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1.
Bovine herpesvirus type 1 (BHV-1) is an important bovine pathogen, exacerbating poor health and the productivity of cattle. The aims of this study were to detect the efficacy of vaccination programmes in lowering the seroprevalence of BHV-1 gE within the dairy herd and to follow the dynamics of the infection in non-vaccinated herds with uninfected heifers. A two-year longitudinal study was carried out on seven herds that were vaccinated, and in five herds with uninfected heifers without applying a control programme. After the start of the vaccination programme, calves born remained free from the virus. However, in one herd, 7 per cent (95 per cent CI 2 to 18) of these animals showed antibodies to BHV-1 two years after the first vaccination. A decline in BHV-1 antibody prevalence was found in vaccinating herds. Among the five herds not under the control programme, one experienced active virus spread, although one herd experienced self-clearance of the virus. In the herds with high BHV-1 prevalence, vaccinating all cattle from three months of age twice a year with a commercial inactivated marker vaccine efficiently protected offspring from becoming infected, and lowered the prevalence of BHV-1 within the herd. A small proportion of herds may experience self-clearance of the virus.  相似文献   

2.
OBJECTIVE: To evaluate the efficacy of a commercially available killed bovine viral diarrhea virus (BVDV) vaccine to protect against fetal infection in pregnant cattle continually exposed to cattle persistently infected with the BVDV. ANIMALS: 60 crossbred beef heifers and 4 cows persistently infected with BVDV. PROCEDURES: Beef heifers were allocated to 2 groups. One group was vaccinated twice (21-day interval between the initial and booster vaccinations) with a commercially available vaccine against BVDV, and the other group served as nonvaccinated control cattle. Estrus was induced, and the heifers were bred. Pregnancy was confirmed by transrectal palpation. Four cows persistently infected with BVDV were housed with 30 pregnant heifers (15 each from the vaccinated and nonvaccinated groups) from day 52 to 150 of gestation. Fetuses were then harvested by cesarean section and tested for evidence of BVDV infection. RESULTS: 1 control heifer aborted after introduction of the persistently infected cows. Bovine viral diarrhea virus was isolated from 14 of 14 fetuses obtained via cesarean section from control heifers but from only 4 of 15 fetuses obtained via cesarean section from vaccinated heifers; these proportions differed significantly. CONCLUSIONS AND CLINICAL RELEVANCE: A commercially available multivalent vaccine containing an inactivated BVDV fraction significantly reduced the risk of fetal infection with BVDV in heifers continually exposed to cattle persistently infected with BVDV. However, not all vaccinated cattle were protected, which emphasizes the need for biosecurity measures and elimination of cattle persistently infected with BVDV in addition to vaccination within a herd.  相似文献   

3.
A study of the safety of a vaccine against lungworm was carried out with pregnant and lactating heifers from three dairy herds with a previous history of lungworm outbreaks in adult cows. Half of the heifers were vaccinated while the other half were not. A slight temporary cough following the vaccination was only observed in one herd. No adverse effects on pregnancy or milk production were seen. All heifers were serologically and coprologically examined before the first, before and after the second immunization, 3 months after introduction to pasture and at the end of the grazing season. Serological and faecal examination of the dairy cows before introduction into pasture confirmed the presence of at least one Dictyocaulus viviparus carrier in each herd. Lungworm infection occurred in all herds during the grazing season, most prominently in the herd with the highest number of heifers. In this herd, mild coughing associated with the lungworm infection was noticed, especially in the non vaccinated heifers. No other signs or symptoms were observed. It is concluded that a vaccine against D. viviparus can be used safely in heifers, before they are introduced into the adult herd, and that this vaccine can be used as a preventive measure against lungworm outbreaks in adult cattle.  相似文献   

4.
Following the first diagnosis of campylobacteriosis in Jamaican cattle a field study was undertaken to determine the pathogenicity of Campylobacter fetus subspecies venerealis Jam (Jamaican strain) and to evaluate the effectiveness of vaccination in controlling the disease. A total of 46 nonpregnant yearling heifers and four two-year-old bulls were used in two separate experiments. The results showed that C fetus subspecies venerealis Jam readily colonised the reproductive tract of susceptible heifers and persisted in some animals (68 per cent of unvaccinated and 33 per cent of vaccinated animals) for the duration of the experiment. Pregnancy was confirmed in 13 of 18 (72 per cent) culture-negative heifers but in only eight of 28 (29 per cent) of the heifers with two or more positive cultures. Vaccination appeared to be curative because 44 per cent of vaccinated heifers were cleared of infection whereas 85 per cent of unvaccinated, inoculated heifers remained infected for at least 17 weeks. Vaccination improved the fertility level of the infected heifers threefold. Infection was not established in vaccinated bulls used for breeding infected heifers.  相似文献   

5.
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6.
Between 2007 and 2009, the largest human Q fever epidemic ever described occurred in the Netherlands. The source was traced back to dairy goat farms, where abortion storms had been observed since 2005. Since one putative cause of these abortion storms is the intensive husbandry systems in which the goats are kept, the objective of this study was to assess whether these could be explained by herd size, reproductive pattern and other demographic aspects of Dutch dairy goat herds alone. We adapted an existing, fully parameterized simulation model for Q fever transmission in French dairy cattle herds to represent the demographics typical for Dutch dairy goat herds. The original model represents the infection dynamics in a herd of 50 dairy cows after introduction of a single infected animal; the adapted model has 770 dairy goats. For a full comparison, herds of 770 cows and 50 goats were also modeled. The effects of herd size and goat versus cattle demographics on the probability of and time to extinction of the infection, environmental bacterial load and abortion rate were studied by simulation. The abortion storms could not be fully explained by demographics alone. Adequate data were lacking at the moment to attribute the difference to characteristics of the pathogen, host, within-herd environment, or a combination thereof. The probability of extinction was higher in goat herds than in cattle herds of the same size. The environmental contamination was highest within cattle herds, which may be taken into account when enlarging cattle farming systems.  相似文献   

7.
Abortion, premature calving, hemolytic anemia and fatal hematuria were associated with high levels (titer > 10(-4)) of antibody to Leptospira interrogans serovar hardjo and with isolation of hardjo in a herd of 265 beef cattle in the Great Clay Belt of northern Ontario. This herd was bred by artificial insemination, after heat detection by vasectomized bulls. The antibody prevalence rate in the herd was 54 to 60% over a five year period. The rate tended to reach 100% by age three years and to be below 5% in yearlings, which were raised in isolation from older cattle. Hardjo was isolated from the urine of a cow that aborted in the eighth month of pregnancy, and from kidneys of yearling steers which had been exposed to an older cow. Maternal antibody levels in calves paralleled those in their dams, protecting calves while they were being naturally exposed to infection, thus contributing to the achievement of balance between host and parasite. A controlled vaccination trial was conducted in 50 initially seronegative yearling steers and heifers. Serological response to vaccine was limited to a maximum agglutinin titer of 10(-2) in 8% of vaccinated cattle. Vaccination reduced the infection rate from 86% in the controls to 46% in the treated group, indirectly reducing the number of calves for which colostral antibody against hardjo would be available. A vaccination program was not implemented in the herd. Hardjo infection appeared to die out over a period of six years following the initial five year study period, with antibody prevalence falling from 60% to 0.7% and reactors persisting only in two eight year old cows. Decline in infection was coincident with changes in management which protected heifers from exposure to infection until their third pregnancy, and which probably lowered the reservoir of infection by increased culling from older age classes.  相似文献   

8.
OBJECTIVE: To determine whether serologic evaluation of 5 unvaccinated 6- to 12-month-old heifers is a valid method for identifying herds that contain cattle persistently infected (PI) with bovine viral diarrhea virus (BVDV). ANIMALS: 14 dairy herds with a history of BVDV infection, with health problems consistent with BVDV infection, or at risk for contracting BVDV infection. PROCEDURE: 5 unvaccinated 6- to 12-month-old heifers were randomly selected from each herd. Neutralizing antibody titers for type-I and -II BVDV were determined. A herd was classified as likely to contain PI cattle when at least 3/5 heifers had antibody titers > or = 128. Virus isolation was performed on all cattle to identify PI cattle. Genotype of isolated viruses was determined by nested multiplex polymerase chain reaction. RESULTS: 6 of 14 herds contained PI cattle. Sensitivity and specificity of serologic evaluation of 5 heifers for identifying these herds were 66 and 100%, respectively. In herds that contained PI cattle, the predominant BVDV titer in the tested heifers corresponded to the genotype of the isolated virus. CONCLUSIONS AND CLINICAL RELEVANCE: Serologic evaluation of unvaccinated 6- to 12- month-old heifers is an accurate method for identifying herds containing PI cattle. Both type-I and -II BVDV antibody titers should be determined to prevent herd misclassification. The genotype of BVDV found in PI cattle can be predicted by the predominant neutralizing antibody titers found in tested heifers. Serologic evaluation of 5 unvaccinated heifers can be used to determine whether a herd is likely to contain PI cattle.  相似文献   

9.
The effectiveness of the vaccination of dairy cows combined or not with antibiotics (i.e. oxytetracycline) to control Coxiella burnetii (Cb) shedding at herd level was investigated in 77 Q fever clinically affected herds. In addition to nulliparous heifers’ vaccination, one out of the four following medical strategies was randomly assigned to dairy cows in each herd: vaccination (using a phase I vaccine) alone, vaccination combined with oxytetracycline, oxytetracycline alone or nothing. Their effectiveness to reduce Cb load in quarterly samples of bulk tank milk (BTM) and of pooled milk of primiparous (MP) was assessed through logistic hierarchical models. A significant reduction in Cb load was observed in herds where the vaccination of ≥80% of dairy cows was implemented; whereas the use of antibiotics was uneffective. Our findings support the interest of a whole vaccination strategy and provide evidence for decreasing the use of antibiotics in dairy cattle herds.  相似文献   

10.
Monthly incidence rates for the detection of bovine leukemia virus (BLV) infection were calculated for a 15-month period for cattle over 12 months of age in a 200-cow dairy herd. Detection of BLV infection was based on the presence of persisting antibodies as measured by agar-gel immunodiffusion using the glycoprotein-51 antigen. A non-parametric procedure was used to examine 6-month trends in cumulative monthly incidence rates. Over the 15-month study, 25 heifers were detected as becoming infected with BLV after 12 months of age. No differences were found between the 12 monthly incidence rates (p = 0.77). Cumulative incidence rates between June and September (the fly season) were not higher than those for any other 6-month period (p = 0.29). Similarly, there was no evidence that BLV infection was transmitted during artificial insemination (p = 0.18) or during routine vaccination procedures (p = 1.0). Cumulative rates for a period corresponding to exposure of heifers to the dry herd were excessively high (p = 0.01). These findings suggest that transmission of BLV infection in the cattle studied was associated with close physical contact between susceptible and infected cattle, and not with biting flies, artificial insemination, or vaccination procedures.  相似文献   

11.
Effectiveness of 2 concentrations of a monovalent vaccine containing Leptospira interrogans serovar hardjo type hardjo-bovis was evaluated for protection of heifers from infection with type hardjo-bovis. Nine heifers were given 2 doses of low-dose vaccine (8.32 x 10(8) cells/dose); 9 heifers were given 2 doses of high-dose vaccine (8.32 x 10(9) cells/dose); and 1 steer and 1 heifer were maintained as nonvaccinated controls. Groups of vaccinated cattle were challenge-exposed with serovar hardjo type hardjo-bovis at 7 (n = 6), 11 (n = 6), or 15 (n = 6) weeks after completion of vaccination. All cattle were challenge-exposed by conjunctival instillation of 1 x 10(5) hardjo-bovis cells on 3 consecutive days. Both control and all vaccinated cattle became infected and shed serovar hardjo type hardjo-bovis in their urine. Leptospires were detected in 15 of 16 (94%) urine samples from control cattle and in 124 of 143 (87%) samples from vaccinated cattle. Leptospires were detected in kidneys of 17 of 18 vaccinated cattle and 2 of 2 control cattle and in the uterus or oviducts of 13 of 18 vaccinates and the 1 control heifer.  相似文献   

12.
A three-year study of Salmonella dublin infection in a closed dairy herd   总被引：3，自引：0，他引：3  
Over a period of three years, Salmonella dublin was isolated occasionally from the faeces of nine adult cattle in a closed dairy herd. The organism was also isolated from 12 of the samples collected after parturition; isolations were made from newborn calves on 11 occasions, from a vaginal swab once and from a milk sample once. Nine of the isolations from the calves were made from swabs obtained within 24 hours of birth. Throughout the investigation isolations were made from heifers, steers and older calves and 11 infected animals were detected. S. dublin was widespread in the farm environment and it was concluded that environmental contamination was an important source of infection for animals of all ages, some of which may have become latent carriers. The family history of one cow, seven of whose offspring were infected with S dublin, suggested the possibility of vertical transmission. Without reliable tests to detect latent carriers, it is suggested that control of this infection must be based on improved hygiene and the use of vaccination to improve the immunity of the herd.  相似文献   

13.
Objective-To determine whether administration of 2 doses of a multivalent, modified-live virus vaccine prior to breeding of heifers would provide protection against abortion and fetal infection following exposure of pregnant heifers to cattle persistently infected (PI) with bovine viral diarrhea virus (BVDV) and cattle with acute bovine herpesvirus 1 (BHV1) infection. Design-Randomized controlled clinical trial. Animals-33 crossbred beef heifers, 3 steers, 6 bulls, and 25 calves. Procedures-20 of 22 vaccinated and 10 of 11 unvaccinated heifers became pregnant and were commingled with 3 steers PI with BVDV type 1a, 1b, or 2 for 56 days beginning 102 days after the second vaccination (administered 30 days after the first vaccination). Eighty days following removal of BVDV-PI steers, heifers were commingled with 3 bulls with acute BHV1 infection for 14 days. Results-After BVDV exposure, 1 fetus (not evaluated) was aborted by a vaccinated heifer; BVDV was detected in 0 of 19 calves from vaccinated heifers and in all 4 fetuses (aborted after BHV1 exposure) and 6 calves from unvaccinated heifers. Bovine herpesvirus 1 was not detected in any fetus or calf and associated fetal membranes in either treatment group. Vaccinated heifers had longer gestation periods and calves with greater birth weights, weaning weights, average daily gains, and market value at weaning, compared with those for calves born to unvaccinated heifers. Conclusions and Clinical Relevance-Prebreeding administration of a modified-live virus vaccine to heifers resulted in fewer abortions and BVDV-PI offspring and improved growth and increased market value of weaned calves.  相似文献   

14.
Leptospirosis is a zoonosis, found worldwide, affecting many species of animals. We conducted a cross-sectional study to estimate the prevalence of Leptospira borgpetersenii sv Hardjo and Leptospira interrogans sv Pomona in cattle in dairy herds in South-Western Victoria, Australia. Fifty-three herds were enrolled in the study. Urine samples were collected from 15 late-lactation cows in each herd. A questionnaire was provided to herd managers at the time of each herd visit, asking them to describe the methods they used for controlling leptospirosis, including vaccination. Urine samples were pooled at the herd level and tested for leptospira spp. using real time PCR. Urine samples from individual cows within the positive pooled samples were then tested for Leptospira Hardjo and Leptospira Pomona using qPCR. Four of the 53 herds showed positive leptospirosis results giving an apparent prevalence of 8 (95% CI 2–18) leptospira-positive herds per 100 herds at risk. Based on the 53 completed questionnaires, leptospirosis vaccination programs were not compliant with label directions in 36 of the 52 vaccinated herds: 69 (95% CI 55–81) of 100 herd managers that routinely vaccinated for leptospirosis did not comply with label directions. One herd was completely unvaccinated. Based on our findings, we estimate that approximately 10% of dairy farms in South-Western Victoria are likely to be infected with leptospirosis. While most herds are vaccinating for leptospirosis, most are not doing so according to label directions. We conclude that herd managers need to be better educated regarding leptospirosis vaccination programs.  相似文献   

15.
An account is given of an outbreak of malignant catarrhal fever which occurred in a 98-cow dairy herd. Ten animals died or were slaughtered and the disease was confirmed by clinical and histological examination. Serological tests for malignant catarrhal fever virus were positive in three of four animals. The diagnosis of malignant catarrhal fever was complicated by the presence of bovine virus diarrhoea virus infection in three of the early cases. The initial cases of malignant catarrhal fever occurred in a group of nine-month-old calves which were housed in an old milking parlour with 19 pedigree Suffolk ewes at lambing time. Later cases occurred in two adult cows and in two heifers. Investigations of the remainder of the herd for evidence of bovine virus diarrhoea virus did not reveal the presence of any persistently infected cattle. Serological examinations for antibody to malignant catarrhal fever and bovine virus diarrhoea virus were carried out on the 19 Suffolk ewes. Six of them had neutralising antibody titres to malignant catarrhal fever virus and three were positive in the indirect immunofluorescence test. The possible roles of bovine virus  相似文献   

16.
Models have been developed to represent the spread of bovine viral diarrhoea virus (BVDV) in cattle herds. Whereas the herd dynamics is well known, biological data are missing to estimate the parameters of the infection process. Our objective was to identify the parameters of the infection process that highly influence the spread of BVDV in a dairy herd. A stochastic compartmental model in discrete time represented BVDV infection in a typical Holstein dairy herd structured into five groups (calves, young versus older heifers, lactating versus dry cows). Model sensitivity was analysed for variations in the probability of birth of persistently infected (P) calves (b(P)), mortality of P animals (m(P)), within- and between-group transmission rates for P and transiently infected (T) animals (respectively, beta(w)(P),beta(b)(P),beta(w)(T),beta(b)(T)). Three to five values were tested per parameter. All possible combinations of parameter values were explored, representing 3840 scenarios with 200 runs for each. Outputs were: virus persistence 1 year after introduction, time needed to reach a probability of 80% for the herd to be virus-free, epidemic size, mean numbers of immune dams carrying a P foetus, of P and of T animals in infected herds. When considered together, m(P) and beta(b)(P) accounted for 40-80% of variance of all outputs; b(P) and beta(w)(T) accounted each for less than 20% of variance; beta(b)(T) and beta(w)(P) accounted for almost no percent of variance of the outputs. Parameters beta(w)(T) and b(P) needed to be more precisely estimated. The influence of m(P) indicated the effectiveness of culling P calves, the influence of beta(b)(P) indicated the role of the herd structure in BVDV spread, whereas the influence of b(P) indicated the possible role of vaccination programs in controlling within-herd BVDV spread.  相似文献   

17.
In the demand for a decision support tool to guide farmers wanting to control Salmonella Dublin (S. Dublin) in Danish dairy herds, we developed an age-structured stochastic, mechanistic and dynamic simulation model of S. Dublin in dairy herds, which incorporated six age groups (neonatal, preweaned calves, weaned calves, growing heifers, breeding heifers and cows) and five infection states (susceptible, acutely infected, carrier, super shedder and resistant). The model simulated population and infection dynamics over a period of 10 years in weekly time steps as: 1) population sizes of each of the six age-groups; 2) S. Dublin incidence and number of animals in each infection state; and 3) S. Dublin related morbidity and mortality in the acutely infected animals. The effects of introducing one infectious heifer on the risk of spread of S. Dublin within the herd and on the duration of infection were estimated through 1000 simulation iterations for 48 scenarios. The scenarios covered all combinations of three herd sizes (70, 200 and 400 cows), four hygiene levels indicating infectious contact parameters, and four herd susceptibility levels indicating different susceptibility parameters for the individual animals in each of the six age groups in the herd. The hygiene level was highly influential on the probability that the infection spread within the herd, duration of infection and epidemic size. The herd susceptibility level was also influential, but not likely to provide sufficient prevention and control of infection on its own. Herd size did not affect the probability of infection spread upon exposure, but the larger the herd the more important were management and housing practices that improve hygiene and reduce susceptibility to shorten durations of infection in the herd and to increase the probability of extinction. In general, disease and mortality patterns followed epidemic waves in the herds. However, an interesting pattern was seen for acute infections and abortions in adult cattle after the first 2 years of infection in herds with poor hygiene and high susceptibility. Repeated infections in young stock lead to a high proportion of resistant adult cattle, which lead to a dampening effect on acute infections in adults and associated abortions. Sensitivity analyses of 24 alternative scenarios showed that a super shedder state was not essential to mimic the infection dynamics and persistence patterns known from field studies, but a persistent carrier state was required in the model to mimic real life S. Dublin infections.  相似文献   

18.
Data from 42,224 cattle from 694 herds collected during the brucellosis eradication campaign were used to examine the effects of calfhood strain 19 vaccination. The prevalence of infection in vaccinated herds was 1.8% compared with 9.1% in non-vaccinated herds (p< 0.005). The mean titre in the former group was lower (p< 0.001). Vaccinated herds required 3.3 herd tests to achieve a provisionally free status compared with 4.8 in non-vaccinated herds (0.001 < p < 0.005). Vaccination did not significantly reduce the number of herd tests in herds with less than 100 breeding females. In tests after the initial herd test only 0.5% reactors were found in vaccinated herds compared with 6.9% in non-vaccinated herds (p< 0.005). There were 0.9% false positive to the Rose Bengal plate test in non-vaccinated and 2.1% in vaccinated animals (p< 0.005) in non-infected herds. In infected herds this percentage was 3.0% and 4.2% respectively by (p< 0.05). In the non-infected herds there were 0.04% false positives to the complement fixation test out of 10,506 non-vaccinated cattle tested and 0.2% out of 24,734 vaccinated cattle.  相似文献   

19.
Two hundred and fifty dairy heifers were vaccinated at three to six months of age with an intranasal infectious bovine rhinotracheitis-parainfluenza-3 vaccine. Eighteen additional heifers were tested prior to vaccination and again three to four weeks after vaccination. Neither cell-mediated nor humoral immunity was significantly raised to parainfluenza-3 virus in either group of cattle.  相似文献   

20.
A vaccination study was conducted in a herd of purebred Hereford cattle representing 4 selection (genetic) lines. For each of 2 years, half of the cattle were vaccinated with a pilus-enriched Moraxella bovis bacterin. Cows were vaccinated before parturition, and calves were vaccinated at 2 to 3 months of age. None of the cattle was vaccinated for 1 year preceding and 1 year after the 2 years in which cattle were vaccinated. There was a significantly (P less than 0.05) lower percentage of infectious bovine keratoconjunctivitis (IBK) in calves during years cattle were vaccinated than during years cattle were not vaccinated. During years cattle were vaccinated, there were lower percentages of IBK in vaccinated calves when compared with the percentages of IBK in nonvaccinated calves. When calves were compared on the basis of selection lines, regardless of the vaccination group, there were consistent differences in the percentages that developed IBK. Although calves with pigmented and nonpigmented eyes (representing all 4 genetic lines) developed IBK, the genetic line of calves with the most pigmented eyes had the lowest (P less than 0.05) percentage of IBK. Also, across all genetic lines, there was less IBK in pigmented eyes than in nonpigmented eyes. Seemingly, vaccination of dams, before parturition, and young calves reduced the occurrence of severe IBK in a herd situation under natural exposure conditions. The resistance or susceptibility in cattle under good management may be influenced by genetic factors.  相似文献   

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