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PubMed1988

Echinococcus granulosus in animals in northern India.

The prevalence of larval Echinococcus granulosus in buffaloes, sheep and goats and in adult stray and shepherd dogs was studied in northern India. A total of 48.1% of 754 buffaloes, 30.5% of 1215 sheep and 21.0% of 447 goats were found to be infected with this parasite. The prevalence of infection in buffaloes was higher in older animals than in younger animals. The lungs and livers appeared to be the sites of predilection. A high percentage of cysts from buffaloes (71.1%) were sterile, whereas a high percentage (90.0%) of cysts from sheep and goats were fertile. Shepherd dogs showed a higher prevalence of infection than stray dogs and the latter examined near the vicinity of slaughter houses had a higher prevalence of infection than those examined in other parts of the city.

Animals↗
PubMed1992

Frequency distribution of Echinococcus granulosus hydatid cysts in sheep populations in the Xinjiang Uygur Autonomous Region, China.

Age-prevalence and age-intensity data of Echinococcus granulosus hydatid cysts in sheep populations were collected in an abattoir in the Xinjiang Uygur Autonomous Region, People's Republic of China. The frequency distribution of the larval cysts per sheep was empirically described by the negative binomial model, with parameter k being 0.5273. A mathematical model for the life cycle of E. granulosus was applied to the collected data and the results show that the infection pressure on sheep was 0.4362 (female) or 0.4119 (male) infections per year, the mean number of cysts increased linearly by 0.8824 (female) or 0.9971 (male) cysts every year and acquired immunity was too low to depress this rate of increase. According to certain definitions of steady states for taeniid populations, it was concluded that at least in some parts of Xinjiang, the life cycle of E. granulosus was and may still be in an endemic steady state. Consequently, the regular dog-dosing program would readily drive the infection from an endemic state towards extinction.

Age Factors↗
PubMed1992

Frequency distribution of Echinococcus granulosus in dog populations in the Xinjiang Uygur Autonomous Region, China.

Age-prevalence and age-intensity data of Echinococcus granulosus in dog populations were collected in four counties in the Xinjiang Uygur Autonomous Region, People's Republic of China. The frequency distribution of the parasite per dog was adequately described by the negative binomial model, with parameter k being 0.0571. The mathematical model of the life cycle of E. granulosus constructed by Roberts et al. (1986--Parasitology, Vol. 92, pages 621-641) was used to estimate the epidemiologic parameters of E. granulosus in Xinjiang. This model showed that the prevailing infection pressure on dogs was 0.4560 infectious insults year-1 and the mean length of an infection was 1.4975 years. The effect of acquired immunity on the prevalence of E. granulosus in dogs was considered to be insignificant.

Age Factors↗
PubMed1995

A model for the control of Echinococcus multilocularis in France.

In some areas of France the prevalence of Echinococcus multilocularis in foxes is as high as 50%, whereas less than one in a thousand voles (principally Microtus arvalis) are infected. In these regions the control of rabies in foxes is achieved by using helicopters to spread bait containing oral vaccine in capsules. A mathematical model has been constructed in an attempt to determine if the addition of praziquantel to bait would be effective in eradicating E. multilocularis, or at least achieve a useful measure of control. It has been shown that the qualitative population dynamics of E. multilocularis are not affected by the detail of its epidemiology in the intermediate host population. The model is, however, sensitive to assumptions about the distribution and longevity of the adult worm in the definitive host. Given these assumptions, a method is provided that determines the feasibility of eradication conditional on the pre-control prevalence in foxes, or predicts the post-control prevalence if eradication is not feasible. If experiments could be designed to provide better information about the biological factors that determine the epidemiology of this parasite in the definitive host, a more reliable assessment of the feasibility of control would be achieved.

Animals↗
PubMedDate not supplied

Metabolic alterations in organs of Meriones unguiculatus infected with Echinococcus multilocularis.

1. 1H-NMR spectra of liver, spleen and kidney extracts from Meriones unguiculatus infected with Echinococcus multilocularis showed decreased levels of glucose. In addition, the liver extracts were severely glycogen-depleted. 2. Both livers and spleens contained less glycine, taurine and acetate. Spleens also had fewer cholines and less lactate but more betaine and alanine. 3. In the kidneys, elevated concentrations of succinate, acetate and lactate were found.

Amino Acids↗
PubMed1994

Partial purification and comparison of the kinetic properties of ovine liver Echinococcus granulosus hydatid cyst fluid malate dehydrogenase and the cytoplasmic enzyme from the host liver.

Ovine liver Echinococcus granulosus hydatid cyst fluid and cytoplasmic healthy ovine liver malate dehydrogenases were purified 24- and 30-fold by Sephadex G-200 and DEAE-Sephadex chromatography. Both enzymes were eluted with the same elution volume and the same salt concentration from the respective columns. The pH optimum of the enzymes from both sources was 8.4 in either Tris-HCl or barbital buffer. The Km values for oxaloacetate were 0.211 and 0.200 mM for hydatid cyst fluid and healthy ovine liver enzymes, respectively. The Km values for NADH were 0.220 and 0.213 mM for hydatid cyst fluid and healthy ovine liver enzymes, respectively. Enzyme from both sources demonstrated similar heat denaturation patterns. Both enzyme preparations were inhibited at high concentrations of either substrate. Neither enzyme was inhibited by para-hydroxymercuribenzoate or fumarate, and both enzyme preparations were specific for NADH as a cofactor. The results are discussed in terms of the possible infiltration of the host enzyme into the cyst fluid.

Animals↗
PubMed2004

Echinococcus granulosus antigen B hydrophobic ligand binding properties.

Antigen B (AgB), an immunodominant component of the cestode parasite Echinococcus granulosus, presents homology to and shares apparent structural similarities with helix-rich hydrophobic ligand binding proteins (HLBPs) from other cestodes. In order to investigate the fatty acid binding properties of AgB, two of its subunit components (rAgB8/1 and rAgB8/2) were expressed in Escherichia coli and purified, and the native antigen was purified from the hydatid cyst fluid by affinity chromatography using a monoclonal antibody raised against rAgB8/1. The interaction of the purified native and recombinant proteins with the fluorescent ligands DAUDA, ANS, DACA and 16-AP was investigated. The palmitic acid derived fluorescent ligand, 16-AP, showed the greatest enhancement in fluorescence when bound to native AgB or to its recombinant subunits, and the dissociation constants for 16-AP binding were determined. Surprisingly, in contrast to HLBPs from other cestodes, interactions with other fatty acids, including palmitic acid, caused an increase in fluorescence instead of competing with 16-AP. Our results suggest that AgB might have evolved different functions in the binding of hydrophobic compounds, dependent on cestode environment.

Animals↗
PubMed2001

A new ImmunoCAP assay for detection of Echinococcus multilocularis-specific IgE.

In alveolar echinococcosis (AE), caused by Echinococcus multilocularis (E.m.), increased levels of total and parasite-specific IgE are frequently found. These may not only have diagnostic but are also supposed to have prognostic value in the follow-up of AE patients. However, there is no commercial test available for quantification of E. m.-specific IgE (sIgE). The only commercial test available is based on E. granulosus (g.) hydatid antigen, which is not optimal for detection of E. m.-specific IgE. Therefore, a new ImmunoCAP with covalently bound crude antigen of E. m. was developed in cooperation with Pharmacia Research Forum for the analysis of E. m. sIgE. The E. m. ImmunoCAP was evaluated in 53 AE patients with different clinical disease progression and 20 healthy controls. Our data showed a higher sensitivity for sIgE determination with E. m. ImmunoCAP compared to the E. g. ImmunoCAP (73.6% vs 61.5%) and a positive correlation between total IgE and sIgE. Furthermore, there was a significant correlation between sIgE in both tests. In conclusion, the new E. m.-specific ImmunoCAP test proved to be a valuable tool for determination of sIgE. It may provide the basis for the development of further E. multilocularis-specific IgE immunotests which are essential for evaluation of sIgE during clinical course of AE.

Adult↗
PubMed1997

Vaccination against echinococcus in perspective.

Vaccination of intermediate hosts will effectively reduce the prevalence of human echinococcosis. The rate of progress can be enhanced by concurrent tactical treatment of definitive hosts. The oncosphere of Echinococcus granulosus contains a specific protein which when expressed on the oncosphere surface will combine with specific antibody In the presence of complement, damage is caused to the plasma membrane, resulting in failure of the oncosphere to develop into a metacestode. Immunisation of sheep with oncosphere secretions or with an oncosphere homogenate results in 99% resistance to a challenge infection of the sheep with E. granulosus eggs. Immunisation of sheep with the specific purified protein results in 92% resistance. The gene coding for the protein has been isolated from an E. granulosus oncosphere cDNA library and expressed in E.coli as a fusion protein with glutathione-S-transferase. A monoclonal antibody to an epitope on the E. granulosus portion of the molecule is able to bind to the surface of oncospheres and to prevent their development to metacestodes in vitro. Immunisation of sheep with the fusion protein has given 97 and 98% resistance to a challenge infection in two separate trials. The shelf-life of formulated vaccine is at least 12 months, and the immunity generated by two injections given 1 month apart persists for at least 12 months. A homologue of the gene has been identified in E. multilocularis. The vaccine has the potential to be used as a tool for control of transmission of E. granulosus through its natural intermediate hosts (particularly domestic ungulates) as part of hydatid control programmes. Traditional methods of hydatid control (anthelmintic treatment of dogs) require regular treatment within the prepatent period for prolonged periods (20-30 years) to achieve satisfactory control, and often sociological factors to do with dog-feeding, dog ownership and dog-control prevent such an achievement. By controlling the disease in both the definitive host and the intermediate host, the shortcomings of either procedure can be overcome, resulting in a cost-effective desired result within a practical time period.

Animals↗
PubMed2003

Analysis of differential gene expression in Echinococcus multilocularis larval stages by means of spliced leader differential display.

All parasitic helminths process a large subset of their mRNA molecules via spliced leader trans-splicing. Here we describe a rapid and efficient method, 'spliced leader differential display', to generate comprehensive expression fingerprints of trans-spliced factors on silver-stained acrylamide gels. The method allows systematic screening of the entire trans-spliced transcriptome of parasitic organisms using only minute amounts of starting material. Spliced leader differential display selectively displays 5' end-fragments of trans-spliced messages thus facilitating the identification of associated proteins and the full-length characterisation of corresponding mRNAs. We employed spliced leader differential display to analyse gene expression patterns of in vitro cultivated protoscoleces and metacestode vesicles from Echinococcus multilocularis. These analyses revealed that the majority of trans-spliced mRNAs are expressed at equal amounts in both larval stages whereas about 25% of the identified transcripts displayed stage-specific differential expression. Full-length transcripts for several of the obtained fragments were isolated and their constitutive or differential expression was verified by competitive PCR and Virtual Northern blotting. Spliced leader differential display was further used to identify genes which are induced in the E. multilocularis metacestode stage under growth promoting conditions in the presence of host hepatocytes. One mRNA, encoding a putative member of the epidermal growth factor family of mitogens, was shown to be 10-fold induced upon co-incubation of metacestode vesicles with host cells which indicates a possible involvement of parasite-determined, epidermal growth factor-like signal transduction systems in metacestode proliferation and development. The successful application of spliced leader differential display to gene expression analyses of echinococcal larvae, combined with easy handling and a low rate of false positives, recommends this method not only for studies on the host-parasite interplay during alveolar echinococcosis, but also for investigations on other parasitic organisms.

Adolescent↗
PubMed1996

Echinococcus granulosus antigen B and seroreactivity in natural ovine hydatidosis.

Hydatid cyst fluid from sheep and camels infected with Echinococcus granulosus, together with partially purified preparations of hydatid fluid antigen B and a recombinant antigen B product, were tested in an ELISA for their ability to detect IgG antibodies against E granulosus in the serum of naturally infected sheep. The antibody activity in sera from sheep naturally infected with Taenia hydatigena cysticercosis or Fasciola hepatica was also tested. All the antigen preparations from native hydatid cyst fluid were able to detect antibodies in the sera from a significant proportion of sheep with natural hydatid cyst infection, as identified by inspection at slaughter, although the seroreactivity was variable. The native antigen B preparation from camel hydatid cyst fluid gave the highest sensitivity in the ELISA (total 90 per cent), with 99 per cent specificity. In all cases, the recombinant antigen B was the least sensitive antigen (25 per cent) although it was highly specific (99 per cent).

Animals↗
PubMedDate not supplied

Echinococcus granulosus: a seroepidemiological survey in northern Israel using an enzyme-linked immunosorbent assay.

Following an intensive health education programme, 8651 finger-prick blood samples, 4122 from a predominantly adult group attending a primary care clinic and 4529 from schoolchildren, were collected in Tamra, northern Israel. An enzyme-linked immunosorbent assay (ELISA) for immunoglobulin G (IgG) was used to detect anti-Echinococcus granulosus antibodies, using both crude and purified antigens. The seroprevalence in the adult group was 0.48% (20/4122); optical density values were 0.1-0.14 in 10 subjects, 0.15-0.19 in 9, and > or = 0.2 in one; prevalences did not differ significantly between males and females or among age groups. Twenty-six of the schoolchildren (0.57%) were seropositive, 23 with optical densities of 0.1-0.14, one of 0.15-0.19, and 2 > or = 0.2. A high correlation was observed between ELISA positivity and both positivity in the arc 5 immunoelectrophoresis test and the presence of a high titre in the indirect immunofluorescence assay. Cross reactivity was observed with sera from schistosomiasis and ancylostomiasis patients, using both crude and purified echinococcal antigens. The results indicated that the IgG ELISA, using both crude and purified antigens, was very useful for seroepidemiological screening for echinococcosis, and that this condition is an emerging disease in northern Israel.

Adolescent↗
PubMed1996

Species of Echinococcus: pattern and process.

Although classification and nomenclature within the cestode genus Echinococcus has, historically, been controversial, the past 20-30 years have provided a period of relative stability. Recent calls for taxonomic revision in the genus have therefore created something of a stir. In this article, Alan Lymbery and Andrew Thompson describe the reasons for the new controversy, and suggest that the problem can only be resolved by agreement on an appropriate species concept and on operational procedures for implementing that concept.

Journal Article↗
PubMed1998

Modelling the prevalence of Echinococcus and Taenia species in small ruminants of different ages in northern Jordan.

A base-line survey of Echinococcus granulosus, Taenia hydatigena and T ovis were undertaken in order to investigate the transmission dynamics of these parasites in northern Jordan. Intensity of E. granulosus infection, in sheep, increased with age in a linear fashion whilst the asymptotic prevalence was one. This implied that E. granulosus is in an endemic steady state with no evidence of protective immunity in the intermediate host. The mean number of cysts increased by 1.66 per year with approximately 0.320 infections per year, each infection consisting of 598 eggs to produce 5.2 cysts. The basic reproduction ratio (R0) was estimated to be 1.5-1.8. A similar pattern was suggested with E. granulosus in goats but the infection pressure appeared to be lower with only 0.128 cysts per year. Although infection in goats appeared to be endemic there was some evidence of departure from the model which might indicate that the model needs adjusting for this species. In the case of T. hydatigena the host age-intensity helminth distribution indicated that this parasite was hyperendemic in both sheep and goats, implying regulation by intermediate host immunity. Consequently, R0 was determined from asymptotic prevalence curves for T hydatigena and was calculated to be 4.0 and 3.1 in sheep and goats, respectively. The lower R0 in goats, together with the higher asymptotic age-intensity and age-prevalences, indicates that goats acquire immunity more slowly to T hydatigena in comparison to sheep. Taenia ovis was not detected in any animals.

Animals↗
PubMedDate not supplied

Correlative CT, MRI and histological findings of hepatic Echinococcus alveolaris: a case report.

Diagnosis of liver infestation by Echinococcus alveolaris (EA) is based on serologic, sonographic and CT findings. Literature review yielded only one report discussing the MRI findings of hepatic EA infestation. In this report, we present a case of hepatic EA infestation with its correlative CT, MRI and histological findings. CT showed hypodense mass involving more than half of the liver with rim and central calcifications. MRI revealed hypointense signal of the infiltrative mass on both T1- and T2-weighted images. On MRI, the portal vein branches were seen coursing through the lesion. Neither CT nor MRI demonstrated any contrast enhancement of the mass. On the histological examination, abundant fibrous and hyalinized tissue surrounding multiple small cysts were observed. MRI may provide invaluable information in the diagnosis of EA infestation of the liver, either by disclosing the infiltrative pattern of infestation without significant effect to vascular structures, or by the signal characteristics.

Adult↗
PubMed2002

The complete mitochondrial DNA sequence of the cestode Echinococcus multilocularis (Cyclophyllidea: Taeniidae).

The 13,738 bp mitochondrial DNA from the cestode Echinococcus multilocularis has been sequenced. It contains two major noncoding regions and 36 genes (12 for proteins involved in oxidative phosphorylation, two for rRNAs and 22 for tRNAs) but a gene for ATPase subunit 8 is missing. All genes are transcribed in the same direction. Putative secondary structures of tRNAs indicate that most of them are conventional clover leaves but the dihydrouridine arm is unpaired in tRNA(Ser(AGN)), tRNA(Ser(UCN)), tRNA(Arg) and tRNA(Cys). The base composition at the wobble positions of fourfold degenerate codon families is highly biased toward U and against C.

Journal Article↗
PubMed2000

Epidemiology of Echinococcus granulosus in Arbil province, northern Iraq, 1990-1998.

During the period 1990-1998, 99 cases of human cystic hydatidosis (12.4 cases per year) were surgically treated at the two main hospitals in Arbil province, northern Iraq, and from this the human occurence for the province was estimated to be 2 per 100,000 inhabitants. In the same area, 1270 sheep, 550 goats and 320 cattle were examined at slaughter for hydatid cysts and prevalence rates were found to be 15.0%, 6.2% and 10.9%, respectively. A decreasing tendency in livestock prevalences was found towards the end of the study period. As in humans, most of the hydatid cysts in livestock were located in the liver. Fertility of sheep cysts, i.e. those containing protoscoleces, was found to be significantly higher (64%) than that of goats (35.7%) and cattle (29.8%). The percentage of fertile cysts containing viable protoscoleces varied between 63 and 82% in the livers and between 72 and 79% in the lungs of the different animal species. A total of 97 stray dogs were examined post-mortem in the years 1991, 1992 and 1998, and Echinococcus granulosus worms were found in the intestines of 48 dogs (49.5%). High worm burdens (> 1000) were observed in 37% of the dogs, medium worm burdens (200-1000) in 41%, and low worm burdens (< 200) in 22%. In 1998, the prevalence of canine echinococcosis (24.3%) was found to be significantly lower than in 1991 (70.4%) and 1992 (60.6%). The prevalence of human hydatidosis did not differ significantly over the years, but the study confirmed that hydatidosis is endemic in northern Iraq, and that housewives, labourers and farmers appear to be at the greatest risk of infection.

Adolescent↗