNA, and two reference tests (an in-house TaqMan real-time PCR and a direct immunofluorescence assay, DFA). Canine faecal samples (n = 40) were tested simultaneously for the detection of G. duodenalis. Using either DFA or TaqMan real-time PCR as reference tests, 77.5% (31/40) and 82.5% (33/40) of dogs tested positive, respectively. Agreement (Kappa) between the DFA and TaqMan real-time PCR was 0.84 (95% CI 0.64 to 1.00). There was substantial G. duodenalis test outcome agreement between the two POC tests, Kappa = 0.75. Combining the two POC tests yielded 77% sensitivity and 100% specificity with DFA as reference, and for TaqMan real-time PCR it was 73% sensitivity and 100% specificity. The MT-PCR was in excellent agreement with each reference test, DFA or TaqMan real-time PCR. Due to the high specificity of both POC tests, they can be confidently used as rule-in diagnostics. Confirmatory testing that detects different biological parameters such as DNA, e.g. PCR (inc. MT-PCR), should be implemented before concluding that a dog is negative for the presence of G. duodenalis.

Systematic Review of Diagnostic Approaches for Human Giardiasis: Unveiling Optimal Strategies

Giardiasis, caused by the protozoan Giardia intestinalis, affects around 400 million people worldwide, emphasizing the critical need for accurate diagnosis to enhance human health, especially in children. Prolonged giardiasis in childhood can lead to intellectual deficits and other complications. A variety of diagnostic tools, including microscopic, immunological, and molecular methods, are available for detecting G. intestinalis infection. Choosing the most suitable method can be challenging due to the abundance of options. This systematic review assesses the reliability and applicability of these diagnostic modalities. Utilizing the Dimensions and Wordart platforms for data analysis, we focus on relevant literature addressing diagnostic methods for human giardiasis. Microscopic techniques, particularly Ritchie's method, emerge as the primary choice, followed by enzyme-linked immunosorbent assay (ELISA) and polymerase chain reaction (PCR). PCR's limited use is attributed to its high cost and infrastructure challenges in developing nations. In conclusion, our analysis supports microscopic methods as the gold standard for giardiasis diagnosis. However, in cases where symptoms persist despite a negative diagnosis, employing more sensitive diagnostic approaches is advisable.

Parasitosis in Pet Dogs from Rondônia, Amazon Biome, and Human Perception of Zoonoses

Zoonotic parasitic diseases in dogs are particularly concerning in regions with low human development indices due to inadequate sanitary services and insufficient environmental and health education. This study aimed to assess the parasitological status of dogs living in households and evaluate their owners' knowledge about zoonoses. A total of 183 dogs from Rolim de Moura, Rondônia State, were screened for the presence of ectoparasites, and 163 fecal samples were collected for analysis. The results showed that 74.23% (112/163) of the animals had at least one species of endoparasite. The most identified pathogens were Ancylostoma spp. (68.71%, 112/163), Trichuris vulpis (11.66%, 19/163), Toxocara canis (6.75%, 11/163), Cystoisospora canis (4.91%, 8/163), Dipylidium caninum (1.23%, 2/163), and Hammondia/Neospora (0.61%, 1/163). Ectoparasites were observed in 43.17% (79/183) of the evaluated animals, with Rhipicephalus sanguineus found in 31.15% (57/183) and Ctenocephalides felis felis in 20.77% (38/183). Only 11.48% (7/61) of the owners were familiar with the term "Zoonoses." However, a significant majority (83.61%, 51/61) believed that dogs can transmit diseases to humans. Our findings highlight the prevalence of parasites in the studied area and associated risk factors, underscoring the urgent need for educational interventions to raise awareness about these diseases and their risks to human health.

[Feline and canine giardiosis: An Update]

Giardia duodenalis is a facultative pathogenic intestinal parasite. Giardiosis in dogs and cats may appear with or without clinical signs. Typical signs include diarrhea with or without vomiting. The prevalence in young animals is high and may amount to up to 50%. There are 8 different genotypes (A - H), which are called assemblages. Assemblages C and D are most common in dogs and assemblage F most frequent in cats. However, animals may also be infected with the zoonotically effective assemblages A and B or exhibit mixed infections. The immunofluorescence test (IFA), the enzyme-linked immunosorbent assay (ELISA) and fecal centrifugation using zinc sulphate solution are currently recommended as diagnostic methods. Polymerase chain reaction (PCR) may be used to determine the corresponding assemblage. Approved treatments for giardiosis include fenbendazole and metronidazole. In addition, undertaking specific hygiene measures is warranted. Only animals showing clinical signs or those living in the same household with high-risk patients (e. g. immunosuppressed humans) are recommended to receive medication. The aim of treatment is clinical improvement of the diseased dogs and cats. Frequently, complete elimination of Giardia is not attained.

Occurrence of Giardia duodenalis in Cats from Queretaro and the Risk to Public Health

Giardia is a protozoan that affects humans as well as a wide range of domestic species. It is distributed worldwide, and the highest frequency is seen in developing countries. Due to the potential for domestic cats to be carriers of this parasite and subsequently transmit the infection to humans, it is important to know the risk of transmission. For this reason, the objective of this study was to determine the frequency of this parasite in the cat population of the city of Santiago de Queretaro, Mexico, and identify the assemblages present to determine the role this host plays in public health, this being the first study of its type to be performed in the country. This was a cross-sectional study during which 200 fecal samples were collected from cats of both sexes and varying ages and strata of origin. The samples were analyzed by microscopy following the flotation technique, having obtained a general frequency of 25%. Giardia cysts were found at higher frequency in pasty stools. The assemblages found were zoonotic, specifically assemblage A, which suggests that the cat poses an important risk for the dissemination of the parasite to humans, making it an important public health problem.

Giardia duodenalis Styles, 1902 Prevalence in Cattle (Bos taurus Linnaeus, 1758) in Europe: A Systematic Review

Giardia duodenalis Styles, 1902 is an infectious agent which can cause enteritic disease in cattle (Bos taurus Linnaeus, 1758) worldwide. As a zoonotic protozoan, it is important to acknowledge Giardia prevalence and assemblages found in cattle and risk factors associated with the Giardia infection in herds. This systematic review aims to estimate the prevalence of G. duodenalis and its assemblages in cattle and to identify the risk factors associated with Giardia infection in cattle in Europe. A systematic review was performed according to Preferred Reporting Items for Systematic reviews and Meta-Analyses (PRISMA) guidelines to collect information from published studies in Europe. A total of 1414 studies were identified and 17 relevant studies were included in this review. Mean Giardia prevalence in cattle in Europe was 35.1%, with the highest prevalence found in neonatal animals (39.6%), but mean heard prevalence was 67.0%. Mixed infections of Giardia assemblages A and E were found most frequently (55.6%), while assemblages A and B were found more frequently in animals under 24 months old. Risk factors, such as deep litter with run-out, prolonged calf contact with the dam, and seasonality, such as winter and spring, were found to be potential risk factors for Giardia presence in the herds.

Occurrence of gastrointestinal parasites in dogs from Cuiabá, Mato Grosso

Gastrointestinal parasitism by helminths and protozoa poses risks to animal and human health owing to clinical changes and transmission of potentially zoonotic agents. Thus, the present study aimed to verify the occurrence of gastrointestinal parasites in dogs from the municipality of Cuiabá, Mato Grosso, Brazil, using coproparasitological tests. From June 2021 to April 2022, faecal samples were collected from domestic dogs at the Veterinary Hospital and Animal Protection Shelters in the Cuiabá municipality. A semi-structured questionnaire was applied to the owners and those responsible for the shelters to analyse the factors associated with gastrointestinal parasitism. A total of 353 faecal samples were collected and subjected to parasitological flotation and sedimentation techniques. Data were analysed using the chi-squared test and exploratory factorial analysis. The occurrence of gastrointestinal parasitism was 22.66% and the parasites found alone or in mixed infections were Ancylostoma spp., Trichuris vulpis, Toxocara spp., Dipylidium caninum, Cystoisospora spp., Giardia duodenalis, and coccidia. It was concluded that the occurrence of gastrointestinal parasites in dogs is frequent, and the variables associated with these infections were source origin, breed, age, coexistence with other animals, and dull fur.

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.

Effectiveness of Fenbendazole and Metronidazole Against Giardia Infection in Dogs Monitored for 50-Days in Home-Conditions

A field trial performed in-home conditions was conducted on 24 dogs naturally infected with Giardia, in order to compare the efficacy of fenbendazole and metronidazole. Animals were allocated in groups randomly in order to obtain two groups of 12 dogs each with similar parasitic loads of Giardia cysts: dogs in Group A were treated with fenbendazole (Panacur®, Intervet Italia Srl) administered at the dose of 50 mg/kg orally once a day for 5 consecutive days, dogs in Group B were treated with metronidazole (Flagyl®, Zambon Italia Srl) administered orally at the dose of 50 mg/kg, once a day for 5 consecutive days. All the dogs that were shedding Giardia cysts after the first treatment (Day 0) were retreated (either at Day 7 or at Day 14 or at Day 21) until a negative result was obtained with the same treatment. Additionally, all the dogs were re-examined at Day 50. All the dogs were tested for the presence of Giardia cysts using a fecal flotation method (FLOTAC). The percent efficacy of the treatments (A and B) was calculated at each sampling point (Days 7, 14, 21, and 50) as reduction in mean Giardia cysts. After the first therapy, on day 7, 4/12 (33.3%) dogs tested positive for Giardia cysts in the Group A and 5/12 (41.7%) in the Group B. Efficacies at (Days 7, 14, 21, and 50) of the treatments against Giardia infection were 80.9, 94, 100, and 97% in the Group A and 70.8, 99, 100, and 97.1% in the Group B. Statistically significant differences were not observed between the efficacy of Fenbendazole and Metronidazole against infection by G. duodenalis (P = 0.686). Molecular analysis revealed full homology (i.e., 100% with JN416550) with the canine specific assemblage D in six positive dogs. Different hypotheses might explain the re-appearance of the Giardia cysts in some dogs after treatment, e.g., re-infection from the home environment, the correct medication given by the owners, the diet, as well as treatment failure, but also biological issues related to the intermittent excretion of Giardia cysts.

Preventive role of probiotic bacteria against gastrointestinal diseases in mice caused by Giardia lamblia

Giardiasis is one of the most prevalent gastrointestinal diseases in the world. It is caused by Giardia, Giardia lamblia, a common and opportunistic zoonotic parasite. The aim of our work is to find a natural and safe alternative treatment for giardiasis, specifically, to determine if probiotic bacteria (Lactobacillus acidophilus, Bifidobacterium bifidum, and Lactobacillus helveticus) can contribute to treatment, and act as preventives. Sixty weanling albino mice, Mus musculus, were divided into control and experimental, probiotic-fed groups. We determined infection intensity, and cure and prevention rates of giardiasis through ELISA (enzyme-linked immunosorbent assay) of stool samples and histopathological comparison of intestinal tissue. In experimental groups, there was a significant reduction in infection intensity (P<0.001) on days 10, 15, and 20, while cure rate reached 87.5%. The control group showed no signs of reduced infection or cure and only the group treated with probiotics prior to infection showed significant prevention rates. In the experimental groups, intestinal changes due to giardiasis appeared 7 days post-infection. However, almost all of these changes disappeared by the 25th day. Our results suggest a beneficial and significant effect of probiotics in the prevention and treatment of giardiasis in mice.

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.

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.

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.

Comparative cost-effectiveness of immunoassays and FLOTAC for diagnosing Giardia spp. infection in dogs

BACKGROUND

Giardia spp. is a protozoan pathogen and is the most common enteric parasite of domestic animals and humans. Assays for detecting infection in fecal samples using direct or indirect examinations are important tools for diagnosing the disease. The objective of the present study was to compare the cost-effectiveness of immunoassays and FLOTAC technique for diagnosing Giardia spp. infection in dogs.

RESULTS

Fecal samples from 80 positive stray dogs were tested for the presence of copro-antigens of Giardia spp. using the direct immunofluorescence assay (IFA), a rapid enzyme-linked immunosorbent assay (ELISA) and the FLOTAC double technique. All methods were performed in accordance with the instructions reported in the original description for each technique. The results showed that ELISA can be run in less time than IFA and almost at the same time of the FLOTAC technique. Among the tests used in this study, FLOTAC had the lowest cost per correct diagnosis, compared with immunoassays.

CONCLUSIONS

The results from this cost-effectiveness analysis, in combination with the sensitivity and specificity of the FLOTAC technique, suggest that the FLOTAC technique can be use in the routine diagnosis of Giardia spp. infection in dogs.