SEARCH · Search PubMed

Results for “Echinococcus”

Search indexed PubMed citations on genomics, clinical trials, systematic reviews and public health. Explore titles, authors and supplied subject terms, then open the PubMed record.

SourceResearch connectionFrom yearThrough year

Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.

At least 469 records · Page 26Linked to original sources

PubMed2004

Genetic relationships between sheep, cattle and human Echinococcus infection in Tunisia.

Allozyme variation at seven polymorphic loci (GPI, EST, MDH, MPI, DIA, PEP, PGM) was studied to examine genetic variation within and between sheep, cattle and human populations of Echinococcus granulosus in Tunisia. A high degree of genetic similarity was shown between the cysts of the three host origins. Nevertheless, whereas, the ovine and human samples were highly similar, the cattle samples were slightly different genetically. We conclude that humans are mostly infected by parasites originating from sheep liver. The intense deficiency in heterozygotes was partly artefactual (Wahlund effect) and partly due to self-fertilisation.

Adolescent↗

PubMed2004

Transmission dynamics of the Echinococcus granulosus sheep-dog strain (G1 genotype) in camels in Tunisia.

Cystic echinococcosis, caused by Echinococcus granulosus, is highly endemic in North Africa and the Middle East. This paper examines the abundance and prevalence of infection of E. granulosus in camels in Tunisia. No cysts were found in 103 camels from Kébili, whilst 19 of 188 camels from Benguerden (10.1%) were infected. Of the cysts found 95% were considered fertile with the presence of protoscolices and 80% of protoscolices were considered viable by their ability to exclude aqueous eosin. Molecular techniques were used on cyst material from camels and this demonstrated that the study animals were infected with the G1 sheep strain of E. granulosus. Observed data were fitted to a mathematical model by maximum likelihood techniques to define the parameters and their confidence limits and the negative binomial distribution was used to define the error variance in the observed data. The infection pressure to camels was somewhat lower in comparison to sheep reported in an earlier study. However, because camels are much longer-lived animals, the results of the model fit suggested that older camels have a relatively high prevalence rate, reaching a most likely value of 32% at age 15 years. This could represent an important source of transmission to dogs and hence indirectly to man of this zonotic strain. In common with similar studies on other species, there was no evidence of parasite-induced immunity in camels.

Animals↗

PubMed2004

Field evaluation of an intravital diagnostic test of Echinococcus multilocularis infection in red foxes.

Echinococcus multilocularis parasitizes the small intestine of red foxes (Vulpes vulpes) and other carnivores, and has a wide distribution throughout the northern hemisphere. This cestode is the causative agent of human alveolar echinococcosis, a life-threatening helminth zoonosis. In 2000-2002, 2130 red foxes were examined for its presence in Slovakia, with a total prevalence of 30.7%. The data on occurrence were obtained by the combination of necropsy of small intestines from red foxes and coproantigen detection in faecal samples. The correlation between the number of detected specimens and the value of optical density of copro-ELISA test was found. When worm burdens were low (1-25 specimens) the sensitivity of the method was 31.3+/-8.64%, when worm burdens were >50 specimens, 81.8+/-0.66%, and with high worm burdens (>1000 specimens) the sensitivity reached 100+/-0.34%. E. multilocularis presence was detected using the nested PCR method from the eggs in the faecal samples with a 100% specificity. In epidemiological surveys of this zoonosis, it is of crucial importance to detect animals with a high level of infection, which are responsible for the bulk of environmental contamination. The advantage of copro-ELISA test lies in allowing the intravital diagnostics to be employed within the epidemiological survey of E. multilocularis occurrence in the protected and urban areas.

Animals↗

PubMed2005

Molecular evidence of ovine (G1) and camel (G6) strains of Echinococcus granulosus in Tunisia and putative role of cattle in human contamination.

Three hundred and seventy-two cysts coming from 50 humans, 166 cattle, 153 sheep and 3 camels were collected in order to establish some epidemiological molecular information in Tunisia for the first time. The analysis by PCR-RFLP of ITS1 sequence showed that all the human, ovine and bovine cysts were due to the common sheep strain of Echinococcus granulosus. The sequencing of the CO1 gene of 37 isolates confirm the G1 genotype of this strain. For seven of these isolates, we found the mutation C56T which is present in the three principal intermediate hosts: human (three cysts), cattle (three cysts) and sheep (one cyst). With regard to the G1 genotype, we identified three other point mutations. The camel strain G6 is uniquely found in the three camels isolates and not in the other intermediate hosts analysed. The fertility of the bovine cyst represents 48% that means that this host is involved in a bovine-dog cycle and consequently represents a reservoir of sheep strain in Tunisia. Our results confirm the importance of the prophylaxis measures in order to disrupt the cycle of transmission sheep-dog in Tunisia. Nevertheless, the supervision of bovine infection should be reinforced because this intermediate host may constitute an important link with the human contamination.

Animals↗

PubMed2005

Viability and infectiousness of eggs of Echinococcus granulosus aged under natural conditions of inferior arid climate.

We studied the viability and infectiousness of aged Echinococcus granulosus eggs by in vivo evaluation in ovines. Our results demonstrated that after 41 months of ageing of the eggs under environmental conditions of an inferior arid climate (Patagonia, Argentina), they were still able to produce infection in 4/4 ovines challenged with 1200 eggs per ovine. In the ovines experimentally infected with these aged eggs, the occurrence of hepatic and pulmonary cysts was determined by necropsy, histologic and genetic studies. The eggs were found in a semi-senescent stage, thus keeping their capacity to generate an infection in the intermediary ovine host.

Animals↗

PubMed2006

Intraspecific variation of Echinococcus granulosus in livestock from Peru.

Echinococcus granulosus infection is a problem of public health in livestock-rearing regions of Latin America, like in Peru. This species is characterized by the morphometry of the large and small rostellar hooks in both metacestodes and adult worms. The aim of this work was to study biometrical characteristics of rostellar hooks in hydatid cysts (lung and liver) from some Peruvian provinces (Arequipa, Cuzco, Huancavelica, Junin and Puno). The biometrical analysis was obtained in a digital system for image analysis. The following parameters were studied: area, perimeter, length and width total of the handle, the blade and the distance between the blade and the guard of large and small hooks. For statistical analysis Student's t-test and Analysis of Variance (ANOVA) with Pos-test of Tukey were used, considering the values of p< or =0.05 as of statistic significance. All morphometric characters of large and small hooks were highly significant (p<0.000), when data were compared among the samples from the different provinces. Rostellar hooks in specimens from Huancavelica presented smallest measurements, whereas hooks in specimens from Junin were bigger in relation to the total and blade measurements. Generally, samples from Arequipa presented the biggest large hooks in relation to the handle parameters. The rostellar hooks of cattle and sheep hosts varied depending on the geographic localization, host and organ. Hooks recovered from the lungs were larger than those collected in the liver. It was concluded that morphometry using computer image analysis allows the characterization of E. granulosus. The rostellar hooks presented morphometric polymorphism.

Analysis of Variance↗

PubMed2006

Genotypic characterisation of Indian cattle, buffalo and sheep isolates of Echinococcus granulosus.

Twelve isolates of Echinococcus granulosus, collected from domestic animals, including cattle, buffalo and sheep were analysed for DNA nucleotide sequence variation within mitochondrial cytochrome c oxidase I (coxI), NADH dehydrogenase subunit I (nadI) and internal transcribed spacer gene I (ITS1). After analysis of sequence information this was found that the fragment size of ITS1 of buffalo isolate was more in comparison to cattle and sheep isolates. Based on the nadI genotype this was found that Indian cattle, buffalo and sheep isolates could be grouped into E. granulosus sensu stricto. Based on coxI genotype two sheep isolates and one buffalo isolate were homologous to G2 genotype. Rests of the isolates were microvariants of G2 genotype. Presence of G2 genotype in buffalo is the first report of this genotype from this host.

Animals↗

PubMed2006

Screening for Echinococcus granulosus in dogs: Comparison between arecoline purgation, coproELISA and coproPCR with necropsy in pre-patent infections.

Echinococcus granulosus is an important zoonotic infection of dogs. The purpose of the present study assessed the performance of two laboratory diagnostic methods with arecoline purgation and necropsy in infected dogs. In total 65 dogs were successfully experimentally infected with protoscoleces of E. granulosus from ovine infection. At 14-34 days post-infection groups of dogs were purged with arecoline hydrobromide and then necropsied. Faecal samples were tested at weekly intervals by coproantigen ELISA and coproPCR. The necropsy infection rate with E. granulosus was 89.2 per cent. Only 43 per cent of dogs were successfully purged after one arecoline dose; this percentage increased to 76.9% for two doses of arecoline purgation. E. granulosus coproantigen was detected by coproELISA in 82.8% of faeces. The positive and negative predictive values for coproantigen ELISA were 96 and 44.4% respectively. E. granulosus DNA was detected in pre-patent faecal samples by coproPCR in 25.9% of dogs. These results indicate that coproELISA is more sensitive than arecoline purgation for the detection of pre-patent E. granulosus infection in dogs. CoproPCR detected E. granulosus DNA in dog faeces by 21 days post-infection before egg production.

Animals↗

PubMed2000

Development and sexual maturation of Echinococcus vogeli in an alternative definitive host, Mongolian gerbil (Meriones unguiculatus).

An alternative definitive host model for Echinococcus vogeli was developed using Mongolian gerbils. The animals treated with prednisolone tert-butylacetate were orally inoculated with protoscoleces of E. vogeli and the development of worms in the small intestine was observed until 50 days post infection (DPI). The parasites were recovered most frequently from the anterior part of the small intestine. The band formation (the sign of proglottisation) of the worm was observed at 7 DPI, the second proglottid and tests formation at 14 DPI, spermatozoa in seminal receptacle and cleavage of ova in uterus at 21 DPI, the hook formation of oncospheres at 28 DPI and the embryophore formation at 34 DPI. Eggs in the feces were first detected at 35 DPI. The coproantigen detection method developed for E. multilocularis could detect the E. vogeli coproantigen early in the infection, at 7 DPI during the prepatent period. Therefore, this technique could be used for the diagnosis of E. vogeli, replacing ordinary fecal egg examination.

Animals↗

PubMed2000

Comparative analysis of two different subunits of antigen B from Echinococcus granulosus: gene sequences, expression in Escherichia coli and serological evaluation.

Two different Echinococcus granulosus antigen B subunits (AgB8/1 and AgB8/2) were characterized and the structure of the genes encoding these two proteins were compared. DNA sequences were expressed in Escherichia coli and the antigens' diagnostic value was then assessed. The genomic sequence of AgB8/1 has a 92 bp intron in the position corresponding to amino acid 16; the AgB8/2 genomic sequence presents a 68 bp intron in the position corresponding to amino acid 20. Both introns are located between the putative N-terminal hydrophobic sequence and the secreted peptide. A comparison between the AgB8/1 and AgB8/2 nucleotide sequences showed a 53.5% identity among exons and a 50% identity between introns. According to the molecular diversity analysis, the elapsed time since both genes shared a common ancestor would be around 4.2x10(7) years. When the native AgB and the two recombinant antigens (rAgB8/1 and rAgB8/2) were tested in an anti-IgG ELISA, the sensitivity of the native antigen B was 77.41% and its specificity was 81.9%, while rAgB8/1 showed 54.84% of sensitivity and 80.17% of specificity and rAg138/2 had an 83.87% sensitivity and a 98.28% specificity. Statistical analysis confirms that rAgB8/2 has a better performance than rAgB8/1 and native AgB in ELISA.

Amino Acid Sequence↗

PubMed2003

Statistics and sample design in epidemiological studies of Echinococcus multilocularis in fox populations.

In this paper possible sampling strategies for estimating the prevalence of Echinococcus multilocularis infections in foxes are discussed. To draw valid conclusions from the analysis of fractions of a total fox population, each member of the total population must have the same chance of being selected for the investigation (random sampling), the sample must be representative with respect to all epidemiologically relevant conditions in the population (e.g. age, endemic status, seasonal effects, population density), and it must be large enough to obtain results with the required precision. For detection/exclusion of infections at a pre-specified prevalence threshold and confidence level (e.g. 99%), the required sample is rather small, but the information obtained from the data is limited. For prevalence estimates, the required sample sizes depend on the expected prevalence, the desired precision of the estimate and the chosen confidence level (e.g. 90, 95, or 99%). The samples need to be taken in spatial units where the variation of the conditions potentially influencing the infection can be neglected. A first impression of the spatial distribution of E. multilocularis infections in foxes can also be obtained by mapping the investigated sample (infected and uninfected animals) using the municipalities where they were shot or found as a spatial grid. To analyse the local influence of environmental factors, data on the geographical positions where the animals were sampled need to be collected and analysed in the context of a Geographic Information System (GIS).

Age Factors↗

PubMed2003

Morphological and genetic characterization of Echinococcus granulosus in the Slovak Republic.

The present study was undertaken to characterize more thoroughly aetiological agent of cystic echinococcosis that still represents a health problem in the Slovak Republic. Sequencing of the mitochondrial ND1 gene, Random Amplified Polymorphic DNA (RAPD) analysis and isoenzyme analyses were used to characterize genetically protoscolices of 37 isolates from pigs and cattle and two isolates from humans collected in different regions of the Slovak Republic. Solely the G7 genotype (pig strain) was identified by ND1 sequences in all 14 pigs isolate examined by this method. This genotype was also found in two human patients and in two cattle. The exclusive finding of the G7 variant has implications for the implementation of control strategies given its unique developmental and biological properties. Despite striking morphological variability, a low degree of the intra-strain variability was found in the Slovak Echinococcus granulosus isolates with the genetic methods used. This was particularly associated with the shape and size of hooks, number of testes and shape of ovaries and uterus. GPI and MDH enzymes were found suitable for the discrimination of G7 and G1 (=cosmopolitan sheep strain) variant.

Animals↗

PubMed1997

The early stages of Echinococcus granulosus development.

The paper points out the essential aspects of host/parasite relationship during the development of oncospheres (ONC) of Echinococcus granulosus into an early cyst. Secretions of the penetration glands in the hatched ONC causes lysis of host tissue during penetration of the activated ONC. It also protects the parasite against the host's immune response while developing the laminated layer. The microvilli, compressed under the plasma membrane in the hatched ONC, are uplifted in the activated larvae; they increase in number and size and are substituted by short and truncated microtriches in metacestodes 3 days old. At that time appears the first lamination of the laminated layer that surrounds the metacestodes as an electron-dense matrix composed of fine microfibrillated material and remnants of sloughed microvilli. The second lamination appears by day 6-8 and is more electron-dense than the first one. The laminated layer is of parasite origin, formed of a series that emanates from the germinal membrane. It is suggested that Vg secretory vesicles, that are elaborated in the perikaryon of the germinal zone and continuously carried to the syncytium via the microtubular-cytoskeleton, are responsible for the laminated layer formation and are involved in initial evasion of the immune response of the host. The cyclical production of laminations could be necessary to create layers that can ultimately be sloughed off as the cyst grows and serve to divert the host cellular response to the parasite.

Animals↗

PubMed1999

Synthetic studies on glycosphingolipids from the parasite Echinococcus multilocularis.

Novel neutral glycosphingolipids isolated from the metacestodes of Echinococcus multilocularis by Persat, may be expected to be involved in host-parasite interactions. We have synthesized these glycosphingolipid analogues containing 2-branched fatty alkyl residues in place of ceramide. The glycosylation of galactosyl donors 4 and 5 with each of the acceptors 2 and 11 in the presence of N-iodosuccinimide (NIS)/TfOH, and the glycosylation of fucosyl donor 13 with acceptors 12 and 20 in the presence of dimethyl(methylthio)sulfonium triflate (DMTST) gave the desired oligosaccharide derivatives at good yield. The fully per-O-acylated 2-(trimethylsilyl)ethyl glycosides 6, 15, 21, and 26 were converted to glycosylimidates 7, 16, 22, and 27, which were condensed with 2-(tetradecyl)hexadecanol and subsequently deacylated give four target glycosphingolipid analogues.

Animals↗

PubMed2001

Immunisation with Salmonella typhimurium-delivered glyceraldehyde-3-phosphate dehydrogenase protects mice against challenge infection with Echinococcus multilocularis eggs.

Recombinant glyceraldehyde-3-phosphate dehydrogenase of the cestode parasite Echinococcus multilocularis was expressed in Escherichia coli and in Salmonella typhimurium. The potential of different forms of the recombinant antigen to protect BALB/c mice against oral challenge infections with E. multilocularis eggs was evaluated. Oral or intraperitoneal immunisation with live attenuated S. typhimurium as a carrier for recombinant glyceraldehyde-3-phosphate dehydrogenase of the E. multilocularis resulted in significant protection, reducing the number of developing metacestodes up to 79.8%. The sera of protected animals did not contain detectable amounts of antibody against glyceraldehyde-3-phosphate dehydrogenase of E. multilocularis. By contrast, although anti-glyceraldehyde-3-phosphate dehydrogenase of E. multilocularis antibodies were detectable in the sera, immunisation with E. coli-expressed recombinant glutathione-S-transferase-fusion protein or with glyceraldehyde-3-phosphate dehydrogenase of E. multilocularis fused to a 6HIS-tag failed to protect the animals against oral challenge infections. These data emphasise that antigen delivery systems play a critical role in vaccination and the induction of protective immunity against helminth parasites.

Amino Acid Sequence↗

PubMed2003

Identification and molecular characterisation of a gene encoding a member of the insulin receptor family in Echinococcus multilocularis.

Receptor kinases play a key role in the communication of cells with their environment and could be important mediators of the effects of host cytokines on endoparasitic organisms. In this paper we describe, for the first time, the characterisation of a receptor tyrosine kinase of the insulin receptor family from a parasitic helminth. Using a degenerative PCR approach, we identified and completely characterised the 5.5kb coding DNA for an Echinococcus multilocularis factor (EmIR) which displays significant homologies to insulin receptors of different phylogenetic origin. EmIR exhibited a domain structure which is typical for the protein family and contained all catalytically important residues at corresponding positions. One striking difference between EmIR and known insulin receptors was the presence of a 172 amino acid insert in the tyrosine kinase region of, as yet, unknown function. In yeast two-hybrid analyses, the ligand binding domains of the human insulin receptor and of EmIR showed comparable affinity to human insulin. The EmIR encoding chromosomal locus (emir) was characterised and comprised 16.5kb. Southern blot hybridisations demonstrated that emir is present as a single copy locus in E. multilocularis. Furthermore, structural comparisons indicated that emir and the insulin receptor genes from mammals and insects derive from a common ancestor. Based on reverse transcriptase-polymerase chain reaction analyses, emir was found to be expressed in the two larval stages metacestode and protoscolex. EmIR is, therefore, likely to play an important role in echinococcal development and possibly also in the interaction with the mammalian host.

Amino Acid Sequence↗

PubMed2003

Echinococcus multilocularis: secondary poisoning of fox population during a vole outbreak reduces environmental contamination in a high endemicity area.

This paper describes the role of fox population level on Echinococcus multilocularis infection in foxes in a highly endemic area in eastern France. Fox population level was monitored by spotlight survey at Le Souillot from 1989 to 2000, and from 1992 to 2000 at Chemin, a control site located in a low endemic area. The infection level of the fox population was estimated at Le Souillot from winter 1995 to winter 1999 using a coproantigen ELISA performed on faeces collected in the field. Population biomass of intermediate hosts (Microtus arvalis and Arvicola terrestris) was monitored using index methods from 1995 to 1999. At Le Souillot, a significant decline in the fox population level was recorded after spring 1997 (P<0.001), and the population level remained low until 2000. The decline occurred when 31% of the grassland area was treated with bromadiolone, an anticoagulant used at a large scale for the control of A. terrestris population outbreaks. No decline of population was recorded at Chemin, where bromadiolone was not used for rodent control. Significant differences among ELISA OD distributions in fox faeces were recorded for the five winters under study at Le Souillot (P=0.0004). The median of ELISA OD distribution was 0.209 and 0.207 before the population decline (winter 1995 and 1996, respectively), significantly increased to 0.306 just after the decline (winter 1997), and then significantly decreased to 0.099 and 0.104 afterwards (winter 1998 and 1999, respectively). Therefore, the decrease in infection level occurred during winter 1998, 1 year after the population decline, when the intermediate host biomass in the field was at its highest. These results suggest a complex dependence between the fox population level and E. multilocularis infection in a high endemicity area. Alternative ways to control fox population as a way to reduce E. multilocularis transmission in a given area are discussed.

4-Hydroxycoumarins↗

PubMed2003

Partial characterisation of carbohydrate-rich Echinococcus granulosus coproantigens.

Coproantigen ELISA based tests for diagnosis of canine echinococcosis provide high specificity and sensitivity. However, the antigenic molecules present in faeces from infected dogs have not yet been characterised. While initial attempts to determine the molecular weights of Echinococcus granulosus coproantigens by SDS-PAGE and Western blotting with coproantigen reactive capture antibodies were equivocal, they suggested presence of a significant carbohydrate component. Periodate treatment of coproantigen positive faecal supernatants resulted in a significant reduction (53%) in ELISA activity, suggesting that carbohydrates are involved in the antigenic structure of E. granulosus coproantigens. Protease treatment of antigenic molecules resulted in an 11% reduction in absorbance in ELISA, indicating that protein components were also present which affected by enzyme activity. Lectin-binding ELISA assays indicated strong affinity of E. granulosus coproantigens to concanavalin agglutinin and Lens culinaris agglutinin, and moderate binding to wheat-germ agglutinin and peanut agglutinin. No binding was detectable to Ulex europaensis agglutinin-I, Bandeiraea simplicifolia or Dolichos biflorus agglutinin. These data indicate that E. granulosus coproantigens from infected dog faeces possibly contained alpha-D-mannose and/or alpha-D-glucose, beta-galactose and N-acetyl-beta-glucosamine residues. To verify the role of carbohydrate moieties in coproantigens, faecal samples were treated with exoglycosidase and tested in the coproantigen ELISA. Treatment with beta-galactosidase or N-acetyl-beta-glucosamine reduced ELISA activity by 44 and 30%, respectively. Incubation with a panel of other specific exoglycosidases including alpha-galactosidase as well as alpha-L-fucosidase, alpha-mannosidase, beta-mannosidase, alpha-glucosidase, beta-glucosidase, beta- fructosidase, or neuraminidase, did not alter coproantigen detection in ELISA. The results indicate that coproantigens present in faeces from E. granulosus naturally infected dogs were highly glycosylated and contain beta- galactose and N-acetyl-beta-glucosamine. The putative relationship of antigenic molecules with the tapeworm glycocalyx is discussed.

Acetylglucosamine↗