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.

Measurement of an eosinophil differentiation factor in sheep before and after infection with Trichostrongylus colubriformis.

A bioassay for the measurement of an ovine eosinophil differentiation factor (EDF) was developed. Recombinant murine interleukin-5 (rmIL-5) and supernatant from concanavalin A stimulated lymphocytes induced eosinophil differentiation and proliferation in ovine bone marrow cell culture, which was determined by an eosinophil peroxidase assay (EPO). The assay was used to measure the production of an ovine eosinophil differentiation factor by lymphocytes following experimental infection of sheep with Trichostrongylus colubriformis. Sixteen sheep were immunised and challenged with T. colubriformis and grouped into responders (n = 10) and non-responders (n = 6) based on the lower 99% confidence limit of the worm burden of the unimmunised control group (n = 10). Total worm burdens of all animals were established 10 days after initial challenge. Peripheral blood lymphocytes at Day 0 (pre-challenge values) and Day 9 (post-challenge values) from all sheep and lymphocytes of mesenteric lymph nodes from eight sheep were stimulated with third stage larval antigen of T. colubriformis. The resulting lymphocyte conditioned medium (LyCM) was tested for EDF by its ability to induce growth and differentiation of eosinophils in liquid bone marrow cell cultures. No significant difference was found between the animal groups. No correlation was found between EDF activity and total worm numbers.

[Endoparasite infection in stray and abandoned dogs in southern Switzerland]. / Endoparasitenbefall bei Findel- und Verzicht-Hunden in der Südschweiz.

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.

Echinococcus multilocularis: parasite-specific humoral and cellular immune response subsets in mouse strains susceptible (AKR, C57B1/6J) or 'resistant' (C57B1/10) to secondary alveolar echinococcosis.

Parasite-specific humoral and cell-mediated immune responses were investigated in highly susceptible (AKR and C57B1/6J) and relatively resistant (C57B1/10) mice undergoing secondary alveolar echinococcosis (infection with Echinococcus multilocularis metacestode). The parasite-specific proliferative immune response of lymph node cells upon in vitro antigen stimulation remained weak in all three mouse strains. By day 30 p.i., CD4+ lymphoblast cells dominated the total population of blast cells in all three mouse strains. There was, however, an unexpectedly high proportion of CD8+ blast cells; by day 90 p.i., a marked proportional increase in CD8+ cells was seen in susceptible (AKR and C57B1/6J), but not in resistant (C57B1/10) mice. Susceptible, but not resistant mice exhibited a significantly decreased responsiveness of lymph node cells to concanavalin A (Con A) stimulation on day 90 p.i. Analysis of the humoral immune response by ELISA showed that resistance in C57B1/10 mice was associated with the ability of the host to synthesize antibodies to Em2 of the IgG3 and IgG1 isotype. Em2 is a lectin-binding carbohydrate antigen of the laminated layer. In susceptible AKR and C57B1/6J mice, low levels of anti-Em2 antibodies of the IgG2a isotype were detected. Anti-Em2 antibodies of the IgG3/IgG1 isotype, however, were absent. Differences in subclass-specific IgG responses were confirmed by immunoblot analyses. Our findings suggest that differences in antigen recognition (with respect to subsets of humoral and cellular immune components), probably controlled by non-H-2 gene(s), coupled to immune suppression modulated by CD8+ cells and/or respective cytokines, may determine susceptibility or resistance in experimental infection with E. multilocularis.

Peroxidase-antiperoxidase labelling of Leishmania amastigotes in formalin fixed and paraffin embedded tissue sections.

A modified PAP-Method (peroxidase-antiperoxidase) is established for laboratory use to demonstrate Leishmania spp. amastigotes in paraffin sections of experimentally and naturally infected dogs. The results demonstrate that the PAP technique is a valuable tool to detect Leishmania amastigotes in tissue sections with low parasite density.

[Acute lead poisoning in calves: clinical, pathological and toxicological findings]. / Akute Bleivergiftung beim Kalb: Klinische, pathologische und toxikologische Befunde.

We present a case of acute lead poisoning in 10 calves. All calves died with few or no clinical signs prior to death. The clinical signs included neurologic and gastrointestinal symptoms but were of an unspecific nature. Several painted iron girders, stored on a field close to the farm, were determined as the source of the poisoning. Postmortem findings were minimal. Some animals presented acid-fast, intranuclear inclusion bodies in the renal tubules. A chemical analysis of some frozen parts of the liver and kidney revealed levels of lead as high as 12 ppm in the liver and 63 ppm in the kidney on a wet-weight basis. This article discusses the etiology, clinical signs, postmortem findings and diagnosis of lead poisoning in calves with special emphasis on the chemical analysis.