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PubMed1987

Ingestion of Giardia lamblia trophozoites by human mononuclear phagocytes.

Mononuclear phagocytes may be important effector cells against Giardia lamblia. Human monocyte-derived macrophages were incubated with G. lamblia trophozoites in 13% heat-inactivated autologous serum. At a G. lamblia/macrophage ratio of 1:1, the number of trophozoites ingested per 100 macrophages ranged from 1 to 12 at 0.5 h and increased for all donors (n = 6) to 10 to 92 at 8 h. Ingestion was confirmed by electron microscopy. Increasing the parasite/phagocyte ratio to 5:1 increased the percentage of macrophages with adherent but not ingested trophozoites. Incubating Giardia cells and macrophages with 20% immune serum increased ingestion of parasites eightfold, indicating that anti-G. lamblia antibody can enhance ingestion. Both phase-contrast microscopy and electron microscopy documented trophozoite destruction within macrophages. Ingestion of parasites elicited an oxidative burst as measured by luminol-enhanced chemiluminescence. In vitro, Giardia trophozoites were killed by greater than or equal to 5 X 10(-5) M H2O2. Fusion of lysosomes with parasite-containing phagosomes was suggested by acridine orange-stained preparations. Human macrophages have the capacity to ingest Giardia trophozoites and to kill intracellular parasites, possibly by oxidative microbicidal mechanisms.

Animals↗
PubMed1993

Variant cysteine-rich surface proteins of Giardia isolates from human and animal sources.

Cloned Giardia isolates obtained from a sheep, a calf, and a human possessed a major membrane protein that showed marked intraspecific variations in size as demonstrated by sodium dodecyl sulfate-polyacrylamide gel electrophoresis following surface biotinylation and radioiodination. Metabolic labeling with [35S] cysteine and electrophoretic analysis also revealed for each cloned isolate a predominant protein that corresponded in size to the major surface protein demonstrated by surface labeling techniques. Immunoprecipitation studies with a polyclonal antiserum specifically directed against the 90-kDa major cysteine-rich protein purified from a subclone of the sheep isolate (O2-4A1) showed that the cysteine-rich protein and the major surface protein are identical. The surface location of the antigen was further corroborated by the reaction of fluorescence-labeled antibodies raised against the 90-kDa O2-4A1 cysteine-rich protein with the entire surface of live trophozoites of the homologous clone. The ability of the cloned Giardia isolates to undergo variations of their cysteine-rich surface protein (CRISP) was demonstrated by the spontaneous appearance of new CRISPs in clonally derived populations during prolonged in vitro culturing and in cultures of the O2-4A1 clone that had survived treatment with the cytotoxic anti-90-kDa CRISP antiserum specific for the surface antigen of this clone. The surviving progeny were devoid of the original CRISP, as judged by resistance to the immune serum. Subsequent cysteine metabolic labeling of the recloned surviving trophozoites demonstrated a large number of new variants, each expressing a single CRISP that varied significantly in molecular weight from those in the different cloned lines. These studies suggest that the presence of CRISPs and their variations are not restricted to Giardia isolates obtained from humans but are universal phenomena among the Giardia duodenalis types of organisms.

Animals↗
PubMed1994

Genotypic heterogeneity within Giardia lamblia isolates demonstrated by M13 DNA fingerprinting.

There has been considerable speculation regarding the possible relationship between the phenotypic and genotypic heterogeneity seen among human isolates of Giardia lamblia and the wide clinical spectrum of human giardiasis. Several workers have suggested that human giardiasis may be a mixed infection consisting of variant strains or subgroups which are present in the same infection and which are selectable, but it is not clear whether these apparent variant strains represent a truly heterogeneous infection or whether the genotypic heterogeneity observed is due to the susceptibility of the Giardia genome to a high rate of structural genetic rearrangement. We have therefore studied variation in Giardia intestinalis genotypes in 19 isolates in vitro and in vivo by using the technique of M13 DNA fingerprinting. Genotypes of isolates changed with time when cultured under standard conditions and when pressured with bile. Sequential isolates and their clones taken from a patient with chronic giardiasis both before and after several treatments with metronidazole had different genotypes. Finally, clones of isolate WB had different initial genotypes, which changed after 4 months in culture. These findings suggest that the apparent genotypic heterogeneity at least in these G. intestinalis isolates is more likely to be due to the plasticity of the Giardia genome than to the presence of a truly mixed population of strains within the same infection.

Animals↗
PubMed2005

Lactobacillus johnsonii La1 antagonizes Giardia intestinalis in vivo.

This study describes the in vivo activity of Lactobacillus johnsonii La1 (NCC533) in Giardia intestinalis-infected gerbils (Meriones unguiculatus). Daily administration of lactobacilli in the drinking water from 7 days before inoculation with Giardia trophozoites efficiently prevented G. intestinalis strain WB clone C6 from infecting gerbils. More specifically, shedding of fecal Giardia antigens (GSA65 protein) was diminished in the La1-treated group, and resolution of infection was observed by 21 days postinoculation. Histology and analysis of enzymatic markers of microvillus membrane integrity revealed that probiotic administration also protected against parasite-induced mucosal damage. In addition, a cellular response to Giardia antigens was stimulated in spleen cells from La1-treated gerbils. Results show for the first time the antigiardial effect of probiotic lactobacilli in vivo and provide further insight into the antagonistic properties of lactic acid bacteria against protozoa involved in intestinal infections.

Animals↗
PubMed1989

Stool diagnosis of giardiasis using a commercially available enzyme immunoassay to detect Giardia-specific antigen 65 (GSA 65).

A commercially available enzyme immunoassay for the diagnosis of giardiasis was evaluated in a clinical trial. The ProSpecT/Giardia diagnostic test (Alexon, Inc., Mountain View, Calif.) was compared with the standard ova and parasite (O&P) microscopic examination. Additionally, several widely used stool fixatives and a commonly used transport medium were assessed for compatibility with the immunoassay. A total of 325 stool specimens were collected and used to evaluate assay performance. Of those, 93 specimens were collected from symptomatic Giardia O&P-positive patients and 232 specimens were randomly collected from patients as part of a routine health screening procedure. All 93 Giardia O&P-positive stool specimens were strongly positive by visual and spectrophotometric examination using the immunoassay. Of the 232 randomly collected specimens, 16 were positive by O&P examination and immunoassay, 6 were negative by O&P examination but positive by immunoassay, and 1 was positive by O&P examination and negative by immunoassay. There was substantial supportive evidence that indicated that the six immunoassay-positive, O&P-negative specimens were true-positives. When these six specimens were accepted as true-positives, the immunoassay detected almost 30% more cases of Giardia infection than did O&P examination. Its sensitivity and specificity were 96 and 100%, respectively, while the sensitivity and specificity of O&P examination were 74 and 100%, respectively. The immunoassay also performed well on specimens treated with 10% neutral Formalin, sodium acetate-Formalin fixative, and Cary-Blair transport medium. However, the test was not compatible with polyvinyl alcohol-treated specimens. Overall, the ProSpecT/Giardia test was a sensitive, specific immunoassay which was easy to run and interpret. It offers a simple solution to traditional difficulties encountered in diagnosing Giardia infection.

Animals↗
PubMed2000

Performance of three enzyme immunoassays and two direct fluorescence assays for detection of Giardia lamblia in stool specimens preserved in ECOFIX.

ECOFIX is a single-vial stool preservative that is both formalin- and mercury-free. We evaluated the abilities of three commercial Giardia lamblia-specific enzyme immunoassays (EIAs) (ProSpecT Giardia Microplate Assay [Alexon-Trend Inc.], Giardia Test [Techlab], and Premier Giardia lamblia [Meridian Diagnostics, Inc.]) and two commercial direct fluorescent-antibody (FA) assays for G. lamblia (Crypto/Giardia IF Test [Techlab] and Merifluor Cryptosporidium/Giardia [Meridian Diagnostics, Inc.]) to detect G. lamblia in 34 G. lamblia-positive and 44 G. lamblia-negative stool specimens (determined by traditional examination for ova and parasites) preserved in ECOFIX compared to their abilities to detect G. lamblia in the same specimens preserved in formalin as the "gold standard" for each assay. Of the 34 formalin-fixed positive specimens, the number detected by each assay was as follows:, Alexon EIA, 34; Meridian EIA, 27; Techlab EIA, 29; Meridian FA assay, 31; and Techlab FA assay, 28. Both FA tests and the Alexon EIA performed well with ECOFIX, but the other two EIAs detected fewer positive specimens (the difference was statistically significant with the Techlab EIA) when ECOFIX was the preservative. Use of G. lamblia cyst antigen from cultured organisms preserved in formalin and ECOFIX demonstrated that the Alexon EIA could detect smaller amounts of antigen in ECOFIX than the other two EIAs could and suggested that cyst antigen is more stable in formalin. We recommend that laboratories use an FA assay or the Alexon EIA if they plan to use ECOFIX as their stool preservative.

Animals↗
PubMed2005

Multiplex real-time PCR assay using Scorpion probes and DNA capture for genotype-specific detection of Giardia lamblia on fecal samples.

Two major genotypic assemblages of Giardia lamblia infect humans; the epidemiologic significance of this phenomenon is poorly understood. We developed a single-vessel multiplex real-time PCR (qPCR) assay that genotypes Giardia infections into assemblages A and/or B directly from fecal samples. The assay utilized Scorpion probes that combined genotype-specific primers and probes for the 18S rRNA gene into the same molecule. The protocol was capable of detecting as few as 20 trophozoites per PCR on fecal DNA isolated using a commercial method or 1.25 trophozoites per PCR on fecal DNA isolated using a G. lamblia-specific oligonucleotide capture technique. The assay was specific for fecal specimens, with no amplification of the discordant genotype with the opposite Scorpion probe. When 97 clinical specimens from Bangladesh were used, the multiplex PCR assay detected 95% (21 of 22) of Giardia microscopy-positive specimens and 18% (13 of 74) of microscopy-negative specimens. Microscopy-negative and qPCR-positive specimens had higher average cycle threshold values than microscopy-positive and qPCR-positive specimens, suggesting that they represented true low-burden infections. Most (32 of 35) infections were assemblage B infections. This single-reaction multiplex qPCR assay distinguishes assemblage A Giardia infections from assemblage B infections directly on fecal samples and may aid epidemiologic investigation.

Animals↗
PubMed1993

Impaired IgA response to Giardia heat shock antigen in children with persistent diarrhoea and giardiasis.

The serum antibody response in Gambian children with persistent diarrhoea and giardiasis has been studied. Total serum IgG, IgA, and IgM concentrations were increased in these patients as compared with controls from the same area. Determination of the concentrations of Giardia specific antibodies by enzyme linked immuno adsorbent assay (ELISA), however, revealed that only IgM was raised while those of IgA and IgG were similar to the controls. Analysis of the antigenic determinants of the IgG and IgA responses by immunoblotting showed that patients with chronic infection unlike those who clear the infection have no IgA response to a 57 kDa Giardia heat shock antigen. The association of high concentrations of Giardia specific IgM, low concentrations of Giardia specific IgA and IgG and inability to clear the infection suggests that the switch from an IgM to an IgG or IgA response is inefficient.

Animals↗
PubMed2003

Identification of genotypes of Giardia intestinalis isolates from dogs in Japan by direct sequencing of the PCR amplified glutamate dehydrogenase gene.

Giardia has been detected in domestic dogs in Japan, but the genotype of isolates has remained unclear because identification has relied on conventional microscopy. Here we tried to identify the genotypes of four isolates from dogs in Japan by direct sequencing of the PCR amplified Giardia glutamate dehydrogenase (GDH) gene. The primer pair GDHF3 and GDHB5, targeting the GDH gene, was designed to prime a region of the GDH gene sequence conserved in the strains found to have the dog-specific genotype. The specific PCR product (approximately 220 bp), amplified with this primer pair, was only observed when Giardia DNA was used as the template. The sequences of the diagnostic fragments were identical among the isolates from dogs, and were differed by 15 bp or 1 bp from the strains, which were found to be the dog-specific genotypes, Assemblage C or D respectively. To verify the identity of the amplified DNA, a phylogenetic analysis was performed. Consequently, the sequence of the isolates from dogs clearly clustered with the strain found to be Assemblage D with neighbor-joining analyses. Therefore, all the isolates from dogs examined were identified as the dog-specific genotype, Assemblage D. In the present study, we revealed the genotype of Giardia isolates in Japan, and showed that direct sequencing of the PCR product amplified with the primer pair GDHF3 and GDHB5 was a useful tool for distinguishing between the zoonotic and dog-specific genotypes.

Animals↗
PubMed2005

Detection of Cryptosporidium sp. Oocyst and Giardia sp. cyst in faucet water samples from cattle and goat farms in Taiwan.

A survey on the presence of Cryptosporidium oocyst and Giardia cyst in livestock drinking water as well as the urban tap water throughout Taiwan was carried out. Water examination for the presence of the protozoa was conducted by filtering through a PTFE membrane followed by immunomagnetic separation (IMS) and immunostaining the sediment with commercially available monoclonal antibody against Cryptosporidium and Giardia. Of the 55 different water samples from various sources examined, 2 were found to contain both of Cryptosporidium oocyst and Giardia cyst, 1 was found to contain Cryptosporidium oocyst only. These protozoa-positive water samples, originating from underground well and from the mountain spring, were also used as drinking water for livestock. However, no Cryptosporidium oocyst was found in the city tap water. This is the first report of Cryptosporidium oocyst and Giardia cyst being found in the drinking water for livestock.

Agriculture↗
PubMed1997

Efficacy of iodine water purification tablets against Cryptosporidium oocysts and Giardia cysts.

The ability to control water-borne diseases is critical for soldiers, hikers, and others who may need to drink directly from an outdoor source. Water-borne protozoan parasites that are specifically of concern are Giardia and Cryptosporidium because of their resistance to halogen disinfection. The purpose of this study was to determine the effectiveness of iodine tablets against Giardia and Cryptosporidium under general- and worst-case water conditions that might be found in the field. Giardia cysts and Cryptosporidium oocysts were exposed to iodine according to manufacturer's instructions (two tablets/L = 13-18 mg/L for 20 minutes). This dose inactivated 3-log10 of Giardia in general-case water and pH 9. In worst-case water, however, only about 35% of cysts were inactivated at pH 5. Fifty minutes were required to achieve a 3-log10 reduction at pH 5. Cryptosporidium oocysts were more difficult to inactivate. Only 10% were inactivated after a 20-minute exposure to iodine according to manufacturer's instructions; even after 240 minutes of exposure to iodine only 66-81% oocysts were inactivated. These data strongly suggest that iodine disinfection is not effective in inactivating Cryptosporidium oocysts in water. Because this organism is common in all surface waters, it is recommended that another method of treatment be used before ingestion.

Animals↗
PubMedDate not supplied

Giardia survey in live-trapped small domestic and wild mammals in four regions in the southwest region of the state of São Paulo, Brazil.

For the first time, a survey on Giardia in live-trapped small domestic and wild mammals was performed in four regions of State of the São Paulo, Brazil, with special attention to the parasitism of Rattus rattus rattus by Giardia. This species was found infected in all studied sites: Botucatu (15.4%), Conchas (28.5%), Itaporanga (38.7%) and São Roque (100%). Two new hosts and their frequency of infection were described for Giardia in Nectomys squamipes, an aquatic rodent and in Bolomys lasiurus, a forest rodent (100% and 14.3%, respectively). Both G. muris and G. duodenalis groups were found in scrapings of intestinal mucosa of those rodents. Mixed infection was observed in some animals. It is important to emphasize the infection by G. duodenalis in the black rat as this species lives as a comensal with man and in N. squamipes as it may contaminate small streams used for domestic consumption. Therefore, further investigation will be necessary to elucidate the potencial of these rodents to act as reservoirs of Giardia for man.

Animals↗
PubMed2000

First findings of Cryptosporidium and Giardia in California sea lions (Zalophus californianus).

We report the detection and identification of Cryptosporidium and Giardia from 1 of 3 species of pinnipeds. Fecal samples were collected from Pacific harbor seal (Phoca vitulina richardsi), northern elephant seal (Mirounga angustirostris), and California sea lion (Zalophus californianus) in the northern California coastal area. By means of fluorescently labeled monoclonal antibodies, Cryptosporidium oocysts were detected in 3 samples from California sea lions, 1 of which also contained Giardia cysts. Oocysts of Cryptosporidium and cysts of Giardia were morphologically indistinguishable from oocysts of C. parvum and cysts of G. duodenalis from other animal origins. Oocysts and cysts were then purified using immunomagnetic separation techniques and identified by polymerase chain reaction (PCR), from which species-specific products were obtained. Sequence analysis revealed that the 452-bp and 358-bp PCR products of Cryptosporidium isolated from California sea lion had identities of 98% with sequences of their template fragments of C. parvum obtained from infected calves. Based on morphological, immunological, and genetic characterization, the isolates were identified as C. parvum and G. duodenalis, respectively. The findings suggested that California sea lions could serve as reservoirs in the environmental transmission of Cryptosporidium and Giardia.

Animals↗
PubMed2003

Cryptosporidium, Giardia, and Cyclospora in ancient Peruvians.

Twenty-two coprolites of human origin, collected from excavations along the north-central coast of Peru, were examined using fluorescent microscopy for the presence of fecal parasites, with emphasis on Cryptosporidium sp., Giardia sp., and Cyclospora sp. Three samples were positive. One coprolite dated between ca. 2,375 and 1,525 BC contained Giardia sp. cysts. This coprolite corresponded to the Peruvian preceramic period. Another positive coprolite ca. AD 770-830 corresponded to Epoch 3 of the Middle Horizon and contained Cryptosporidium sp. oocysts. The third positive coprolite (corresponding to the Middle Horizon. ca. AD 500-900) contained Giardia sp. cysts. This report demonstrates that Giardia sp. and Cryptosporidium sp. were present in Peruvian coastal populations for at least 4,300 and 1,100 BP.

Animals↗
PubMed2003

Identification of assemblage A Giardia in white-tailed deer.

Fecal samples were collected from hunter-killed white-tailed deer (Odocoileus virginianus) during a managed hunt in a central Maryland county. Fecal samples were cleaned of debris and concentrated by CsCl density gradient centrifugation and stained with MerIFluor reagents. Stained samples were examined by fluorescent microscopy for the presence of Giardia sp. cysts. One of 26 samples was found to be positive for Giardia sp. Polymerase chain reaction amplification using primers directed to the beta-giardin and TPI genes identified the same sample as the only positive one. Sequencing of the beta-giardin and TPI genes revealed that the Giardia sp. belonged to assemblage A, a genotype infectious for humans and also reported in a small percentage of cattle. This is the first report of assemblage A Giardia sp. in deer and suggests that deer could be a potential source of infectious cysts for humans and cattle.

Animals↗
PubMed2005

Zoonotic genotype of Giardia intestinalis detected in a ferret.

Giardia intestinalis has been found in a variety of mammals, including humans, and consists of host-specific and zoonotic genotypes. There has been only 1 study of G. intestinalis infection in weasels, but the genotype of its isolate remains unclear. In this study, we report the isolation of Giardia in a ferret exhibited at a pet shop. The isolate was analyzed genetically to validate the possibility of zoonotic transmission. Giardia diagnostic fragments of the small subunit ribosomal RNA, beta-giardin, and glutamate dehydrogenase genes were amplified from the ferret isolate and sequenced to reveal the phylogenetic relationships between it and other Giardia species or genotypes of G. intestinalis reported previously. The results showed that the ferret isolate represented the genetic group A-I in assemblage A, which could be a causative agent of human giardiasis.

Animals↗
PubMed1982

Giardia prevalence among 1-to-3-year-old children in two Washington State counties.

A survey of intestinal parasites was conducted in two Washington counties. Giardia prevalence among 518 children surveyed was 7.1 per cent and was unrelated to the source of domestic drinking water (surface or well), day care center attendance, or parental occupation. Identified risk factors for Giardia infection include a history of drinking untreated surface water and having two or more siblings between the ages of 3 and 10 years. Of 47 family members of Giardia positive children, 10 (21.3 per cent) were Giardia positive.

Child↗
PubMed2006

Evaluation of activated sludge treatment and the efficiency of the disinfection of Giardia species cysts and Cryptosporidium oocysts by UV at a sludge treatment plant in Campinas, south-east Brazil.

Among many waterborne diseases the giardiasis and cryptosporidiosis are of particular public health interest, because Giardia cysts and Cryptosporidium oocysts can persist for long periods in the environment, and both pathogenic protozoa have been implicated as the cause of many outbreaks of gastroenteritis in the last 25 years. In order to evaluate the efficiency of cysts and oocysts' removal by the activated sludge process, and by UV reactor in inactivating cysts and oocysts in one wastewater treatment plant (WWTP) of Campinas, three sampling points were selected for study: (1) influent, (2) treated effluent without UV disinfection and (3) treated effluent with UV disinfection. Giardia spp. cysts prevailed with higher density in the three different sample types. Cryptosporidium spp. oocysts were observed in only two samples of influent and just one sample of treated sewage with UV disinfection. In the animal infectivity assay for Giardia spp, one mouse of the UV treated group revealed trophozoites in intestinal scrapings. The results of the present study indicate that treatment by activated sludge process delivered a reduction of 98.9% of cysts and 99.7% of oocysts and UV disinfection was not completely efficient regarding the inactivation of Giardia cysts in the case of the WWTP studied.

Animals↗