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Biomedical subjects

J Eckert

Publications and source records attributed to J Eckert.

At least 91 records · Page 5Linked to original sources
PubMed1994

Parasite control in transhumant situations.

Transhumance is defined as 'seasonal moving of livestock to regions of different climate'. It is an integral part of livestock production in many parts of the world and takes several forms including moving of livestock from lowland to mountainous pastures or from dry to humid areas. The impact of transhumance on parasite populations of livestock and on parasite control is described, mainly using examples from Europe. The epidemiology of trichostrongylidosis of cattle, mainly caused by Ostertagia ostertagi and Cooperia oncophora, is characterised by prolonged survival of overwintered infective larvae until the end of June. Cattle moved to such contaminated pastures in a transhumant grazing system are exposed to these larvae and may be protected, during the second half of the grazing season until autumn, by a late application (June/July) of an intraruminal drug-release device. Community pastures used in a transhumant system with mixed grazing of young cattle originating from various farms may enhance transmission of dictyocaulosis. Therefore, specific prophylactic measures are required. Hill sheep nematode populations may differ from those in lowland sheep in that Haemonchus contortus generally plays a minor role in hill sheep in which Ostertagia circumcincta and Nematodirus spp. predominate. Infections with Fasciola hepatica and Dicrocoelium dendriticum can be acquired on mountainous pastures by cattle, sheep and other livestock grazing in a transhumant system as intermediate hosts of these parasites may find suitable habitats in these regions. There is evidence that in the prealpine and alpine area both parasites are mainly transmitted in two-season cycles. Further examples for the impact of transhumance on parasite-host inter-relationships include cysticercosis in cattle, echinococcosis, psoroptic manage in sheep, tick-borne fever of cattle, and hypodermosis in cattle. These are described and discussed.

Animal Husbandry↗
PubMed1994

Maternal transfer of antibodies induced by infection with Eimeria maxima partially protects chickens against challenge with Eimeria tenella.

Infection of breeding hens with Eimeria maxima induces production of Eimeria-specific IgG antibodies which are transferred to hatchlings via the egg yolk and confer a high degree of maternal immunity against homologous challenge and partial immunity to infection with another important species, Eimeria tenella. As an example, in an experiment using hatchlings from eggs collected between days 28 and 39 after infection of the hens with 20,000 sporulated E. maxima oocysts, control chicks (challenged with 100 sporulated oocysts) excreted 6.8 +/- 1.2 million (mean +/- S.E., n = 10) or 5.8 +/- 1.2 million (n = 8) oocysts of E. maxima or E. tenella, respectively, compared to 0.9 +/- 0.4 million (n = 5) E. maxima oocysts or 2.2 +/- 0.4 million (n = 9) E. tenella oocysts excreted by hatchlings of infected hens. This represents an 87% reduction in oocyst excretion with regard to E. maxima and a 62% reduction in oocyst excretion with regard to E. tenella in the progeny of the infected hens. In another experiment, eggs were collected from days 28 to 37 and again from days 114 to 123 after infection of the hens with E. maxima and hatchling oocyst excretion rates were 82% and 62%, respectively, reduced for E. maxima and 43% and 41%, respectively, reduced for E. tenella in the progeny of hens infected with E. maxima compared to the progeny of uninfected hens. ELISA and Western blot analyses of maternally-derived IgG revealed a high degree of cross-reactivity to antigens of E. maxima and E. tenella.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1994

Eimeria maxima: ELISA and western blot analyses of protective sera.

Infection of chickens with Eimeria maxima induces the production of parasite-specific antisera which can be used passively to protect naive chickens against infection. Globulin fractions of these antisera can also be used passively to protect chickens. Similarly, intramuscular injection of soybean lectin affinity purified gametocyte antigens of E. maxima in Freund's Complete Adjuvant induces production of antibodies which are maternally transferred and thereby protect hatchlings against E. maxima. ELISA analyses of serum pools having varying protective capacities revealed good correlations between passive protection and levels of anti-unsporulated oocyst, anti-sporulated oocyst, anti-merozoite and anti-gametocyte antibodies. Western blotting demonstrated that the sera mainly recognized a number of high molecular weight antigens in all developmental stages and that the intensity of the reactions reflected the degree of protection induced by the sera. Sera from birds immunized with gametocyte antigens also recognized high molecular weight antigens from all the developmental stages, with banding patterns remarkably similar to those observed for sera from infected birds. Taken together, these results indicate that antibodies can protect against infection with E. maxima and these antibodies may recognize and act against asexual and/or sexual stages of the parasite.

Animals↗
PubMed1994

Access to the abomasum of sheep via a rumen fistula for follow-up studies during trichostrongylid infections.

A technique is described for the examination of the abomasum of adult sheep via a rumen fistula. The size of the fistula allowed a manual exploration of the rumen which was necessary to achieve an access to the abomasum. In four adult sheep, two of them infected with Haemonchus contortus, fibreoptic endoscopy was used to investigate the abomasal mucosa macroscopically as well as histopathologically and ultrastructurally by means of mucosal biopsy specimen. The acidity of the abomasal contents was measured directly by introducing an electrode into the abomasum or indirectly in abomasal fluid which was obtained via a stomach catheter through the rumen fistula. The measured values in all four sheep ranged between pH2 and 4. The fibreoptic examination of the abomasum did not influence the plasma pepsinogen and gastrin levels. The possibility of combining histological, serological and coprological data in follow-up studies on the pathophysiology of trichostrongylid infections in the abomasum of individual sheep seems to be useful for the investigation of primary and secondary infections and may contribute to a reduction of the number of experimental animals in such studies.

Abomasum↗
PubMed1994

Maternal transmission of immunity to Eimeria maxima: western blot analysis of protective antibodies induced by infection.

Infection of breeding hens with Eimeria maxima induces production of parasite-specific antibodies which are transferred, via the egg yolk, to hatchling chicks. These antibodies (immunoglobulin G) are highly protective, mediating up to a 97% reduction in oocyst excretion in challenged hatchlings. However, the degree of maternally derived immunity transferred by the hens to their offspring declines with increasing time after infection of the hens. This decline in immunity is directly related to declining immunoglobulin G titers. However, sera from highly protected hatchlings recognize only a very few E. maxima proteins on Western blots (immunoblots). In particular, a 230-kDa protein band is outstanding for its association with maternally derived immunity to E. maxima in hatchlings. This band was excised from a sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE) preparative gel of crude merozoite protein extract. The SDS-PAGE cutout was emulsified in Freund's adjuvant and injected, intramuscularly, into six breeding hens on two occasions, 2 weeks apart. Eggs were collected from these hens 28 to 39 days after the second injection, and the hatchlings from these eggs were challenged with 150 sporulated oocysts of E. maxima. Subsequent oocyst excretion in these hatchlings was, on average, 54% lower than oocyst excretion by control chicks but only 37% lower (significant at P < 0.05) than that by chicks from hens sham immunized with Freund's adjuvant. The latter result is apparently due to the ability of the adjuvant to induce production of antibodies which recognize Eimeria spp. and thereby transfer some degree of protection to hatchlings. These experiments indicate that protective, maternally derived immunoglobulin G antibodies may be useful for the identification of putative anticoccidial vaccine candidates.

Animals↗
PubMed1994

Maternal transmission of immunity to Eimeria maxima: enzyme-linked immunosorbent assay analysis of protective antibodies induced by infection.

Vaccination of broiler chickens against Eimeria infection is problematic because of the need to ensure that birds are protected from the time of hatching. We have therefore investigated the feasibility of protecting hatchling broilers via maternal transfer of protective antibodies from hens to their offspring. Oral infection of broiler breeder hens with 20,000 sporulated Eimeria maxima oocysts caused production of antibodies which were passed into the egg yolk and subsequently to hatchlings. The level of specific antibodies in the yolks to unsporulated oocysts, sporulated oocysts, merozoites, and gametocytes was assessed by enzyme-linked immunosorbent assays. The levels in yolks of antibodies to all developmental stages peaked 3 to 4 weeks after infection of the hens. Groups of 10 hatchlings were challenged at 3 days of age by oral infection with 100 sporulated E. maxima oocysts. In the first experiment, the mean 4-day (days 6 to 9 post-infection) total number of oocysts excreted in the feces of chicks from eggs collected 3 weeks after infection of the hens was (0.6 +/- 0.4) x 10(6) (mean +/- standard error) compared with (9.9 +/- 1.4) x 10(6) for the progeny of uninfected hens, which represents a greater than 90% reduction. However, oocyst excretion by chicks from eggs collected 7 or 8 weeks after infection of the hens was only 47 or 68% lower than control values, reflecting declining levels of protective antibodies. In a second experiment, in which the hens were somewhat older and pretreated by intramuscular injection of saline in the emulsifying agent, Arlacel A, the period for which protective antibodies were transferred to hatchlings was prolonged. Thus, oocyst excretion by challenged hatchlings from eggs collected for an 8-week period after infection of the hens was more than 90% lower than oocyst excretion by control chicks, and even hatchlings of eggs collected 19 weeks after infection of the hens showed a 60% reduction in oocyst output. In both experiments, the levels of immunoglobulin G (IgG) antibodies to all developmental stages in yolks or hatchling sera were very strongly correlated with maternally derived immunity to E. maxima. In contrast, parasite-specific IgM or IgA was not detectable, either in egg yolk or egg white. These results demonstrate the ability of IgG antibodies to protect against E. maxima in poultry, thus raising the possibility of using protective maternally derived IgG antibodies to identify potentially protective parasite antigens and indicating the feasibility of using maternal immunization as a means for parasite control.

Animals↗
PubMed1994

Detection of Echinococcus coproantigens in stray dogs of northern Spain.

An enzyme-linked immunosorbent assay (ELISA) was assessed for its suitability to diagnostically detect Echinococcus coproantigens in fecal samples of dogs infected with E. granulosus. The specificity of the test was determined by investigating fecal samples from 177 Echinococcus-free dogs infected with Taenia spp., 41 dogs with non-taeniid helminths and 24 dogs free of helminth infections. An overall specificity of 97% was determined. The diagnostic sensitivity was in close association to the worm burden of infected individuals: when dogs harboured less than 100 worms, six from 21 samples (29%) were found to be positive in coproantigen ELISA, whereas sensitivity was much higher (23 ELISA-positive from 25 samples = 92%) when dogs had more than 100 worms. Despite the relatively low average sensitivity (63%), the test enabled detection of more than 90% of the biomass of adult Echinococcus present in the respective dog populations. Conclusively, coproantigen detection allows diagnosis of most individual intestinal Echinococcus infections relevant for the egg contamination of the environment and is therefore a valuable tool to determine the relative prevalence of adult stage E. granulosus prevalence in a given endemic area.

Animals↗
PubMed1994

[Trichinellosis in slaughtered and wild animals in Switzerland using a digestion method and a serologic method (E/S-ELISA)].

For many decades trichinellosis has not been reported among Swiss domestic pigs. Considering the fact that Trichinella occurs in a sylvatic cycle in Switzerland, a study was designed to reevaluate the present epidemiologic situation by investigating 10,904 fattening pigs, 218 pigs with free access to pasturage or being kept on an alp, 104 domestic boars, 106 horses, 44 wild boars and 538 foxes using a direct and an indirect diagnostic technique (digestion method and serology with ELISA and an excretory/secretory antigen, respectively). The digestion method was performed according to EC-guidelines. Furthermore, 25,239 sera originating from a Swiss sow-serum bank were tested retrospectively for anti-Trichinella antibodies. Trichinella was not detectable in all domestic pigs using the digestion method. Serologically, 3 fattening pigs (0.027%) and 9 sows (0.036%) demonstrated weak antibody reactivities against the Trichinella E/S-antigen. Based upon statistical calculations for the negative-positive threshold, these antibody-reactions were considered to be within the normal range of variability of the test. Although statistically restricted, the results of the present study indicate the absence of Trichinella within the Swiss pig population. Based upon the rational applicability of the ELISA and its diagnostic sensitivity and specificity, this test appears as the most suitable method to perform large-scale screenings among slaughter pigs. Pigs with free access to pasturage and boars were all parasitologically and serologically negative for Trichinella. The digestion method showed that horses and wild boars were all parasitologically negative, whereas 1.3% of the foxes were positive for Trichinella larvae.

Abattoirs↗
PubMed1994

[The early or late administration of Paratect Flex bolus in heifers].

The effect of the time of administration of the Paratect Flex -Bolus (PF-Bolus) on the course of infections with gastrointestinal nematodes was investigated in a field experiment with three groups of 9 first year grazing heifers in the Swiss midland region. The heifers of groups A and B received the PF-Bolus at turnout on May 7 (early season application) and on July 16 (late season application), respectively. The heifers of group C remained untreated. All heifers were grazed together throughout the experiment. The mean egg excretion of the heifers of group A remained very low for a period of 70 days and peaked at the end of September reaching a mean value of 167 eggs per gram of faeces (epg). After the administration of the PF-Bolus to the heifers of group B, the egg excretion was reduced by 97% and remained below 50 epg for the rest of the season. While the mean serum pepsinogen values of the heifers of groups A and B only reflected subclinical infections, the mean values of the heifers of group C exceeded 4400 mU tyrosine and 4 heifers exhibited signs of parasitic gastroenteritis. At the end of the experiment (Oct 8) heifers of group A were 14 kg heavier than the controls (not significant) whereas the heifers of group B outperformed the control heifers by 20 kg (significant, p > 0.01).(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1994

Comparative genetic analysis of Swiss and Spanish isolates of Echinococcus granulosus by southern hybridization and Random Amplified Polymorphic DNA technique.

Swiss and Spanish isolates of Echinococcus granulosus were compared using different molecular biological techniques: Genomic DNAs isolated from parasites originating from various intermediate hosts were subjected to Southern hybridization with different probes, the same source of DNA was used for DNA amplification using the Random Amplified Polymorphic DNA (RAPD) technique. With both methods the various isolates (metacestodes) of E. granulosus exhibited characteristic banding patterns which allowed us to assign them to the following groups of homologous profiles: (a) isolates of horse and donkey origin from Spain and Switzerland; (b) isolates of cattle origin from Switzerland; (c) isolates of sheep, cattle and human origin from Spain; (d) isolates of pig origin from Spain and Switzerland and of goat origin from Spain. By RAPD (Southern hybridization not examined) two isolates of human origin from Switzerland were showing banding patterns distinct from groups (a-d). The results provide further evidence that the morphological and biological differences of several strains of E. granulosus are also detectable on the genetic level using molecular biological techniques.

Animals↗
PubMed1993

[Selected ectoparasitoses in animals].

Selected ectoparasitoses of animals are reviewed with special reference to the situation in Switzerland. The review contains information on the parasitoses leishmaniasis of dogs, parafilariasis of equines and cattle, onchocercosis of cattle and horses, ixodiosis, demodicosis of dogs and scabies of domestic animals, fly infestation, myiasis, and infestation with fleas and black flies (simuliidiosis). In addition to information on prevalence, biology and pathogenic effects of ectoparasites, the review provides indications on diagnosis and control.

Animals↗
PubMed1993

Further evidence for the occurrence of a distinct strain of Echinococcus granulosus in European pigs.

The morphology, adult development and genetic characteristics of Echinococcus granulosus isolated from pigs in Poland were examined and compared with those of other recognised strains of E. granulosus. The isolates were characterised by their distinct morphology, rapid maturation and unique DNA hybridisation profiles. The form of E. granulosus that occurs in European pigs may therefore be a distinct strain that can be separated morphologically and genetically from other strains and that exhibits features of epidemiological significance, including a rapid rate of development in dogs and an apparent low infectivity to humans and domestic ungulates.

Animals↗
PubMed1993

Use of IgG- and IgM-specific ELISAs for the assessment of exposure status of chickens to Eimeria species.

Simple and reliable methods for the determination of the exposure status of chickens to Eimeria species are required. For this purpose an enzyme-linked immunosorbent assay (ELISA) detecting specific IgG and IgM antibodies in serum samples was evaluated. Sera from chickens hyperimmunized by intramuscular injection of a saline extract of Eimeria tenella sporozoites were used to determine optimal reaction conditions in the ELISA which were found to be at a serum dilution of 1:100 and an antigen concentration of 0.2 microgram per reaction well. Saline extracts of sporulated oocysts and purified sporozoites of E. tenella were also potent antigens but most studies were carried out with sporozoite antigen. In a trial with 80 chickens, concentrations of serum IgM directed against sporozoite antigen increased significantly 9 days after primary infection with 10,000 oocysts of E. tenella per animal. IgM levels subsequently decreased rapidly reaching a plateau level only slightly higher than uninfected controls by about 15 days post-infection. In chickens challenged with 10,000 oocysts 21 days after primary infection significant increases of IgM levels were observed 2, 6 and 12 days later. In contrast IgG levels increased only slightly after primary infection but significant increases occurred after challenge infection so that by Day 12 after challenge sporozoite-specific IgG levels were much higher than in control chickens. Thus, it may be possible to discriminate between chickens actually infected with Eimeria (as indicated by high levels of antiparasite IgM), chickens which have been repeatedly exposed to Eimeria (as indicated by high levels of antiparasite IgG) and unexposed birds. The applicability of this ELISA, using sporozoite antigen of E. tenella to practical situations was substantially confirmed, since sampling of over 1000 sera from commercially reared broilers and laying hens indicated that broilers, maintained on medicated food, had low levels of IgM and IgG whereas 84-97% of the laying hens, receiving drug-free feed, had relatively high IgG concentrations. These results reflect low and rare exposure to Eimeria infections in broilers and repeated exposure of the hens.

Analysis of Variance↗
PubMed1993

Improved primary immunodiagnosis of alveolar echinococcosis in humans by an enzyme-linked immunosorbent assay using the Em2plus antigen.

Alveolar echinococcosis (AE) in humans is generally a fatal disease when not diagnosed early enough to provide curative treatment such as radical surgery. Immunodiagnosis for early detection of AE was improved by the isolation of an affinity-purified metacestode Em2 antigen and by the synthesis of recombinant Echinococcus multilocularis antigen II/3-10. Both antigens were individually assessed by enzyme-linked immunosorbent assay (ELISA) and demonstrated high specificities and diagnostic sensitivities, although both missed approximately 4 to 11% of diagnostic cases of AE. To provide an optimal serodiagnostic test, we investigated the two purified antigens by using a test employing a mixture of both purified antigens (designated Em2plus antigen) in one assay. For comparative purposes, crude E. multilocularis and Echinococcus granulosus metacestode antigens were investigated as well. The Em2plus ELISA proved to be the optimal diagnostic test with the highest diagnostic sensitivity, 97%, in serum samples from 140 patients with AE and an overall specificity of 99% for infections due to other Echinococcus and non-Echinococcus parasites. The new test combination (Em2plus ELISA) is suggested for the serodiagnosis of AE in patients and for seroepidemiological surveys.

Animals↗