Epidemiology of Echinococcus multilocularis and E. granulosus in central Europe

Two species of Echinococcus are known to occur in central Europe, namely E. multilocularis and Echinococcus granulosus, causing the alveolar and the cystic form of echinococcosis in humans, respectively. Recent studies have shown that in central Europe E. multilocularis occurs further north, south and east than previously anticipated. This parasite is endemic in Belgium, Luxembourg, France, Switzerland, Liechtenstein, Austria, Germany, Poland, and the Czech Republic. The prevalence rates of E. multilocularis in foxes are alarmingly high in some areas with average rates > 40%. Infection rates in dogs and cats are much lower. In recent years accidental infections with the metacestode stage of E. multilocularis have been observed in various animal species (dog, domestic pig, wild boar, nutria and monkeys) and in humans. The mean annual incidence rates of alveolar echinococcosis in humans are low varying between 0.02 and 1.4 cases per 100,000 inhabitants in several European countries and regions. For monitoring of the infection in final host populations new techniques are now available, notably the coproantigen ELISA and for selected cases also egg detection by the Polymerase Chain Reaction. E. granulosus has an uneven geographical distribution in Europe with very low prevalence rates in some of the northern and central European countries, with medium endemicity in others and high endemicity in areas of southern and eastern Europe. Cystic echinococcosis in humans is still a significant public health problem, predominantly in the Mediterranean area. Up to now five strains of E. granulosus have been identified in central Europe which differ in their life cycles as well as in morphological, biochemical, genetic and some other features. Several molecular techniques are now available which allow the identification of Echinococcus species and certain strains using genetic markers. Epidemiological evidence and molecular studies indicate that the so-called sheep, cattle, and cervid strains of E. granulosus are infective to humans whereas the horse strain may have no or low infectivity. Polish patients were found to be infected with E. granulosus similar to a pig strain.

Evaluation of NemX, a New Cultivar of Cotton with High Resistance to Meloidogyne incognita

The level of resistance to root-knot nematode, Meloidogyne incognita, in NemX, a new cultivar of the Acala-type upland cotton, was evaluated in relation to four resistant breeding lines (N6072, N8577, N901, and N903) and four susceptible cultivars (Maxxa, SJ2, Royale, and Prema). In growth pouch tests, an average of only 4 nematode egg masses was produced on roots of NemX or the resistant lines, compared to a significantly higher average of 21 on the susceptible cultivars. In pot tests, the nematode reproduction factor (RF = Pf/Pi) in NemX and the resistant lines averaged 0.7, compared to a significantly higher average of 10 on the susceptible cultivars. Root galling in NemX or other resistant cotton averaged 15%, compared to 74% on the susceptible cultivars, in either pot or field tests. In plots with low levels of nematode infestation (Pi </= 150 second-stage juveniles [J2]/500 g soil), lint yield of NemX averaged 1,370 kg/ha and was less than the yield of susceptible Maxxa (1,450 k g /h a ). However, in plots with medium or high levels of nematode infestation (Pi = 151-300 or >300 J2/500 g soil, respectively), yields of NemX decreased only slightly and averaged 1,300 or 1,050 kg/ha, respectively, whereas yields of Maxxa were severely reduced to 590 or 503 kg/ha, respectively. Fusarium wih symptoms were observed on both NemX and Maxxa, and percent occurrence increased with increasing preplant nematode density. In plots with the highest nematode densities, 22% of NemX and 65% of Maxxa plants were wilted. NemX was highly effective against five M. incognita isolates and moderately effective against a sixth isolate that had been exposed to resistant cotton over several seasons. These results showed that NemX is as resistant to M. incognita as the four breeding lines, and much more resistant than the tested susceptible cultivars of cotton.

Epidemiological investigation of trichinellosis in Switzerland

Domestic pigs in Switzerland have been considered Trichinella-free for decades, despite the occurrence of Trichinella in the wildlife cycle. In order to reevaluate the present epidemiological situation, tissue samples from 11226 domestic pigs, 356 wild boars and 452 foxes were examined using the standard artificial digestion method. A simultaneous serological study, extended to include 25239 sera from sows provided by a Swiss pig serum bank, was also undertaken. The results of both studies support the conclusion that Trichinella spp. do not occur within the domestic pig population in Switzerland. Among the fox population, Trichinella was detected in four (0.9%) of the animals tested using the digestion method, and Trichinella britovi was identified as the infecting species by RAPD fingerprint analyses.

Veterinary parasitology and human health

Veterinary parasitology is a subdiscipline of veterinary medicine and is concerned (a) with diseases in animals caused by protozoan and metazoan parasites, (b) with parasitic zoonoses and (c) with parasites acting as disease vectors. Veterinary parasitology is related to human health and well-being in a number of ways. It plays a role in treatment, prevention and control of parasitoses in animals which serve as food sources for humans, which are used in agriculture as farm animals or which are companion animals of humans. Of direct significance to human health are activities of veterinary parasitology in prevention and control of food-, water-, vector-borne and other zoonoses, such as toxoplasmosis, cryptosporidiosis, leishmaniosis, taeniosis/cysticercosis, echinococcosis and others. In this context the evolution of veterinary parasitology, progress in the control of parasitic animal diseases, the concerns of mass-treatment of livestock against parasitoses, environment related problems and other factors are discussed. Finally, examples of current and predictable future research trends in veterinary parasitology are summarized. It is concluded that an innovative veterinary parasitology in cooperation with other disciplines will be in a position to contribute further to the improvement of human health and well-being.

Ratio of inner cell mass and trophoblastic cells in blastocysts derived from porcine 4- and 8-cell embryos and isolated blastomeres cultured in vitro in the presence or absence of protein and human leukemia inhibitory factor

In this study we investigated effects of developmental stage at onset of individual in vitro culture on the progress of development in intact embryos and individual blastomeres derived from 4-cell and 8-cell porcine embryos (referred to as 1/4 and 1/8, respectively), the necessity of serum or BSA supplementation in culture media for embryos and blastomeres (in contrast to development in a defined medium), and the role of two concentrations of human leukemia inhibitory factor (hLIF) on development of blastomeres and embryos. More (p < 0.05) 1/4 blastomeres developed to the blastocyst stage than did 1/8 blastomeres. In the serum-supplemented medium, the percentage of inner cell mass (ICM)/total cells in 8-cell- and 1/8-derived blastocysts was higher (p < 0.05) than that in 4-cell- and 1/4-derived embryos. Development to blastocysts was similar in BSA-supplemented and defined medium as compared to that in serum-enriched medium in intact 4-cell and 8-cell embryos, and 1/4 blastomeres. More (p < 0.05) 1/8 blastomeres developed to the blastocyst stage in serum-supplemented medium than in defined medium. The high hLIF concentration (1000 IU/ml) decreased (p < 0.05) blastocyst development in 1/4 blastomeres in defined medium, but fewer blastocysts (p > 0.05) lacked an ICM (blastocyst-like vesicles) than in defined medium without hLIF. It is concluded that 1) porcine intact embryos and isolated blastomeres can be cultured individually in defined medium up to the blastocyst stage from the 4-cell stage onwards; 2) more 1/4 isolated blastomeres develop to blastocysts with more total cells but with a lower ratio of ICM to total cells than blastocysts derived from 1/8 blastomeres; 3) the effects of hLIF are dependent on proteins present in the culture medium and on the embryonic stage; and 4) in defined medium, high concentrations of hLIF are inhibitory to blastocyst formation, but fewer blastocyst-like vesicles are formed. The defined culture system employed in this study allows examination of the effects of growth factors or cytokines in porcine early embryonic development.

Alternatives to animal experimentation in parasitology

In parasitology, several measures can contribute to the aims of 3R (Reduction, Refinement and Replacement of animal experimentation). These include legal regulations, international guidelines for evaluating antiparasitic drugs, the refinement of animal models for parasitic infections, cryopreservation and cultivation of parasites in vitro or in chicken eggs, the maintenance of arthropods by artificial feeding, and the use of immunological and molecular in vitro techniques (e.g. the production of recombinant antigens for vaccines). Considerable progress has been achieved in the development of alternative techniques but both their standardisation and validation are not far advanced. A wider acceptance and use of alternative methods will only be achieved if research can offer economic alternatives that are as effective and reliable as animal experiments. Great efforts are needed for further progress.

Fetendo-clip: a fetal endoscopic tracheal clip procedure in a human fetus

Fetal tracheal occlusion accelerates lung growth and corrects the often fatal pulmonary hypoplasia seen in fetuses with congenital diaphragmatic hernia. Fetoscopy presents a unique opportunity to glimpse into the world of the fetus, but its use, until recently, has been limited to diagnostic and simple procedures. Using fetoscopic techniques ("Fetendo"), we now report successful tracheal occlusion in a 30-week-old fetus for the treatment of congenital diaphragmatic hernia.

Glutamatergic dysfunction in catatonia? Successful treatment of three acute akinetic catatonic patients with the NMDA antagonist amantadine

Therapeutic efficiacy of the NMDA antagonist amantadine is reported in three acute neuroleptic free akinetic catatonic patients. Intravenous infusion of amantadine led to the resolution of catatonic symptoms and considerable reductions of scores in various motor scales (Simpson Angus scale for extrapyramidal side effects (SEPS), the abnormal involuntary movement scale (AIMS), Rogers catatonia and schizophrenia scales). The therapeutic effect of amantadine showed a characteristic temporal pattern with most pronounced effects four to six hours after administration and recurrence of catatonic symptoms by 24 hours later, at least partially. Such a temporal pattern of therapeutic efficacy and decreasing efficacy occurred in all three patients on all days. The results suggest the central importance of glutamatergic dysfunction in catatonic syndrome.

Intraspecific variation of Echinococcus granulosus and related species with emphasis on their infectivity to humans

Four species are presently recognised within the genus Echinococcus, namely Echinococcus granulosus, E. multilocularis, E. oligarthrus and E. vogeli, which are infective to humans. Evidence for strain diversity within the species E. granulosus, previously mainly based on morphological, biological and biochemical features, has been principally confirmed by recent genetic studies. Several molecular techniques are now available which allow the identification of E. granulosus strains. Epidemiological evidence and molecular studies indicate that the so-called sheep, cattle and cervid strains of E. granulosus are infective to humans, while the horse, camel and pig strains may be less or not infective, but this question warrants further studies. A recent study indicates that E. granulosus infecting patients in Poland shares close molecular affinity with a genotype of pig origin (G7) but exhibits some clear differences. Therefore, it may represent a previously undescribed genotype of E. granulosus, designated as G9. Phylogenetic analysis of molecular data has demonstrated the need to reappraise the taxonomic status of currently recognised strains. Clear evidence for strain variation in the other species of Echinococcus does not exist at present.

Comparative reproduction of Cryptosporidium baileyi in embryonated eggs and in chickens

At 2 days of age, each of 20 chickens was perorally or intracloacally infected with 3 x 10(5) oocysts of Cryptosporidium baileyi and maintained for 13 days post infection. In parallel, 20 embryonated chicken eggs were inoculated with 3 x 10(5) oocysts at day 10 of embryonation and were incubated for a further 7 days. The average reproduction rates in the two groups of chickens were x560 after peroral infection and x533 after intracloacal infection as compared with x256 in the eggs. Although the rate of reproduction of parasites seen in the eggs was only about 50% of that observed in chickens, large numbers of oocysts could be harvested (on average, 77 million per egg versus 161 and 168 million from chickens). Nearly the same number of oocysts could be obtained from two eggs as compared with one chicken. The use of embryonated eggs accommodates the sense of animal-protection regulations, is less expensive, and allows the isolation of oocysts under sterile conditions.

[Significance of membership in new religious movements for regulation of self concept exemplified by the Hare Krischna movement]

222 members of the Hare-Krishna-Movement were investigated with the Narcissism Inventory by Deneke and Hilgenstock (1989). The results show that life in the Hare-Krishna-Movement makes certain defensive functions possible. The Hare Krishnas seem to reach a stabilization of their self experience through idealizing transferences and overemphasizing their value-system. High scores on the scale derealisation/depersonalisation hint at an ego-weakness of the members.

Diagnosis of the Echinococcus multilocularis infection in final hosts

In view of the considerable public health significance of Echinococcus multilocularis, the causative agent of the highly lethal human alveolar echinococcosis, there is an urgent need for reliable and simple techniques for the diagnosis of the infection in populations of final hosts (foxes, dogs, cats) and also in individual dogs and cats. The standard technique presently used is parsitological examination of the small intestine at necropsy. This reliable technique requires high expenditure and special safety precautions. An alternative approach is coproantigen detection. Recently, in our laboratory an ELISA was evaluated using rabbit and chicken polyclonal antibodies against E. multilocularis antigens (affinity purified coproantigens and somatic adult worm antigens). The specificity of this test (evaluated in 20 foxes and 661 dogs with helmintic infections other than E. multilocularis) was very high (95%-99.5%). Average sensitivity in 35 foxes infected with E. multilocularis was 80%, but reached 93% in foxes with individual worm burdens over 55. A Polymerase Chain Reaction (PCR) was used for detecting DNA of E. multilocular is in faecal samples of foxes after the parasite eggs had been isolated by a sieving procedure. In a total of 55 foxes specificity was 100% and sensitivity 94%. For field application the coproantigen ELISA has the potential of replacing parasite detection at necropsy, and PCR is a valuable method for confirmation of positive coproantigen results and for diagnosis in individual animals. Detection of circulating anti-Em2 antibodies by ELISA may be useful for primary screening of fox populations but antibody prevalence rates do not correlate with prevalence rates of the intestinal infection with E. multilocularis.

Prophylaxis of bovine trichostrongylidosis and dictyocaulosis in the alpine region: comparison of an early and late administration of the oxfendazole pulse release bolus to first year grazing calves

The effect of the oxfendazole pulse release bolus (OPRB) administered at turnout, in May, or in mid-July on the development of infections with gastrointestinal nematodes and lungworms in first year grazing calves was investigated with three groups of nine animals, all grazing the same pastures in the Swiss midland region. In the calves of Group A (OPRB on 21 May) less than 20 eggs per gram of faeces (e.p.g.) and less than three Dictyocaulus larvae per 10 g (1.p.10 g) of faeces were shed for a period of 126 and 140 days respectively. Towards the end of the grazing period calves of this group excreted significantly higher levels of lungworm larvae (P < 0.05) compared with the other groups. Prior to OPRB administration on 14 July, the calves of Group B developed subclinical infections with trichostrongyles and lungworms which were similar to the untreated control Group C. By 4 weeks after bolus-administration the excretion of trichostrongylid eggs and lungworm larvae declined to levels below 20 e.p.g. and six l.p.10 g respectively. Serum pepsinogen values of the calves of Groups A and B were significantly lower (P < 0.05) compared with the control animals on days 84 and 98 after turnout and reflected mainly subclinical infections. With the exception of one Group A calf developing clinical parasitic gastroenteritis (p.g.e.) at the end of the season, clinical disease was not observed in the treated calves, while seven out of nine control animals grazing on the same pastures exhibited clinical p.g.e. with mean serum pepsinogen values exceeding 4400 mU tyrosine. Calves of Groups A and B gained significantly more weight (P < 0.01) compared with Group C (+36 kg and +41 kg respectively); differences between Groups A and B were not significant. The results indicate that in mixed grazing systems of treated and untreated calves, which are often found in the alpine region, administration of the OPRB in May or July provided good results with respect to performance of the calves. However, late administration of the OPRB has the additional advantage of coverage of the period of higher infection risk with trichostrongyles and lungworms in the late season until stabling, and should therefore be recommended.

Neutron diffraction study of [Pt(en)2][Pt(en)2I2](ClO4)4 at 20 K: structure and evidence of a new phase transition

The structure at 20 K of fully deuterated [Pt(en)2][Pt(en)2I2](ClO4)4, where en = ethylenediamine, has been determined by neutron diffraction on a single-crystal. It is shown that the symmetry is monoclinic with cell parameters a = 16.650 (7), b = 5.760 (2), c = 14.751 (2) Å and β = 99.19 (1)°, that is, with respect to the previously reported room-temperature structures, a doubling of the c parameter is observed. The space group is C2/c and the refinements lead to an R value of 0.0374. All the bond lengths (C—C, C—N, C—D, N—D and Cl—O) and angles are consistent with the expected values and the main difference with respect to the previously reported room-temperature structures results in an ordering of the stacking of the ethylenediamines. The iodines are distributed over two sites, which gives two Pt—I distances, 2.712 (3) Å, attributed to the PtIV—I bond, and 3.048 (3) Å, attributed to PtII—I. Actually, very weak diffraction peaks that provide evidence for an additional doubling of the a and b parameters are also observed and a space group C2 is therefore proposed. This could result from a very slight ordering of the chains with respect to one another, but, due to the weakness of such signals and the large number of atoms to be considered, no reliable refinement has been obtained in C2. On the other hand, on heating the crystal the diffraction peaks with I odd greatly decrease in intensity between 150 and 160 K, which unambiguously argues for the existence of a phase transition presumably connected to an order—disorder of the ethylenediamines.

Cestodes. Echinococcus

This article deals with cystic echinococcosis (CE) and alveolar echinococcosis in humans caused by the cestode parasites Echinococcus granulosus and Echinococcus multilocularis. The life cycles of these parasites and their epidemiologic aspects are briefly discussed, and a detailed review is presented on clinical aspects of the diseases, including diagnosis and therapy. Considerable progress has been made in chemotherapy but the results are not yet satisfactory. A new alternative for treatment of CE is puncture of cysts, aspiration of fluid, injection of ethanol, and reaspiration of fluid (PAIR).

An improved test system for PCR-based specific detection of Echinococcus multilocularis eggs

For the sensitive detection of eggs of Echinococcus multilocularis in fox faeces by PCR we have evaluated a method based on the previous concentration of helminth eggs by a combination of sequential sieving of faecal samples and flotation of the eggs in zinc chloride solution. The eggs were microscopically detected in the fractions retained in 40 and 20 microns mesh sieves. DNA of the taeniid eggs retained in the 20 microns sieve was obtained after alkaline lysis and PCR was performed using E. multilocularis species-specific primers. Compared to the parasitological findings after examination of the small intestines of the foxes, the specificity of the PCR was 100% (no false-positive result with 20 foxes free of E. multilocularis) and the sensitivity was 94% (33 positive results from total 35 foxes proven to be infected with E. multilocularis). Both false-negative results were obtained with faeces from foxes harbouring immature worms. Using faecal volumes between 2 and 20 ml, no inhibition of PCR was observed as was demonstrated by the amplification of size-modified target in parallel reactions. The tests were undertaken with fresh faeces stored in 70% ethanol, but egg detection by PCR was also possible after inactivation of eggs by freezing the faeces at -80 degrees C for one week or by incubation at +70 degrees C for 2 h.

[Status of development and areas of employment of in vitro production of cattle embryos]

Efficient methods for the collection of oocytes derived from slaughterhouse ovaries and living animals are available. Maturation, fertilization and culture of bovine oocytes/embryos can be performed in vitro with high success rates. The in vitro culture from the fertilized oocyte up to the blastocyst stage currently is the most limiting step of the whole procedure. The establishment of a completely defined culture system would allow the identification of the physiological requirements for preimplantation embryo development and the stepwise improvement of the in vitro production system. The physiological integrity of in vitro produced embryos compared to their in vivo counterparts can be assessed either by molecular biological techniques or in metabolism studies. The in vitro production of bovine embryos with its variety of areas of applications is a useful tool in maintenance and improvement of competitiveness of future cattle breeding.

Workshop summary: food safety: meat- and fish-borne zoonoses

In this workshop, J.P. Dubey (USA), Th. Hiepe (Germany), and P. Deplazes (Switzerland), were invited speakers. The main areas covered were toxoplasmosis, microsporidiosis, trematode infections, taeniosis/cysticercosis and trichinellosis. The public health and economic impact of meat- and fish-borne parasitic zoonoses is considerable in terms of morbidity and even mortality in humans as well as in losses due to reduced productivity in animals and condemnation of parasitised meat and fish. In this context, the increasing demands of consumers for meat and fish free of pathogens and chemical residues has to be considered. Among the parasitic zoonoses some are widespread and frequent, for example toxoplasmosis. About 30-50% of women of child-bearing age are at risk of acquiring the infection during pregnancy with the potential of prenatal infection and severe disease of the foetus. In addition, toxoplasmosis plays an increasing role as an AIDS-associated infection. There are some recent indications that Toxoplasma infections acquired by adults by ingestion of sporulated oocysts may be more pathogenic than cyst-induced infections. In such cases, eye lesions are quite frequent and were previously thought to be predominantly acquired by prenatal infection (J.P. Dubey, USA). Fish- or crustacean-borne trematodes (species of Clonorchis, Opisthorchis, Paragonimus, intestinal flukes) infect about 39 million people, and about 550 millions are at risk (WHO, 1995). Other zoonotic infections are less frequent but may cause severe and lethal diseases, for example Taenia solium cysticercosis.

[Vaccines against parasitic diseases of domestic animals]

This review presents short information on the present status and some future perspectives of vaccination against parasitoses of domestic animals. For the control of such parasitoses in some European countries only a few vaccines are registered: Paracox and Livacox (for coccidiosis in chickens), Toxovax (for toxoplasmosis in sheep), Pirodog (for babesiosis in dogs) and Dictol (for dictyocaulosis in cattle). These are live vaccines containing attenuated parasites, except Pirodog. As a world-wide innovation in 1994 a vaccine against ixodid tick infestation (Boophilus microplus) in cattle was marketed in Australia under the trade name TickGARD which contains a recombinant protein antigen. A recombinant vaccine against Taenia ovis cysticercosis in sheep was developed in Australia/New Zealand but has not yet been registered. The development of vaccines against further parasitoses of domestic animals is a fascinating and promising field. Present research activities are focussed on molecular antigen vaccines and vector vaccines. First reports (for example regarding leishmaniosis and malaria) indicate that nucleic acid vaccines represent a new potential of development.