Albendazole as an alternative therapeutic agent for childhood giardiasis in Turkey

The efficacy of albendazole for the treatment of giardiasis has been indicated by previous in-vitro and in-vivo studies. In order to compare the therapeutic efficacy of albendazole and metronidazole, 107 Giardia-positive children (aged 3-15 years), diagnosed by three consecutive positive stool examinations, were enrolled in the study. Of these children, 52 were given a single daily dose of albendazole 10 mg/kg for 5 days, and 55 were given metronidazole 20 mg/kg daily in three doses for 7 days. Parasite eradication was achieved in 47 (90.4%) of 52 children treated with albendazole and 49 (89.1%) of 55 children treated with metronidazole (p > 0.05). These results suggest that albendazole is an effective treatment option for childhood giardiasis.

Experimental infections of neonatal mice with cysts of Giardia lamblia clone GS/M-83-H7 are associated with an antigenic reset of the parasite

Transmission of the protozoan parasite Giardia lamblia from one to another host individuum occurs through peroral ingestion of cysts which, following excystation in the small intestine, release two trophozoites each. Many studies have focused on the major surface antigen, VSP (for variant surface protein), which is responsible for the antigenic variability of the parasite. By using trophozoites of G. lamblia clone GS/M-83-H7 (expressing VSP H7) and the neonatal mouse model for experimental infections, we quantitatively assessed the process of antigenic variation of the parasite on the transcriptional level. In the present study, variant-specific regions identified on different GS/M-83-H7 vsp sequences served as targets for quantitative reverse transcription-PCR to monitor alterations in vsp mRNA levels during infection. Respective results demonstrated that antigenic switching of both the duodenal trophozoite and the cecal cyst populations was associated with a massive reduction in vsp H7 mRNA levels but not with a simultaneous increase in transcripts of any of the subvariant vsp genes analyzed. Most importantly, we also explored giardial variant-type formation and vsp mRNA levels after infection of mice with cysts. This infection mode led to an antigenic reset of the parasite in that a VSP H7-negative inoculum "converted" into a population of intestinal trophozoites that essentially consisted of the original VSP H7 type. This antigenic reset appears to be associated with excystation rather than with a selective process which favors expansion of a residual population of VSP H7 types within the antigenically diversified cyst inoculum. Based on these findings, the VSP H7 type has to be regarded as a predominant variant of G. lamblia clone GS/M-83-H7 which (re-)emerges during early-stage infection and may contribute to an optimal establishment of the parasite within the intestine of the experimental murine host.

Potential diagnosis of Giardia lamblia infection through specific antibody detection in saliva

Thirty six patients presenting with gastrointestinal symptoms were studied for the presence of specific anti-Giardia lamblia salivary IgA antibodies. Stool samples were examined for parasites especially G. lamblia by direct smear. Duodenal aspirate was examined for the parasite. Saliva samples were collected from each patient and examined by ELISA technique for the specific anti-Giardia lamblia IgA antibodies. 94.4% of positive cases for G. laimblia by stool analysis had positive anti-Giardia salivary IgA antibodies. 33.3% of stool negative cases were positive for anti-Giardia salivary IgA antibodies. All Giardia negative cases by duodenal aspirate examination were negative for anti-Giardia salivary IgA antibodies. Detection of antiGiardia salivary IgA antibodies was an excellent tool for screening G. lamblia in patients with long standing symptoms of more than one month duration.

Genotyping of human giardiasis in relation to anti-Giardia secretory IgA and mucosal histopathology

Comparative study between the prevalence of pathological grading and Giardia genotypes revealed that, in patients infected with Giardia group I and II, out of patients having Giardia genotype I the prevalence of grade 0 was 13.16%, grade I was 21.05%, grade II was 47.37%, grade III was 13.16% and grade IV was 2.26% in comparison to 0%, 30.77%, 46.15%, 7.69% and 15.38% in genotype II (13 patients) and 10%, 40%, 20%, 20% and 10% in group III (10 patients) also in relation to 25%, 43.75%, 18.75%, 6.25% and 6.25% in mixed genotype infections group (16 patients) and 25%, 25%, 35.71%, 10.71% and 3.57% in undetermined infection group (28 patients) for grade 0, I, II, III & IV pathology respectively. There was no statistically significant difference regarding the prevalence of pathological grading in different Giardia genotypes in Gs I & II (P > 0.05). The mean OD of anti-Giardia secretory IgA in relation to Giardia genotypes in patients infected with Giardia Gs I & II was significantly different in the mean OD values of anti-Giardia secretory IgA in patients with different Giardia genotypes which were 1.091 +/- 0.377, 1.079 +/- 0.474, 1.524 +/- 0.503, 1.292 +/- 0.472 & 1.004 +/- 0.31 groups of genotype I, II, III, mixed genotypes infection and undetermined infection group respecttively (P > 0.05), being more increased in patients infected with Giardia genotype III and in mixed genotype infection.

[Giardia lamblia and duodenal involvement]

Giardia lamblia (GL) is one of the causes of diarrhoea. GL is a frequent parasite in our country. In the literature, endoscopic aspects of Giardia duodenitis are mentioned. Some authors tried even to make the diagnosis on endoscopic criteria.

AIM

The purpose of the study is to find the endoscopic and histopathology changes produced by giardiasis.

METHODS

214 patients entered this study and underwent upper digestive endoscopy. Duodenal and gastric multiple biopsies were taken. Biopsies were stained with hematoxylin-eosine for Helicobacter pylori and Giemsa for Giardia lamblia. CP-test was also performed for Helicobacter and duodenal aspirate for giardiasis.

RESULTS

The results indicates a high incidence of endoscopic and histopathology duodenitis in patients with giardiasis. The whitish spots on the erythematous duodenitis (60, 46%) and concentric ex-ulcerations (4, 16%) might be considered specific. On histology samples all the cases presented duodenitis, the first degree duodenitis was the most common (76, 63%).

CONCLUSIONS

It is concluded that there are specific endoscopic and histopathology features of giardiasis.

Epidemiological and molecular evidence supports the zoonotic transmission of Giardia among humans and dogs living in the same community

Giardia duodenalis isolates recovered from humans and dogs living in the same locality in a remote tea-growing community of northeast India were characterized at 3 different loci; the SSU-rDNA, elongation factor 1-alpha (ef1-alpha) and triose phosphate isomerase (tpi) gene. Phylogenetic analysis of the SSU-rDNA and efl-alpha genes provided poor genetic resolution of the isolates within various assemblages, stressing the importance of using multiple loci when inferring genotypes to Giardia. Analysis of the tpi gene provided better genetic resolution and placed canine Giardia isolates within the genetic groupings of human isolates (Assemblages A and B). Further evidence for zoonotic transmission was supported by epidemiological data showing a highly significant association between the prevalence of Giardia in humans and presence of a Giardia-positive dog in the same household (odds ratio 3.01, 95% CI, 1.11, 8.39, P = 0.0000).

Évolution de la prévalence des parasitoses digestives au CHU de Fort-de-France (Martinique)

OBJECTIVE

Determine the prevalence of intestinal parasitosis between January 1, 1997 and December 31, 1999 in the microbiology laboratory of the Fort de France University Hospital.

METHOD

Retrospective study of the results of 4684 parasitological examinations of stools performed in 2704 patients between January 1, 1997 and December 31, 1999 in this laboratory.

RESULTS

This survey showed the high prevalence of anguillulosis, found in 51.69% of infested patients and in 4.56% of the population studied, the ever high prevalence of non or scarcely pathogenic amoebas (Endolimax nanus, Dientamoeba fragilis, Entamoeba coli) found in 27.19% of infested patients and 1.88% of the population studied, together with that of hookworms (12.80% of infested patients and 1.13% of the population), and the persistence of lambliasis. This study also revealed the presence of cryptosporidies (7 cases) and microsporidies (4 cases) in the patients infected by the human immunodeficiency virus.

DISCUSSION

These results confirm the trend of the past twenty Years and the results of surveys initiated by the national statistics board (INSERM) in 1978, 1988 and 1995-1995, with the regression of bilharziosis and the persistence of anguillulosis and hookworms.

CONCLUSION

The improvement in living conditions and hygiene, the combined efforts of the health care workers and Authorities in Martinique over the past 30 Years in the fight against parasites have led to a great reduction in the prevalence of classical intestinal parasitosis. However, new parasites associated with HIV infection have appeared.

Dietary lipids containing gangliosides reduceGiardia murisinfectionin vivoand survival ofGiardia lambliatrophozoitesin vitro

We examined whether a ganglioside supplemented diet affected the course ofGiardia murisinfection in mice and survival ofGiardia lambliatrophozoitesin vitro. Female CD-1 mice were fed 1 of 5 experimental diets: standard lab chow as a control diet; semi-synthetic diets containing 20% (w/w) triglyceride based on the fat composition of a conventional infant formula; triglyceride diet; triglyceride diet containing a low level of ganglioside (0·1% w/w); and triglyceride diet containing a high level of ganglioside (1·0% w/w of diet). After 2 weeks of feeding, mice were inoculated withG. murisby gastric intubation and fed the experimental diets during the course of the infection. Cysts released in the faeces and trophozoites present in the small intestine were enumerated at various times post-infection. The average cyst output and the number of trophozoites during the course of the infection in mice fed ganglioside-containing diet were found to be significantly lower (3-log10reduction) compared to animals fed control diets. The results ofin vitrogrowth studies indicated that gangliosides may be directly toxic to the parasites. Thus, gangliosides have a protective effect againstG. murisinfectionin vivoand affect the survival ofG. lambliatrophozoitesin vitro.

[Prevalence of infection by intestinal parasites in north Lebanon: 1997-2001]

We determined the prevalence of intestinal parasites in the north of Lebanon between 1997 and 2001. We analysed the parasitology records of 17126 patients and evidence of parasitic infections was found in 5 713 (33.35%) cases. There was no significant difference in prevalence for males or females for any of the parasites. The most prevalent parasites were Entamoeba coli (38.45%), Ascaris lumbricoides (37.14%), Giardia lamblia (15.39%), Ent. histolytica (4.57%) and Taenia sp. (3.3%). A comparison between our data and results of previous studies in Lebanon in 1937, 1939, 1956, 1967 and 1993 showed an increase in the prevalence of A. lumbricoides and G. lamblia in the period 1997-2001, with less marked changes in the prevalence of the other parasites.

Efficacy of antigiardial drugs

The flagellated protozoa Giardia duodenalis is the most commonly detected parasite in the intestinal tract of humans. Infections with the parasite result in diarrhoeal disease in humans and animals, with infants at risk from failure-to-thrive syndrome. The incidence of giardiasis worldwide may be as high as 1000 million cases. Current recommended treatments include the nitroheterocyclic drugs tinidazole, metronidazole and furazolidone, the substituted acridine, quinacrine, and the benzimidazole, albendazole. Paromomycin is also used in some situations, and nitazoxanide is proving to be useful. However, treatment failures have been reported with all of the common antigiardial agents, and drug resistance to all available drugs has been demonstrated in the laboratory. In addition, clinical resistance has been reported, including cases where patients failed both metronidazole and albendazole treatments. The identification of new antigiardial drugs is an important consideration for the future, but maintaining the usefulness of the existing drugs is the most cost-effective measure to ensure the continued availability of antigiardial drugs.

Egyptian genotyping of Giardia lamblia

Out of 105 patients infected with Giardia, 38 patients have Genotype I (36.19%), 13 have Genotype II (12.38%), 10 have Genotype III (9.52%), 16 have mixed Genotype infection (15.24%) and 28 with undetermined Giardia infection by PCR (26.67%). None of the control group gave positive results for Giardia in stool by PCR. So, the sensitivity of the test for detection and identification of Giardia Genotypes from the original stool samples was 73.33% and specificity was 100%. Out of 61 cases in the symptomatic group, the prevalence of Giardia Genotype I was 32.79%, Genotype II was 16.39%, Genotype III was 9.84%, mixed Genotype infection was 16.39% and undetermined Genotype was 24.59% as compared to 40.91%, 6.82%, 9.09%, 13.64% & 29.55% in the asymptomatic group respectively. There is statistically insignificant difference between both groups as regarding the prevalence of the different Giardia Genotypes. (P < or = 0.05). The use of PCR as a routine work for diagnosis of giardiasis is not accepted at least in the developing and under-developing countries due to its high cost, the high quality of technical staff and advanced laboratory equipments required for PCR performance. Its application is usually limited to research activities, the detection of water sources contamination and for the detection of a potential source of Giardia infection in epidemics.

Influence of temperature and salinity on the viability and infectivity of Giardia lamblia and Cryptosporidia parvum

The present work was designed to assess the effect of different degrees of temperature and salinity on the viability and infectivity of G. lamblia and C. parvum at different storage time. The results revealed that boiling of protozoa for one minute minimized their viability to less than 1% and rendered them non-infectious, while exposure to 4 degrees C and -4 degrees C up to seven days preserved their viability and infectivity. Whereas it was found that salinity was effective at high concentration (50 ppt) or for long storage time at lower concentrations.

Molecular characterization of Egyptian Giardia lamblia isolates

Six Giardia lamblia strains (4 from Egypt, one from the USA and one from Sudan) were used to study the phenotypic and genotypic variation in some Egyptian G. lamblia strains compared to other G. lamblia strains, which may be responsible for the difference in their behavioral characteristics. By using SDS-PAGE for antigenic study, E1 strain appeared different from the rest of the strains with two bands; one at 121 Kda and the other at 34 Kda which were not present in other strains, while bands at 130 and 43 Kda were present in all strains but absent in E1 strain. Another difference between E1 strain and the rest of the strains was obtained by CAE, using PGM enzyme where E1 strain gave a different zymodeme than the other strains. Based on the computerized RAPD- PCR analysis, 4 rapdemes were identified; rapdeme 1 contained E1 strain, rapdeme 2 contained E2, E3 and E4 isolates, rapdeme 3 contained Sudan strain and rapdeme 4 contained USA strain. In conclusion this study revealed diversity between G. lamblia strains especially E1 strain which showed unique characters.

[Detection of antibodies against Lamblia antigens in serum from atopic patients]

The method of solid-phase immune-enzyme assay was used to test the sera of atopic patients for the purpose of detecting IgG to lamblias. A high degree of protozoal invasion was established especially among pre-school and school children. It was proven as expedient to make the serological examinations of atopic patients in cases the clinical finding is unclear.

Common intestinal parasites

Intestinal parasites cause significant morbidity and mortality. Diseases caused by Enterobius vermicularis, Giardia lamblia, Ancylostoma duodenale, Necator americanus, and Entamoeba histolytica occur in the United States. E. vermicularis, or pinworm, causes irritation and sleep disturbances. Diagnosis can be made using the "cellophane tape test." Treatment includes mebendazole and household sanitation. Giardia causes nausea, vomiting, malabsorption, diarrhea, and weight loss. Stool ova and parasite studies are diagnostic. Treatment includes metronidazole. Sewage treatment, proper handwashing, and consumption of bottled water can be preventive. A. duodenale and N. americanus are hookworms that cause blood loss, anemia, pica, and wasting. Finding eggs in the feces is diagnostic. Treatments include albendazole, mebendazole, pyrantel pamoate, iron supplementation, and blood transfusion. Preventive measures include wearing shoes and treating sewage. E. histolytica can cause intestinal ulcerations, bloody diarrhea, weight loss, fever, gastrointestinal obstruction, and peritonitis. Amebas can cause abscesses in the liver that may rupture into the pleural space, peritoneum, or pericardium. Stool and serologic assays, biopsy, barium studies, and liver imaging have diagnostic merit. Therapy includes luminal and tissue amebicides to attack both life-cycle stages. Metronidazole, chloroquine, and aspiration are treatments for liver abscess. Careful sanitation and use of peeled foods and bottled water are preventive.

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.

Giardia intestinalis

PURPOSE OF REVIEW

Giardia intestinalis (syn. duodenalis or lamblia) is one of the most common intestinal parasites in the world, with an estimated 2.8 x 10(6) infections per year in humans, and it contributes to diarrhea and nutritional deficiencies in children in developing regions. The wide prevalence of Giardia and its unique place in evolutionary biology have led to ongoing research.

RECENT FINDINGS

Research into the basic biology of Giardia has highlighted some of its unique properties as an 'early-branching' eukaryote. Although Giardia do not contain mitochondria, they have developed pathways to perform some mitochondrial functions. Investigations into encystation and excystation have identified new gene products that are important in cyst wall formation, and signal transduction events that occur during excystation. The ability to transfect Giardia stably will lead to an improved understanding of its development and metabolism. Molecular typing of G. intestinalis isolates indicates that most animal parasites are not associated with human infection. Insights into immunology have helped define the role of IL-6 in the early control of murine giardiasis, and the contributions of IgA in controlling infection. Further studies of giardiasis in poorly nourished children in developing regions supports an important contributing role of Giardia in stunting and cognitive impairment. Finally, new diagnostic assays using antigen detection are being evaluated and a new agent, nitazoxanide, has been approved in the USA for the treatment of giardiasis and cryptosporidiosis in children.

SUMMARY

Research into the biology of Giardia should increase knowledge about protist differentiation and will complement studies in other biological systems. Continued study of the role of Giardia in chronic diarrhea and malnutrition in developing regions will help focus strategies to improve childhood growth and nutrition.

[Are domestic Cryptosporidium and Giardia infections in Norway underdiagnosed?]

BACKGROUND

Cryptosporidium and Giardia are recognised as common causes of waterborne disease in several countries. In order to describe investigative practices for these protozoan parasites in Norway, we surveyed medical microbiology laboratories nationwide for faecal screening policies and methods used for detection of Cryptosporidium and Giardia.

MATERIAL AND METHODS

All medical microbiology laboratories in Norway received questionnaires on laboratory methods, indications for screening, and numbers of samples investigated over the 1998-2002 period.

RESULTS

Of the 22 laboratories that receive faecal samples, 17 had established diagnostic routines for Giardia detection, 14 for Cryptosporidium. Examination for Giardia cysts was standard procedure in all 17 laboratories, mainly in specimens from immigrants and travellers returning from abroad. Examination for Cryptosporidium was, on the other hand, infrequent. Ten of the 14 laboratories reported less than 10 examinations per year. Giardia was frequently detected, with 1 to 6% positive samples in the various laboratories. Cryptosporidium was seldom detected; all laboratories reported only 0-1 positive sample per year.

INTERPRETATION

While laboratories frequently screen faecal samples for Giardia, screening for Cryptosporidium is rare. Little is known about the public health significance of domestic infections with these parasites in Norway; further investigation is needed in order to estimate the burden of disease they cause and to implement control measures if required.

Whipple disease associated with giardiasis

We tested 53 fixed duodenal biopsy samples from 25 patients with Whipple disease for the presence Giardia and 6 fresh duodenal biopsy samples for Giardia duodenalis DNA by polymerase chain reaction (PCR). We also used histological examination and PCR assay to determine the prevalence of G. duodenalis in duodenal biopsy samples from 150 control patients without Whipple disease. Three of 25 patients with Whipple disease had histological evidence of giardiasis, whereas only 1 of 150 control patients was affected (P<.001). By PCR, we found Giardia in 2 of 6 patients with Whipple disease whom we tested, but in only 2 of 150 control patients (P<.001). In a literature review, we identified 15 other cases of coinfection. The occurrence of these diseases may be promoted by a common immune defect or a common source of infection, or infection with one may predispose to infection with the other.

[Usefulness of 2 coproparasitological methods and their utilization in an antigiardiasis therapeutic trial]

A study of 456 children aged 1-5 from 4 day care centers of San Miguel del Padron municipality was conducted in 1998, to evaluate the diagnosis of Giardia lamblia and other intestinal protozoa by using comparatively the coproparasitological diagnostic methods of direct examination and Ritchie's concentration technique or formol-ether. Besides, a therapeutical trial was developed with tinidazole and albendazole for treating the infection caused by G lamblia. Ritchie's concentration technique was more effective than the microscopic direct examination for diagnosing Giardia lamblia, Entamoeba histolytical/Entamoeba dispar and Cyclospora cayetanensis. It was demonstratyed that the serial examination was more sensitive than the analysis of just one sample (p< 0.01). On the other hand, tinidazole proved to be more efficient than albendazole to treat the infection produced by G. lamblia, with a greater cure percentage (72 % vs. 334.6%), (p < 0.01).

Protein trafficking in Giardia lamblia

Giardia, a protozoan parasite of humans and other vertebrates, is a common cause of intestinal disease worldwide. Besides its medical importance, Giardia is considered an excellent system to study the evolution of fundamental cellular processes because it belongs to the earliest branches of the eukaryotic lineage of descent. Giardia trophozoites lack organelles typical of higher eukaryotes such mitochondria, peroxisomes and compartments involved in intracellular protein trafficking and secretion, such as the Golgi apparatus and secretory granules. Nevertheless, the minimal machinery for protein transport and sorting is present in this parasite. When Giardia undergoes encystation, the biogenesis of secretory organelles necessary to transport cyst wall constituents to the cell surface takes place. Recent studies in both vegetative and encysting trophozoites have provided interesting information regarding the secretory pathway of this important human pathogen.