Morphological identification of cryptosporidia in the intestines of calves using light and scanning electron microscopy

Small and large intestines of ten calves of the age from 7 to 21 days, suffering from cryptosporidiosis were examined. It is recommended to perform the histopathological identification of cryptosporidia by prolongation of the basic staining with haematoxylin to one hour and by additional staining with tartrazine. Out of the special methods the most suitable are as follows: Wolbach's modification of Giems' staining method or staining with toluidine or polychromous blue. Mucopolysaccharides are in the granules and in the capsules of some developmental stages of cryptosporidia. By means of scanning electron microscope (SEM) cryptosporidia are clearly visible. As a rule, they are more or less immersed in the microvilli of enterocytes. In the intestines destructed by inflammation they occur even outside the epithelium, in the cases studied in the necrotic matter obstructing the outlets of the crypts of Lieberkühn in the caecum of the calves.     

The effect of administration of non-soluble fungal glucan on the level of delayed skin hypersensitivity and phagocytic activity of leukocytes in the blood of calves]

The level of delayed skin hypersensitivity (DSH) was evaluated in vivo after dinitrofluorobenzene induction (3rd and 7th week of the experimental) while the level of phagocytic activity (FA) of blood leucocytes (in weekly intervals during six weeks of observation) was evaluated in calves (4.5 to 5.5 months of age) after administration of particular fungal glucane (from oyster mushroom) at a dose of 10 mg/kg live weight. In calves which were administered glucane (abbr. G), a significantly stronger cell-mediated immune response was recorded by means of DSH test in the 3rd week of observation, namely in comparison with its starting value (P < 0.01) and also with the value of control animals (P < 0.01; K group)-Tab. I. In the seventh week of the experiment there was not a statistical difference in the average values of DSH any more (Tab. I). But at that time 100 percent of calves showed a skin reaction above 6.5 mm (mean = 7.64 +/- 0.55) evoked by the used sensibilizer in the G group; this reaction was significantly higher (P < 0.01) in comparison with the value of DSH in a majority (80%) of calves of the K group (mean = 6.15 +/- 0.21)-Fig.1. The immunostimulating effect of the used glucane on the FA of blood leucocytes was less significant.(ABSTRACT TRUNCATED AT 250 WORDS)     

Chlortetracycline residues in the meat of slaughter calves in relation to transmissible microbial resistance to antibiotics

The occurrence of chlortetracycline residues in the meat of slaughter calves in 62% herds under study (the additive of the medicated premix AUREOVIT to feed without observing the withdrawal times) did not influence significantly the Gram-negative resistant and R+ microflora isolated from the same material, in comparison with control herds that were administered no antibiotics. Neither was the spectrum of donors and transferring R plasmids influenced significantly nor the incidence of different resistance determinants. The effect of chlortetracycline addition to feed was negative (at P = 0.05) only in the occurrence of R+ microflora isolated from stable environment where the slaughtered calves had been housed.     

Molecular evidence of Babesia caballi (Nuttall and Strickland, 1910) parasite transmission from experimentally-infected SCID mice to the ixodid tick, Haemaphysalis longicornis (Neuman, 1901).

Molecular evidence that suggests the possible role of the ixodid tick, Haemaphysalis longicornis and its eggs in the transmission of equine Babesia caballi parasites is presented herein. Using polymerase chain reaction (PCR) to assay for DNA in parasites, presumably acquired by ticks that were allowed to feed on splenectomized-SCID mice, experimentally exposed to in vitro-cultivated B. caballi, we have obtained positive bands that corresponded to the expected B. caballi-specific 430bp gene fragment in 50% of female ticks used, and in 75 and 25% of eggs and larval progeny, respectively. Also, parasite DNA was detected in ticks, eggs and larvae as late as the 16th to the 20th day post-host infestation. Present findings support to the potential role of H. longicornis in the transmission of B. caballi parasites. Its capability, however, to successfully transmit the infection to horses under natural conditions in the field needs to be further ascertained. To our knowledge, this is the first documented study incriminating H. longicornis as a most and likely biological vector of equine babesias.     

Causes of anaphylactoid reactions in cattle after administration of lipoid preparations]

In 1986-1988, adverse anaphylactoid reactions (AR) were observed in animals in Czechoslovakia after the administration of oil adjuvant-containing vaccines or other lipoid drugs. Treated animals showed signs resembling the classic anaphylactic reaction, i.e. restlessness, salivation, pruritus, oedema and cyanosis of udder and vulva, and eyelid oedema, developing within a few minutes. The reactions were not elicited by the antigen alone, but by the oil adjuvant. The aim of our experiments was to identify substances eliciting the reaction in susceptible animals and to investigate possible induction mechanisms. The emulsifier Tween 80 has been demonstrated to be an AR inducing component of vaccines and drugs (Tab. I and III). Weak or moderate reactions were observed in 33% of animals treated with 5% Tween and 66% of those treated with 10% Tween showed strong reactions. On the other hand, no reactions were elicited by treatment with several paraffin oils of different quality (Tab. I) nor with an oil-in-water emulsion containing Montanid as an emulsifier (Tab. II). The role of the vegetative nervous system in the rise of AR has been confirmed. AR were suppressed in animals pretreated with parasympatholytic atropine and enhanced in a part of those pretreated with parasympathomimetic pilocarpine (Tab. III). The percentage of animals affected and the intensity of AR were also lower in animals pretreated with complement inhibitor epsilon-aminocapronic acid (Tab. IV). A major role of complement activation is suggested in the discussion of possible mechanisms of AR induction. It is possible to draw a conclusion on the basis of the results presented here and of the analysis of individual cases that a certain degree of animal susceptibility, depending on the phase of reproductive cycle, metabolism level and neurovegetative balance is necessary besides the administration of an AR inducer (Tween 80 in our case). Hence it seems that the adverse anaphylactoid reactions results from interactions of the two factors, i.e. administration of an AR inducer to susceptible animals.     

Pharmacokinetics of norfloxacin and its N-desethyl- and oxo-metabolites in broiler chickens.

Norfloxacin was given to 2 groups of chickens (8 chickens/group) at a dosage of 8 mg/kg of body weight, IV and orally. For 24 hours, plasma concentration was monitored serially after each administration. Another group of chickens (n = 30) was given 8 mg of norfloxacin/kg orally every 24 hours for 4 days, and plasma and tissue concentrations of norfloxacin and its major metabolites desethylenenorfloxacin and oxonorfloxacin were determined serially after the last administration of the drug. Plasma and tissue concentrations of norfloxacin, desethylenenorfloxacin, and oxonorfloxacin were measured by use of high-performance liquid chromatography. Pharmacokinetic variables were calculated, using a 2-compartment open model. For norfloxacin, the elimination half-life (t1/2 beta) and the mean +/- SEM residence time for plasma were 12.8 +/- 0.59 and 15.05 +/- 0.81 hours, respectively, after oral administration and 8.0 +/- 0.3 and 8.71 +/- 0.23 hours, respectively, after IV administration. After single oral administration, norfloxacin was absorbed rapidly, with Tmax of 0.22 +/- 0.02 hour. Maximal plasma concentration was 2.89 +/- 0.20 microgram/ml. Oral bioavailability of norfloxacin was found to be 57.0 +/- 2.4%. In chickens, norfloxacin was mainly converted to desethylenenorfloxacin and oxonorfloxacin. Norfloxacin parent drug and its 2 major metabolites were widely distributed in tissues. Considerable tissue concentrations of norfloxacin, desethylenenorfloxacin, and oxonorfloxacin were found when norfloxacin was administered orally (8 mg/kg on 4 successive days). The concentration of the parent fluoroquinolone in fat, kidneys, and liver was 0.05 micrograms/g on day 12 after the end of dosing.     

Diagnosis of avian encephalomyelitis

The diagnostic value of laboratory examination methods was assessed in the diagnosis of avian encephalomyelitis in seven to twenty-two days old chickens. Histological examination and immunofluorescent test are expedient methods meeting the requirements for timely application of infection-control measures. The agreement of histological examination with the over-all laboratory examination is 70 to 81% and the agreement of the immunofluorescence test is 76%. Bioassay on chickens followed by a histological examination appears to be the best method, providing results with the highest significance. However, it is lengthy, applicable to the necessary demonstration of a virus or to cases when the histological or immunofluorescence examinations are dubious. With the over-all laboratory evaluation the method shows agreement in 95 to 100% of cases. The diagnostic value of the method of virus isolation in chick embryos is reduced by the fact that intercurrent viruses (adenoviruses, IB and others) may be passaged at the same time.