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PubMed1990

Electrophoretic characterization of Giardia isolated from humans, cattle, sheep, and a dog in Switzerland.

Nine isolates of Giardia lamblia from humans, cattle, sheep, and 1 dog were compared by employing agarose gel isoenzyme electrophoresis and isoelectric focusing of total soluble cell protein on polyacrylamide gels. The banding patterns of the 14 enzymes examined showed remarkable similarities among the Swiss Giardia isolates. This was true also of the total soluble trophozoite proteins. The electrophoretic mobilities of most enzymes and other proteins obtained for the Swiss isolates were the same as those of 2 isolates from humans in other geographical areas, the WB and the Portland-1 strains. Only the human isolate CH-H2 could clearly be distinguished from all other isolates analyzed. The great biochemical similarities observed among the Swiss isolates contrast with the extensive heterogeneity previously demonstrated for G. lamblia by other investigators who used similar analytical techniques. These data are consistent with recent transmission studies of Giardia and suggest that in Switzerland domestic animals may serve as a reservoir of human Giardia infections and that cross-transmission between humans and animals is likely to occur.

Animals↗
PubMed1990

Antigenic variation of Giardia lamblia in experimental human infections.

To determine if Giardia surface Ag vary in human infections volunteers were inoculated enterally with trophozoites of uncloned GS/M-85 and in later experiments with two clones derived from GS/M. The surface Ag of trophozoites reisolated from 6/6 volunteers differed from the inoculum. To determine if the surface Ag of trophozoites derived from clones would also change, volunteers were inoculated with two clones, B6 or H7. B6 possesses a 200-kDa surface Ag recognized by mAb 3F6 and H7 has a 72-kDa surface Ag recognized by mAb G10/4. One of thirteen B6 and four of four H7-inoculated volunteers became infected. Analysis of Giardia obtained on day 22 from the intestines of the four H7-infected volunteers and cultures derived from these trophozoites revealed loss of the initial major surface Ag as determined by surface IFA using mAb, surface radiolabeling and loss of cytotoxicity to mAb, and Western blots. Loss of the 72-kDa Ag began after day 14 and was practically complete by day 22. The 200-kDa surface Ag was almost totally absent from the surface of Giardia isolated from the single B6-infected volunteer. Serum surface-reactive antibodies, as measured by IFA and cytotoxicity to H7 and the day 22 isolates, showed high levels of antibodies to H7, primarily to the 72-kDa surface Ag, but negligible or low levels of late-appearing antibodies to the day 22 isolates. These studies document antigenic variation of Giardia in human infections and show that humoral responses are in part isolate-specific.

Animals↗
PubMed1989

Intestinal IgA responses to Giardia muris in mice depleted of helper T lymphocytes and in immunocompetent mice.

Immunocompetent mice infected with Giardia muris generate an intestinal antibody response to this parasite and clear G. muris infection. Previous work has shown that G. muris infection is prolonged in mice that have been depleted of helper (CD4+) T lymphocytes by treatment with a monoclonal antibody (mAb) directed against the murine CD4 antigen. The aim of the present study was to compare the intestinal anti-Giardia antibody response in immunocompetent mice and in mice depleted of helper T (Th) lymphocytes by treatment with anti-CD4 mAb. Immunocompetent mice generated an IgA response to G. muris, as judged by the presence of IgA on Giardia trophozoites harvested from the intestine of these animals more than 10 days after the start of the infection. The anti-Giardia IgA response was impaired in mice depleted of Th lymphocytes, as judged by virtual absence of immunofluorescent staining of trophozoites from these animals for surface-bound IgA. Clearance of G. muris infection was impaired by treatment of mice with anti-CD4 mAb. The results suggest that Th (CD4+) lymphocytes are important for the generation of a local IgA response against G. muris trophozoites in the mouse intestine and that IgA anti-trophozoite antibody may contribute to the clearance of G. muris from the intestine of immunocompetent mice.

Animals↗
PubMed1984

Occurrence of specific secretory immunoglobulin A in bile after inoculation of Giardia lamblia trophozoites into rat duodenum.

We studied the appearance of specific secretory immunoglobulin A (IgA) antibody in bile after inoculation of live Giardia lamblia trophozoites into rat intestine. Serial bile specimens collected before and after inoculation of trophozoites were assayed for IgA antibodies by indirect immunofluorescence. Secretory IgA antibodies to Giardia lamblia were first detected in bile at 3 days after inoculation, remained elevated through 12 days, and then returned to control levels. Positive immunofluorescence of trophozoites for IgA was observed at bile titers of 1:80 to 1:160, whereas control biles were usually negative at dilutions of 1:10 or less. Scanning electron microscopic examination of Giardia in conjunction with immunocytochemistry revealed IgA antibodies bound to the flagella and surfaces of the trophozoites including the adhesive disk. These data demonstrate the occurrence of a secretory IgA immune response directed against surface antigens of Giardia lamblia trophozoites in the rat.

Animals↗
PubMed1995

Detection of Giardia antigen in stool samples before and after treatment.

A double antibody sandwich ELISA technique, using a chromatography purified Giardia antiserum, was applied to detect faecal antigen in patients infected with Giardia lamblia before and after treatment. The assay could detect antigens in 98% of infected cases with false positive reactions in 3 cases infected with E. histolytica. There was a significant direct relation between the antigen level in stool samples and the number of Giardia cysts. The mean level of copro-antigen was slightly lower in children, below 10 years, than in older patients, without significant difference. On the other hand, the lowest cyst count was noticed in elder patients, over 20 years. The level of faecal antigens decreased significantly after successful treatment in patients with giardiasis. It was concluded that detection of Giardia antigens by ELISA technique in the stool samples was a highly sensitive (98%) and specific (91%) diagnostic method. It is also considered as a good monitor for treatment success.

Adolescent↗
PubMed1995

Risk factors for development of first symptomatic Giardia infection among infants of a birth cohort in rural Egypt.

Giardia infection is associated with diarrheal diseases among infants and young children in both industrialized and developing countries. A study was conducted to demonstrate the predisposing factors for occurrence of the first symptomatic Giardia infection among infants in rural Egypt. The study cohort was followed from birth through the first year of life. Univariate and multivariate analyses of data revealed that infants less than six months of age were at special risk for developing their first symptomatic infection compared with infants more than six months of age. Analysis of the data, furthermore, revealed an increased risk of infant Giardia infection associated with living in a household without a latrine (relative risk [RR] = 2.63, confidence interval [CI] = 1.4-4.9, P < 0.05), a mud floor in the sleeping rooms (RR = 1.79, CI = 1.O30-3.0, P < 0.05), and household exposure to more than 10 chickens (RR = 2.5, CI = 1.13-5.56, P < 0.05). In contrast, the mother's education beyond the primary level (RR = 0.28, CI = 0.09-0.85, P < 0.05), drinking water stored in metallic containers (RR = 0.33, CI = 0.11-0.98, P < 0.05), and male sex (RR = 0.52, CI = 0.3-0.89, P < 0.05) were associated with decreased risk of Giardia infection. These data suggest that in addition to age of infants, poverty, low education, gender discrimination, and certain environmental conditions potentiated the risk for developing the first symptomatic infection.

Animals↗
PubMedDate not supplied

[Diagnostic limitations of the isolation of trophozoites of Giardia lamblia in duodenal aspirates].

Examination of fecal specimens for detection of Giardia lamblia cysts is known to produce a high percentage of false negative results while it is generally believed that duodenal juice often contains trophozoites even when the stool examination is negative. The aim of this study was to compare the detection of trophozoites in duodenal aspirate with the findings of cysts in stool samples for the diagnosis of asymptomatic giardiasis. Forty five children with iron deficiency anemia (one to six years of age) were studied, 21 with giardiasis and 24 without giardiasis. For each subject, one to five stool samples were examined for cysts of Giardia lamblia employing the formol-ether concentration method. Duodenal juice from all children were examined for the presence of trophozoites of Giardia lamblia. Fecal excretion of cysts was demonstrated in 20 (95%) of the 21 patients with giardiasis; however, only nine (43%) exhibited the presence of trophozoites in their duodenal aspirates. In one child trophozoites were observed in the duodenal aspirate; but the parasitologic investigation was negative for cysts in the feces. All the children without giardiasis had at least three stool samples and duodenal aspirate negative for Giardia lamblia. In conclusion, fecal examination by formol ether concentration method exhibited a greater number of positive results than did the duodenal aspirate microscopy method in the diagnosis of giardiasis.

Animals↗
PubMedDate not supplied

[Giardia lamblia extract (giardine): its immunologic mechanism].

Giardia lamblia is a protozoa that invades the high portions of human small bowel, as well the gall bladder and biliary passages. The absorption from the gut of extrinsic particles which have all properties occurs at full scale in the small bowel. Infections by this protozoa may lead to different clinical symptoms: departing free-symptom, urticarial manifestations of variable intensity and malabsorption syndromes, as well. In Cuba, Giardia lamblia parasitism constitutes a health problem because of its high incidence and prevalence. Investigators have showed allergic dermatological disorders and others, in patients with giardiasis, that may obey from two mechanisms: first, the parasite or its metabolic products might be antigenic for the host; second, the parasite may act as a hapten, that in successive sensitizations might lead to such manifestations, producing specific antibodies which have been found in patients' sera with giardiasis. We recently have elaborated an allergenic extract from Giardia lamblia (we called it giardine ), for demonstrating cutaneous sensitization to such protozoa. In other way, Prausnitz and Küstner, in 1921, showed that a dermal allergic reaction could be passively transferred by means of sensitized patient's serum to a non-sensitized subject. More recently, in 1967, Ishizaka and Ishizaka and Johansson and Benich, in separate studies, showed that skin sensitizing antibodies belonged to a different kind of immunoglobulin, IgE, and it could be measured in serum from sensitized patients. So, a study of sensitization to Giardia lamblia has been performed. Twenty-two patients have been studied suffering from giardiasis with at least 3 month evolution of this disease.(ABSTRACT TRUNCATED AT 250 WORDS)

Adolescent↗
PubMed1994

[Diagnostic value of specific Giardia fecal antigen tests].

Two commercial faecal antigen tests, based on Giardia specific antigens, were compared with traditional microscopical examination of faeces in 40 clinical patients, including 14 patients with a confirmed Giardia infection as well as in a survey among 96 children in four day care centers. The results obtained with these faecal antigen tests were not much better than by using traditional microscopy by a well trained parasitologist. Specific Giardia antigen (GSA 65) has been still detected in faeces up to day 4th after treatment of giardiasis, when microscopical examination of faeces was already for a few days negative. The Giardia antigen detection test was not very useful in examining the unconcentrated duodenal content.

Adolescent↗
PubMed1994

Effect of immunosuppression of the virulence of Giardia lamblia cysts.

This study was done to evaluate the pathological effects of Giardia lamblia cysts obtained from immunosuppressed host on the small intestine and liver of immunocompetent hosts. Thirty mice, subdivided into two groups, were infected with G. lamblia cysts in a dose of 5000 cysts/mouse. The first group (10 mice) was inoculated with Giardia cysts obtained from immunocompetent patients and the second group (20 mice) was inoculated with Giardia cysts obtained from already immunosuppressed mice (injected with cyclophosphamide). Stool examination revealed that mice in both groups passed cysts on day 6 +/- 1 after infection. The pathological changes of small intestine in both groups were more or less similar. The changes were in the form of shortening and widening of the villi with cellular inflammatory infiltrate in the lamina propria. The liver of both groups showed no pathological changes. It can be concluded that, although immunosuppression affects the immune system and the defensive mechanism of the host, yet it has no effects on the virulence of the excreted Giardia lamblia cysts.

Animals↗
PubMed1994

Periparturient rise in the excretion of Giardia sp. cysts and Cryptosporidium parvum oocysts as a source of infection for lambs.

The possibility of a periparturient rise (PPR) in the excretion of Cryptosporidium parvum oocysts and Giardia duodenalis-type cysts and its implications in the epidemiology of these 2 pathogens were investigated. Fecal samples were taken from 32 lambing ewes every 2 wk from 4 wk before lambing until 8 wk after the start of lambing. Samples from both ewes and lambs were examined with a quantitative immunofluorescence assay. Excretion of Giardia sp. cysts by ewes increased at 2 wk prepartum, peaked at zero and 4 wk postpartum, and returned to low levels at 6 and 8 wk postpartum. Some ewes also excreted C. parvum oocysts at the start of lambing. Excretion rates and intensities of Giardia sp. cysts by lambs were high, whereas those of C. parvum oocyst excretion were light. The PPR in excretion of Giardia sp. cysts by ewes was considered to be the major source of giardiasis for lambs. Excretion of C. parvum oocysts by ewes at parturition also played a role in initiating cryptosporidiosis in lambs.

Age Factors↗
PubMed1996

Giardiasis in travellers: evaluation of an antigen-capture ELISA for the detection of Giardia lamblia-antigen in stool.

Diagnosis of giardiasis relies largely on the microscopical detection of trophozoites or cysts in feces. However, this method is labour- and time-intensive and depends highly on the skill of an experienced microscopist. In order to identify the prevalence of Giardia lamblia in travellers returning from overseas, we evaluated sensitivity and specificity of a commercially available ELISA kit for the detection of Giardia-lamblia-antigen in stool. Nine hundred seventy-eight stool samples from 795 patients were examined by microscopy (iron-hematoxyilin-stain, SAF-concentration) and ELISA. Altogether, Giardia infection could be detected in 74 subjects. On evaluation of all samples, the ELISA turned out to be more sensitive than microscopy (95.5% vs. 81.8%) and 99.7% specific for Giardia lamblia. Especially with microscopy, the examination of more than one stool specimen did improve diagnostic sensitivity. It seems therefore advisable to retain the practise of examining at least three stool samples before considering a patient as not infected. The coproantigen-ELISA is especially advantageous in situations where only a single stool sample can be examined. It should not, however, replace microscopical examination of stool specimens for ova and parasites since other potential pathogens would otherwise escape detection.

Animals↗
PubMed1998

Calves as a potential reservoir of Cryptosporidium parvum and Giardia sp.

Studies on cryptosporidiosis and giardiosis were carried out between March and April 1997 on 75 calves from 9 selected farms of Wielkopolska macroregion. Faecal specimens from calves, 3-13 days old, were screened for oocysts of C. parvum using Ziehl-Neelsen staining and both for oocysts of C. parvum and cysts of Giardia sp. using direct immunofluorescent (MerIFluor Cryptosporidium/Giardia) assay. The oocysts of C. parvum assessed by Ziehl-Neelsen staining were revealed on 6 (67%) of 9 farms examined. The prevalence of infection ranged from 20-88%, and in some farms intensity of oocyst shedding was very high. However, in 35 calves assessed for mixed infections of C. parvum and Giardia sp., oocysts of Cryptosporidium were found in 18 (51%) calves and cysts of Giardia sp. were detected in 5 (14%) of 35 calves. Only in one calf was found coinfection with both parasites. The intensity of Giardia sp. infection was extremely low. Histological examination of the gut sections from immunosuppressed BALB/c mice experimentally infected with C. parvum isolates from calves revealed endogenous stages of C. parvum on the brush border of the ileum. The high prevalence and intensive shedding of cryptosporidial oocysts by calves in farms examined in this study suggests that naturally infected calves may be significant reservoirs for C. parvum infections in man and wild animals.

Animals↗
PubMed1980

Pathogenesis of malabsorption in Giardia infection: an experimental study in rats.

It is well established that infection with Giardia lamblia can cause malabsorption although the pathogenesis of this is unknown. Transport studies were made on the intestinal segments of male albino rats infected with Giardia cysts obtained from human stools to investigate this pathogenesis. The results were compared with those seen in a normal group and in a control group that was fed with a Giardia-free stool suspension. There was a significant fall in the transport of glucose and glycine, both of which were actively absorbed. On the other hand, potassium, which diffuses passively in a bidirectional manner across the bowel wall, was not affected. Furthermore, it was observed that the transport mechanism was deranged in the presence of an entirely normal small intestinal mucosa, as judged by light microscopy. It is concluded that Giardia trophozoites interfere with the active transport mechanisms of the small intestinal mucosa. This defect could result either from structural damage to the substrate carriers or from an alteration in cell maturation.

Animals↗
PubMed1994

Infection pattern of Cryptosporidium and Giardia in calves.

Faecal samples were collected weekly over a 3 month period from 0- to 20-week-old calves on an Ohio dairy farm, and examined for Cryptosporidium oocysts and Giardia cysts by a quantitative direct immunofluorescence assay. Oocysts and cysts were detected as early as 4 days of age. Shedding of Cryptosporidium oocysts peaked at 1 week and was low by 3 weeks. Some calves, however, continued to pass low numbers of oocysts. Shedding of Giardia cysts peaked at 2 weeks of age with high levels maintained until 7 weeks of age. Most calves continued to pass low numbers of Giardia cysts after weaning. Cumulative infection rates for both Cryptosporidium parvum and Giardia sp. were 100%.

Animals↗
PubMed2004

Meta-analysis in assessment of the prevalence and annual incidence of Giardia spp. and Cryptosporidium spp. infections in humans in the Nordic countries.

We aimed to apply the meta-analysis in the studies of protozoan pathogens in order to obtain a general overview of the prevalence and annual incidence of Giardia spp. and Cryptosporidium spp. infections in asymptomatic and symptomatic human populations in the Nordic countries of Denmark, Finland, Norway and Sweden. In combining the data of 13 clinically and methodologically non-heterogeneous studies published before 2004 using the random effects model with DerSimonian-Laird estimator, we estimated the prevalence (% prevalence: 95% confidence limits) of Giardia cases in the asymptomatic (i.e. no gastroenteric symptoms) general population to be 2.97% (2.64; 3.31) and in the symptomatic population 5.81% (5.34; 6.30). For Cryptosporidium the prevalences were 0.99% (0.81; 1.19) and 2.91% (2.71; 3.12), respectively. In analyzing the data, we estimated that there will be 4670 (4300; 5060) symptomatic cases of Giardia and 3340 (3110; 3580) symptomatic cases of Cryptosporidium annually per 100,000 general population in the Nordic countries. The vast majority of cases will remain unregistered in the national registers of infectious diseases, since for single registered cases there will be 254-867 cases of Giardia undetected/unregistered and 4072 to 15,181 cases of Cryptosporidium, respectively.

Animals↗
PubMed2005

Efficacy of a combination of febantel, pyrantel, and praziquantel for the treatment of kittens experimentally infected with Giardia species.

This study evaluated the effect of two combination products containing febantel, pyrantel, and praziquantel (FPP) for the treatment of Giardia species in experimentally infected kittens. In experiment 1, five kittens were administered the United States (US) formulation of FPP at doses of 37.8 mg/kg, 7.56 mg/kg, and 7.56 mg/kg, respectively, PO, q24h, for 5 days and four kittens remained as controls. In experiment 2, five kittens were administered the European formulation of FPP at the doses of 12.5 mg/kg, 12 mg/kg, and 4.16 mg/kg, respectively, PO, q24h, for 5 days and four kittens remained as controls. In experiment 3, six kittens were administered the US formulation of FPP at 56.5 mg/kg, 11.3 mg/kg, 11.3 mg/kg, respectively, PO, q24h, for 5 days and five kittens remained as controls. Thirteen days after treatment, kittens testing negative for Giardia species cysts were administered 20 mg/kg methylprednisolone acetate, IM, weekly for a maximum of two injections. Feces were analyzed for Giardia species cysts using a direct immunofluorescence test. After experiment 3, four of the six treated kittens, but no control kittens, remained negative for Giardia species after the administration of methylprednisolone acetate.

Aging↗
PubMed1998

Virulent Avian Giardia duodenalis Pathogenic for Mice.

Early in 1995, a sulphur-crested cockatoo captured in the wild died along with several other cage mates, apparently of an overwhelming, acute infection of Giardia. Trophozoites isolated from the dead bird and established in traditional Giardia axenic medium were infective to mice and established chronic infections associated with weight gain impairment. Genetically and morphologically, the Giardia isolated from the bird belonged to the duodenalis group. Here, Jacqui Upcroft, Ann McDonnell and Peter Upcroft present data on pathogenic avian Giardia with he potential to contaminate watersheds and discuss the implications.

Journal Article↗