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PubMed1985

Echinococcus granulosus: diagnosis of hydatid disease in man.

Several antigen fractions were prepared from sheep hydatid fluid and scolices of Echinococcus granulosus by salting out with ammonium sulphate. Sera from subjects with hydatid disease and from uninfected controls were assayed by the IHA, Latex, ELISA and Complement Fixation tests. The greatest sensitivity was given by the hydatid fluid 0.8 M fraction in the IHA test. This antigen also gave good results with the ELISA technique. Antigens from sheep fertile fluid were diagnostically superior to those from scolices. The specificity was excellent for all antigens examined.

Antibodies↗
PubMed1989

Echinococcus multilocularis: ultrastructural effect of in vivo albendazole and praziquantel therapy, singly and in combination.

Cotton rats with Echinococcus multilocularis infections of one month's standing were treated for six months with albendazole (50 mg kg-1 day-1), or praziquantel (500 mg kg-1 day-1), or both drugs simultaneously. The germinal layer of albendazole-treated cysts differed little from control tissue apart from marginal increase in cyton vesiculation and the presence of small lamellated residual bodies. Protoscolex tissue appeared unaffected. The germinal layer of praziquantel-treated cysts differed markedly from control tissue, with increased vesiculation and mitochondrial number in those with intact germinal layers, and disintegration and detachment of the layer in other cysts. Protoscoleces were necrotic. After combined therapy, the germinal layer was either intact but with increased vesiculation and residual bodies present, or was disintegrating and detaching from the laminated layer.

Albendazole↗
PubMed1989

Albendazole is effective against established Echinococcus granulosus in gerbils: comparison of serum concentrations achieved by gavage and feed administration.

Serum levels of albendazole sulphoxide in gerbils infected with Echinococcus granulosus and treated with albendazole (20 or 50 mg kg-1 day-1) by gavage were dose dependent, whereas albendazole administered in feed at a rate equivalent to 80 mg kg-1 day-1 achieved serum levels calculated to be equivalent to those produced by administration of 40 mg kg-1 day-1 by gavage. This regimen, over a three-month period, was effective and reduced parasite weight to 4.6% of that in control gerbils, and the treated parasite tissue showed ultrastructural changes ranging from severe accumulation of residual bodies to total disintegration of the germinal layer.

Administration, Oral↗
PubMed1990

A programme to reduce the risk of infection by Echinococcus multilocularis: the use of praziquantel to control the cestode in a village in the hyperendemic region of Alaska.

This paper reports the results of a 10-year field trial designed to reduce the risk of infection by Echinococcus multilocularis to residents of a village in a hyperendemic area (Savoonga, St. Lawrence Island). The objective was to prevent dispersal of infective eggs of the cestode within the village by means of monthly treatments of dogs with praziquantel. Northern voles, Microtus oeconomus, present in the village as commensals, served as an index of risk, as the incidence of infection in the voles provides information about the availability of eggs within the confines of the inhabited area. Voles were examined annually during early June before the population of overwintering voles was diluted by the first annual litters. The pretreatment infection-rate within the village was 29% (range 22-35%), and in control areas at some distance from the village for the entire study period it averaged 53% (284 infected voles from a sample of 533). Some fluctuation in incidence of infection in village voles occurred, apparently depending on the extent to which the residents kept their dogs chained and thus available for treatment. The success of the programme was demonstrated by the reduction in prevalence of infection to about 1% of voles in 1985, and an average infection rate during the last five years of the study of 5% (29 infected voles in a sample of 582). This 83% average reduction in the prevalence of the larval cestode within the village reflects a corresponding reduction in the risk of acquiring by the residents of the village. The method would be applicable for the control of E. multilocularis in most hyperendemic regions. Success depends, however, on elimination of unrestrained dogs and a precise schedule of treatment.

Alaska↗
PubMed1991

The growth and development of Echinococcus granulosus of sheep origin in dogs and foxes in Britain.

Four separate experiments were carried out by dosing dogs (Beagles and Border collies) and red foxes with protoscoleces obtained from hydatid cysts in sheep from mid-Wales. The dogs and foxes were killed at intervals over a period from 34-180 days after infection and the intestines were examined for Echinococcus granulosus. Border collie dogs were efficient hosts in that large numbers of worms developed, with gravid segments present by 55 days after infection; but Beagle dogs were poor hosts in that only small numbers of immature worms developed. Foxes were poor hosts in that few or no worms developed, but gravid segments were seen in three of 29 foxes. The worms showed morphological features similar to the 'sheep' rather than the 'horse' strain.

Animals↗
PubMed1991

Membrane transport of amino acid enantiomers in protoscoleces of Echinococcus granulosus (Cestoda).

Protoscoleces of Echinococcus granulosus absorb both L- and D-alanine. Concentration ratios exceed 1 with values for D-alanine exceeding those for the L-isomer, suggesting that both are absorbed by active mechanisms. Uptake of both isomers involves both diffusion and carrier-mediated components. Values for the diffusion component (Kd) for L- and D-alanine were 0.21 and 0.38 nmol mg-1 protein/1.5 min mM-1 respectively, and values for Kt, the transport constants, 0.17 mM and 0.21 mM respectively. Uptake of both isomers was inhibited competitively by a number of other amino acids.

Alanine↗
PubMed1991

Experimental infection of Libyan sheep with Echinococcus granulosus.

The growth rate of unilocular hydatid cysts over a two-year period was studied in Libyan sheep dosed orally with gravid segments of Echinococcus granulosus taken from stray town dogs. Seven of the eight sheep dosed with 20-100 gravid segments (say 4000-20,000 eggs) had developed only infertile hydatid cysts after 107-611 days. Sheep dosed with 1000 gravid segments (say 200,000 eggs) had developed only sterile cysts when examined 358 days after dosing. Fertile cysts were recovered from the lungs after 428 days, and after 584 days from the liver. Only sterile cysts were seen in the heart, spleen and kidneys.

Animals↗
PubMed1992

Analysis of host components in hydatid cyst fluid and immunoblot diagnosis of human Echinococcus granulosus infection.

To improve serodiagnosis of cystic hydatidosis, immunoblotting studies were performed to look for a highly specific parasite antigen(s). First, commercially available hydatid cyst fluid antigen preparations were characterized by SDS-PAGE and by immunoblotting with sera specific for parasite and host animal proteins. One preparation, designed for use in complement fixation tests, did not appear to be suitable for immunoblotting because of the low concentrations of parasite antigens. Several host proteins, including serum albumin and IgG, were detected in the cyst fluid. Sera from patients with Echinococcus granulosus infections and other parasitic diseases were examined by immunoblotting for antibodies against specific cyst fluid parasite antigens. Several parasite antigens were variably recognized. Only one antigen, a 40 kDa protein, was recognized by all E. granulosus-infected patients. Reactivity against this antigen was also observed in all sera from E. multilocularis, cysticercosis, and schistosomiasis patients as well as in some filariasis cases. Two E. granulosus antigens, molecules of 12.5 and approximately 17 kDa, were only recognized by antibodies from some E. granulosus patients.

Animals↗
PubMed1994

Echinococcus granulosus infections in the dogs of Kathmandu, Nepal.

The prevalence, incidence and risk factors of infection by Echinococcus granulosus were studied in the domestic and street dogs of Kathmandu, Nepal. Using an ELISA coproantigen test as a screening method, the highest prevalence (5/88 = 5.7%) was seen in domestic dogs from an area of the city used for slaughtering livestock. A prevalence of 1.8% (3/171) was found in domestic dogs seen at eight veterinary clinics distributed around the city. Although none of the 73 street dogs sampled in the ELISA screening survey was positive, three of 20 street dogs killed with poison as part of the city's dog-control programme harboured from one to five adult worms. As none of 99 dogs treated with an anthelmintic was found re-infected 3 months later, it was impossible to calculate accurately the of infection over a 3-month period. Information about the feeding, sleeping and roaming practices of the dogs was also gathered using questionnaires and direct observations.

Animals↗
PubMed1999

Echinococcus granulosus larvae in the livers of sheep in Tunisia: the effects of host age.

A baseline survey of hepatic hydatid disease in sheep in Tunisia was undertaken. Prevalence and intensity (i.e. the number of cysts/liver) were both found to increase with age. The age-specific trends in these two parameters indicate that Echinococcus granulosus is in an endemic equilibrium steady-state in Tunisia and therefore amenable to control. The distribution of parasites within the livers of the hosts followed a negative binomial distribution. The negative binomial constant, k, increased with age, indicating that there was a lower propensity for aggregation of parasites in the hosts as the sheep became older.

Age Factors↗
PubMed2006

Vaccination of dogs against Echinococcus granulosus, the cause of cystic hydatid disease in humans.

Dogs are pivotal in Echinococcus granulosus transmission to humans, and dog vaccination provides a very practical and cost-effective prevention strategy. We vaccinated dogs with soluble native proteins isolated from protoscoleces of E. granulosus and induced significant suppression of worm growth and egg production. Accordingly, we tested for vaccine efficacy using recombinant proteins derived from a developmentally regulated gene family (egM) specifically expressed in mature adult E. granulosus worms. Three egM genes--egM4, egM9, and egM123--were subcloned into an expression vector that expressed the molecules as soluble glutathione S-transferase (GST) fusion proteins in Escherichia coli. The 3 fusion proteins were purified for dog vaccination trials (3 doses of 80 microg/protein/dog) in which the dogs were challenged and then necropsied 45 days after infection. Compared with worms in the control dogs that received GST, the 3 recombinant proteins induced a very high level of protection (97%-100%) in terms of suppression of worm growth and, especially, of egg development and embryogenesis. We have thus shown that vaccination of the dog host against E. granulosus is feasible when recombinant proteins are used. Because the egg stage is crucial in the echinococcal life cycle, successful suppression of egg development by vaccination would halt transmission to intermediate hosts, thereby effecting long-term control.

Animals↗
PubMed1990

Effects of albendazole on Echinococcus multilocularis infection in the Mongolian jird.

Albendazole chemotherapy of larval Echinococcus multilocularis was studied in the Mongolian jird by administration of medicated feed at various concentrations and durations. The effects were evaluated by comparison of treated and control groups in terms of host mortality, larval metastases to the lungs, and final weight and histologic appearance of larval tissue. Viability of larval tissue at necropsy of each animal was tested by inoculation into two noninfected jirds. Albendazole-medicated feed (0.05%-0.10%) significantly inhibited larval growth. Other effects of the drug included larval degeneration and necrosis, inhibition of protoscolex formation, decreased pulmonary metastases, and reduced mortality of hosts. Adverse effects on the parasite correlated significantly with serum albendazole metabolite levels and duration of therapy. However, serum albendazole levels in jirds equal to or exceeding concentrations achieved in humans receiving daily doses of 10 mg/kg of body weight did not kill the parasite.

Albendazole↗
PubMed2004

Impeded Th1 CD4 memory T cell generation in chronic-persisting liver infection with Echinococcus multilocularis.

Memory T cells of the CD4 lineage coordinate immune responses against pathogens via the antigen-induced secretion of potent effector cytokines. The efficacy of these responses is thought to depend on both the overall number of pathogen-specific memory T cells and the particular array of cytokines that these cells are programmed to secrete. It is unknown to what extent cellular immunity can be induced by Echinococcus multilocularis infection. To examine the immunological memory provided by the adaptive cellular immune system in control of the chronic-persisting infection, peripheral lymphocytes of patients with alveolar echinococcosis (AE) were studied ex vivo. Stimulation of memory cells was performed with E. multilocularis vesicular fluid, purified protein derivative as recall antigen and phytohemagglutinin. Cytomegalovirus latency served as disease control. Frequencies of circulating CD4(+) T cells secreting IFN-gamma, IL-2, tumor necrosis factor-alpha, IL-4, IL-5 and IL-10 were determined by both cytokine flow cytometry and ELISPOT assays. Most strikingly, in chronic AE the frequencies of E. multilocularis antigen-specific cells committed to T(h)1-cytokine production were low (mean 0.5% of CD4(+) T cells). However, an E. multilocularis-specific response of CD4(+) T cells at frequencies of >/=0.1% was detected in the majority of AE patients (68%). Low numbers of cells committed to T(h)1 cytokine secretion were invariably seen in patients with active and inactive disease. Interestingly, the number of specific CD4(+) memory T cells was not increased in cured AE patients after complete surgical removal of the metacestode. Hyporesponsiveness during the chronic helminth infection was E. multilocularis specific. Thus, our results demonstrate that antigen-specific memory function against E. multilocularis is markedly different from that against viral or bacterial pathogens. Whether the antigen-specific cellular hyporesponsiveness with impeded T(h)1 CD4(+) memory T cell generation is a cause or a result of the progressive metacestode activity remains to be determined.

Adult↗
PubMed1986

Protoscolicidal effect of praziquantel--in-vitro and electron microscopical studies on Echinococcus granulosus.

Praziquantel was investigated in an in-vitro culture system of protoscoleces of Echinococcus granulosus (hydatid disease). Live protoscoleces were obtained from ovine pulmonary and hepatic cysts. As well as testing for serial viability, protoscoleces were examined by scanning and transmission electron microscopy. Praziquantel concentrations as low as 50 micrograms/l had a profound and rapid effect on the viability of protoscoleces. Electron microscopy of treated parasite demonstrated gross damage to the tegument. Praziquantel is a most effective and rapid scolicidal agent which may well be of clinical value.

Animals↗
PubMed2004

In vitro effects of nitazoxanide on Echinococcus granulosus protoscoleces and metacestodes.

OBJECTIVES: Infection of humans and domestic ruminants with the larval stage (metacestode) of Echinococcus granulosus results in cystic echinococcosis (CE). The metacestode causes a space-occupying lesion in visceral organs, most commonly in the liver. Benzimidazole carbamate derivatives, such as mebendazole and albendazole, are currently used for chemotherapeutic treatment of CE. In human patients, benzimidazoles have to be applied in high doses for extended periods of time, and adverse side effects are frequently observed. In order to evaluate alternative treatment options, the in vitro efficacy of nitazoxanide, a broad-spectrum drug used against intestinal parasites and bacteria, was investigated. METHODS: Freshly isolated E. granulosus protoscoleces were subjected to nitazoxanide treatment (1, 5 and 10 microg/mL), and the effects on parasite viability were monitored by Trypan Blue staining and scanning electron microscopy. Protoscolex cultures were maintained further, until metacestode development took place. Metacestodes were then subjected to nitazoxanide treatment (10 microg/mL), and corresponding effects were visualized by scanning and transmission electron microscopy. RESULTS: Dose-dependent protoscolex death within a few days of nitazoxanide treatment was observed. Subsequent in vitro culture of drug-treated protoscoleces confirmed the non-viability of parasites, while further cultivation of non-treated protoscoleces for a period of at least 3 months resulted in stage conversion and the formation of small metacestodes 3-4 mm in diameter. Nitazoxanide had a deleterious effect on these metacestodes, which was comparable to that of albendazole. CONCLUSIONS: Our study indicates a potential for nitazoxanide as an alternative treatment option against CE.

Albendazole↗
PubMed1990

Complete life cycle of the canid tapeworm, Echinococcus multilocularis, in laboratory rodents.

Mongolian gerbils, Meriones unguiculatus, when treated at intervals of 2-6 days with prednisolone tertiary butyl acetate, sustained infection with adult Echinococcus multilocularis in the small intestine, with the tapeworm exhibiting normal strobilation and egg production as in the natural canid host. Host age is critical for the survival of the tapeworm in normal gerbils; parasites survive for only 2 days in 20-wk-old animals, 4 days in 4-wk-old animals, but at least 7 days in 3-wk-old animals. The host age dependence in parasite recovery between days 28-37 postinfection was not affected by treatment from around the day of infection. Starting the treatment before infection (on day -17 relative to infection) remarkably improved the tapeworm's survival within the intestine of older animals. Eggs produced in this rodent model system 28 days postinfection were infective to rodents such as Mongolian gerbils and gray red-backed voles, Clethrionomys rufocanus bedfordiae, by oral or intraperitoneal inoculation. The E. multilocularis/Mongolian gerbil system can replace the natural canid hosts as a new way to obtain infective eggs and to analyze host-parasite interactions. The development of an alternative definitive host for zoonotic tapeworms may accelerate experimentation in this field.

Aging↗
PubMed1984

CT findings in hepatic involvement by Echinococcus granulosus.

The CT findings in hepatic involvement by Echinococcus granulosus are described. Pathognomonic signs of the hydatid nature of a cystic lesion are visualization of the cystic wall on plain CT, calcification of the cyst wall, daughter cysts, and membrane detachment.

Adolescent↗
PubMed2007

Case report: Echinococcus disease of the bone presenting as a femoral shaft nonunion.

Osseous hydatidosis (Echinococcus infection) is a rare parasitic bone infection that poses challenges in diagnosis and treatment. We present a novel case of osseous hydatidosis of the femoral shaft that was diagnosed at the time of surgery for a recalcitrant femoral shaft nonunion. We know of no reports of osseous hydatidosis presenting as a femoral shaft nonunion. A discussion of the challenges in diagnosis and treatment of osseous hydatidosis are discussed, and the literature on osseous hydatidosis is reviewed.

Albendazole↗