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P Deplazes

Publications and source records attributed to P Deplazes.

At least 55 records · Page 3Linked to original sources
PubMed2001

Prevention and treatment of Encephalitozoon cuniculi infection in rabbits with fenbendazole.

The efficacy of fenbendazole for preventing an experimental infection of Encephalitozoon cuniculi and for eliminating the spores from the central nervous system of naturally infected rabbits was investigated. Fenbendazole (20 mg/kg bodyweight daily) was administered from seven days before until two or 21 days after rabbits had been infected orally with 10(6) spores of E. cuniculi. Both regimens were effective in preventing the establishment of the parasites, as demonstrated by negative parasitic-specific serology and by the failure to isolate the parasite from brain tissue. In naturally infected, seropositive rabbits, parasites were successfully isolated from seven of nine untreated animals, but not from the brain tissue of eight animals treated with fenbendazole-medicated pellets for four weeks.

Animals↗
PubMed2001

Diagnosis of psoroptic sheep scab with an improved enzyme-linked immunosorbent assay.

An enzyme-linked immunosorbent assay (ELISA) was developed for the detection of specific antibodies against crude Psoroptes antigen. The diagnostic sensitivity was 93.7% in 191 sheep with clinical signs associated with mange. These animals originated from 29 flocks in which psoroptic mites were detected. All of 59 sheep infested with Psoroptes ovis were seropositive. Additionally, in 49% of 70 clinically unaffected sheep originating from P. ovis-infested flocks, specific antibodies could be detected, suggesting that asymptomatic infestations can be diagnosed by serology. The specificity of the ELISA was 96.5% as determined with 254 sheep originating from 44 flocks without clinical mange. Cross-reactivity in a low range was detected with selected sera of sheep with clinical chorioptic or forage mite infestations. Four sheep seroconverted 2 weeks after experimental P. ovis infestation, i.e. 2 weeks before clinical signs became obvious. After successful doramectin treatment of 14 sheep with naturally acquired P. ovis infestation, the ELISA values declined slowly but remained positive in seven cases beyond 17 weeks.

Animals↗
PubMed2001

[Echinococcus multifocal. Epidemiology, clinical findings and treatment].

Infection with the fox dwarf tapeworm, Echinococcus multilocularis, has for the first time been found in a fox in Denmark, and E. multilocularis infection is therefore now a possible diagnosis in Danish patients. This paper reviews the life cycle, epidemiology, clinical symptoms, diagnosis, and treatment of E. multilocularis infections.

Animals↗
PubMed2001

Comparison of heavy metal concentrations in tissues of red foxes from adjacent urban, suburban, and rural areas.

The red fox (Vulpes vulpes) is a representative of the canid family with wide distribution in the Northern Hemisphere and Australia. The increasing utilization of urbanized habitats by red foxes prompted us to test whether this species may be used to monitor the presence of anthropogenic pollutants in cities or suburbs. For that purpose, we compared the concentrations of heavy metals (Cd, Pb, Cu, Zn) in foxes from urban, suburban, and rural areas within the municipality of Zürich (Switzerland). The kidney and liver of suburban and rural foxes contained the highest Cd concentrations, whereas urban foxes contained the highest Pb levels. In the kidney of suburban foxes, Cd concentrations increased from a median value of 0.73 mg/kg in juvenile animals to 1.82 mg/kg in adults. Similarly, the liver of suburban foxes contained increasing Cd levels from a median of 0.21 mg/kg in juvenile animals to 0.94 mg/kg in adults. An age-dependent storage of Cd was also found in foxes from the rural surroundings, but no such accumulation occurred in urban foxes from the city center, where even adult animals contained very low Cd levels. Conversely, foxes from the urban center were characterized by elevated Pb concentrations during the first 2 years of life, but this transient Pb accumulation was absent in suburban or rural animals. The liver of juvenile foxes contained a median Pb concentration of 0.99 mg/kg in the city compared to only 0.47 and 0.37 mg/kg in the suburban and rural area, respectively. Thus, we found that animals from separate environmental compartments contain different patterns of tissue residues, implying that red foxes may serve as a bioindicator species to detect certain toxic hazards in urbanized habitats.

Animals↗
PubMed2001

Assessment of the epidemiological status of Echinococcus multilocularis in foxes in France using ELISA coprotests on fox faeces collected in the field.

The aim of this study was to estimate the relevance of Echinococcus multilocularis coproantigen detection in fox faeces collected in the field to identify different levels of endemicity for Echinococcus multilocularis on a large scale (n x 10 km(2)). Six study sites were selected in a high endemicity area and two study sites in a low endemicity area in eastern France on the basis of landscape composition. Sampling was undertaken in the winters of 1996-97, 1997-98 and 1998-99. At each site, (i) necropsy and intestine examination was undertaken on a sample of shot foxes (total number of foxes, 222), and (ii) fox faeces were collected in the field along road verges, and scored for degradation status (total number of faeces, 625). Fox faeces were also sampled in a control area (n=30) in western France in the summer of 1998. Intestines were examined according to the sedimentation method. Echinococcus multilocularis coproantigens were detected by using two ELISA tests: EM-ELISA and EmA9-ELISA. The necropsy prevalence in high and low endemicity areas was 63.3% and 19.4%, respectively, and the distribution of adult worms in the fox population was highly overdispersed (75.5% of the total biomass was harboured by 11.6% of foxes). Using the two ELISA tests, there was no difference in the detection of E. multilocularis coproantigens in field faeces, regardless of the degradation status. The medians of EM- and EmA9-ELISA OD values of field faeces in high endemicity area were significantly higher than in low endemicity area (P<0.001 for both ELISA). The distribution of EM-ELISA OD values in low endemicity area was significantly higher (P=0.002) than in the control area. Moreover, for the two ELISA, the observed ELISA OD value distributions in high endemicity area, low endemicity area and control area seemed representative of the distribution of adult worms in fox populations. These results indicate that E. multilocularis coproantigen detection in field faeces could serve for large-scale surveillance, as an alternative to necropsy.

Animals↗
PubMed2001

Comparing apical preparations of root canals shaped by nickel-titanium rotary instruments and nickel-titanium hand instruments.

This study measured displacement of canal centers in extracted human teeth after preparation by Lightspeed and nickel-titanium K-files. The specimens were divided into two groups (n = 11), after radiographing the roots from the buccolingual and mesiodistal planes with pathfinding files in situ. More strongly and less strongly curved canals were, respectively, assigned to the Lightspeed and nickel-titanium K-file groups. Using a reassembly technique, cross-sections at 1.25 mm, 3.25 mm, and 5.25 mm from the apices were made of the experimental roots embedded in clear plastic. Stereomicroscopic 35-mm slides were taken of the uninstrumented sectioned canals. The sections were reassembled and then prepared to size 50 Master Apical Rotary and size 40 Master Apical Files, for the Lightspeed and K-file groups, respectively. Similar 35-mm slides of the instrumented canals were taken and electronically superimposed over their uninstrumented counterparts. Displacements of root canal centers after preparation and increases in cross-sectional areas of the prepared root canals were evaluated at specific levels. No significant differences in displacement of canal centers or between the mean cross-sectional areas of the instrumented root canals were recorded between the Lightspeed and K-file groups. Both types of instruments produced similar displacement of canal centers after preparation.

Anatomy, Cross-Sectional↗
PubMed2001

Major carbohydrate antigen of Echinococcus multilocularis induces an immunoglobulin G response independent of alphabeta+ CD4+ T cells.

Echinococcus multilocularis causes alveolar echinococcosis, one of the most lethal helminthic (accidental) infections in humans, as the life cycle predominantly includes wildlife rodents as intermediate hosts. The physical barrier between the proliferating parasitic metacestode and the host tissue is the acellular laminated layer (LL), which is characterized by its rich high-molecular-weight polysaccharide composition. Conversely to a crude protein-rich vesicular fluid antigen, a major carbohydrate antigen of the LL--the Em2(G11) antigen--did not stimulate murine T-cell proliferation in vitro. In fact, the persistent metacestode growth and antigenic stimulation induced a Th2 shift in vivo following conventional infection by intraperitoneal inoculation of 100 metacestode vesicles into C57/BL6 mice. Concurrently, the expression of Th1 cytokines (interleukin-2 and gamma interferon) remained persistently low until the late stage of chronic infection. In comparison to a recombinant proteinic II/3 antigen, the specific immunoglobulin G (IgG) response against the Em2(G11) antigen (including all IgG isotypes) maintained persistently low avidity. Furthermore, the Em2(G11) antigen induced a specific IgM and IgG response in T-cell-deficient athymic nude, TCRbeta(-/-), major histocompatibility complex class II (MHCII)(-/-)(CD4-deficient), and CD40(-/-) mice. The Em2(G11)-specific IgG synthesized in nude TCRbeta(-/-) and MHCII(-/-) mice was predominantly of the IgG3 and IgG2a isotypes and of the IgG3 and IgG2b isotypes in CD40(-/-) mice. This finding suggested that in vivo, the IgG response to major carbohydrate antigen Em2(G11) of E. multilocularis could take place independently of alphabeta+ CD4+ T cells and in the absence of CD40-CD40 ligand interactions; thus, the Em2(G11) antigen of the acellular LL represents a T-cell-independent antigen. Functionally, the encapsulating LL, and especially its major carbohydrate antigen, Em2(G11), seems to be one of the key factors in the parasite's survival strategy and acts by modulating the host immune response by virtue of its T-cell-independent nature.

Animals↗
PubMed2000

High prevalence of Echinococcus multilocularis in urban red foxes (Vulpes vulpes) and voles (Arvicola terrestris) in the city of Zürich, Switzerland.

Over a period of 26 months from January 1996 to February 1998, 388 foxes from the city of Zürich, Switzerland, were examined for intestinal infections with Echinococcus multilocularis and other helminths. The prevalence of E. multilocularis in foxes sampled during winter increased significantly from 47% in the urban to 67% in the adjacent recreational area, whereas prevalence rates of other helminths were similar in both areas. Seasonal differences in the prevalence of E. multilocularis were only found in urban subadult male foxes which were significantly less frequently infected in summer than in winter. The distribution of the Echinococcus biomass, as expressed by worm numbers per fox was overdispersed in 133 infected foxes randomly sampled in winter. Ten of these foxes (8%) were infected with more than 10,000 specimens and carried 72% of the total biomass of E. multilocularis (398,653 worms). Prevalences did not differ significantly in these foxes in regard to age and sex but worm burdens were significantly higher in subadult foxes as compared with adult foxes. In voles (Arvicola terrestris) trapped in a city park of Zürich, E. multilocularis metacestodes were identified by morphological examination and by PCR. The prevalence was 20% among 60 rodents in 1997 and 9% among 75 rodents in 1998. Protoscoleces occurred in 2 of the cases from 1997. The possible risk for human infection is discussed with respect to the established urban E. multilocularis cycle.

Animals↗
PubMed2000

Phagocytic uptake of Encephalitozoon cuniculi by nonprofessional phagocytes.

Encephalitozoon cuniculi is an obligate intracellular, spore-forming parasite belonging to the microsporidia that can cause disseminated infection in immunocompromised persons. E. cuniculi spores infect host cells by germination, i.e., by explosively everting the polar filament, through which the spore contents (sporoplasms) are subsequently injected into the cytoplasm. In addition, we observed intracellular, nongerminated spores in various nonprofessional phagocytes. In MRC5 cells, the number of internalized spores was approximately 10-fold higher than the number of injected sporoplasms. Compared to the rate of uptake by human monocyte-derived macrophages, internalization rates by A549 cells, MRC5 cells, and 293 cells were 0.6, 4.4, and 22.2%, respectively. The mechanism of uptake was studied in MRC5 cells. Killed spores were internalized at the same rate as live spores, indicating that nongerminated parasites do not actively participate in cell entry. Cytochalasin D inhibited uptake of spores by 95%, demonstrating an actin-dependent process. By electron and epifluorescence microscopy, intracellular spores were found in a tightly fitting membrane-bound compartment. The vacuole containing the spores was positive for the lysosomal membrane protein LAMP-1 and colocalized with the late endosomal-lysosomal content marker rhodamine dextran. Our results show that, in addition to the unique way in which microsporidia infect cells, E. cuniculi spores enter nonprofessional phagocytes by phagocytosis and traffic into a late endosomal-lysosomal compartment.

Actins↗
PubMed2000

Molecular characterization of Cryptosporidium isolates obtained from human immunodeficiency virus-infected individuals living in Switzerland, Kenya, and the United States.

A total of 22 Cryptosporidium isolates from human immunodeficiency virus-infected patients from Kenya, Switzerland, and the United States were examined at three genetic loci: the 18S ribosomal DNA, HSP-70, and acetyl coenzyme A synthetase genes. Four distinct Cryptosporidium genotypes were identified: (i) the Cryptosporidium parvum "human" genotype, (ii) the C. parvum "cattle" genotype, (iii) Cryptosporidium felis, and (iv) Cryptosporidium meleagridis. This is the first report of C. meleagridis in a human host. These results and those of others indicate that immunocompromised individuals are susceptible to a wide range of Cryptosporidium species and genotypes. Future studies are required to understand the full public health significance of Cryptosporidium genotypes and species in immunocompromised hosts.

AIDS-Related Opportunistic Infections↗
PubMed1999

Genetic and phenotypic intraspecific variation in the microsporidian Encephalitozoon hellem.

Encephalitozoon hellem is a microsporidian species that causes disseminated infections in HIV-positive patients. Identical genotypes of E. hellem, as assessed by the sequence of the rDNA internal transcribed spacer, have been identified in isolates from humans and from a psittacine bird. However, by analysing the rDNA ITS of four E. hellem isolates from Switzerland (three) and Tanzania (one), two new genotypes were identified. Differences among the E. hellem isolates were also detected by Western blot analysis, but there was no absolute match between ITS genotype and antigen profile. Hence, strain variation exists in E. hellem and the ITS sequence seems a valuable marker in obtaining further insight into the epidemiology of this pathogen.

Acquired Immunodeficiency Syndrome↗
PubMed1999

Alveolar echinococcosis in humans: the current situation in Central Europe and the need for countermeasures.

Alveolar echinococcosis (AE) in humans is caused by a larval stage (metacestode) of Echinococcus multilocularis, which exhibits a tumor-like growth, initially in the liver, with the potential to induce serious disease. At the end of the 1980s, E. multilocularis was known to occur in four countries of Central Europe, but has now been identified in ten countries. Red foxes are the principal definitive hosts of E. multilocularis and sources of human infection, but dogs and cats can also be infected. Growing populations of foxes and their increasing immigration to urban areas are new risk factors. Human AE is rare but its potential high fatality rate, considerable costs of treatment and the persisting infection risk should be reasons for health authorities in European countries to establish coordinated systems of surveillance and risk assessment in combination with measures to reduce morbidity and mortality of AE in the human population. Here, J. Eckert and P. Deplazes outline the current epidemiological situation in Central Europe, and discuss options for surveillance, prevention and control.

Animals↗
PubMed1999

Sequence and PCR-RFLP analysis of the internal transcribed spacers of the rDNA repeat unit in isolates of Cryptosporidium from different hosts.

The Cryptosporidium ITS1, 5.8S and ITS2 rDNA regions from a number of Cryptosporidium isolates from different hosts and geographical areas were cloned and sequenced in order to investigate the extent of sequence heterogeneity between human and cattle-derived isolates from different geographical locations and also between isolates of Cryptosporidium from different hosts such as cats, pigs, mice and a koala. Calf-derived isolates from different continents were virtually identical as were human-derived isolates from the UK and Australia. Genetic differences between Cryptosporidium isolates were extensive and were in fact greater than the level of nucleotide divergence between Toxoplasma gondii and Neospora caninum rDNA sequences. Based on the sequence information derived from this study, PCR-RFLP of the ITS1 region was undertaken in order to directly amplify and genotype Cryptosporidium isolates from different hosts. This PCR-RFLP approach can now be used for molecular epidemiology studies, circumventing the need for costly sequencing and allowing a wider range of genetically different isolates to be examined.

Animals↗
PubMed1999

Molecular karyotype diversity in the microsporidian Encephalitozoon cuniculi.

The microsporidian Encephalitozoon cuniculi can infect numerous mammals, including man. Three strains of E. cuniculi have been identified so far, the major marker being the number of a tetranucleotide repeats in the rDNA internal transcribed spacer. We investigated diversity at the chromosomal level through the electrophoretic karyotypes obtained from 15 E. cuniculi isolates from 5 different host species. All preparations provided patterns with 9-12 bands within a narrow molecular size range. Six karyotype forms were distinguished, involving subdivision of strain I into 3 types (A, B, C) and strain II into 2 types (D, E). The types A, B and C were mainly associated with isolates from rabbits of different geographical origins. The types D, E and F were characterized by a reduced chromosome size range, 2 of these appearing specific to a carnivorous host species (D in dog and F in blue fox). Hybridization experiments showed that all E. cuniculi isolates possess 11 chromosomes, with a size polymorphism entailing occasional electrophoretic comigration of heterologous chromosomes and differential migration of homologous ones. DNA rearrangements should occur during mitosis and the hypothesis of diploidy for the basic state of E. cuniculi seems likely.

Animals↗
PubMed1999

High prevalence of Enterocytozoon bieneusi in swine with four genotypes that differ from those identified in humans.

The microsporidial species Enterocytozoon bieneusi is found among immunocompromised, particularly HIV-infected, patients with chronic diarrhoea, and rarely also among immunocompetent persons with self-limited diarrhoea. Only recently, E. bieneusi was detected in 4 pigs in Switzerland raising the question of a potential zoonotic nature of this parasite. We examined faecal samples of 109 pigs, 24 cows, horses and red foxes each for the presence of E. bieneusi by PCR and compared these isolates with isolates obtained from stool samples of 13 HIV-infected patients living in Switzerland. In animals, E. bieneusi was only identified in pigs with a prevalence of 35%. Analysis of the rDNA internal transcribed spacer (ITS) sequence allowed the classification of E. bieneusi from 28 pigs into 4 distinct genotypes which grouped very closely (identity 96.3-98.8%) together with 2 of the 3 human-derived E. bieneusi genotypes. Hence, E. bieneusi seems to be a common parasite in swine, but no genotypes were identified that were found in humans. Nevertheless, swine might serve as a new animal model for enterocytozoonosis.

Animals↗
PubMed1999

Single nucleotide variation in rDNA ITS-2 differentiates Psoroptes isolates from sheep and rabbits from the same geographical area.

Psoroptic sheep scab and psoroptic otoacariasis of domestic rabbits occur in the same geographical regions of Switzerland. To address the question as to whether Psoroptes mites are naturally transmitted between sheep and rabbits, we determined the sequences of the rDNA second internal transcribed spacer (ITS-2) from psoroptic mites from sheep (5 field isolates from Switzerland and 2 laboratory isolates from Ireland and the UK) and from rabbits (8 field isolates from Switzerland). The ITS-2 sequences for all Psoroptes mites originating from sheep were identical and differed at 1 nucleotide position from all the sequences of the rabbit-derived isolates. A statistically significant difference between a rabbit-derived isolate and isolates originating from sheep was also obtained by morphometric analysis of the lengths of the outer opisthosomal setae. For comparative purposes, the ITS-2 sequences from Chorioptes and Sarcoptes collected in Switzerland were also determined. No intraspecies variation was found in 6 sarcoptic isolates from red foxes, with a sequence identity of 41% as compared to Psoroptes. The ITS-2 sequences of 3 chorioptic isolates differed by 24-29% from the Psoroptes sequence. Identical sequences were found for the Chorioptes isolates from sheep and a camel, which differed by 18% from the sequence of an isolate from a cow. These genetic data of psoroptic mites originating from sheep and rabbits from the same geographical area suggest the existence of epidemiologically separated populations.

Animals↗