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1.
The effects of experimental Theileria annulata infection on the i.m. (20 mg/kg) pharmacokinetics of oxytetracycline were investigated in crossbred calves. The serum concentration-time curves of oxytetracycline (OTC-LA), before and after experimental infection, were best described by a one-compartment open model. The experimental infection by subcutaneous administration of ground-up tick supernate (GUTS), equivalent to 30 Hyalomma anatolicum anatolicum ticks infected with Theileria annulata, produced a clear temperature rise and signs of clinical disease in calves. Subsequently, haemoglobin, packed cell volume, total leucocyte count and serum Cu, Fe and Zn concentrations decreased after infection. The absorption and elimination half-lives (t1/2 Ka and t1/2 Ke), mean absorbance time (MAT), time to peak concentration (Tmax), mean residence time (MRT), area under the serum concentration time curve (AUC infinity) and the bioavailability (F) were significantly (P < 0.05) decreased. The peak serum concentration (Cmax), however, remained unchanged after infection. These changes may necessitate alterations in the dosage regimen of oxytetracycline used to treat Theileria annulata infections in cattle under field conditions.  相似文献   

2.
Antigens derived from partially engorged nymphs of Hyalomma anatolicum anatolicum were used in immunizing crossbred (Bos indicus×Bos taurus) cattle against larval, nymphal and adult H. a. anatolicum and H. dromedarii. The cattle were either infected with Theileria annulata at low parasitaemia or were uninfected. Whole nymphal extract (WNE), nymphal membrane antigens (NMA) and nymphal soluble antigens (NSA) were used for immunization. The group immunized with WNE showed significant and better rejection of H. a. anatolicum ticks as compared to calves immunized with either NMA or NSA. The moulting rates of both engorged larvae and nymphs remained unaffected. Nymphs which engorged on the immunized calves were fully susceptible to infection by T. annulata as indicated by the intensity and abundance of Theileria infections in the resulting adult ticks from immunized and unimmunized Theileria infected cattle. These ticks also transmitted fatal theileriosis to susceptible calves.  相似文献   

3.
Eighteen seven to 21-day-old crossbred (Bos taurus cross Bos indicus) calves were allocated to four groups (A to D). Groups A and B each consisted of six calves and groups C and D three calves each. Each calf in groups A, B and C was inoculated with ground-up tick supernate (GUTS) equivalent to two infected acini prepared from Theileria annulata-infected Hyalomma anatolicum anatolicum. Each calf in group A was also given a single intramuscular injection of buparvaquone, 2.5 mg kg-1 bodyweight simultaneously with GUTS, whereas each calf in group B was given a single intramuscular injection of long-acting oxytetracycline, 20 mg kg-1 bodyweight following inoculation of GUTS. In calves of group A clinicopathological reactions were negligible, whereas in calves of group B mild to severe reactions were observed resulting in the death of three of the six calves. All the calves of group C (infected, untreated controls) died of acute theileriosis. All the surviving calves of groups A and B withstood a lethal homologous challenge given on day 30 after immunisation, indicating no difference in the immune status of the surviving calves of the two groups. Group D, challenge control, all calves died of theileriosis within 18 days of challenge.  相似文献   

4.
Sixty three cross-bred (Bos taurus X Bos indicus) 4-5-day-old calves were divided into 16 groups (A-P). Each calf in Groups A and B was given ground-up-tick supernate prepared from Theileria annulata-infected or non-infected Hyalomma anatolicum anatolicum (GUTS) equivalent to 5 ticks (50 infected acini). Groups D and E received infected GUTS equivalent to 2 ticks (20 infected acini) and Groups G and H were given infected GUTS equivalent to 1 tick (10 infected acini). Each calf in Groups J, K and L received infected GUTS equivalent to 5 infected acini (0.035 tick), and Group O was inoculated with non-infected GUTS equivalent to 5 ticks. Each calf in Groups A, D, G, J, K and O was also given a single intramuscular injection of long acting oxytetracycline, 20 mg kg-1 body weight just after inoculation of GUTS. Severe reactions resulted in the death of five of eight, three of eight, five of six, one of five and one of five calves in Groups A, D, G, J and K respectively and all of the calves in Groups B, E, H, and L. The surviving calves of Groups A, D, G, J, K and O were challenged on Day 45 post-immunization along with freshly introduced susceptible control calves of Groups C, F, I, M, N and P. All the calves of Groups A, G, J and K withstood the challenge dose; in Group D four of five and in Groups C, F, I, M, N, O, and P all the calves died of theileriosis. It is concluded that though the infection and treatment method of immunization may be used for neonatal bovines, the dose of immunogen should be based on actual counts of infected salivary acini of ticks instead of the number of ticks.  相似文献   

5.
Twenty cross-bred (Bos taurus X Bos indicus) calves, 7-21 days old, were infected by a ground-up tick supernate of Hyalomma anatolicum anatolicum infected with the Hisar isolate of Theileria annulata. Six calves acted as untreated controls and they all died of theileriosis within 17 days of infection. The remaining 14 calves were divided into Group A and B, each consisting of seven calves. All the calves of Groups A and B were treated intramuscularly with buparvaquone (BW 720C) on Day 11 post-infection, when clinical signs of theileriosis were apparent. Each calf received 2.5 mg BW 720 C kg-1 body weight as a single injection. In addition, each calf of Group B was given proprietary haematinics by intramuscular injection, daily for 12 days. In Group A, two calves died of cerebral theileriosis and five were clinically cured. However, four of these five calves later died of anaemia. In Group B, all the calves were clinically cured and none died during the observation period of 1 month. The parasitaemia declined to less than 1% within a fortnight of treatment. The initial declines in haemoglobin concentration and packed cell volume were halted and preinfection values were soon restored. No toxic signs attributable to treatment with buparvaquone were observed.  相似文献   

6.
Hyalomma anatolicum anatolicum nymphs were collected from two localities in the Sudan: Eddamer in Northern Sudan and Wad-Medani in Central Sudan. They were allowed to moult to adult ticks, which were assessed for Theileria infection in their salivary glands using Feulgen stain. At Eddamer, 49.6% of 123 ticks examined were infected with Theileria and the mean intensity of infection was 1.3 (i.e. the number of infected acini/number of infected ticks). At Wad-Medani, 8.6% of 162 ticks were infected and the mean intensity of infection was 7.9. The prevalence of infection was higher in female than in male ticks at both localities. When adult H. a. anatolicum were applied onto two susceptible calves, both animals developed the severe form of theileriosis.  相似文献   

7.
Fifteen calves were infected by the injection of stabilate of a suspension of Hyalomma anatolicum anatolicum ticks infected with the Ankara strain of Theileria annulata. Three were kept untreated, as controls, and they all died of theileriosis. Three groups of four calves were treated intramuscularly with parvaquone (Clexon; Wellcome) when early signs of theileriosis were clinically apparent. One group received 20 mg (kg bodyweight)-1 of parvaquone 10 days after infection. Two of these calves were clinically cured and two died of theileriosis. The remaining two groups of four calves received two doses of parvaquone, each of 10 mg (kg bodyweight)-1, either on days 10 and 11 or days 10 and 12. Three calves in each group were clinically cured while one in each group died of theileriosis. Total parasitological cure was not achieved in any of the calves. No symptoms of toxicity due to parvaquone treatment were observed.  相似文献   

8.
Two Bos taurus calves were made resistant to tick infestation by exposing them to approximately 500 rabbit-reared nymphs of Hyalomma anatolicum anatolicum twice at a 2-week interval. These two calves, together with a tick-susceptible control calf, were inoculated with a stabilate of Theileria annulata (Ankara). Patent infection resulted in all three calves. Seven-hundred and fifty gerbil-reared nymphs were then applied on each of these calves as well as another tick-susceptible calf that was Theileria free. This infestation was carried out on Day 8 post-inoculation. Ticks that dropped on Day 13 post-inoculation were examined to note the development of T. annulata in them and the histological changes that occurred in the gut and salivary glands. During the second phase of feeding, the gut epithelia of the ticks from the tick-resistant calves were less active. There were no notable differences in the characteristics of the developmental stages of T. annulata between the ticks from the tick-resistant calves and those from the susceptible calf. However, ticks from one calf that acquired a higher level of tick resistance were significantly less susceptible to infection by T. annulata. Bovine tick resistance therefore compromises the vector capacity of H. a. anatolicum and this may be of epidemiological significance in the endemic areas of tropical theileriosis.  相似文献   

9.
利用蜱传播试验确定小亚璃眼蜱对中国新分离的牛的巴贝斯虫未定种和环形泰勒虫的传播能力与传播方式，进而明确其在中国牛梨形虫病传播中的流行病学意义。试验结果表明：小亚璃眼蜱可在雌虫阶段受到巴贝斯虫未定种的感染，并可在次代若虫（2／2）和成虫（3／3）阶段将病原传播给试验牛；小亚璃眼蜱幼虫和若虫吸入环形泰勒虫，饱血脱落的幼虫和若虫所蜕化发育的饥饿若虫（2／2）和成虫（2／2）均可将病原传递给敏感动物；感染巴贝斯虫未定种的小亚璃眼蜱饱血雌虫所孵育出的次代幼虫和若虫仍可被环形泰勒虫感染，所发育出的若虫（2／2）和成虫（2／2）可在一次传播试验中将环形泰勒虫和巴贝斯虫未定种同时传播给试验动物。  相似文献   

10.
In an attempt to develop vaccine against Hyalomma anatolicum anatolicum and Theileria annulata, three antigens were expressed in prokaryotic expression system and protective potentiality of the antigens was evaluated in cross bred calves. Two groups (grs. 1 and 4) of male cross-bred (Bos indicus × Bos taurus) calves were immunized with rHaa86, a Bm86 ortholog of H. a. anatolicum, while one group of calves (gr. 2) were immunized with cocktails of two antigens viz., surface antigens of T. annulata (rSPAG1, rTaSP). One group each was kept as negative controls (grs. 3 and 5). The animals of groups 1, 2 and 3 were challenged with T. annulata infected H. a. anatolicum adults while the animals of groups 1, 3, 4 and 5 were challenged with uninfected adult ticks. A significantly high (p<0.05) antibody responses to all the three antigens were detected in immunized calves, but the immune response was comparatively higher with rHaa86 followed by rTaSP and rSPAG1. Upon challenge with T. annulata infected ticks, animals of all groups showed symptoms of the disease but there was 50% survival of calves of group 1 while all non immunized control calves (group 3) and rSPAG1+rTaSP immunized calves died. The rHaa86 antigen was found efficacious to protect calves against more than 71.4-75.5% of the challenge infestation. The experiment has given a significant clue towards the development of rHaa86 based vaccine against both H. a. anatolicum and T. annulata.  相似文献   

11.
The influence of endotoxin on the disposition kinetics of oxytetracycline (OTC) (10 mg/kg) was investigated in five healthy ruminating male crossbred calves. The serum concentration-time data of OTC before and after endotoxin challenge were best described by a two-compartment open model. Repeated administration of Escherichia coli endotoxin (1 microg/kg, i.v.) at an interval of 12 h up to 48 h produced a clear rise in the body temperature and an increase in the pulse and respiration rates. Endotoxin caused a significant reduction in mean transit time in tissue compartment (MTTT) (P < or = 0.05), mean residence time in the peripheral tissue compartment (MRTT) (P < or = 0.05), mean residence time in the body (MRTB) (P < or = 0.05), elimination half-life (t1/2lambda2) (P < or = 0.05) and distribution space in tissues (VT) (P < or = 0.01) and at steady-state (Vd(ss)) (P < or = 0.01). Endotoxin had no effect on the distribution clearance (ClD), systemic clearance (Cl) and distribution half-life of OTC, while the values of first order rate constant of transfer of drug from tissue to central compartment (K21) and the zero time intercept at terminal phase (C2) were significantly high. The drug dosage regimens to maintain serum OTC concentrations of 0.5, 1, 2, 4, 6 and 8 microg/mL were also determined in febrile and clinically healthy animals.  相似文献   

12.
Therapeutic and prophylactic efficacies of parvaquone and long-acting oxytetracycline were tested against Theileria annulata infection, induced by injecting a suspension of infected ground tick tissues (GUTS) into groups of 4 or 5 calves. This infection killed two of four control calves, while all the animals given a single intramuscular dose of 20 mg kg-1 parvaquone or long-acting oxytetracycline on the day of infection underwent mild reactions and recovered. Two separate doses of parvaquone of 10 mg kg-1 administered on the first and second days of fever protected four out of five calves. All the recovered animals from both treated and control groups resisted a homologous challenge with GUTS on Day 45 post-infection which killed three out of four susceptible unimmunized control calves.  相似文献   

13.
In this comparative study unfed nymphs of four Hyalomma tick species (Hyalomma anatolicum anatolicum, Hyalomma anatolicum excavatum, Hyalomma detritum and Hyalomma marginatum marginatum) were allowed to engorge on calves experimentally infected with Theileria annulata. The infection prevalence in the salivary glands of the adult female and male ticks of each Hyalomma species used in the study were assessed. The infection prevalence with T. annulata was high and did not vary markedly in the four Hyalomma tick species. The mean number of infected acini per tick in female and male ticks was different with female ticks having higher numbers of infected acini than the male ticks. The sex difference was more significant between H.a. anatolicum and H.a. excavatum than between H. detritum and H.m. marginatum. This study clarifies the roles of four Hyalomma tick species, and their sex, in the development of T. annulata.  相似文献   

14.
Five experiments were carried out to determine the efficacy of immunization against theileriosis in an endemic area of Kenya using artificial infection with a mixture of stabilates of Theileria parva stock or natural infection and treatment with parvaquone or several formulations of oxytetracyclines. For the first four experiments, introduced, susceptible Sahiwal/Friesian crosses were used and in the fifth, calves of Boran/Maasai zebu crosses born on the site. Cattle were infected either artificially with sporozoite stabilates of local isolates of T. parva parva derived from cattle and T. parva lawrencei derived from African buffalo or exposed to natural tick challenge on the ranch mostly derived from buffalo. The cattle were then given various treatment regimens using either parvaquone or long- and short-acting formulations of oxytetracycline. Treatment of natural infections, although it can be effective, was not considered a practical method on a large scale because of the need for intensive monitoring in the case of parvaquone treatment and the possibility of cattle not becoming infected in the case of prolonged application of long-acting formulations of oxytetracycline. Both methods were relatively expensive. Artificial infection treatment proved more practical and methods were developed where the monitoring of cattle was not required during the immunization procedure. Out of a total of 16 drug regimens investigated, one (consisting of two treatments of a short-acting formulation of oxytetracycline at 10 mg kg-1 body weight on Days 0 and 3 or 4 after infection) was found to be the most efficacious and the cheapest, and has now been used on a routine basis. This method can be used successfully on calves greater than 1 month of age.  相似文献   

15.
Portions of ground supernate material from Theileria annulata-infected and prefed adults of the Hyalomma anatolicum anatolicum were irridiated by 60Co source at 0, 3, 5, 6, 7, or 9 krads. These portions were injected subcutaneously into different groups of cross-bred calves. The calves injected with 0-, 3-, or 5-krad irradiated tick supernate had severe reactions (rectal temperature 39.8 to 41.6 C, two- to fourfold enlargement of prescapular lymph gland, mean peak parasitemia 27.3% to 32.5% infected erythrocytes, decreased PCV 41.7% to 60.7%, and hemoglobin concentration 37.5% to 50.8%), and many died, whereas those injected with 6- or 7-krad irradiated tick supernate had minimal reactions (rectal temperature 39.2 to 39.8 C, slight enlargement of prescapular lymph gland, parasitemia less than 1%, decrease packed cell volume 15.1%, and hemoglobin concentration 20.1%), with no mortality. All surviving calves injected with nonirradiated (0-) or 3-, 5-, 6-, or 7-krad irradiated tick supernate developed comparable indirect fluorescent antibody titers and were resistant to challenge exposure with infective material from 30 ticks. The calves injected with 9-krad irradiated tick supernate showed no reactions and did not develop indirect fluorescent antibody titers; they were also susceptible to challenge exposure with infective tick material.  相似文献   

16.
The minimal inhibitory concentrations (MIC) of mecillinam, a novel beta-amidinopenicillanic acid derivative with unusual activity against Gram-negative bacteria, were compared with the MIC of cephazolin, cephalothin, amoxycillin, oxytetracycline, chloramphenicol, dihydrostreptomycin, neomycin, kanamycin, gentamicin and sulfadoxin/trimethoprim (TMP) against pathogenic Gram-negative bacteria recovered from neonatal calves. The MIC values of mecillinam ranged between 0.05 microgram/ml and 12.5 micrograms/ml, and the MIC90 values were 1.56 micrograms/ml and 3.12 micrograms/ml. The activity of mecillinam against salmonella, Escherichia coli and Pasteurella multocida was similar to or slightly greater than the activities of the first-generation cephalosporins, gentamicin and sulfa/TMP. Mecillinam concentrations less than or equal to 3.12 micrograms/ml inhibited the growth of the majority of isolates which were resistant (MIC90 greater than 100 micrograms/ml) to the other antibiotics studied. The minimum bactericidal concentration (MBC) values of mecillinam were two- to three-fold higher than the MIC values. The two-compartment open model was appropriate for the analysis of serum mecillinam concentrations measured after intravenous administration. The distribution half-life (t1/2 alpha) was 11.7 min, the elimination half-life (t1/2 beta) was 53.3 min, and the apparent volume of distribution (Vd (area)) and the distribution volume at steady state (Vd (ss)) were 0.568 and 0.896 l/kg, respectively. The drug was quickly absorbed after intramuscular (i.m.) injection; peak serum drug concentrations were directly related to the dose administered. They were obtained 30 min after treatment and the i.m. t1/2 was approximately 65 min.(ABSTRACT TRUNCATED AT 250 WORDS)  相似文献   

17.
The effect of experimental synovitis on the distribution of antibacterial drugs into the joint space was studied in 7-day-old calves. Intrasynovial sodium urate was used to induce inflammation in the tibio-tarsal joint of calves and oxytetracycline (OTC) (11 mg/kg) or sodium penicillin G (PEN) (13.2 mg/kg) was administered intravenously 3 hours after synovitis was induced. Oxytetracycline and PEN concentrations were measured in serum and synovial fluid and pharmacokinetic parameters were calculated. The data indicate that synovitis neither enhanced nor impaired the levels of antibiotics achieved in the joint fluid. Mean peak concentrations (micrograms/ml) of the drugs in control and inflamed joints were, respectively, 8.04 and 8.79 for OTC and 9.35 and 8.92 for PEN. Rates of elimination of OTC and PEN were similar in joint fluid and serum; t1/2 beta ranged from 11.83-19.81 h for OTC and 0.980-1.125 h for PEN. The distribution and elimination of OTC and PEN from serum was described by a two-compartment model whereas elimination from joint fluid was described using a single-exponential model.  相似文献   

18.
Ole-Mapenay, I.M., Mitema, E.S. and Maitho, T.E., 1997. Aspects of the pharmacokinetics of doxycycline given to healthy and pneumonic East African dwarf goats by intramuscular injection. Veterinary Research Communications, 21 (6), 453-462The effect of experimentally induced Pasteurella haemolytica pneumonia on the pharmacokinetics of doxycycline (Doxycen Retard) administered intramuscularly was studied in seven East African dwarf goats. The study was conducted in two consecutive phases, separated by a washout period of four weeks. The experimental infection, induced by intratracheal administration of 5 ml of 107 to 109 cfu/ml of Pasteurella haemolytica, produced a temperature rise, depression and laboured breathing within 6-12 days after inoculation.The concentrations of doxycycline in the serum were determined by a quantitative microbiological assay using an agar-gel diffusion method employing Bacillus cereus var mycoides (ATCC 11778) as the test organism, with a level of detectability of approximately 0.05 µg/ml. The concentration-time curve of doxycycline in the serum after intramuscular injection of 20 mg/kg bodyweight of the long-acting formulation before and after experimental infection was adequately described by a one-compartment open model.The maximum serum concentrations (Cmax) of doxycycline were lower in pneumonic goats than in healthy goats (3.87 ± 0.52 and 5.56 ± 0.213 µg/ml, respectively), suggesting an increased distribution volume in the peripheral compartment. The mean ± SEM absorption rate (ka) before infection (1.13 ± 0.02 h-1) was smaller than that after infection (8.23 ± 3.81 h-1), but the difference was not significant. The apparent elimination half-life (t1/2) (24.51 ± 0.02 h) after infection was significantly increased (p < 0.05), while the corresponding rate constant () was decreased (p < 0.01). The absorption half-life (t1/2) (0.137 ± 0.03 h) was significantly decreased (p < 0.01) after infection. The distribution volume (Vd()) was significantly increased after infection (p < 0.05). It is concluded that, although experimental infection had an effect on the disposition kinetics of doxycycline, this was not sufficiently pronounced to require alteration of the dosage during disease.  相似文献   

19.
The treatment of an outbreak of acute pneumonia in 50 four- to eight-month-old Friesian and Friesian cross calves is described. At the first visit (day 0) 16 calves received 20 mg/kg bodyweight of oxytetracycline dihydrate intramuscularly and 15 received 10 mg/kg of the macrolide tilmicosin subcutaneously. The remaining 19 in-contact animals were not considered ill enough to be included in the trial and received 20 mg/kg of oxytetracycline dihydrate. The rectal temperature, demeanour, respiratory rate and respiratory effort of each calf was assessed on days 1, 2, 3, 9, 14, 21 and 28, and calves which had not responded were given repeat injections of the same antibiotic. All the calves recovered from the outbreak and of the 19 calves treated strategically, three required a second injection. Among the calves with clinical pneumonia, fewer treatments (P less than 0.01) were required by those treated with tilmicosin. The rectal temperatures of both groups decreased (P less than 0.05) after the first injection, but on day 3 the decrease was greater (P less than 0.05) in the group treated with tilmicosin. Respiratory rates varied widely but respiratory effort was less (P less than 0.05) on day 2 in the calves treated with tilmicosin. When long-acting antibiotic injections are used to treat enzootic pneumonia it is suggested that a second visit should be made on day 3 to assess the animals' response to treatment.  相似文献   

20.
Groups of Theileria annulata infected Hyalomma anatolicum anatolicum adults prefed on a calf for 1 to 6 days were separately ground in tissue culture medium-199, supplemented with bovine albumin powder, Fraction-V. Supernatant fluid was collected, made up with additional medium, so that each millilitre represented material from 25 ticks, and was injected subcutaneously into groups of cross-bred male calves. The results indicated that ground-up tick supernate (GUTS) prepared from unfed ticks was not infective, whereas that prepared from 1 to 6 days prefed ticks was infective. GUTS prepared from 3 days prefed ticks appeared to contain highest infectivity and 1 ml of it induced fatal theileriosis.  相似文献   

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