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PubMed2006

Giardia and Cryptosporidium join the 'Neglected Diseases Initiative'.

Giardia and Cryptosporidium are ubiquitous enteric protozoan pathogens that infect humans, domestic animals and wildlife worldwide. Both pathogens are significant causes of diarrhea and nutritional disorders in institutional and community settings. They are also significant waterborne pathogens. In developing regions of the world, Giardia and Cryptosporidium constitute part of the complex group of parasitic, bacterial and viral diseases that impair the ability to achieve full potential and impair development and socio-economic improvements. All diseases included in the WHO Neglected Diseases Initiative have a common link with poverty and, as the current view is to take a comprehensive approach to all these diseases, both Giardia and Cryptosporidium were included in 2004. Our current state of knowledge of Giardia and Cryptosporidium is summarized here, and some important questions are raised that need to be addressed if control strategies are to be effective.

Animals↗
PubMed2004

The zoonotic significance and molecular epidemiology of Giardia and giardiasis.

The taxonomy and molecular epidemiology of Giardia and Giardia infections are reviewed in the context of zoonotic and waterborne transmission. Evidence to support the zoonotic transmission of Giardia is very strong, but how frequent such transmission occurs and under what circumstances, have yet to be determined. Zoonotic origin for waterborne outbreaks of Giardia infection appears to be uncommon. Similarly, livestock are unlikely to be an important source of infection in humans. The greatest risk of zoonotic transmission appears to be from companion animals such as dogs and cats, although further studies are required in different endemic foci in order to determine the frequency of such transmission.

Animals↗
PubMed2005

Comparison between natural infection by Cryptosporidium sp., Giardia sp. in dogs in two living situations in the West Zone of the municipality of Rio de Janeiro.

In order to compare natural infection by Cyptosporidium sp. and Giardia sp. in clinically healthy dogs living in two situations (animal shelter and household pets), we conducted 166 faecal exams using the technique of centrifugation-flotation in a sugar-saturated solution. Of the faecal samples, 94 came from shelter dogs and 72 from house pets. Eighty-two (49.4%) contained parasite eggs, cysts or oocysts. Of these, four (2.41%) contained Cryptosporidium sp. oocysts and 52 (31.33%) contained Giardia sp. cysts. There was no statistically significant difference between the origin of the dogs and Cryptosporidium sp. infection. Infection by Cryptosporidium sp. was not associated with the living conditions and sex. With respect to Giardia sp., we observed a statistically significant difference (p < 0.001) between the shelter dogs (45%) and the household pets 12.3%. There was no association of infection by Giardia sp. with age or sex.

Age Factors↗
PubMed2005

Natural infection by Giardia sp. and Cryptosporidium sp. in dairy goats, associated with possible risk factors of the studied properties.

Visits were made to six farms raising dairy goats located in the mountain region of the state of Rio de Janeiro, Brazil, seeking to identify parasitism by Giardia sp. and Cryptosporidium sp. During the visits, fecal samples were collected from approximately 10% of the stock of each property. A questionnaire was given to the keepers on each property to obtain data for epidemiological analysis. A total of 105 fecal samples was collected, 56 from adult animals (over 12 months of age) and 49 from juvenile animals (less than 12 months). The fecal material was processed and subjected to the centrifuge-flotation technique and to staining with safranine-methylene blue. Protozoans of the genus Cryptosporidium were found at two properties, where the hygiene conditions of the installations were considered average and the stalls were made of wood slats raised from the ground. A total of five (4.8%) of the samples was found to be positive for the presence of this protozoan, all from juvenile animals. Cysts of the genus Giardia were found at two properties. Of the 105 samples analyzed, the protozoan was detected in 15 (14.3%), all in juvenile animals, and animals in the age range of 1-3 months had significantly more infections. Age, sanitary condition of the stalls and stalls made of wood slats and raised from the ground, can be pointed out as possible risk factors for infection by Giardia sp. and Cryptosporidium sp. The study reports for the first time the occurrence of Cryptosporidium sp. and Giardia sp. in goats in the state of Rio de Janeiro.

Animal Husbandry↗
PubMed2006

Inhibition of krr1 gene expression in Giardia canis by a virus-mediated hammerhead ribozyme.

Giardia, a most primitive eukaryote, infects several species including human and it is a major agent of waterborne outbreak of diarrhea. It has been difficult to employ standard genetic methods in the study of Giardia, but the RNA virus-based transfection system has been developed and used for the genetic manipulation. KRR1 protein is responsible for ribosome biosynthesis in Giardia. In this study, cDNA encoding hammerhead ribozyme flanked with various lengths of antisense Krr1 RNA were cloned into a viral vector pGCV634/GFP/GCV2174 derived from the genome of Giardia canis virus (GCV). RNA transcripts of the plasmids showed high cleavage activities on Krr1 mRNA in vitro. They were electroporated into GCV-infected G. canis trophozoites and Krr1 mRNA level was decreased by 72% with the ribozyme KRzS and 86% with the ribozyme KRzL, while the control ribozyme TRzS showed no effect on the level of Krr1 mRNA. The two hammerhead ribozyme transfected cells grew slowly, their internal structures got blurred and the cells were deformed. These results indicated that GCV could be useful tool for gene manipulation of G. canis.

Animals↗
PubMed2006

Occurrence of Giardia and Cryptosporidium in Norwegian red foxes (Vulpes vulpes).

Faecal samples from 269 Norwegian wild red foxes (Vulpes vulpes) shot during the hunting season (October-April) in 2002-2004 were examined for the presence of Giardia and Cryptosporidium. Cryptosporidium oocysts were detected in samples from 6 (2.2%) of the foxes, and Giardia cysts in 13 (4.8%) of the foxes. The prevalence of Giardia infection was significantly higher in juvenile male foxes than in adult male foxes, but no other significant differences between age and sex were found. No significant differences in prevalence related to geographical origin of animals were found. Insufficient nucleated Cryptosporidium oocysts were isolated for successful PCR, but genotyping of Giardia duodenalis isolates from seven foxes demonstrated a high degree of heterogeneity amongst them, with all isolates belonging to the zoonotic Assemblages A and B.

Age Factors↗
PubMed2004

Detection of enteric viruses, Giardia and Cryptosporidium in two different types of drinking water treatment facilities.

In this study, two types of drinking water treatment facilities (two conventional drinking water treatment plants (DWTPs) and two compact units (Cus)) were compared referring to their production capacity. Water samples were collected from three main points: (a) different water treatment steps (b) washings of sand filters and (c) distribution system at different distances from the water treatment plants. Both viruses and protozoa were concentrated from each water sample by adsorption and accumulation on the same nitrocellulose membrane filters (0.45 microm pore size). Enteroviruses were detected by plaque infectivity assay in BGM cells and HAV, HEV and Norovirus were detected by RT-PCR. Giardia and Cryptosporidium were detected by conventional staining methods and PCR. The results revealed that enterovirus load at the intake ranged between 10-15 PFU/L for the two compact units and between 4.5 and 75 PFU/L for the two conventional DWTPs. The virus load in distribution system of the first type DWTPs at 1 km from the plant was the same as that of the intake. Viruses in the other type of treatment plants CUs at 1, 5 and 7 km, were much reduced. Investigation of raw water sediments of the two DWTPs showed enterovirus counts between 12 and 17.5 PFU/L. Virus count was reduced in sand of filters after washing. Giardia cysts were equally detected by microscopy and PCR in only intake samples of EL-Hawamdia CU (33.3%) and Meet Fares DWTP (50%). Cryptosporidium oocysts were equally detected by microscopy and PCR in intake samples of Abo EL-Nomros CU (100%), EL-Hawamdia CU (66.7%) and Fowa DWTP (50%). At Meet Fares DWTP three positive intake samples for Cryptosporidium were detected by PCR, compared with only two positive samples by microscopy. Giardia cysts and Cryptosporidium oocysts were detected in raw water sediment and sand of filters before washing. Only one sample from Meet Fares DWTP sand of filters after washing was positive for both Giardia and Cryptosporidium. It can be concluded that the poor microbial quality of the water may be due to improper operational skills and management of the various water treatment plants (especially at the two high capacity treatment plants).

Animals↗
PubMed1998

Efficacy of albendazole against Giardia and hookworm in a remote Aboriginal community in the north of Western Australia.

The parasitological, clinical efficacy and tolerability of albendazole in the treatment for both giardiasis and hookworm infection in a remote Aboriginal population was investigated. Albendazole at a dose rate of 400 mg daily for 5 days was highly effective in reducing hookworm egg numbers and both Giardia antigen and cysts. The 36.6% prevalence of Giardia prior to treatment fell to 12% between days 6 and 9, 15% for days 10-17 and rose to 28% between days 18 and 30. Tolerability and clinical efficacy were excellent. The effect of albendazole on hookworm was longer lasting than that on Giardia, reducing percent infection from over 76-2% on days 6-9 and zero by day 18-30 despite conditions highly conducive to rapid re-infection. We conclude that albendazole is highly efficacious against both parasites when used as described but that long term community benefit may require additional education programmes to avoid re-infection with Giardia although treatment strategies would seem appropriate for hookworm.

Adolescent↗
PubMed2004

Variation in Giardia: implications for taxonomy and epidemiology.

The taxonomy, life cycle patterns and zoonotic potential of Giardia infecting mammals and birds have been poorly understood and controversial for many years. The development of molecular tools for characterising isolates of Giardia directly from faeces or environmental samples has made an enormous contribution to resolving these issues. It is now clear that the G. duodenalis morphological group is a species complex comprising a series of what appear to be largely host-adapted species, and at least two zoonotic species for which humans are the major host, but which are also capable of infecting other mammals. It is proposed that this new information be reflected in the redesignation of several species of Giardia described previously. The molecular epidemiological tools that are now available need to be applied in different endemic foci of Giardia transmission, as well as in outbreak situations, in order to understand better the frequency of zoonotic transmission as well as to develop more effective approaches to controlling giardiasis.

Animals↗
PubMed1998

Episomal and integrated maintenance of foreign DNA in Giardia lamblia.

Giardia lamblia is an early diverging eukaryote which causes gastrointestinal disease throughout the world. Different subgroups of Giardia have been defined based on several biochemical and genetic criteria. We have developed a method for stably introducing DNA into the nuclei of the parasite using puromycin acetyltransferase (pac) as a dominant selectable marker. Transfected circular DNAs were maintained as episomes in the isolate WB, a representative of one Giardia subgroup. When input DNAs were linearized, integration was observed to occur by homologous recombination producing gene replacements in this isolate. In isolate GS, which represents a different subgroup, both linear and circular transfected DNAs were integrated into the genome by homologous recombination. In GS, linear DNA again produced gene replacements, while circular DNA produced duplicative integration events. The failure of GS to replicate episomes may reflect differences in the structure or recognition of DNA replication origins between these subgroups. A plasmid shuttle vector was also developed for expression of other genes in Giardia lamblia. Utilizing the green fluorescent protein as a reporter gene in the WB isolate, we show that gene expression from this vector correlated with plasmid copy number over a range of two orders of magnitude. Together these tools should greatly enhance our ability to study both the basic biology and the pathogenesis of this ubiquitous parasite.

Acetyltransferases↗
PubMed1998

Sequence survey of the Giardia lamblia genome.

The parasitic protozoan Giardia lamblia represents one of the earliest diverging lineages in the evolutionary history of eukaryotic organisms as well as an important human pathogen. A representative sampling of gene sequences from this early diverging protozoan could provide insights into genotypic and phenotypic innovations associated with the origin of eukaryotes. Currently, known giardial gene sequences are heavily biased toward a few gene families, including variant surface proteins (VSPs), structural proteins, and ribosomal RNA genes. One-pass sequences of Giardia genomic DNA were obtained using vector flanking priming sequences on the ends of cosmids in two independent libraries. Comparisons of 2304 of these sequences against the GenBank database identified 205 potential giardial genes with BLAST scores P(n) < 10(9). These coding regions encompass a wide range of metabolic, repair, and signaling enzymes, and include some genes not predicted by our current understanding of Giardia biochemistry. The efficiency of identification of putative genes is consistent with earlier findings that coding regions in the Giardia genome are densely packed and do not appear to contain introns. Our current results suggest that direct genome sequencing is an efficient method for identifying giardial genes for evolutionary and biochemical studies.

Animals↗
PubMed2002

An IC-PCR method for detection of Cryptosporidium and Giardia in natural surface waters in Finland.

We developed an immunocapture-based polymerase chain reaction (PCR) assay for simultaneous detection of Cryptosporidium parvum oocysts and Giardia intestinalis cysts in surface water. Using primer pairs Cry9/Cry15 and LaxA/LaxB for Cryptosporidium and Gdh1/Gdh4 for Giardia, the sensitivity of the entire detection procedure (dealing with concentration, separation, DNA purification and PCR amplification) was at the level of 50-100 oocysts and cysts. Of 54 surface water samples, 4 were positive for Cryptosporidium and 1 for Giardia. Cryptosporidium and Giardia were detected for the first time in surface water in Finland.

Animals↗
PubMed1999

The effect of waste water reuse in irrigation on the contamination level of food crops by Giardia cysts and Ascaris eggs.

In Marrakech, raw sewage has been used for farming purposes for several decades for many types of crops. This study aimed to determine the contamination level of Giardia cysts and Ascaris eggs for crops designated for human consumption. Collected crops in irrigated fields were turnip, marrow, squash, potatoes, pepper and eggplant. Field trials were also carried out on four crops, coriander, carrots, mint and radish, using three water types for irrigation, i.e. raw waste water, treated waste water (sedimentation and 16 days retention) and fresh water. Giardia cysts were detected at a level of 5.1 cysts/kg in potatoes, while Ascaris eggs were observed in numbers varying between 0.18 eggs/kg in potatoes and 0.27 eggs/kg in turnip. Field trials confirmed that irrigation of crops by raw waste water leads to contamination. Giardia and Ascaris were isolated in coriander at concentrations of 254 cysts/kg and 2.7 eggs/kg, respectively; mint was also highly contaminated with numbers reaching 96 cysts/kg and 4.63 eggs/kg. Carrots and radish were contaminated and respective numbers observed for Giardia were 155 and 59.1 cysts/kg; Ascaris was discovered in numbers of 0.7 and 1.64 eggs/kg, respectively. However, cultures irrigated with treated waste water and fresh water were free from contamination. Cysts and eggs on coriander persisted for a maximum of 8 days.

Agriculture↗
PubMed1999

Expression of tubulin polyglycylation in Giardia lamblia.

By means of immunofluorescence, immunoelectron microscopy and immunoblotting, we show that polyglycylation, a posttranslational modification of tubulin widely spread among eukaryotes, is present in the diplomonad, Giardia lamblia, a putative ancestral cell possessing a highly developed microtubular cytoskeleton. This modification was recently discovered in the ciliated protist, Paramecium, and was not found in the Euglenozoa, a lineage considered as ancient. We used two monoclonal antibodies (mAbs), TAP 952 and AXO 49, specifically recognizing mono- and polyglycylated tubulin isoforms, to detect this modification in Giardia extracts and to localize it in the different classes of microtubules within the cell. The alpha- and beta-tubulin subunits were recognized by the two mAbs, indicating that both tubulin subunits are glycylated, in agreement with lately reported mass spectrometry results. Noticeably, Giardia tubulin was much more reactive with AXO 49 than with TAP 952. In situ, AXO 49 intensely labeled the microtubules present in the four pairs of flagella and the median body, and lightly decorated the microtubules from the adhesive disc. In contrast, TAP 952 intensely labeled only the microtubules of the median body. The results indicate a differential expression of glycylated isoforms within various microtubular structures of Giardia lamblia. They also suggest that the complete set of enzymes required for polyglycylation is expressed in very divergent eukaryotes.

Animals↗
PubMed2003

Prevalence and genotyping of Giardia duodenalis from beef calves in Alberta, Canada.

Giardia infections in domestic cattle has come under increasing scrutiny owing to the potential contamination of surface and ground waters through manure distribution on fields and pasture runoff. The objective of the study was to determine the prevalence and genotypes of Giardia duodenalis in beef calves in major beef cow calf farms in Alberta, Canada. Fecal samples were collected from beef calves aged 2-10 weeks at nine farms in Alberta. Samples were examined for the presence of G. duodenalis cysts by immunofluorescent staining. Giardia cysts were found in 168 of the 495 fecal samples examined, with prevalence ranging from 7 to 60% among farms. Genotypic analysis of positive isolates utilizing PCR and sequencing of a 292 bp fragment of the 16S-rRNA locus, revealed the hoofed livestock genotype in 41 of the 42 isolates. One isolate was identical to the Assemblage A genotype. The results of this study demonstrate that beef calves in this area are primarily infected with the livestock genotype which is thought to be specific to artiodactyl hosts and non-infective to humans. This suggests that the Giardia carried by beef cattle may be a minimal zoonotic threat.

Alberta↗
PubMed1997

Morphological changes in the jejunum of calves naturally infected with Giardia spp. and Cryptosporidium spp.

Giardiosis and cryptosporidiosis are frequently diagnosed in calves at the large animal clinic of the veterinary school. Few studies have been reported in the literature regarding pathogenesis of these two intestinal protozoa. The aims of this study were to follow the histological changes in the villi and crypts and the changes in the number of intraepithelial lymphocytes in the jejunum of naturally infected calves during the acute phase of infection. For this purpose, 29 calves aged between 7 and 10 days were bought at a local auction. The animals were housed in individual pens to avoid cross-contamination. Fecal samples were examined microscopically for the presence of Giardia cysts and Cryptosporidium oocysts, three times per week for a period of 45 days. Six calves did not pass any cysts or oocysts and were used as controls. Fifteen calves passed Giardia cysts only, five passed both cysts and oocysts, and three passed oocysts only. The villus to crypt ratio index was 1.76 in the control group and 1.08 in the Giardia-infected group. In the Cryptosporidium-infected calves, the ratio was 1.18 and calves infected with both parasites had an index of 1.37. The number of intraepithelial lymphocytes per millimeter of jejunum tissue was 21 in the control group. This number was doubled in the calves infected with Giardia, but was slightly lower in the other infected groups. All of the infected calves had intermittent diarrhea and mucus was seen in many fecal samples.

Animals↗
PubMed1996

Possible contamination of surface waters with Giardia spp. through muskrats.

Muskrats were examined for Giardia infections. Collected faecal samples were processed by means of sucrose density gradient centrifugation, using a 1 M sucrose solution. Identification of cysts was done by phase contrast microscopy, by the immunofluorescence test, or by both methods. From July 1994 to September 1995, a total of 234 muskrats from two different geographical areas in western parts of Germany were examined for the presence of Giardia cysts. 176 animals (75.2%) were found to be Giardia-positive. This study corroborates the assumption that animals such as muskrats living close to surface water bodies could contaminate water bodies with parasites such as Giardia.

Animals↗
PubMed2002

Inferring protein function from genomic sequence: Giardia lamblia expresses a phosphatidylinositol kinase-related kinase similar to yeast and mammalian TOR.

Functional assays of genes have historically led to insights about the activities of a protein or protein cascade. However, the rapid expansion of genomic and proteomic information for a variety of diverse taxa is an alternative and powerful means of predicting function by comparing the enzymes and metabolic pathways used by different organisms. As part of the Giardia lamblia genome sequencing project, we routinely survey the complement of predicted proteins and compare those found in this putatively early diverging eukaryote with those of prokaryotes and more recently evolved eukaryotic lineages. Such comparisons reveal the minimal composition of conserved metabolic pathways, suggest which proteins may have been acquired by lateral transfer, and, by their absence, hint at functions lost in the transition from a free-living to a parasitic lifestyle. Here, we describe the use of bioinformatic approaches to investigate the complement and conservation of proteins in Giardia involved in the regulation of translation. We compare an FK506 binding protein homologue and phosphatidylinositol kinase-related kinase present in Giardia to those found in other eukaryotes for which complete genomic sequence data are available. Our investigation of the Giardia genome suggests that PIK-related kinases are of ancient origin and are highly conserved.

Amino Acid Sequence↗