PubMed Health⌕ Search

Biomedical subjects

P Deplazes

Publications and source records attributed to P Deplazes.

At least 91 records · Page 5Linked to original sources
PubMed1997

Two Encephalitozoon cuniculi strains of human origin are infectious to rabbits.

The microsporidian Encephalitozoon cuniculi can infect a wide variety of mammals including man. In this study, E. cuniculi isolates of animal origin were compared with 6 isolates obtained from HIV-infected patients. Based on results of Western blot analysis, random amplified polymorphic DNA (RAPD) and the sequence of the rDNA internal transcribed spacer (ITS) the isolates were classified into 3 groups with the repeated element 5'GTTT-3' in the ITS being a reliable genetic marker. Five isolates from Swiss patients were found to be homologous to isolates from Swiss rabbits (strain I). The sixth isolate from a patient from Mexico differed by all methods and could be attributed to E. cuniculi strain III that has been described from 2 dogs from the USA. All of these isolates were distinguished from isolates from blue foxes from Norway (strain II). Intraspecific nucleotide divergence of the SSU rRNA gene of E. cuniculi belonging to the 3 strains was in the same low range (0.00-0.15%) as was found for the corresponding sequence of 2 E. hellem isolates. Groups of 2 rabbits were infected by oral inoculation of 10(7) E. cuniculi spores (2 isolates from strain I of human and rabbit origin, 1 from strain III) as shown by antibody responses and the re-isolation of the parasites from brain material. The results provide further evidence that per oral transmission of the parasite between various hosts is feasible.

Animals↗
PubMed1997

Microsporidia (Encephalitozoon cuniculi) in wild rabbits in Australia.

OBJECTIVE: To determine the prevalence of infection with Encephalitozoon cuniculi in wild rabbit populations in Western Australia, and to isolate the organism from seropositive rabbits. DESIGN: Serological screening of wild and clinically affected domestic rabbit populations. SAMPLE POPULATION: Eighty-one wild rabbits from south-western Western Australia and 29 laboratory rabbits. PROCEDURE: Indirect immunofluorescence antibody technique and in-vitro amplification of parasite isolates in fibroblast cultures. RESULTS: Of the 81 wild rabbits and 29 laboratory rabbits, 20 and 22 respectively, had antibodies to E cuniculi. E cuniculi from the urine of one seropositive laboratory rabbit and from brain and kidney tissues of eight and five seropositive laboratory and wild rabbits respectively were isolated in fibroblast cultures. CONCLUSION: E cuniculi infection has been shown for the first time to be prevalent in wild rabbits in Australia. Techniques have been developed for the isolation and culture of the causative agent. Comparative studies can now be undertaken to determine risk factors for clinical disease in domestic rabbits and the relationship among E cuniculi isolates from wild and domestic rabbits.

Animals↗
PubMed1996

Isolates of Encephalitozoon cuniculi from farmed blue foxes (Alopex lagopus) from Norway differ from isolates from Swiss domestic rabbits (Oryctolagus cuniculus).

Encephalitozoon cuniculi has a wide host range among mammals, but whether it represents a homogeneous species is a subject of controversy. We have isolated, cultivated (in human MRC-5 cells) and, for the first time, characterized by immunological and molecular biological methods four isolates of E. cuniculi from Norwegian blue foxes with a history of encephalitozoonosis. The isolates were compared with nine isolates from domestic rabbits from Switzerland. Two E. cuniculi subtypes were identified according to their host species. A 5'-GTTT-3' tetranucleotide repeat was present twice in the rDNA intergenic spacer in all isolates from foxes as opposed to three times in all isolates from rabbits. Furthermore, random amplified polymorphic DNA analysis showed one polymorphic band among the subtypes, and Western-blot analysis using serum from an infected fox discriminated between the two subtypes on the basis of their banding patterns in the ranges of 31-33 and 38-40 kDa. The 5'-GTTT-3' tetranucleotide repeat is a valuable genetic marker for these two subtypes of E. cuniculi and will be of use in continued studies on the molecular epidemiology of this parasite.

AIDS-Related Opportunistic Infections↗
PubMed1996

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.

Animals↗
PubMed1996

Immunologic and molecular characteristics of Encephalitozoon-like microsporidia isolated from humans and rabbits indicate that Encephalitozoon cuniculi is a zoonotic parasite.

To assess the zoonotic potential of Encephalitozoon-like microsporidia, we isolated and cultivated spores from specimens of urine, respiratory secretions, and stool from six patients infected with human immunodeficiency virus and from nine rabbits. Because spores of Encephalitozoon-like species are indistinguishable by microscopy, we characterized the isolates by western blot analysis and by restriction enzyme analysis of the small subunit (SSU) rDNA after amplification by the polymerase chain reaction. We identified Septata intestinalis in one patient and Encephalitozoon hellem in two symptomatic patients. Encephalitozoon cuniculi was found in all rabbits and in three patients. One of these patients had clinical manifestations of infection with this parasite (severe interstitial pneumonitis). We observed abatement of symptoms and cessation of parasite excretion when these patients were treated with albendazole. Our findings suggest that E. cuniculi may be pathogenic in humans and that it is a zoonotic parasite.

AIDS-Related Opportunistic Infections↗
PubMed1996

[PCR for detection and characterization of parasites (Leishmania, Echinococcus, Microsporodia, Giardia)].

The application of PCR for the diagnosis and the characterisation of parasites is discussed using four examples. (1) A PCR assay that was developed for the detection of Leishmania was shown to be as highly sensitive as in vitro cultivation of the parasites from lymph node aspirates and bone marrow biopsies. (2) Single eggs of Echinococcus multilocularis can principally be detected and identified by PCR. However, a cumbersome sample preparation is inevitable in order to remove PCR-inhibitory substances present in fox faeces. (3) Analysis of the amplified SSU rRNA gene of Encephalitozoon-like isolates from humans, rabbits and farm foxes confirmed for the first time that E. cuniculi-isolates from humans and animals are indistinguishable and that they are of importance as opportunistic parasites in HIV-infected patients. (4) Swiss isolates of Giardia originating from humans, calves, sheep and a dog could be allocated into three distinct genetic groups by analysing several PCR-amplified genes that encode for variant-specific surface proteins. There was no evidence for the presence of host-specific genotypes.

AIDS-Related Opportunistic Infections↗
PubMed1996

[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.

Animals↗
PubMed1996

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.

Animals↗
PubMed1995

[New parasitic diseases in man: infections caused by Microsporida and Cyclospora species].

The non-taxonomic term microsporidia relates to a group of organisms belonging to the order Microsporida of the phylum Microspora. Microsporidia are obligate intracellular spore-forming protozoa and have no metabolically active stages outside the host cell. Their host range is extensive and includes most invertebrates and all 5 classes of vertebrates. More than 100 microsporidial genera and almost 1000 species have now been identified. 5 genera (Enterocytozoon, Encephalitozoon, Septata, Pleistophora and Nosema) and unclassified microsporidia have been associated with human disease. Only 10 cases of microsporidiosis have been described among persons not infected with HIV. In contrast, microsporidia have gained increasing attention as important opportunistic pathogens in the evolving pandemic of HIV infection. Diagnosis depends on morphological demonstration of the organisms themselves. The potential sources and modes of transmission of human microsporidial infections are uncertain. The clinical manifestations of microsporidiosis are diverse and include intestinal, pulmonary, ocular, muscular, and renal disease. Preliminary observations of the possible utility of albendazole for infections due to Septata intestinalis and Encephalitozoon sp. have been reported. The success of therapy for intestinal Enterocytozoon bieneusi infection has been limited. Cyclospora sp. are recently described protozoa capable of causing diarrhea in immunocompetent and immunodeficient patients. Groups at risk for infection are children in the developing world, travellers and HIV-infected patients. Diagnosis depends on light-microscopic detection of oocysts in stool smears stained with acid-fast stains. Diarrhea is usually self-limiting. Diarrhea, however, may often last weeks to months, causing significant morbidity. Cotrimoxazole appears to be the drug of choice for treatment of Cyclospora infection.

Adult↗
PubMed1995

Pathophysiological studies of sheep during the build-up of immunity against Ostertagia leptospicularis and after a challenge infection.

Four groups of three lambs were used to investigate the pathophysiological changes during the development of a protective immunity against Ostertagia leptospicularis induced by a trickle infection. Three groups (A, B and C) were infected daily with 1000 third-stage larvae (L3) for a period of 26 weeks; group D remained uninfected until challenged. Egg excretion ceased after about 10 weeks in groups A, B and C and at the end of the trickle infection no parasites were found in group A sheep after slaughter. The sheep of groups B and C were highly refractory to two challenge infections, with 100,000 and 200,000 L3, given four and 17 weeks after the end of the trickle infection. Both challenge infections were followed by short term increases in the concentrations of gastrin and pepsinogen in the serum. Group C sheep were immunosuppressed with flumethasone during the second larval challenge and had higher pepsinogen concentrations but similar gastrin concentrations to the untreated sheep of group B.

Animals↗
PubMed1995

Effect on humoral tolerance (IgG and IgE) in dogs by oral administration of ovalbumin and Der pI.

The effect of oral administration of ovalbumin (OVA) or recombinant house dust mite allergen (Der p I) to dogs upon specific IgG and IgE reactions to subcutaneous immunization with these antigens was studied. Daily feeding of 10 x 10 g of OVA resulted in a non-responsiveness to subsequent parenteral immunization with OVA in two young dogs. The same two dogs were also immunized parenterally with Der p I and showed a pronounced IgG response against native Der p I, confirming that the non-responsiveness to OVA was antigen-specific. Thus, it has been demonstrated that it is possible to induce oral tolerance in dogs. Two other dogs of the same litter that received 2 x 10 mg of recombinant Der p I in a crude yeast lysate per os reacted to immunization with OVA with pronounced IgG and IgE production against OVA, further confirming the antigen-specificity of the OVA tolerance. However, tolerance to Der p I was not induced, as evidenced by a strong IgG response to immunization after per os application of the antigen, possibly because the oral dose was too small.

Administration, Oral↗
PubMed1995

Cytokine and immunoglobulin subclass responses of rats to infection with Eimeria nieschulzi.

SIV rats infected with a high dose (50,000 oocysts) of Eimeria nieschulzi displayed clinical symptoms of coccidiosis such as diarrhoea (days 6 and 7 post-primary infection) and weight loss (days 6-8 post-primary infection) and were completely immune to challenge with a similar dose. The ability of rats to produce tumour necrosis factor (TNF) in vivo was enhanced during the period of oocyst excretion in the primary infection but significant production of TNF did not occur after challenge infection. Thus, TNF does not appear to be an important factor in resistance to infection with E. nieschulzi but may play some role in resistance to primary infection and in the pathology associated with E. nieschulzi infection. Parasite-specific serum IgM levels (measured by enzyme-linked immunosorbent assay) were also increased during primary infection but returned to background levels at the end of the patent period and were not affected by challenge infection. In contrast to TNF and IgM, serum concentrations of E. nieschulzi-specific IgG1, IgG2a, IgG2b, IgG2c and intestinal tissue levels of IgA did not begin to increase until after day 12 post-primary infection, reached peak levels between days 20 and 30 post-primary infection and were slightly increased by challenge infection.

Animals↗
PubMed1995

Specific IgG1 and IgG2 antibody responses of dogs to Leishmania infantum and other parasites.

Sera from dogs naturally infected with Leishmania infantum were analysed for the IgG subclass specificity of their antibody response by ELISA. Dogs infected with L. infantum produced both IgG1 and IgG2 antibodies with IgG2 being associated with asymptomatic infections and IgG1 being associated with disease (symptomatic dogs, non- or low-responsive to chemotherapy). The differential responses of IgG1 and IgG2 serum antibodies in asymptomatic and symptomatic dogs may indicate a dichotomous immune response to infection with L. infantum. To confirm this, on a broader scale, sera from dogs naturally exposed to an asymptomatic protozoan infection, Toxoplasma gondii, were also analysed as were sera from dogs exposed to the helminths, Dirofilaria immitis and Toxocara canis. Antibodies specific for T. gondii antigen detected in sera from 17 dogs were of the IgG2 subclass only. Both IgG1 and IgG2 antibodies to D. immitis and T. canis were present in the sera of naturally infected dogs but IgG1 appeared to be the predominant subclass. Furthermore, in dogs experimentally infected with T. canis, selective regulation of IgG2 and IgG1 responses was apparent since production of the two subclasses occurred at different times following infection, with IgG2 levels declining as IgG1 levels rose. Thus, the analysis of IgG subsets in parasitized dogs provides evidence of a dichotomous response to infection: IgG2 is associated with asymptomatic protozoan infections and IgG1 is associated with helminth infections and disease caused by protozoan infection.

Animals↗
PubMed1995

PCR and in vitro cultivation for detection of Leishmania spp. in diagnostic samples from humans and dogs.

A PCR assay for the diagnosis of leishmaniosis was developed by using primers that were selected from the sequence of the small-subunit rRNA gene. The assay was optimized for routine diagnostic use. Processing of the clinical samples is rapid and simple (lysis of erythrocytes in Tris-EDTA buffer, digestion with proteinase K directly in PCR buffer, and no further purification steps). Furthermore, an internal control is included in every specimen in order to detect the presence of PCR inhibitors. The PCR was compared with diagnostic in vitro cultivation of promastigote stages for the detection of Leishmania spp. in clinical specimens from humans and dogs with a tentative diagnosis of leishmaniosis. PCR and cultivation gave identical results with all but 1 of the 95 specimens from humans. The PCR result in this case was false negative, possibly because of unequal apportionment of this sample. With 10 skin biopsies from six patients with cutaneous leishmaniosis, the sensitivity was 60%. For six human immunodeficiency virus-positive patients with visceral leishmaniosis, all bone marrow biopsies and 7 of 11 whole blood samples (after isolation of leukocytes by Ficoll-Paque) were positive in both tests. PCR detected one more case with the use of 500 microliters of whole blood with direct lysis of the erythrocytes in Tris-EDTA buffer. With dog lymph node aspirates, the sensitivity was 100% (16 of 16 samples) for both methods; furthermore, PCR was positive for 5 of 13 whole blood samples from dogs with leishmaniosis. The specificity of the PCR was 100% (70 specimens from patients without leishmaniosis). This PCR assay proved to be feasible as a routine diagnostic test, being reliable and faster than in vitro cultivation.

Animals↗
PubMed1995

[Endoparasite infection in stray and abandoned dogs in southern Switzerland].

At their entry into the animal domicile, "La Stampa", in Lugano (canton Tessin), 217 stray dogs and 154 unwanted dogs were examined for infections with intestinal parasites, filariae, Babesia and Leishmania. The following techniques were used for detection of intestinal parasites: combined sedimentation-flotation, MIFC technique and scotch tape adherence test. Prevalences of helminth egg excretion in stray dogs and in unwanted dogs, respectively, were as follows: 34% and 22% for Trichuris, 17% and 14% for Toxocara, 3% and 5% for hookworms, 4% and 0% for taeniids. Dipylidium, Toxascaris and Capillaria were diagnosed sporadically. Samples positive for taeniids were further tested for the presence of Echinococcus coproantigens in a sandwich ELISA: one of 9 dogs was strongly positive. This dog was euthanized for security reasons and upon dissection, 11 Taenia hydatigena and more than 10,000 gravid Echinococcus granulosus worms were found. Microfilariae were detected in the blood of 3 stray dogs and one unwanted dog by the Difil-test. In all 4 cases the infective species was Dirofilaria immitis as confirmed by morphology, acid phosphatase activity analysis of microfilariae and by detection of specific antigens in blood plasma by ELISA. Specific antibodies against antigen of Leishmania infantum could not be detected in any of these dogs by ELISA. However, 3 stray dogs had specific antibodies against antigen of Babesia canis as demonstrated by IFAT.

Animals↗
PubMed1995

[Parasitology and human medical preventive importance of Toxoplasma gondii].

UNLABELLED: Present knowledge of the biology and distribution of Toxoplasma gondii allows to provide recommendations for primary prevention of infection with the parasite. The recommendations are chiefly designed for "seronegative" pregnant women without specific serum anti-T.-gondii-IgG and for persons with continuous or temporary immune deficiencies. Prevention should focus on 3 main sources of infection risk: Meat: meat should only be eaten when well cooked or when it has been frozen prior to preparation; do not prepare raw food in the same place and with the same utensils as for raw meat preparation; no mouth-finger-contact while handling raw meat. ENVIRONMENT: fruit and vegetables should be carefully washed prior to consumption (also including fruit and vegetables from the consumer's own garden or orchard). Cats: household cats should be preferably fed with canned food rather than with raw meat; contact with any utensil which may have been contaminated by cat's feces, as well as with the cat's litter, must be strictly avoided. If cleaning the cat's toilet is inevitable, plastic gloves must be worn. Disinfect the cat's toilet daily with boiling water. All primary prevention measures apply also to the areas of agriculture, veterinary practices, pet shops and gastronomy. Secondary prevention by means of serological monitoring of seronegative pregnant women can only be envisaged when associated with precise primary prevention recommendations.

Animals↗
PubMed1994

Primary infection of dogs with Echinococcus granulosus: systemic and local (Peyer's patches) immune responses.

Local and systemic lymphocyte proliferation and antibody production were tested in five dogs 35 days after primary experimental infection with Echinococcus granulosus. A significant cell proliferation was demonstrated by [3H] thymidine incorporation in mesenteric, popliteal and/or Peyer's patches (PPs) cells in response to E. granulosus protoscolex or adult worm antigen in three of five infected dogs, but not in five control animals. In contrast, blood mononuclear cells responded very weakly in only two of the infected dogs to parasite antigens. Elevated levels (compared with preinfection status) of protoscolex- and adult worm antigen-specific serum IgG were detected (ELISA) in four of the five dogs 35 days after infection. Furthermore, slightly elevated levels of parasite-specific IgE and IgA were observed in the sera of three and four in four infected dogs, respectively. Specific serum IgM was not significantly higher 35 days after infection than before infection. Local antibody production was studied in vitro using PPs, mesenteric and popliteal cells isolated from three infected and three uninfected dogs by ELISA using adult worm antigen. In two of three cultures of unstimulated PPs cells of infected dogs, parasite-specific IgG was detectable. Parasite-specific IgA and IgM were detected in one of the unstimulated PPs cell culture derived from an infected dog. Following in vitro stimulation with parasite antigen, PPs cells from two infected dogs showed increased parasite-specific IgG and PPs cells of all three infected dogs produced parasite-specific IgA. PPs cells from uninfected dogs did not produce significant quantities of parasite-specific antibodies and cells from mesenteric and popliteal lymph nodes of infected or uninfected dogs neither produced antibodies whilst in in vitro cultures.

Animals↗