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1.
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   

2.
The aim of the study was to investigate the influence of diarrheic infections during the early postnatal phase of calves on the concentrations of hormones controlling reproduction and metabolism. Blood samples were collected from 20 male and female calves via jugular vein catheters every 15 min for 6 hr at Days 3, 9, and 21 of life. The animals were classified into three groups. Group 1 (controls): healthy calves (n = 9). Group 2: calves affected with diarrhea at Day 9 (n = 7). Group 3: calves with diarrhea at Days 3 and 9 (n = 4). Infections occurred spontaneously and were mainly due to E. coli infections. All affected calves had recovered at Day 21. Mean GH concentrations in the calves in Groups 2 and 3 compared to control calves had increased by Day 3 (P<0.01; P<0.001). Cortisol levels of calves in all groups were highest at Day 3 and decreased thereafter (P<0.001). Cortisol concentrations were lower at Day 3 in animals in Groups 2 (P<0.001) and 3 (P<0.05) than in controls. Pulsatile LH release was detectable at Days 9 and 21 only in healthy calves. Insulin increased at Day 9 during diarrhea. The results indicate that cortisol concentrations decreased whereas GH concentrations were increased before diarrhea was observed. The onset of pulsatile LH release was delayed in diarrheic calves. It is concluded that diarrhea exerts effects upon the release of reproductive and metabolic hormones in early postnatal calves.  相似文献   

3.
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   

4.
Field efficacy of moxidectin, a macrocyclic lactone endectocide, was evaluated in cattle naturally infested with Psoroptes ovis. Three groups of six animals were used based on parasitological and clinical status. Group 1 animals received one subcutaneous injection of injectable moxidectin at 0.2 mg kg-1 body weight; Group 2 animals received topically one dose of 0.5 mg kg-1 body weight of pour-on moxidectin; Group 3 individuals remained untreated as controls. Efficacy was assessed by (a) taking skin samples from each animal on Days -4, 14, 28, 42 and 56 post-treatment (PT) and observing numbers of viable mite stages and species and (b) clinical examination of animals on Days 14, 28, 42 and 56 with the percentage of affected body surface calculated for each animal on Days -4, 28 and 56. Both formulations gave 100% efficacy as no live mites were found in Groups 1 or 2, 14, 28 and 56 days after treatment. Clinical indices showed a sharp decrease in the affected body surface area from a mean of 5.48% and 6.1% on Day -4 in Groups 1 and 2, respectively, to 0% in both groups on Days 28 and 56 PT. All untreated animals remained positive until Day 28. The clinical condition of the controls worsened rapidly during the experiment (mean clinical index: 2.87% and 13.05% on Days -4 and 28, respectively) and they were given an emergency treatment on Day 28. No side-effects were observed with either formulation.(ABSTRACT TRUNCATED AT 250 WORDS)  相似文献   

5.
Susceptibility to Trypanosoma congolense, T. vivax challenge and cross species-superchallenges, and related effects on health and productivity were assessed in N'Dama cattle. Twenty-five N'Dama bulls aged 3-4 years and previously primed with trypanosome infections through natural tsetse exposure over more than one year were used. The experimental herd was divided in five groups each composed of five randomly selected animals. Group 1 was challenged with T. congolense, Group 2 with T. vivax, Group 3 was inoculated with T. congolense followed by a cross-superchallenge with T. vivax, Group 4 was inoculated with T. vivax followed by T. congolense cross-superchallenge. Animals in Group 5 were used as controls. Both T. vivax and T. congolense cross-superchallenges were carried out on Day 14 subsequent to respective initial T. congolense and T. vivax inoculations. All challenges were performed by intradermal needle inoculation of stocks of trypanosome bloodstream forms. In challenged animals (Group 1 to 4), parasitaemia profiles and packed red cell volumes (PCV) were measured for four months. Weight changes were recorded monthly and daily weight gain (DWG) computed. All cattle challenged with T. congolense became parasitaemic. Conversely, one animal in Group 2 and two in Group 3 never displayed patent T. vivax parasitaemia. Both in single (Group 1), initial (Group 3) and cross-superchallenged (Group 4) cattle higher percentage of positive blood samples and higher parasitaemia level were obtained following T. congolense than T. vivax inocula (Group 2, 3 and 4) (P<0.04 or greater). Overall the pre-challenge period, PCV values and DWGs were nearly identical in the five groups. Conversely, over the post-challenge period, cattle singly, initially and cross-superinoculated with T. congolense (Group 1, 3 and 4) displayed lower PCV values and DWGs in comparison with both control animals (Group 5) and with singly T. vivax challenged cattle (Group 2) (P<0.05 or greater). No difference in mean PCV levels and DWGs was found between animals in Group 2 and cattle in Group 5. It was concluded that trypanotolerant N'Dama cattle suffered more from T. congolense and mixed T. congolensel T. vivax infections, while pure T. vivax infection did not produce appreciable negative effects on their health and productivity. Therefore, considering that tsetse and trypanosomosis control campaigns are costly and are justified only when derived economic benefits exceed those of control, and also that an ample mosaic of farming systems exists in West Africa, species-specific trypanosome prevalence and relative impact should be assessed in various cattle populations and breeds differing in trypanosome susceptibility before advising any intervention. Moreover, virulence and related effects of T. congolense and T. vivax endemic stocks on health and productivity in local cattle populations should also be estimated in order to counsel appropriate economic protection measures against trypanosmosis, i.e. vector control and/or strategic use of trypanocidal drugs.  相似文献   

6.
This study was carried out to establish whether cattle can develop resistance to re-infection by Calicophoron microbothrium by assessing the response of intestinal mucosal globule leukocytes, eosinophils, mast cells and basophils, and the establishment of the parasite in the host. A total of 24 1-year-old Tuli steers were randomly divided into four groups of six animals each and infected with C. microbothrium metacercariae. On the first day of the study, animals in Groups I and II were immunized with 5000 metacercariae and then challenged with 15,000 metacercariae on Day 150 post-immunization. Animals in Group III were immunized with 15,000 metacercariae at the same time that Groups I and II animals were challenged to act as a positive control group. Animals in Group IV were left uninfected and acted as a negative control group. Three animals from each group were slaughtered on Day 28 post-challenge and the remainder were slaughtered on Day 42 post-challenge. The established amphistomes were recovered and histopathological and cytological examinations were done on the jejunum, duodenum, abomasum and the rumen. The establishment rates of the challenge infection in the immunized and challenged groups were lower and ranged from 0 to 0.2% as compared to 6% from naive animals infected as positive controls. Animals immunized and then challenged with C. microbothrium had significantly higher eosinophil, mast cell and globule leukocytes counts in the intestinal mucosa (P < 0.05) as compared to those of the control group. The study indicates that cattle can develop resistance to C. microbothrium re-infection and that eosinophils and mast cells may be important cells in the rejection of the parasite.  相似文献   

7.
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   

8.
Ehrlichia phagocytophila infection in sheep is characterized by persistent neutropaenia, indicative of decreased phagocytic capacity. This predisposes infected animals to other infections. A whole blood flow cytometrical method was used to document the degree and extent of reduced phagocytic and respiratory burst activity in phagocytes during an experimental infection with E. phagocytophila, and monitored until 56 days post-infection. Six sheep at 5 months of age were inoculated with an intravenous injection of infected blood. Six age-matched sheep were used as controls. A period of reduced respiratory burst lasting up to Day 17 post-infection was recorded. The population of cells showing phagocytic activity without respiratory burst was larger in the infected animals compared to controls up to Day 45 post-infection.  相似文献   

9.
A recombinant bovine herpesvirus 5 lacking thymidine kinase and glycoprotein E genes (BoHV-5gEΔTKΔ) was evaluated as a live experimental vaccine. In a first experiment, ten-months-old calves were vaccinated intramuscularly (n=9) or remained as controls (n=8) and 42 days later were challenged with BoHV-5 or BoHV-1 intranasally. The four control calves challenged with BoHV-5 developed severe depression and neurological signs and were euthanized in extremis at days 13 and 14 pos-infection (pi); the five vaccinated animals challenged with BoHV-5 remained healthy. The titers of virus shedding were reduced (p<0.01) from days 3 to 7 post-infection (pi) in vaccinated animals. Control and vaccinated calves challenged with BoHV-1 presented mild transient respiratory signs; yet the magnitude of virus shedding was reduced (p<0.05) in vaccinated animals (days 5, 9 and 11pi). In a second experiment, young calves (100-120 days-old) were vaccinated (n=15) or kept as controls (n=5) and subsequently challenged with a BoHV-1 isolate. Control calves developed moderate to severe rhinitis and respiratory distress; two were euthanized in extremis at days 5 and 9 pi, respectively. In contrast, vaccinated animals were protected from challenge and only a few developed mild and transient nasal signs. The duration and titers of virus shedding after challenge were reduced (p<0.05) in vaccinated animals comparing to controls. In both experiments, vaccinated animals developed antibodies to gE only after challenge. These results demonstrate homologous and heterologous protection and are promising towards the use of the recombinant BoHV-5gEΔTKΔ in vaccine formulations to control BoHV-5 and BoHV-1 infections.  相似文献   

10.
Sheep were vaccinated with a killed Staphylococcus aureus vaccine (2 doses) which had been cultured in vitro (Group 1), a killed S. aureus vaccine (2 doses) cultured in vivo (Group 2) or a single dose of a live vaccine (Group 3). Other sheep were used as non-vaccinated controls. All sheep were challenged by intravenous injection of 2.6 x 10(11) washed, viable S. aureus organisms, the vaccinated animals being given the challenge inoculum at various intervals after vaccination. The control sheep survived for 29h (mean) after challenge. Animals given killed vaccines survived longer, (particularly Group 2) if challenged less than 40 days post-vaccination, compared with those challenged more than 40 days post-vaccination. Animals in Group 3 survived longer if challenged after 40 days post-vaccination than those in Groups 1 or 2. There were no significant differences between the treatment groups for numbers of S. aureus recovered from blood in the 3h period following challenge. Histological and bacteriological evidence showed that the kidneys were more severely affected by the challenge inoculum than heart, spleen, liver or lungs. The kidneys showed both toxigenic and lymphoreticular reactions and large numbers of staphylococci were recovered more reliably from kidneys than other organs.  相似文献   

11.
Weaned Dorper lambs on natural pasture were predosed with 40 000 infective larvae (L3) of Trichostrongylus axei, irradiated (0,3 kGy) L3 of T. axei or closantel at 10 mg/kg either in September or November 1978 and were compared with Merino yearlings predosed with 40 000 L3 of T. axei in November 1977. The following summer (December-March) only 178,6 mm of rain fell and very few H. contortus were present on pastures. Artificial challenge with 20 000 L3 of Haemonchus contortus with the local strain from the University of Pretoria's experimental farm was given 6-7 months after predosing with T. axei. When compared with the controls, significant reductions occurred only in Group 11 (T. axei irradiated at 0,3 kGy on Day +63) (P = 0,025); Group 2 (T. axei on Day 0) (P = 0,003) and Group 4 (T. axei and closantel on Day 0) (P = 0,049). We concluded that predosing with T. axei was unsuccessful in Dorpers and Merinos artificially challenged 6-7 months later with H. contortus.  相似文献   

12.
The clinical course of the primary experimental Fasciola gigantica infection was investigated in riverine buffalo calves of the Murrah breed. Nine male calves aged 12-15 months were randomly assigned to two groups of five (Group I) and four (Group II) animals. Each animal in Group I, was orally infected with 1000 metacercariae (mc) of F. gigantica, whereas Group II animals did not receive any infection dose and served as uninfected controls. No clinical signs of fasciolosis were observed until the sixth week post-infection (PI). Group I animals, however, developed recognised symptoms of acute fasciolosis, comprising apyrexic inappetance, anemia, poor weight gain, diarrhoea and sub-mandibular and facial oedema, respectively, from 5, 6, 8, 16 and 17 weeks PI. The signs were intermittent in nature and of variable duration. The prepatent period was of 92-97 days (mean 95.2 +/- 3.1). One of the five infected animals died on Day 147 PI. At necropsy, 36.8 +/- 11.0% of the infection dose was recovered as adult fluke population. The gross lesions were primarily biliary in nature. Group II, the uninfected controls, throughout the study period of 165 days PI, did not show any symptom and were negative for F. gigantica. The study demonstrated that the onset of adverse effects of F. gigantica on the growth and health of the infected host was mainly noted during late prepatency much before coprological prediction and diagnosis. The significance of preventive therapy against fasciolosis during prepatency has been stressed in endemic areas.  相似文献   

13.
The aim of this study was to compare the immune responses to live Neospora caninum tachyzoites and N. caninum native antigens formulated with immune stimulating complexes matrix (ISCOM-matrix) in calves. Fifteen calves were used in this study: 3 were intravenously inoculated with 1 × 10(8) live tachyzoites (Group A), 3 were inoculated twice with N. caninum native antigens formulated with ISCOMs (Group B); 3 with N. caninum native antigens in phosphate-buffered saline (PBS) (Group C); 3 received ISCOM-matrix (ISCOMs without antigen) (Group D) and 3 were negative controls receiving PBS (Group E). The last four groups were inoculated subcutaneously. The specific total IgG and its subtypes were analyzed by an indirect enzyme-linked immunosorbent assays (ELISAs) and by Western blot. IFN-γ levels in plasma was quantified using a commercial kit. All calves were challenged intravenously with 1 × 10(8) live tachyzoites at week 11 after receiving the first dose. Parasitemia was assessed in plasma samples by semi-nested PCR. Neospora-specific antibodies were detected in animals from Groups A and B in the week 2 after inoculation. The ELISA OD values were higher in Group B compared with Group A from weeks 6 to 11 (P<0.05). Analysis of the subisotype specific antibodies in experimentally infected calves revealed a predominant IgG(2) response; however, a predominant IgG(1) response was observed in animals inoculated with N. caninum native antigens formulated with ISCOM-matrix. Control calves remained seronegative until challenge infection. The pattern of bands by Western blot was similar when testing sera from animals in Groups A and B. The levels of IFN-γ production after respective immunization schedules were similar between Groups A and B. Neospora-DNA was detected in plasma samples shortly after intravenous challenge in calves from all groups including those receiving the experimental vaccine formulation. The duration of the parasitemia was similar in all groups.  相似文献   

14.
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   

15.
The present study was conducted to examine how the social cue emanating from rams, the ram-effect, would influence the onset of melatonin-induced reproductive activity in anestrous ewes. Twenty non-lactating ewes were randomly allocated into 4 groups as follows based on a combination of the melatonin treatment (MEL) and the ram-effect (RAM): ewes of Groups A (MEL + RAM) and B (MEL) were subcutaneously implanted with melatonin capsules on April 18 (Day 0), which increased plasma melatonin levels by about 200 pg/ml for at least 5 months, while Groups C (RAM) and D (control) were untreated with melatonin. Rams were introduced to Groups A and C on Day 0, whereas Groups B and D were isolated from rams. Ovarian function of the ewe was assessed on June 9-21 (Days 52-64) by monitoring plasma progesterone (P) profiles. Luteal function (plasma P greater than 1 ng/ml for a week or longer) was evident in all the melatonin-treated ewes but only one in those untreated: 5/5 in Group A, 5/5 in Group B, 1/5 in Group C and 0/5 in Group D. By ultrasonography on Day 105 all the Group A ewes were diagnosed pregnant but none in the Group C despite that both the two groups had been run with rams. These results indicate that chronic melatonin treatment is capable of advancing the reproductive recrudescence in seasonally anestrous ewes, and that progonadal effects of rams are subtle, if any, during the mid-anestrous period.  相似文献   

16.
Thirty-five castrate or intact Holstein male calves, ranging in weight from 122 to 210kg, were used in the study. On study Days -15 and -14, all study calves were treated with fenbendazole 10% paste at 10mg/kg to remove existing nematode infections. All cattle had zero egg counts on Day -1. Experimental infections of a mixed species inoculum were administered to all calves on Day 0. The inoculum consisted of Cooperia spp. (primarily C. punctata, but also C. pectinata, C. spatulata, C. oncophora and C. surnabada-total 40,961); Ostertagia ostertagi-1550; Trichostrongylus colubriformis-4996; and Oesophagostomum radiatum-38. Necropsy results from two of three monitor calves slaughtered on Day 6 after infection indicated that Day 6 was an appropriate time to evaluate efficacy of moxidectin against fourth larval stages (L(4)). The remaining 32 calves were randomly allotted to four groups of eight based on body weights. Eight calves (Group 1) were treated with moxidectin 0.5% pour-on at 0.5mg/kg on Day 6 to evaluate efficacy against nematode larval stages; eight control calves (Group 2) were matched with these principals. Eight calves (Group 3) were also treated with moxidectin pour-on at the same dosage on Day 23 in order to determine efficacy against adult nematodes; eight control calves (Group 4) were matched with these principals. In both cases, principals and controls of the Days 6 and 23 treatments were necropsied at 14-15 days after treatment. C. punctata was the only species found in a sufficient number of controls to evaluate moxidectin efficacy against the L(4). Moxidectin pour-on was not effective (P<0.05) against C. punctata L(4) by arithmetic means, but was highly effective based on geometric means. Regardless of whether arithmetic or geometric means were used for percent efficacy calculations, moxidectin pour-on was demonstrated to be highly effective (>99%) against the adult stages of C. oncophora, C. punctata, C. spatulata, C. surnabada, Cooperia spp. adult females and T. colubriformis adults.  相似文献   

17.
Two controlled tests were conducted in equine foals and yearlings to determine the optimal oral dosage and the duration of activity of closantel for the prevention of Gasterophilus spp larval infections. Additional data were collected on the activity of closantel against Strongylus vulgaris larval infections. In experiment 1, 12 foals and 12 yearlings were equally allocated to 4 experimental groups, and were given oral treatments with closantel at dosages of 0 (nontreated controls), 2, 5, or 8 mg/kg of body weight every 2 months during bot season. The foals and yearlings were allowed to graze on open pasture throughout the experiment to provide a natural source for bot and helminth infections. All animals were euthanatized and necropsied 6 weeks after the final treatment. Closantel was highly effective (98.6% to 100%) at all doses in preventing Gasterophilus spp larval infections in the foals, but only the 8 mg/kg dose had significant (P less than 0.05) activity (99.7%) in the yearlings. This dose also significantly reduced the numbers of 4th-stage and immature adult S vulgaris (86.0%) in the mesenteric arteries as compared with nontreated controls. In experiment 2, 9 foals and 9 yearlings received a single oral treatment of 8 mg of closantel/kg of body weight; 3 foals and 3 yearlings were kept as nontreated controls. Groups of 6 treated (3 foals, 3 yearlings) and 2 control (1 foal, 1 yearling) animals were euthanatized and necropsied 1, 2, and 3 months after treatment. Closantel remained effective for 2 months in preventing infections of G intestinalis larvae in these foals and yearlings. Clinical signs of toxicosis were not observed in the treated animals of either study.  相似文献   

18.
Killed Corynebacterium parvum was used as an adjuvant for the production of non-specific resistance against Theileria annulata in cattle. Groups of cross-bred (Bos indicus X Bos taurus) calves were administered C. parvum adjuvant subcutaneously and were then challenged with T. annulata-infected ticks on 45, 60 or 90 days later. The challenge caused mild reactions in the protected calves. None of the 10 immunized calves died due to theileriosis, whereas all three paris of susceptible control calves died due to theileriosis. It appears from this pilot study that cattle can be protected non-specifically with C parvum adjuvant against T. annulata.  相似文献   

19.
Three groups of five parasite-naive calves were used. The treatments were: (a) Group 1 calves were weighed on Day 0 and injected with doramectin at 200 microg/kg. From Day 1 to 19 they were dosed orally with 2000 infective larvae of Dictyocaulus viviparus. On Day 28 they were again injected with doramectin, and infected with D. viviparus larvae from Days 33 to 41. They were then left untreated until Day 81 when they were infected with 20 infective larvae of D. viviparus per kg body weight. They were killed on Day 110 and lungworms were counted; (b) Group 2 calves were immunised with oral lungworm vaccine on Days 0 and 28, and infected and slaughtered as Group 1 on Days 81 and 110, respectively; (c) Group 3 calves acted as infection controls. Blood samples were taken at Days 0, 21, 49, 77 and 110 for antibody tests to D. viviparus. At autopsy there were no significant differences between the number of lungworms from Groups 1 and 2 (Means 17.4 and 31.3, respectively); Group 1 had significantly less value than Group 3 (Mean 228) (p < 0.05). Increased antibody titres to the larval sheath of the infective larvae were observed from Groups 1 and 2, showing that the larvae in Group 1 had penetrated the intestine before being killed by the circulating anthelmintic. This experiment shows that if calves are exposed to infective larvae while under systemic endectocide cover, an immune reaction is stimulated.  相似文献   

20.
Parvaquone (BW993C), 2-cyclohexyl-3-hydroxy-1,4-naphthoquinone, and buparvaquone (BW720C) 2-(trans-4-t-butylcyclohexyl-methyl)-3-hydroxy-1,4-naphthoquinone, were evaluated to determine their therapeutic efficacy in the treatment of theileriosis caused by Theileria annulata infection in cattle in Iran. One hundred and fifty-nine pure and crossbred Bos taurus cattle, experimentally or naturally infected with T annulata, were treated. Parvaquone was injected into 86 animals with up to three doses of 20 mg kg-1 or 10 mg kg-1 at intervals of 48 hours between doses. Buparvaquone was injected into 73 animals. Up to three doses of 2.5 mg kg-1 were injected with an interval of 48 hours between doses. The recovery rate of animals treated with parvaquone was 60.7 per cent and with buparvaquone it was 88.7 per cent. No significant side effects of relapse of disease were observed following the use of either compound. It is concluded that buparvaquone at a dose of 2.5 mg kg-1 has a satisfactory therapeutic index and is a more effective treatment of T annulata infection than parvaquone. The prophylactic use of schizont tissue culture vaccine and chemotherapy with buparvaquone could be the most promising means of controlling theileriosis in Iran.  相似文献   

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