Numbers of Giardia in the feces of infected children

Is there added value from using three serial samples when surveying the occurrence of intestinal parasites in children?

BACKGROUND

Surveys for intestinal parasitic infections (IPIs) often involve samples from three sampling dates analysed by various microscopy techniques. However, analysis of three samples per individual is a huge burden on time and resources. We compared the value from analysing three or fewer samples.

METHODS

In this cross-sectional study, three faecal samples were collected every other day from 332 children from two locations in Guantanamo province, Cuba. Samples were analysed by wet mount with Lugol stain, Willis flotation method and Kato-Katz thick smear.

RESULTS

Most parasites were detected by wet mount, although helminth eggs not found by wet smear were detected by the Willis flotation method (in particular) and Kato-Katz smear. Blastocystis spp. was the most commonly detected parasite (about 65%), then Giardia duodenalis and then Entamoeba spp. Although analysis of two stool samples significantly increased occurrence data for Blastocystis, this was not so for the other parasites. For none of the protozoan parasites were results from analysing three samples significantly higher than results from analysing just two samples.

CONCLUSIONS

Analysing two faecal samples by wet mount and the Willis flotation method provides useful data for estimating the prevalence of IPIs in relatively high prevalence settings. Analysing further samples provides limited additional information and adds an extra burden in terms of time and resources.

Giardia duodenalis in a clinically healthy population of captive zoo chimpanzees: Rapid antigen testing, diagnostic real-time PCR and faecal microbiota profiling

Giardia duodenalis is one of the most common intestinal parasites of humans, with a worldwide distribution. Giardia duodenalis has been reported in both wild and captive populations of non-human primates, namely chimpanzees. In this study we investigated an entire troop of clinically healthy chimpanzees (n = 21) for the presence of G. duodenalis and its association with faecal microbiota profile. Faecal samples (n = 26) were collected from the chimpanzee exhibit from a zoo in Sydney, Australia. Diagnosis of G. duodenalis was made using a Rapid Antigen Test (RAT) as a point-of-care-test and compared to a reference standard real-time PCR test. Approximately half of the chimpanzee faecal samples tested positive for G. duodenalis by both RAT (13/26, 50%) and real-time PCR (14/26, 53.85%). The RAT sensitivity was 85.7% (95% CI: 63.8%–96%) and specificity was 91.7% (95% CI: 68.3%–99%) when compared to the in-house real-time PCR. Genotyping of the samples revealed the presence of zoonotic assemblage B. Microscopic analysis revealed the presence of Troglodytella spp. (14/26), Balantioides sp. (syn. Balantidium sp.) (8/26) as well as Entamoeba spp. (3/26). Microbiota profile based on 16S rRNA gene sequencing revealed that the community was significantly different between G. duodenalis positive and negative samples if RAT results were taken into an account, but not real-time PCR diagnostics results. Proteobacteria and Chloroflexi were the significant features in the dataset that separated G. duodenalis positive and negative samples using LEfSe analysis. Being able to rapidly test for G. duodenalis in captive populations of primates assists in point-of-care diagnostics and may better identify animals with subclinical disease. Under the investigated conditions of the zoo setting, however, presence of G. duodenalis either detected by RAT or real-time PCR was not associated with clinically apparent disease in captive chimpanzees.

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Whole troop investigation of healthy captive chimpanzees for Giardia duodenalis.

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Whole chimpanzee troop faecal microbiota profiled.

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Diagnosing G. duodenalis with Rapid Antigen Test (RAT) as a point-of-care-test.

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Comparison of RAT and reference real-time PCR test.

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Presence of G. duodenalis assemblage B.

Modelling faecal pathogen flows and health risks in urban Bangladesh: Implications for sanitation decision making

Faecal-oral infections are a major component of the disease burden in low-income contexts, with inadequate sanitation seen as a contributing factor. However, demonstrating health effects of sanitation interventions - particularly in urban areas - has proved challenging and there is limited empirical evidence to support sanitation decisions that maximise health gains. This study aimed to develop, apply and validate a systems modelling approach to inform sanitation infrastructure and service decision-making in urban environments by examining enteric pathogen inputs, transport and reduction by various sanitation systems, and estimating corresponding exposure and public health impacts. The health effects of eight sanitation options were assessed in a low-income area in Dhaka, Bangladesh, with a focus on five target pathogens (Shigella, Vibrio cholerae, Salmonella Typhi, norovirus GII and Giardia). Relative to the sanitation base case in the study site (24% septic tanks, 5% holding tanks and 71% toilets discharging directly to open drains), comprehensive coverage of septic tanks was estimated to reduce the disease burden in disability-adjusted life years (DALYs) by 48-72%, while complete coverage of communal scale anaerobic baffled reactors was estimated to reduce DALYs by 67-81%. Despite these improvements, a concerning health risk persists with these systems as a result of effluent discharge to open drains, particularly when the systems are poorly managed. Other sanitation options, including use of constructed wetlands and small bore sewerage, demonstrated further reductions in local health risk, though several still exported pathogens into neighbouring areas, simply transferring risk to downstream communities. The study revealed sensitivity to and a requirement for further evidence on log reduction values for different sanitation systems under varying performance conditions, pathogen flows under flooding conditions as well as pathogen shedding and human exposure in typical low-income urban settings. Notwithstanding variability and uncertainties in input parameters, systems modelling can be a feasible and customisable approach to consider the relative health impact of different sanitation options across various contexts, and stands as a valuable tool to guide urban sanitation decision-making.

Wastewater-based epidemiology-surveillance and early detection of waterborne pathogens with a focus on SARS-CoV-2, Cryptosporidium and Giardia

Waterborne diseases are a major global problem, resulting in high morbidity and mortality, and massive economic costs. The ability to rapidly and reliably detect and monitor the spread of waterborne diseases is vital for early intervention and preventing more widespread disease outbreaks. Pathogens are, however, difficult to detect in water and are not practicably detectable at acceptable concentrations that need to be achieved in treated drinking water (which are of the order one per million litre). Furthermore, current clinical-based surveillance methods have many limitations such as the invasive nature of the testing and the challenges in testing large numbers of people. Wastewater-based epidemiology (WBE), which is based on the analysis of wastewater to monitor the emergence and spread of infectious disease at a population level, has received renewed attention in light of the current coronavirus disease 2019 (COVID-19) pandemic. The present review will focus on the application of WBE for the detection and surveillance of pathogens with a focus on severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) and the waterborne protozoan parasites Cryptosporidium and Giardia. The review highlights the benefits and challenges of WBE and the future of this tool for community-wide infectious disease surveillance.

Assessing the Impact of Cyanuric Acid on Bather’s Risk of Gastrointestinal Illness at Swimming Pools

Current regulatory codes for swimming pool disinfection separately regulate free chlorine (FC) and cyanuric acid (CYA). It is well-known that CYA affects disinfection rates by reversibly binding to FC in aqueous solutions. However, limits for these regulated parameters have neither systematically accounted for this chemistry nor been based on the risk of gastrointestinal illness. This study was intended to determine the minimum concentration of FC relative to CYA based on the risk of gastrointestinal illness from normal fecal sloughing of selected pathogens and to find a simple regulatory rule for jointly managing FC and CYA for consistent disinfection. Literature data on CYA’s effect on microbial inactivation rates were reanalyzed based on the equilibria governing hypochlorous acid (HOCl) concentration. A model was developed that considers the rates of pathogen introduction into pool water, disinfection, turbulent diffusive transport, and pathogen uptake by swimmers to calculate the associated risk of illness. Model results were compared to U.S. Environmental Protection Agency (EPA) untreated recreational water acceptable gastrointestinal illness risk. For Cryptosporidium, correlation between log inactivation and Chick–Watson Ct was far better when C refers to HOCl concentration than to FC (r = −0.96 vs. −0.06). The HOCl concentration had a small variation (± 1.8%) at a constant CYA/FC ratio for typical FC and CYA ranges in swimming pools. In 27 U.S. states, the allowed FC and CYA results in HOCl concentrations spanning more than a factor of 500. Using conservative values for a high bather load pool with 2 mg/L FC and 90 mg/L CYA, the model predicted a 0.071 annual probability of infection for Giardia, exceeding the EPA regulatory 0.036 limit for untreated recreational waters. FC and CYA concentrations in swimming pools should be jointly regulated as a ratio. We recommend a maximum CYA/FC ratio of 20.

Risk factors for sporadic Giardia infection in the USA: a case-control study in Colorado and Minnesota

Giardia duodenalis is the most common intestinal parasite of humans in the USA, but the risk factors for sporadic (non-outbreak) giardiasis are not well described. The Centers for Disease Control and Prevention and the Colorado and Minnesota public health departments conducted a case-control study to assess risk factors for sporadic giardiasis in the USA. Cases (N = 199) were patients with non-outbreak-associated laboratory-confirmed Giardia infection in Colorado and Minnesota, and controls (N = 381) were matched by age and site. Identified risk factors included international travel (aOR = 13.9; 95% CI 4.9-39.8), drinking water from a river, lake, stream, or spring (aOR = 6.5; 95% CI 2.0-20.6), swimming in a natural body of water (aOR = 3.3; 95% CI 1.5-7.0), male-male sexual behaviour (aOR = 45.7; 95% CI 5.8-362.0), having contact with children in diapers (aOR = 1.6; 95% CI 1.01-2.6), taking antibiotics (aOR = 2.5; 95% CI 1.2-5.0) and having a chronic gastrointestinal condition (aOR = 1.8; 95% CI 1.1-3.0). Eating raw produce was inversely associated with infection (aOR = 0.2; 95% CI 0.1-0.7). Our results highlight the diversity of risk factors for sporadic giardiasis and the importance of non-international-travel-associated risk factors, particularly those involving person-to-person transmission. Prevention measures should focus on reducing risks associated with diaper handling, sexual contact, swimming in untreated water, and drinking untreated water.

Advancements in Parasite Diagnosis and Challenges in the Management of Parasitic Infections: A Mini Review

Intestinal parasitic infections (IPIs) remain a widespread public health concern causing severe implications in both developed and developing countries. Globally, numerous studies have been carried out ranging from various communities to schoolchildren as well as indigenous communities. The infections are commonly caused by helminths (e.g. Ascaris lumbricoides, Trichuris trichiura and hookworm) and protozoa (e.g. Blastocystis hominis, Cryptosporidium sp., Entamoeba histolytica and Giardia duodenalis). Poor sanitation and poverty are some of the factors associated with IPIs. With the ever-increasing impact of IPIs, newer detection approaches have been developed and studied. The efficacy of diagnostic method is crucial to give an accurate identification of these parasites. Recent developments of diagnostic tools such as serology- and molecular-based assays are assisting the conventional method of microscopy in detecting and further confirming current or past infections and the specific species of parasites. Ongoing investigations in parasitic infections using these advanced tools will provide useful information that will enable the evaluation of the effectiveness of the current control program and thus, assist future planning for improved strategies in eradicating these parasitic infections.

Molecular Biology Can Change the Classic Laboratory Approach for Intestinal Protozoan Infections

For many years microscopy has been considered the mainstay of the diagnosis of parasitic infections. In our laboratory, before the advent of molecular biology, the approach for the identification of parasitic infections in stools was the microscopic exam of three samples. Once we adopted molecular biology, a real-time PCR on one single sample was added to the classical coproparasitological exam of three samples. Given the high sensitivity of real-time PCR (Rt-PCR), we then decided to evaluate if a change of our routine was justified. In detail, we intended to assess if a much more practical routine, based on the analysis of a single fecal sample, was sufficiently sensitive to replace the routine described above. The new approach to be evaluated included, on the same and unique fecal sample, a classical coproparasitological exam plus Rt-PCR. The data obtained showed that the sensitivity of the new proposed approach remains very high, despite the reduction of coproparasitological exams from three to one, with the advantage of reducing costs and saving time, both for patients and for the laboratory.

Checking the detail in retail: Occurrence of Cryptosporidium and Giardia on vegetables sold across different counters in Chandigarh, India

Fresh produce has been recognized as a vehicle of infection for protozoan parasites, particularly Cryptosporidium, and, to a lesser extent, Giardia. For both parasites, outbreaks associated with fresh produce have been documented. Although documented outbreaks tend to be from industrialized countries, contamination of fresh produce with these parasites is a global issue. In developing countries, infections with these parasites are often endemic in the community, and basic infrastructure and hygiene measures may be inadequate, thus the likelihood of contamination of fresh produce with these parasites may be higher. Realization of the importance of this transmission route comes against a backdrop of raw salads and more Western culinary habits gaining a foothold, and fresh produce being encouraged as part of the diet due to their associated health benefits. However, if consumption of uncooked fresh produce is going to increase its market sector in India, it is important that it is safe. In this study, various types of fresh produce obtained from three types of vendors in Chandigarh, a major city in Northern India, were analyzed for contamination with Cryptosporidium oocysts and Giardia cysts using a method that has been previously validated in inter-laboratory spiking experiments. A total of 284 samples of different fresh produce items were analyzed, obtained from the different retailers situated in different societal layers of the city. The overall prevalence of contamination of fresh produce with these parasites was just under 11%, with 6% of the vegetables contaminated with Cryptosporidium oocysts, and 5% with Giardia cysts. Contaminated vegetables included turnip, cabbage, carrot, chili, coriander, cucumber, radishes, and tomatoes. Molecular analyses identified contamination with Cryptosporidium parvum and Giardia duodenalis of Assemblage A and Assemblage D, indicating that contamination from animals may be of relevance. Although the prevalence of contamination is similar to those reported in previous studies, the levels of contamination on some items of fresh produce were relatively high. Although the different socioeconomic areas of Chandigarh from which the samples were obtained was not associated with likelihood of contamination, fresh produce from supermarkets had heavier contamination with Cryptosporidium oocysts than fresh produce purchased through other sales outlets. The results are discussed in relation to the fresh produce chain and sales models in Chandigarh, both in terms of where contamination may occur and the potential importance of fresh produce as a transmission vehicle.

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.

Giardiasis outbreaks in the United States, 1971-2011

Giardia intestinalis is the leading parasitic aetiology of human enteric infections in the United States, with an estimated 1·2 million cases occurring annually. To better understand transmission, we analysed data on all giardiasis outbreaks reported to the Centers for Disease Control and Prevention for 1971-2011. The 242 outbreaks, affecting ~41 000 persons, resulted from waterborne (74·8%), foodborne (15·7%), person-to-person (2·5%), and animal contact (1·2%) transmission. Most (74·6%) waterborne outbreaks were associated with drinking water, followed by recreational water (18·2%). Problems with water treatment, untreated groundwater, and distribution systems were identified most often during drinking water-associated outbreak investigations; problems with water treatment declined after the 1980s. Most recreational water-associated outbreaks were linked to treated swimming venues, with pools and wading pools implicated most often. Produce was implicated most often in foodborne outbreaks. Additionally, foods were most commonly prepared in a restaurant and contaminated by a food handler. Lessons learned from examining patterns in outbreaks over time can help prevent future disease. Groundwater and distribution system vulnerabilities, inadequate pool disinfection, fruit and vegetable contamination, and poor food handler hygiene are promising targets for giardiasis prevention measures.

Copro prevalence and estimated risk of Entamoeba histolytica in Diarrheic patients at Beni-Suef, Egypt

Amoebiasis diagnosis is usually based on microscopy that cannot differentiate pathogenic E. histolytica from morphologically identical non-pathogenic species. 194 fecal samples were collected from diarrheic &/or dysenteric patients and examined for Entamoeba complex microscopically, E. histolytica/E. dispar coproantigen using ICT and E. histolytica coproantigen using Tech lab E. histolytica II ELISA test. Entamoeba complex trophozoites/cysts, E. histolytica/E. dispar coproantigen and E. histolytica coproantigen were detected in 22.2, 14.4 and 3.6 % of samples, respectively. Microscopy and ICT method had limited sensitivity with poor PPV (9.3 and 7.1 %, respectively) and both slightly agree with ELISA test. The prevalence of E. histolytica was low (3.6 %) in studied individuals and was 14 times lower than non-pathogenic amoebae. E. histolytica detection studied individuals was positively associated with mucoid and bloody stool, which makes them disease predictors. E. histolytica fecal ELISA assay for E. histolytica detection surpassed microscopy and E. histolytica/E. dispar ICT assay. This has highlighted the need for practical non-microscopic detection methods that can differentiate between amoeba infections to avoid unnecessary and possibly harmful therapies and to determine the true prevalence and epidemiology of E. histolytica.

Diagnosis of Parasitic Infections

Methods for the diagnosis of parasitic infections have stagnated in the past three decades. Labor-intensive methods such as microscopy still remain the mainstay of several diagnostic laboratories. There is a need for more rapid tests that do not sacrifice sensitivity and that can be used in both clinical settings as well as in poor resource field settings. The fields of diagnostic medical parasitology, treatment, and vaccines are undergoing dramatic change. In recent years, there has been tremendous effort to focus research on the development of newer diagnostic methods focusing on serological, molecular, and proteomic approaches. This article examines the various diagnostic tools that are being used in clinical laboratories, optimized in reference laboratories, and employed in mass screening programs.

Diagnostic testing for Giardia infections

The traditional method for diagnosing Giardia infections involves microscopic examination of faecal specimens for Giardia cysts. This method is subjective and relies on observer experience. From the 1980s onwards, objective techniques have been developed for diagnosing Giardia infections, and are superseding diagnostic techniques reliant on microscopy. Detection of Giardia antigen(s) by immunoassay is the basis of commercially available diagnostic kits. Various nucleic acid amplification techniques (NAATs) can demonstrate DNA of Giardia intestinalis, and have the potential to become standard approaches for diagnosing Giardia infections. Of such techniques, methods involving either fluorescent microspheres (Luminex) or isothermal amplification of DNA (loop-mediated isothermal amplification; LAMP) are especially promising.

Factors associated with parasitic infection amongst street children in orphanages across Lima, Peru

Infection caused by intestinal parasites has significant public health consequences amongst children in the developing world. Street children are an under-studied group of society subjected to increased health risks when compared to their peers. To estimate the prevalence of intestinal parasitic infection and ascertain risk factors for parasitosis amongst this population, stool samples were collected from 258 children across four orphanages in three districts of Lima, Peru. Surveys were used to determine associations between risk factors and infection status. The prevalence of parasitic infection within the study sample was 66·3%, with 30·6% testing positive for pathogenic species. Entamoeba coli was the most commonly detected parasite (41·9%) and Giardia lamblia was the most commonly detected pathogenic parasite (17·1%). Of the group 15·1% had helminth infection. When testing for association, age and BMI were risk factors for infection. A notable difference in prevalence (P < 0·00001) based on orphanage was observed, but the duration of residence in an orphanage was not a predictor for infection. A sub-analysis conducted amongst children who were given anti-parasitic treatment 5 months beforehand found no significant difference in parasitosis between those who had been given treatment and those who had not (P = 0·218). It is suggested that a single dose of albendazole alone may not be effective in combating long-term infection rates.

Giardia duodenalis arginine deiminase modulates the phenotype and cytokine secretion of human dendritic cells by depletion of arginine and formation of ammonia

Depletion of arginine is a recognized strategy that pathogens use to evade immune effector mechanisms. Depletion depends on microbial enzymes such as arginases, which are considered virulence factors. The effect is mostly interpreted as being a consequence of successful competition with host enzymes for the substrate. However, both arginases and arginine deiminases (ADI) have been associated with pathogen virulence. Both deplete arginine, but their reaction products differ. An ADI has been implicated in the virulence of Giardia duodenalis, an intestinal parasite that infects humans and animals, causing significant morbidity. Dendritic cells (DC) play a critical role in host defense and also in a murine G. duodenalis infection model. The functional properties of these innate immune cells depend on the milieu in which they are activated. Here, the dependence of the response of these cells on arginine was studied by using Giardia ADI and lipopolysaccharide-stimulated human monocyte-derived DC. Arginine depletion by ADI significantly increased tumor necrosis factor alpha and decreased interleukin-10 (IL-10) and IL-12p40 secretion. It also reduced the upregulation of surface CD83 and CD86 molecules, which are involved in cell-cell interactions. Arginine depletion also reduced the phosphorylation of S6 kinase in DC, suggesting the involvement of the mammalian target of rapamycin signaling pathway. The changes were due to arginine depletion and the formation of reaction products, in particular, ammonium ions. Comparison of NH(4)(+) and urea revealed distinct immunomodulatory activities of these products of deiminases and arginases, respectively. The data suggest that a better understanding of the role of arginine-depleting pathogen enzymes for immune evasion will have to take enzyme class and reaction products into consideration.

Comparison of the Triage Micro Parasite Panel and Microscopy for the Detection of Entamoeba histolytica/Entamoeba dispar, Giardia lamblia, and Cryptosporidium parvum in Stool Samples Collected in Kenya

Entamoeba histolytica, Giardia lamblia, and Cryptosporidium parvum are three of the most important parasitic causes of acute diarrhea worldwide. Laboratory diagnosis of these parasites is usually done by ova and parasite examination (O&P examination) via microscopy. The sensitivity and specificity of O&P examination varies among laboratories and can be labor intensive and time consuming. The Triage Micro Parasite Panel (BioSite, San Diego, California) is an enzyme immunoassay kit that can detect E. histolytica/E. dispar, G. lamblia, and C. parvum simultaneously using fresh or frozen stool. The present study evaluated the Triage Micro Parasite Panel in detecting E. histolytica/E. dispar, G. lamblia, and C. parvum compared to O&P examination in 266 stool samples collected at medical facilities in Kenya. The sensitivity and specificity results for the Triage Micro Parasite Panel were: for E. histolytica/E. dispar: 100%, 100%, G. lamblia: 100%, 100% and C. parvum: 73%, 100%. There was no evidence of cross reactivity using the kit with other parasites identified in the stool specimens. These results indicate that the Triage Micro Parasite Panel is a highly sensitive kit that can be used for screening purposes in large scale studies or outbreak investigations or as a possible alternative to O&P examination.

Intestinal parasitic infections among children in central Albania

Although intestinal parasitic infections (IPI) among children remain a global issue, the current information on such infections in Albanian children is very limited. A cross-sectional study of the IPI in 321 children living in the Albanian counties of Tirana (152) and Elbasan (169) was therefore conducted in 2008, with a pre-tested standard questionnaire employed to gather the relevant personal and clinical data. Using formalin-ether concentration and permanent stains, stool samples were examined microscopically for the ova, cysts and oocysts of any parasites. The overall prevalence of IPI was 19% (61 of 321), with protozoan infections (11·5%) apparently more common than infections with soil-transmitted helminths (STH; 8·1%). Giardia duodenalis was the parasite most frequently detected (10·9%), followed by hookworm (5·6%), Ascaris lumbricoides (1·9%), Trichuris trichiura (0·6%), Cryptosporidium (0·3%) and Entamoeba histolytica/dispar (0·3%). The results of a univariate analysis indicated that the children from Tirana county were significantly more likely to be found infected with STH compared with the children from Elbasan county (12·5% v. 4·1%; P=0·006). Children sampled in the community were also more likely to be found STH-positive than the children sampled as they attended hospitals and health clinics (10·5% v. 6·0%) but this difference did not reach statistical significance. The children found STH-positive were five times more likely to be suffering from diarrhoea than the other children checked in clinical settings (P=0·004) and were also more likely to be suffering from abdominal pain (P=0·054) and/or diminished appetite (P=0·016).

Rapid detection and enumeration of Giardia lamblia cysts in water samples by immunomagnetic separation and flow cytometric analysis

Giardia lamblia is an important waterborne pathogen and is among the most common intestinal parasites of humans worldwide. Its fecal-oral transmission leads to the presence of cysts of this pathogen in the environment, and so far, quantitative rapid screening methods are not available for various matrices, such as surface waters, wastewater, or food. Thus, it is necessary to establish methods that enable reliable rapid detection of a single cyst in 10 to 100 liters of drinking water. Conventional detection relies on cyst concentration, isolation, and confirmation by immunofluorescence microscopy (IFM), resulting in low recoveries and high detection limits. Many different immunomagnetic separation (IMS) procedures have been developed for separation and cyst purification, so far with variable but high losses of cysts. A method was developed that requires less than 100 min and consists of filtration, resuspension, IMS, and flow cytometric (FCM) detection. MACS MicroBeads were used for IMS, and a reliable flow cytometric detection approach was established employing 3 different parameters for discrimination from background signals, i.e., green and red fluorescence (resulting from the distinct pattern emitted by the fluorescein dye) and sideward scatter for size discrimination. With spiked samples, recoveries exceeding 90% were obtained, and false-positive results were never encountered for negative samples. Additionally, the method was applicable to naturally occurring cysts in wastewater and has the potential to be automated.

The efficiency of immunoenzyme assay in the diagnosis of lambliosis

The aim of this study is to determine the difference in efficiency of direct immunoenzyme-linked assay (EIA) and conventional microscopy (CM) plus conventional concentration technique (CCT) using comparative analysis in the diagnosis of symptomatic and asymptomatic lambliosis when only one stool sample is to be tested. The study enrolled 577 examinees: 208 patients and 369 asymptomatic examinees. Lambliosis was diagnosed using CM plus CCT (three stool samples) and direct EIA (the first sample). All statistical parameters of the EIA method were 100% in the patients with symptoms of infection. In addition to that, in the group of asymptomatic carriers of Giardia lamblia (G. lamblia) some very high values of these parameters were recorded too, with sensitivity and negative predictive value being both at 100%. In contrast to the EIA method, CM plus CCT of the first stool sample demonstrated significantly lower sensitivity (66.67%) compared to the reference standard. The study did not demonstrate any statistically significant differences in diagnostic efficiancy between the EIA testing of one stool sample and CM plus CCT (p<0.05). However, the observed difference in diagnostic efficiency between the methods was very close to the cut-off value for statistical significance (p=0.06).

Comparison of microscopy, real-time PCR and a rapid immunoassay for the detection of Giardia lamblia in human stool specimens

Giardia lamblia is one of the most common intestinal parasites worldwide, with microscopy being the diagnostic reference standard for use with human stools. However, microscopy is time-consuming, labour-intensive and lacks sensitivity when single stools are examined. In the present study, microscopy, real-time PCR and a rapid immunoassay were compared for the detection of G. lamblia in human stools. All three methods were highly sensitive, with values of 99%, 100% and 98%, respectively. Specificity and positive and negative predictive values were >or=97%, except when using real-time PCR, for which the specificity and positive predictive value were 92% and 93%, respectively. The lower specificity of real-time PCR was associated mostly with failure to detect specimens regarded as true positives for G. lamblia DNA, although cross-contamination was suspected in a minority of cases because of the large amount of G. lamblia DNA present in most positive specimens. It was concluded that microscopy should remain the primary diagnostic tool for identifying G. lamblia in human stools, mainly because of its ability to simultaneously detect other gastrointestinal parasites. However, the simple and rapid immunoassay is a valuable tool to decrease turn-around time. Real-time PCR provides additional sensitivity, although there is a risk of cross-contamination. Based on this observation, and the need for other real-time assays to be developed to detect other intestinal parasites, real-time PCR is currently useful only as an additional test supplementary to microscopy.

WITHDRAWN: Drugs for treating giardiasis

BACKGROUND

There can be a high rate of recurrence of disease after initial drug treatment for giardiasis. These drugs also have a range of adverse effects.

OBJECTIVES

The objective of this review was to assess the effects of drug treatments for giardiasis.

SEARCH STRATEGY

We searched the Cochrane Infectious Diseases Group Specialized Register, CENTRAL, MEDLINE, EMBASE, Current Contents, and reference lists of articles.

SELECTION CRITERIA

Randomised and quasi-randomised trials of drug therapy for giardiasis compared with placebo or another drug.

DATA COLLECTION AND ANALYSIS

Two reviewers independently assessed trial quality and extracted data.

MAIN RESULTS

Thirty-four trials were included. Only one trial was without serious methodological flaws. Compared with placebo, drug treatment was associated with an improved cure rate (odds ratio 11.51, 95% confidence interval 2.29 to 57.98). Metronidazole treatment longer than three days had a better parasitological cure rate than other long treatment courses (odds ratio 2.41, 95% confidence interval 1.31 to 4.44), but there was significant heterogeneity between the trials. Available evidence has not detected a difference in cure between single dose therapy and longer treatment courses (odds ratio 0.33, 95% confidence interval 0.08 to 1.34). Within the single dose regimens, the available evidence did not demonstrate a difference in parasitological cure rate between tinidazole and other short therapies (odds ratio 3.39, 95% confidence interval 0.95 to 12.04), but had a higher clinical cure rate (odds ratio 5.33, 95% 2.66 to 10.67).

AUTHORS' CONCLUSIONS

A single dose of tinidazole appears to give the highest clinical cure rate for giardiasis with relatively few adverse effects.

A rational approach to the stool ova and parasite examination

BACKGROUND

Examination of multiple stool specimens per patient to rule out parasitic infection continues to be recommended in the literature. Attractive alternatives have been proposed, such as examination of a single specimen, but data to support their use have been inconclusive.

METHODS

We reviewed the results of comprehensive stool ova and parasite examinations performed during a 1-year period to determine the incremental value of examining >1 specimen. Next, we implemented rejection criteria, allowing analysis of only a single specimen in most cases, and studied the impact of the change by reviewing data from a subsequent year.

RESULTS

Prior to implementation of rejection criteria, 91% of parasites were detected in the first specimen submitted, although many clinical evaluations (72%) involved the submission of only 1 stool specimen. When at least 3 specimens were submitted, the sensitivity of examining the first in the series was 72%. Even the latter sensitivity provides negative predictive values of approximately 98%, approximately 97%, approximately 95%, or approximately 93% when the prevalence of parasites among those tested is 5%, 10%, 15%, or 20%, respectively. Examination of additional specimens after examination of the first specimen that yielded a positive finding revealed previously undetected parasites in only 10% of cases. After the application of rejection criteria, the parasite detection rate did not change significantly.

CONCLUSIONS

Comprehensive examination of a single stool specimen is sufficient for most patients, when the prevalence of infection among the tested population is up to 20%. Rational use of the stool ova and parasite examination relies on communication between clinician and laboratory, and retention of deferred specimens in case examination of additional specimens is clinically warranted.

Cyst morphology and sequence analysis of the small subunit rDNA and ef1 alpha identifies a novel Giardia genotype in a quenda (Isoodon obesulus) from Western Australia

Sequence analysis of the small subunit ribosomal DNA (SSU-rDNA) and elongation factor 1 alpha (ef1 alpha) was performed on Giardia cysts isolated from faeces collected from a quenda (Isoodon obesulus) in the southwest of Western Australia. The SSU-rDNA and ef1 alpha were sequenced in their entirety and correspondingly aligned with the published sequence information of other known species and genotypes of Giardia. Phylogenetic analysis of the SSU-rDNA and ef1 alpha sequences identified the quenda isolate as a novel genotype of Giardia not previously reported. We believe that this quenda Giardia isolate constitutes a distinct species, which may be endemic within the Australian native fauna.

Reducing illness transmission from disinfected recreational water venues: swimming, diarrhea and the emergence of a new public health concern

Recreational water-related illnesses are associated with swimming in contaminated water venues. The transmission of diarrheal illness in disinfected settings is influenced by several factors which include: chlorine resistance in waterborne pathogens; poor facility maintenance of disinfectant levels; and lack of healthy swimming habits. Health care providers can help to disseminate healthy swimming messages to their patients and help to prevent and control this emerging public health concern.

Triple Faeces Test: an effective tool for detection of intestinal parasites in routine clinical practice

Microscopic examination of stool specimens is the cornerstone of detection of intestinal parasites in parasitology laboratories. In Europe, fresh, nonpreserved stool specimens are generally used for examination. Because intestinal parasites are shed intermittently, patients are asked to deliver multiple stool samples for examination. The limitation of this diagnostic approach is that detection of the vegetative stages of protozoa may be missed because of delays in processing and/or low compliance with the request to submit multiple stool samples. To overcome this limitation, a diagnostic test that combines multiple sampling (on 3 consecutive days), a fixative (SAF; sodium acetate acetic acid formalin), a concentration method and an easy-to-use permanent stain (chlorazol black dye) was developed for use in routine clinical practice. The results of the test, called the "Triple Faeces Test" (TFT), were compared with those of the conventional diagnostic method, i.e. ether sedimentation of a single fresh stool specimen. Stool samples from 544 patients were examined. Vials from the TFT-sets were filled by patients precisely according to instructions in 462 of 544 (85%) of the cases. Using the conventional method and the TFT, 106 and 209 patients, respectively, were diagnosed with infection by one or more parasitic species ( P<0.005). Pathogenic species were detected by the conventional method and by the TFT in 39 and 94 cases, respectively, and nonpathogenic species were detected in 124 and 288 cases, respectively ( P<0.05). Additional costs for the sampling device, laboratory reagents and handling of the TFT were acceptable. The results of this study suggest that the TFT is an effective method for detection of intestinal parasites in stool samples in routine clinical practice.

Evaluation of three commercial assays for detection of Giardia and Cryptosporidium organisms in fecal specimens

There is an increasing demand for diagnostic testing for Giardia intestinalis (G. lamblia) and Cryptosporidium parvum, with a priority being placed on obtaining diagnostic results in an efficient and timely manner. Several commercial companies have developed rapid diagnostic tests that are simple to perform and can be completed in less time than traditional methods for detecting Giardia and Cryptosporidium: We compared one of these rapid tests, the ImmunoCard STAT! (Meridian Bioscience, Inc.) lateral-flow immunoassay, with the MERIFLUOR direct fluorescent-antibody (DFA) test, the ProSpecT EZ microplate assay for Giardia and the ProSpecT microplate assay for Cryptosporidium, and modified Kinyoun's acid-fast stained smears for the detection of Cryptosporidium using 246 specimens. The MERIFLUOR DFA (Meridian Bioscience, Inc.) test detected the largest number of cases (32 Giardia and 37 Cryptosporidium) infections and was used to calculate the sensitivity and specificity of the other tests. For Giardia, the sensitivities of the ImmunoCard STAT! and the ProSpecT Giardia EZ microplate assay (Alexon-Trend, Inc.) were 81 and 91%, respectively. For detection of Cryptosporidium, the sensitivities of the ImmunoCard STAT!, the ProSpecT Cryptosporidium microplate assay (Alexon-Trend, Inc.), and modified Kinyoun's acid-fast stained smears were 68, 70, and 78%, respectively. Test specificities were equal to or greater than 99%. Specimens with very small numbers of organisms were not detected by the ImmunoCard STAT!, the ProSpecT microplate assay or modified Kinyoun's acid-fast stained smears.

The Efficiency of Duodenal Aspirate in the Diagnosis of Parasitosis and Candidiasis

A hundred patients presenting with dyspepsia and/or symptoms suggesting parasitosis/candidiasis were subjected to oesophago-gastroduodenoscopy (OGD) in the Endoscopy Unit of Basrah Teaching Hospital Duodenal ulcers were found in 23% of them. Duodenal aspirate and stool samples were taken and examined microscopically for parasitosis and candidiasis. Examination of duodenal aspirates revealed the presence of Giardia lamblia in 15% of the cases, B. hominis in 5%, C. parvum in 4% and Candida spp. in 16%; the respective figures for those microorganisms in stool samples were 8%, 12%y 2% and 7%. There was no characteristic pH level of the duodenal aspirate in relation to parasitosis, candidiasis or endoscopic findings.

Brush cytology: an adjunct to diagnostic upper GI endoscopy

Endoscopic brush cytology (EBC) was performed in antral and duodenal brushings of children subjected to upper GI endoscopy for the detection of H. pylori (Hp) and trophozoites of Giardia lamblia (Glt) in addition to routine endoscopic grasp biopsy (EGB). It was hospital based prospective study. EBC was performed in children subjected to upper GI endoscopy with a sheathed cytology brush. Mucosal brushings were collected from antrum, body of the stomach and second or third part of duodenum by gently rubbing the surface of the brush with the mucosal wall in all the directions, brush withdrawn and brushings performed on a glass slide. The smears were placed in 95% ethyl alcohol and later examined for Glt and Hp using Giemsa and Hematoxylin & Eosin stain. EGB was taken from antrum, body of the stomach and duodenum from sites other than those used for brushings. One hundred and seventy children between 1-13 years (median age = 5 years) were subjected to upper GI endoscopy for malabsorption (n = 94), recurrent abdominal pain (n = 49), failure to thrive (n = 16) and recurrent vomiting/regurgitation (n = 11) and EBC was performed in addition to routine EGB. Thirty five children (20.4%) were colonized by Hp, 14 (8.2%) were detected to have Glt and in 6 cases (3.5%) both Hp as well as Glt were detected. Out of 41 cases colonized by Hp, 24 cases (58.5%) were detected by EGB and 27 cases (65.8%) were detected by EBC. Out of 20 children in whom Glt were detected from their duodenum, the detection was by EBG in 12 cases (60%) and by EBC in as many as 19 cases (95%). Comparison of EGB and EBC suggested that detection rates with EBC were higher than EGB. Detection by EBC was significantly higher for Glt than Hp. There were no complications attributed to EBC and procedure time for endoscopy was not significantly prolonged. On the contrary, detection of Hp and particularly Glt in higher proportion of cases with the help of EBC was helpful in their appropriate management. Our results suggest that EBC is a safe and useful tool to enhance the value of diagnostic endoscopic procedure when used in combination with routine EGB.

Use of an enzyme immunoassay does not eliminate the need to analyze multiple stool specimens for sensitive detection of Giardia lamblia

The relative sensitivities of a commercially available enzyme immunoassay (EIA) (ProSpecT Giardia; Alexon-Trend Inc., Ramsey, Minn.) and conventional ovum-and-parasite (O&P) examination for the detection of Giardia lamblia in preserved stool specimens were determined. Paired stool samples collected independently within a 7-day period from 103 patients were analyzed by both methods. A total of 54 specimens from 30 patients (18 asymptomatically infected with G. lamblia and 12 with symptoms consistent with intestinal giardiasis) were determined to be positive for G. lamblia, of which 48 (88.9%) were positive by microscopy and 52 (96.3%) were positive by EIA. Both specimens submitted were positive for G. lamblia by O&P examination for 66.7% (20 of 30) of the positive patients; for 26.7% (8 of 30) a single specimen was positive by O&P examination, and for 6.7% (2 of 30) of those determined to be infected with G. lamblia, both samples were negative by microscopy. The sensitivity of conventional O&P examination was somewhat higher in symptomatically infected individuals, with 75% (9 of 12) of patients in this category having G. lamblia detected in both samples, compared with 61% (11 of 18) of asymptomatic patients. A total of 24 positive patients (80%) had G. lamblia antigen detected by EIA in both submitted samples, 4 positive patients (13.3%) had one specimen positive by EIA, and the EIA was negative in both specimens from 2 infected individuals (6.5%), the sensitivity of EIA was substantially equivalent in asymptomatic and symptomatic individuals (77 versus 83% of patients with positive results on both specimens). Although the sensitivity of EIA for the detection of G. lamblia on a single stool specimen was somewhat higher than that of conventional O&P examination in symptomatic patients (83 versus 75%), in asymptomatic patients (77 versus 61%), and overall (80 versus 67%), examination of two specimens by either EIA or microscopy was necessary to achieve a diagnostic sensitivity of greater than 90%.

[Comparison of 4 techniques for the diagnosis of Giardia lamblia in stool of children from Belém city, Pará State, Brazil]

We report the evaluation of four techniques for Giardia lamblia diagnosis in children's stool. The Iron haematoxilin staining and direct examination with lugol showed lower positivity, while the method of Faust et al. Continues to be a good option for G. lamblia diagnosis and Immunoenzymatic assay increases the detection of this parasite.

PCR detection of Giardia lamblia in stool: targeting intergenic spacer region of multicopy rRNA gene

A PCR based detection that amplifies the 552-bp intergenic spacer (IGS) region of multicopy rRNA gene of Giardia lamblia and 320-bp internal sequences to first PCR product has been used in diagnosis of giardiasis in stool sample. The primers were found highly specific to Giardia spp. only, because no amplification was observed with DNAs from other enteric pathogens like Escherichia coli, Shigella dysenteriae and Entamoeba histolytica. The test could detect even less than 2 pg of genomic DNA from Giardia trophozoites. In direct diagnosis of Giardia lamblia in stool samples, it was observed that PCR amplification of IGS followed by nested PCR could enhance the sensitivity and specificity of the tests manifold and the system was able to detect as low as 10 parasites in 100 microl of stool. The comparative evaluation of the present system with conventional microscopy, CIEP and ELISA in the diagnosis of giardiasis from diarrhoeic stool samples and control subjects demonstrated a 100% correlation among nested PCR, microscopic examination and ELISA in patients suggestive of giardiasis (Group I) and control subjects (Group II). In Group I cases (patients suffering from other than giardiasis), CIEP, ELISA and nested PCR showed better results than microscopic examination. However, among them, PCR was found most sensitive and specific because 20% positivity was noticed by PCR whereas CIEP and ELISA showed only 7.14% and 12.85%, respectively. Break-up results showed that all the samples which were positive by CIEP or ELISA, also found positive by PCR. The present observation clearly suggests the use of PCR that amplifies the intergenic spacer region of multicopy rRNA gene of Giardia lamblia followed by nested PCR for routine, quick and reliable detection of Giardia lamblia in stool samples.

Drugs for treating giardiasis

BACKGROUND

There can be a high rate of recurrence of disease after initial drug treatment for giardiasis. These drugs also have a range of adverse effects.

OBJECTIVES

The objective of this review was to assess the effects of drug treatments for giardiasis.

SEARCH STRATEGY

We searched the Cochrane Infectious Diseases Group trials register, the Cochrane Controlled Trials Register, Medline and Embase, Current Contents, reference lists of articles.

SELECTION CRITERIA

Randomised and quasi-randomised trials of drug therapy for giardiasis compared with placebo or another drug.

DATA COLLECTION AND ANALYSIS

Two reviewers independently assessed trial quality and extracted data.

MAIN RESULTS

Thirty-four trials were included. Only one trial was without serious methodological flaws. Compared with placebo, drug treatment was associated with an improved cure rate (odds ratio 11.5, 95% confidence interval 2.3 to 58). Metronidazole treatment longer than three days had a better parasitological cure rate than other long treatment courses (odds ratio 2.4, 95% confidence interval 1.3 to 4.4), but there was significant heterogeneity between the trials. Single dose therapy appeared equally effective as longer treatment courses (odds ratio 0.33, 95% confidence interval 0.08 to 1.34). Within the single dose regimens, tinidazole had a comparable parasitological cure rate to other short therapies (odds ratio 3.4, 95% confidence interval 0.95 to 12), but had a higher clinical cure rate (odds ratio 5.3, 95% 2.7-10.7).

REVIEWER'S CONCLUSIONS

A single dose of tinidazole appears to give the highest clinical cure rate for giardiasis with relatively few adverse effects.

Detection of a giardia lamblia coproantigen by using a commercially available immunoenzymatic assay, in belo horizonte, brazil

It is known that fecal examination to detect Giardia lamblia cysts or trophozoites produces a high percentage of false-negative results. A commercially available immunoenzymatic assay (ProSpecT Giardia Microplate Assay, Alexon, Inc., BIOBRAS) to detect G. lamblia specific coproantigen was evaluated for the first time in Brazil. A total of 90 specimens were tested. Each specimen was first tested as unpreserved stool, and then it was preserved in 10% Formalin to be tested 2 months later. The assay was able to identify all the 30 positive patients (sensitivity = 100.0%) by visual or spectrophotometric examination in the unpreserved specimens and was negative in 57 of the 60 patients without G. lamblia (specificity = 95.0%). The assay identified 27 of the 30 positive patients (sensitivity = 90.0%) and was negative in 59 of the 60 negatives (specificity = 98.3%) in the preserved stools according to both readings. A marked difference was observed in the optical densities in both groups, preserved and unpreserved stools, when the G. lamblia-positive specimens were compared to the negative or positive for other intestinal parasites than G. lamblia. The assay seems a good alternative for giardiasis diagnosis, especially when the fecal examination was repeatedly negative and the patient presents giardiasislike symptoms.

Giardia duodenalis: inter-strain variability of proteins, antigens, proteases, isoenzymes and nucleic acids

Giardia duodenalis isolates from asymptomatic or symptomatic patients and from animals present similarities and differences in the protein composition, antigenic profile, pattern of proteases and isoenzymes, as well as in nucleic acids analysis. In the present overview, these differences and similarities are reviewed with emphasis in the host-parasite interplay and possible mechanisms of virulence of the protozoon.

Comparison of nine commercially available enzyme-linked immunosorbent assays for detection of Giardia lamblia in fecal specimens

Overall performance, including ease of use, total hands-on time, incubation and processing times, sensitivity, and specificity, of each of nine enzyme-linked immunosorbent assays (ELISAs) were compared by using 222 individual fecal samples submitted for the detection of Giardia lamblia. The assays evaluated were manufactured by Alexon, Inc., Cambridge Biotech Corp., Meridian, Inc., and Trend Scientific, Inc. All assays used polyclonal antibodies except the "new and improved" Microplate (direct and diluted methods) by Alexon, which is a monoclonal antibody assay. Seventy specimens were positive for G. lamblia by ELISA, ova and parasite test, and/or direct fluorescent-antibody assay. One hundred fifty two were negative by all three methods. Sensitivities and specificities ranged from 88.6 to 100% and 99.3 to 100%, respectively. The total hands-on time needed to run one specimen ranged from 1 min to 2 min 17 s per specimen. All except one commercially available ELISA were found to be rapid, sensitive, and specific for the detection of G. lamblia in fecal specimens.

Sensitivity of microscopy versus enzyme immunoassay in the laboratory diagnosis of giardiasis

The substitution of enzyme immunoassay (EIA) techniques for microscopy as a screening tool for Giardia lamblia infection was assessed. Paired stool samples obtained within a ten-day period from 366 patients with persistent diarrhea were examined by microscopy. In addition, two commercially available Giardia lamblia-specific EIAs were performed. Compared with microscopy, EIA for copro-antigen detection was more sensitive, based on examination of either one or two stool samples. Repeated examinations increased the number of cases detected, more so for microscopy than EIA. The negative predictive values of the two EIAs performed on the first stool sample were 98.7% and 97.8%. The results show that EIA for detection of copro-antigens in a single stool sample may be almost as sensitive for identifying Giardia infection as repeated microscopy on two sequential stool samples.

Severe giardiasis and cryptosporidiosis in Scotland, UK

Hospital discharge data from 1990-4 for 26 hospitals were used to estimate and compare the cost and describe the epidemiology of severe giardiasis and cryptosporidiosis in Scotland, UK. The incidence of severe cryptosporidiosis was almost double that of severe giardiasis and the median duration of hospitalization was longer for cryptosporidiosis than giardiasis. Impaired immunity was frequently listed as co-diagnosis with cryptosporidiosis and associated with extended hospitalization. Although both infections were associated with infants, the median age was lower for cryptosporidiosis (5 years compared with 30 years). Whereas hospitalization was not significantly longer for infants with cryptosporidiosis, hospitalization for this age group with giardiasis was longer (4 days compared with 3 days). Comparison with similar data for giardiasis from USA revealed various differences and similarities. These points are discussed in relation to the epidemiology of these infections and published data were used to estimate costs of hospitalization.

The approach to stool examination for parasites

This article presents the sequences followed in order to maximize the yield of laboratory assistive diagnosis of parasitic infections in the physiologic passage and/or collection of specimens for those parasites producing pathologic disease in the gastrointestinal tract and liver. The advantages and disadvantages of the many methods available to the clinician and laboratorian in the examination of those specimens are presented in a work-flow mode. The controversy relative to the current practice of controlling unwarranted specimen submission and the reasons for their rejection of limited examination and interpretation are discussed. Quality assurance and safety practices are also addressed.

Occurrence of Giardia lamblia in children of municipal day-care centers from Botucatu, São Paulo State, Brazil

Considering that the number of day-care centers for pre-school-age children has expanded rapidly in developing countries, and that these institutions presenting conditions that facilitate the transmission of many enteric agents, a parasitological survey was carried out in three municipal day-cares from Botucatu: two in the urban area (one in downtown area and the other one in the city periphery area) and the third in the rural area. Three separate stool specimens were collected from 147 children ranging from 0 to 72 months old and 20 staff members. Each stool specimen was processed by Lutz and zinc sulfate flotation methods. The frequency of giardiasis observed among children of downtown, periphery and rural day-cares was 69.6%, 52.7% and 69.6%, respectively. Only one employee was positive for G. lamblia. The examination of three stool specimens increased the positivity for G. lamblia: from the ninety three final positive examinations, 24 (25.5%) and 8 (8.5%) were positives only after examination of the second and third samples, respectively. Others intestinal organisms like Ascaris lumbricoides (20.4%), Trichuris trichiura (19.0%). Hymenolepis nana (8.8%), Entamoeba coli (22.4%) and Blastocystis hominis (32.0%) were frequently found in the children. There was no significant association among localization of the day-cares, sex of the children and the levels of G. lamblia infection. According to the age, G. lamblia was found mainly in children between 12 to 47 months old.

Detection of Giardia lamblia cysts in stool samples by immunofluorescence using monoclonal antibody

The diagnostic potential of indirect immunofluorescence to detect Giardia cysts in stool samples using a cyst-specific anti-Giardia lamblia monoclonal antibody was evaluated in comparison to conventional light microscopy. One hundred fifty specimens from clinically suspected Giardia infections and 50 control samples from microscopically proved Giardia infections were tested. Giardia cysts were found in 15 of 150 (10%) samples tested by light microscopy, whereas immunofluorescence microscopy detected 35 of 150 (23%) positive samples. Forty-six of the 50 reference samples previously shown to contain Giardia cysts were positive. Apparently, the four discrepant samples contained very low numbers of parasites, as none could be detected by conventional microscopy. The results show that Giardia lamblia cysts are detected significantly more frequently using the antibody marker. The doubled number of positive stool specimens and detection of as little as four cysts per sample suggest that microscopical examination of samples can be improved by immunofluorescent staining of Giardia lamblia cysts.

Prevalence of giardiasis among primary school children

This cross-sectional study was conducted to investigate the prevalence of intestinal parasites among primary school children in Northern Jordan. Stool specimens were collected from 1100 children of both sexes from urban and rural schools. A questionnaire covering relevant informations was completed for each child. Wet mount preparation, formaline-ether concentration technique, and trichrome stain were prepared for the recovery and identification of parasites. Giardia lamblia was observed in 396 (36%) of the stool specimens examined. The infection rates were higher in the younger age group where several of them had diarrhoea and reported variable symptoms. The infection rates declined with age and children were asymptomatic. Rates were higher in children from the rural areas, from low income families, and it was higher in boys than girls. Contaminated drinking water is suspected to be the major potential source of infection. The importance of the asymptomatic cases and the epidemiological factors contributing to the transmission in these areas are discussed.