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PubMed1987

Echinococcosis in Libya. I. Prevalence of Echinococcus granulosus in dogs with particular reference to the role of the dog in Libyan society.

Of 151 dogs examined in 14 localities in Libya, 42 (27.81%) were infected with Echinococcus granulosus. The prevalence of the worms was generally higher in the coastal areas. Infections were light (1-200 worms) in 24 of the infected dogs, medium (201-1000 worms) in ten and high (over 1000 worms) in eight. The maximum number of worms was 12,821, recorded in a four-year-old dog. Infection rates differed with age: 12.5% in dogs aged up to one year, 36.6% for one to two years, 19.3% for two to three years, 44.2% for three to four years and 14.3% for dogs aged over five years. The role of dogs in Libyan society is discussed.

Animal Feed↗
PubMed1987

Use of two polysaccharide antigens in ELISA for the detection of antibodies to Echinococcus granulosus in sheep sera.

Polysaccharide antigens were obtained from either the secretions produced during in vitro cultivation of Echinococcus granulosus protoscoleces or from mouse hydatid cyst membranes by phenol extraction. When either of these antigens was used in an enzyme-linked immunosorbent assay antibody activities were detected in sera from sheep infected 27 or more weeks earlier with at least 100 E granulosus eggs. These antibody responses were significantly higher (P less than 0.05) than those of sheep infected with Taenia hydatigena or T ovis and tested with the E granulosus antigens. Very high cross-reacting antibody responses in sera from sheep recently infected with T hydatigena were only detected with the protoscoleces secretions antigen. Neither antigen was sufficiently sensitive or specific for serodiagnostic use. However, when sera were first tested with one antigen and then with the other, and only sera that were positive in both tests were regarded as positive, the overall sensitivity and specificity of this two antigen method increased to about 80 per cent.

Animals↗
PubMed1979

Echinococcus granulosus and E. multilocularis: in vitro culture of the strobilar stages from protoscoleces.

The techniques for the in vitro culture of Echinococcus granulosus and E. multilocularis are described in detail. The sheep strain of E. granulosus was grown to sexual maturity but fertile eggs were not produced due to the failure to achieve insemination in vitro. The horse strain of E. granulosus grew only slightly in vitro and then ceases to develop, although remaining active for long periods. E. multiloculoris differentiated largely into unsegmented, sexually mature, "monozoic" forms; some organisms developed "pseudo-proglottids" with the interproglottid membrane absent or poorly formed. After prolonged culture, some strobila of E. multilocularis developed an extra scolex.

Animals↗
PubMed1979

Cross-protection between the cysts of Echinococcus granulosus, Taenia hydatigena and T ovis in lambs.

Lambs were infected orally at 14 weeks of age with either Taenia hydatigena, T ovis or Echinococcus granulosus eggs. To induce high levels of resistance to oral reinfection, they were then injected intramuscularly with eggs of the homologous species four weeks and eight weeks later. The degree of immunity was then tested by oral challenge with eggs from either the homologous or an heterologous species. Autopsy results indicated that prior infection with an homologous species induced a very high degree of immunity to challenge infection. Prior infection with all combinations of heterologous species resulted in a lesser degree of immunity, which appeared to have acted on the establishment phase of development and did not influence cyst survival.

Animals↗
PubMed1968

Taxonomic characters in the genus Echinococcus (Cestoda: Taeniidae).

Not more than 4 species of cestodes of the genus Echinococcus Rudolphi, 1801, are recognised as valid. The larval stage of at least 3 of them is able to develop in man, causing respective types of hydatid disease. Accurate characterization of these cestodes, including both larval and adult stages, is essential for identification, upon which depends development of methods for preventing infection of man and domestic animals. Because morphological characteristics of the larval cestodes may be modified according to the species of host in which they develop, identification should be based upon taxonomic characters of specimens from the respective natural hosts, which can be identified by means of ecological investigations in endemic areas in combination with controlled infection of experimental animals. The morphological and biological characteristics of the known species are discussed, and the two species most important to public health and economically-E. granulosus (Batsch, 1786) and E. multilocularis Leuckart, 1863-are distinguished.

Echinococcus↗
PubMed1968

Screening of drugs and their assessment for use against the strobilate stage of Echinococcus.

From time to time, reports of anthelmintic trials are published indicating that a compound is, or is not, effective against Echinococcus granulosus in dogs. In some of these reports, an attempt is made to assess the efficacy of the compound from inadequate data. This paper reviews the problems associated with selecting, screening and defining the therapeutic dose-rate of a compound against E. granulosus. From this evaluation, a programme is defined, which, if followed, should result in the selection of promising compounds and the rejection of unsuccessful compounds at specific stages during the programme.

Animals↗
PubMed1979

[Echinococcus multilocularis: superinfections in experimentally infected mice (author's transl)].

The influence of subcutaneous superinfections following an intraperitoneal primary infection after 4 and 14 weeks respectively has been examined in Echinococcus multiolcularis infected NMRI-mice. It could be shown that the growth of subcutaneous echinococci is inhibited in superinfected mice (372 mg) if compared with control mice (903 mg parasite weight). Other differences (composition of serum proteins and white blood cells, hemoglobin content) are exclusively due to the primary intraperitoneal infection.

Animals↗
PubMedDate not supplied

Characterization of allergens in Schistosoma mansoni, Fasciola hepatica and Echinococcus granulosus.

Various antigens interacting specifically with IgE antibodies from infected humans were identified in S. mansoni, F. hepatica and E. granulosus soluble extracts by means of radioimmunoelectrophoresis. Two allergens common to adult worm and cercariae were identified in S. mansoni extracts. They proved to be distinct from genus--or species--specific antigens previously identified in the parasite. In adult F. hepatica extract a species-specific antigen and another lipoprotein were shown to interact with IgE antibodies of patients with fasciolasis. Two major allergens were also found in whole fluid of sheep E. granulosus cysts. One of them corresponded to Echinococcus genus specific antigen. These results are discussed according to immunological findings in parasitic infections.

Allergens↗
PubMed1981

A biochemical study of adult and cystic stages of Echinococcus granulosus of human and animal origin from Kenya.

A comparative biochemical study was performed on adult and cystic stages of Echinococcus granulosus. Basic quantitative differences in metabolism were apparent between the cystic forms of sheep origin from the UK and Kenya which suggest that each may represent a different geographical strain or sub-strain. The biochemistry of the human and sheep forms from Kenya was very similar, which probably reflects a certain close affinity between the two. The fact that the cattle, goat and camel forms of E. granulosus, from that country, were distinct biochemically, both from each other and from the sheep and human types, suggests the existence of an unusually complex strain picture there, and that these organisms are either non-infective or only poorly infective to man. The differences in biochemical composition and metabolism observed between adults produced experimentally and those obtained from naturally infected dogs, may have been as a result of their original hydatid source and/or their differing stage of development.

Animals↗
PubMed1984

Comparison of cestode antigens in an enzyme-linked immunosorbent assay for the diagnosis of Echinococcus granulosus, Taenia hydatigena and T ovis infections in sheep.

Nine antigens, prepared from somatic tissue, cyst fluids or produced during in vitro culture of Echinococcus granulosus, Taenia hydatigena, T ovis or T crassiceps were tested for their suitability for the diagnosis of larval cestode infections in sheep by the enzyme-linked immunosorbent assay (ELISA). The sensitivity and specificity of each of these antigens were assessed using sera from sheep experimentally infected with graded monospecific infections of E granulosus, T hydatigena or T ovis eggs and sera from naturally infected aged sheep. The ability of eight of the antigens to detect the antibody response to larval cestode infection was also compared over 12 months using sera from serial bleedings. Using the ELISA, all of the antigens were able to detect the presence of larval cestodes, even in sheep with only one or two cysts. Over 12 months, the antibody responses were not generally statistically related to the total number of cysts present in the animals. None of the antigens was able to detect specific infections only. The antigen with least non-specific background activity, which consistently detected the highest antibody titres in the sera of all infected animals was the secretion from T ovis worms cultured in vitro, and is, therefore, the antigen of choice for the detection of non-specific infections with larval cestodes in sheep.

Animals↗
PubMed1978

Survival of protoscolices of Echinococcus granulosus at constant temperatures.

A study was conducted to determine the effects of storage at constant temperatures upon the survival of protoscolices of Echinococcus granulosus from hydatid cysts removed from infected sheep. Parallel tests were conducted on intact cysts from both lung and liver, and on protoscolices stored within 1-ml samples of hydatid fluid. The longest survival times of any of the samples tested at each temperature were: -20 C, 1 hr; -10 C, 4 hr; 1 C, 16 days; 10 C, 16 days; 20 C, 8 days; 30 C, 4 days; 40 C, 2 days, and 50 C, 2 hr. In general, protoscolices survived considerably better when stored within intact cysts than when in 1 ml of hydatid fluid. At temperature ranges where putrefaction occurred, protoscolices in cysts from lung survived longer than those from liver. The ability of these protoscolices to survive extended periods of time after an infected sheep has died or been killed suggests that stringent preventive and control measures should be established in areas where hydatid disease is endemic. Animal pits at community dumping grounds where sheep carcasses might be discarded should be enclosed or covered, and all stray and roving dogs in those regions should be rigidly controlled.

Animals↗
PubMed1983

Fine structure and freeze-etch study of the protoscolex tegument of Echinococcus multilocularis (cestoda).

Freeze-etch replicas of the protoscolex tegument of Echinococcus multilocularis were examined and compared with conventional thin sections by TEM. The microtopography of the protoscolex tegument was also examined by SEM. The protoscolex consisted of morphologically-distinct, apical and basal tegumentary regions, the latter of which lacked microtriches. The hook area of the apical region contained long, slender, filamentous microtriches that obscured the hook arrangement. These microtriches were structurally different from those found on the suckers and rostellum of the protoscolex. Freeze-etch replicas of the tegumental membrane of the sucker and rostellar microtriches showed that the protoplasmic (P) and exoplasmic (E) faces of the microthrix base and tip contained numerous intramembranous particles (IMP). The densities of the IMP on both the P and E faces of the microthrix tip were approximately twice the number of the larger diameter IMP found on the P and E faces of the microthrix base. No freeze-etch replicas of the microtriches from the hook area were obtained. The basal tegumentary region of the protoscolex consisted of irregularly-distributed, knoblike processes that were variable in size and shape, and contained an electron-dense cap. The IMP on the P face of the knoblike processes measured approximately the same diameter as those on the P face of the microthrix base. However, their density was about half that of the latter. The density of IMP on the E face of the knoblike processes could not be determined from the freeze-etch replicas.

Animals↗
PubMed1983

Paraffin embedded "Echinococcus granulosus" protoscoleces as suitable antigen in the indirect immunofluorescence test for human hydatid disease.

The employment of Echinococcus granulosus protoscoleces embedded in paraffin as antigen for the indirect immunofluorescence (IIF) test for human hydatid disease is described. An evaluation of its sensitivity and specificity is made studying 108 pre-operative sera from surgically confirmed hydatidosis and 91 control sera. Using the positivity criterion based on the serological reactivity at which minimum cross-reactivity was observed, the IIF test showed an overall sensitivity of 83.3% and 2.2% of cross-reactions. No differences in sensitivity between sera from hepatic and pulmonary hydatidosis was observed. The advantages of the method are pointed out.

Cross Reactions↗
PubMed1983

Freeze-etch characterization of the teguments of three metacestodes: Echinococcus granulosus, Taenia crassiceps, and Taenia taeniaeformis.

The objective of this study was to characterize the teguments of metacestodes of Echinococcus granulosus, Taenia crassiceps, and Taenia taeniaeformis using the freeze-etch technique. Metacestodes of E. granulosus (19 mo old), T. crassiceps (28 days old), and T. taeniaeformis (34 days old) from gerbils, mice and rats, respectively, were fixed for 2 hr in 3% glutaraldehyde and then prepared for freeze-etching and thin sectioning by standard techniques. Freeze-etch replicas of the teguments of all three species displayed morphologic characteristics that were generally in agreement with previous ultrastructural work, although some new features and interpretations arose from use of this technique. For each species there was a concentric ring structure within the microthrix base, and cytoplasmic extensions of the perikarya into the distal tegument were membrane-bound rather than confluent bridges; these extensions frequently branched within the tegument. In addition, channels running from the proximal tegumental membrane to, and opening at the distal surface of, the tegument were seen in thin sections.

Animals↗
PubMed1977

Permeability studies on taenid metacestodes: I. Uptake of proteins by larval stages of Taenia taeniaeformis, T. crassiceps, and Echinococcus granulosus.

Host immunoglobulins of several different classes were detected within the bladder fluids of Taenia taeniaeformis, T. crassiceps, and Echinococcus granulosus. Radioiodinated proteins were taken up in vitro by larvae of both T. taeniaeformis and T. crassiceps and were shown to retain their physicochemical and antigenic characteristics. Rates of uptake were similar in the 2 species and were not related to the molecular weight of the proteins. Immunoglobulins were taken up both in vitro and in vivo by larvae of T. taeniaeformis. Absorbed immunoglobulins were shown to retain both antigen binding capacity and biologic functions associated with the Fc portion of the molecules. Not all cysts of E. granulosus contained detectable host proteins. Uptake of 125I occurred when hydatid cysts were exposed to labeled proteins in vitro, but it appeared that rapid degradation of the labeled carrier led to the appearance of dialysable fragments. This may be attributable to proteolysis within the bladder fluid. We conclude that taeniid metacestodes are capable of absorbing a variety of proteins, and that these macromolecules can retain their structural and functional integrity following transport. This absorptive capacity accounts for the presence of host serum components within bladder fluids.

Animals↗
PubMed1977

Further observations on the specificity of antigen 5 of Echinococcus granulosus.

The presence of IgE antibodies to antigen 5 of Echinococcus granulosus was detected by means of radioimmunoelectrophoresis in the sera of two of six patients infected with E. multilocularis. Sera from three of these patients gave a precipitin band in gel diffusion tests identical to that produced by a monospecific rabbit anti-E. granulosus antigen 5 serum, when tested against whole hydatid fluid. Sera from 19 individuals infected with Fasciola hepatica, 20 with Schistosoma mansoni, and 5 with with Taenia saginata showed no detectable antibodies against antigen 5 of E. granulosus, The monospecific rabbit anti-E. granulosus antigen 5 serum did not react in immunodiffusion with homologous antigen when absorbed with either 4 mg/ml of whole hydatid fluid or with 200 mg/ml of a soluble E. multilocularis extract. Absorption of the monospecific antiserum with crude antigens of either F. hepatica, Onchocerca volvulus, S. mansoni, or T. saginata did not abolish the reaction with antigen 5. It appears, therefore, that antigen 5 can no longer be considered specific for E. granulosus, but is also present in E. multilocularis. In the light of this observation, some reevaluation of immunodiagnostic tests in hydatid disease will be necessary.

Antibody Formation↗
PubMed1978

[Fenbendazole therapy of experimental larval echinococcosis. I. The effect of fenbendazole on worm burden and protoscolex development of Echinococcus multilocularis (author's transl)].

Application of fenbendazole (methyl-5-(phenyl-thio)-benzimidazole-2-carbamate) in Echinococcus multilocularis infected mice showed a significant efficiency on the development of the cysts; the worm burden and the number of protoscolices were significantly reduced in the treated animals in comparison with the non-treated control mice. The degree of efficiency was subject to the way of application, the duration of medication, and the parasite strain: 1. On application of f. as medicated feed (500 ppm) worm burden and protoscolex number were reduced the most an average parasite weight of 105 mg and 2 protoscolices against 1942 mg and 99 protoscolices. Treatment by oral application with emulsion of 2.5% (1 ml/mouse/day, 5 x per week over a period of 2--5.5 months) the efficiency was less expressed (845 mg, 53 protoscolices). 2. By extending the treatment from 60 to 102 and 165 days resp. the reduction of worm burden can be increased from 81 to 95%. 3. From 2 parasite strains one which was recently isolated from a fox, reacted more on the treatment than the other one: 85 mg parasite weight against 1218 mg in the nontreated controls. On the other strain continued since about 25 years by intraperitoneal inoculation, the efficiency was more reduced: The worm burden was 866 against 2666 mg in the control mice.

Animals↗
PubMed1977

Antigenic characterization of Echinococcus granulosus cysts.

Limited numbers of antigens were detected in the structural components of Echinococcus granulosus cysts by double diffusion and immunoelectrophoresis tests using homologous and heterologous antisera without antibody activity to host serum contaminants. Although antigens common to the germinal membranes, laminated layers and protoscoleces were demonstrated, no evidence was found of antigen sharing between the laminated layer and hydatid fluid from fertile and sterile cysts. These fluids, however, had antigenic determinants in common with protoscoleces. Antigens responsible for the formation of a characteristic cathodic are were detected but only in the three structural cyst components. In contrast, E. granulosus arc 5 antigens were found solely in hydatid fluid. These observations suggest that these two antigen groups are of somatic and metabolic origin, respectively. The results are discussed in terms of current knowledge of the immunobiology of hydatid cysts.

Animals↗